diff --git a/Makefile b/Makefile
index 1883aeb919a416a50da88dc169a737137a0e724a..1cb5ff0fd82c20755767af54ada3b066a03b96e3 100644
--- a/Makefile
+++ b/Makefile
@@ -839,6 +839,9 @@ KBUILD_CFLAGS += $(stackp-flags-y)
 KBUILD_RUSTFLAGS-$(CONFIG_WERROR) += -Dwarnings
 KBUILD_RUSTFLAGS += $(KBUILD_RUSTFLAGS-y)
 
+KBUILD_HOSTRUSTFLAGS-$(CONFIG_WERROR) += -Dwarnings
+KBUILD_HOSTRUSTFLAGS += $(KBUILD_HOSTRUSTFLAGS-y)
+
 ifdef CONFIG_FRAME_POINTER
 KBUILD_CFLAGS	+= -fno-omit-frame-pointer -fno-optimize-sibling-calls
 KBUILD_RUSTFLAGS += -Cforce-frame-pointers=y
@@ -1742,8 +1745,14 @@ PHONY += rustfmt rustfmtcheck
 rustfmt:
 	$(Q)find $(abs_srctree) -type f -name '*.rs' \
 		-o -path $(abs_srctree)/rust/alloc -prune \
+		-o -path $(abs_srctree)/rust/proc-macro2 -prune \
+		-o -path $(abs_srctree)/rust/quote -prune \
+		-o -path $(abs_srctree)/rust/syn -prune \
 		-o -path $(abs_objtree)/rust/test -prune \
 		| grep -Fv $(abs_srctree)/rust/alloc \
+		| grep -Fv $(abs_srctree)/rust/proc-macro2 \
+		| grep -Fv $(abs_srctree)/rust/quote \
+		| grep -Fv $(abs_srctree)/rust/syn \
 		| grep -Fv $(abs_objtree)/rust/test \
 		| grep -Fv generated \
 		| xargs $(RUSTFMT) $(rustfmt_flags)
diff --git a/rust/.gitignore b/rust/.gitignore
index d3829ffab80ba0dbadfb3c3e007c199c45c95775..e43e6fba6b96dbe57948550f3c069c19d24b0725 100644
--- a/rust/.gitignore
+++ b/rust/.gitignore
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
+*.rlib
 bindings_generated.rs
 bindings_helpers_generated.rs
 doctests_kernel_generated.rs
diff --git a/rust/Makefile b/rust/Makefile
index 4eae318f36ff7474d8c7c27c2d4beb28cfbfc4ab..8c47ecee06ef7327a69c495770afc0fbce024e49 100644
--- a/rust/Makefile
+++ b/rust/Makefile
@@ -11,6 +11,7 @@ always-$(CONFIG_RUST) += exports_core_generated.h
 obj-$(CONFIG_RUST) += helpers/helpers.o
 CFLAGS_REMOVE_helpers/helpers.o = -Wmissing-prototypes -Wmissing-declarations
 
+always-$(CONFIG_RUST) += libproc_macro2.rlib libquote.rlib libsyn.rlib
 always-$(CONFIG_RUST) += libmacros.so
 no-clean-files += libmacros.so
 
@@ -58,12 +59,61 @@ alloc-cfgs = \
     --cfg no_rc \
     --cfg no_sync
 
+proc_macro2-cfgs := \
+    --cfg 'feature="proc-macro"' \
+    --cfg wrap_proc_macro
+
+proc_macro2-skip_flags := \
+    -Wrust_2018_idioms \
+    -Wunreachable_pub
+
+proc_macro2-flags := \
+    -Amissing_docs \
+    $(proc_macro2-cfgs)
+
+quote-cfgs := \
+    --cfg 'feature="proc-macro"'
+
+quote-skip_flags := \
+    --edition=2021 \
+    -Wrust_2018_idioms
+
+quote-flags := \
+    --edition=2018 \
+    -Amissing_docs \
+    --extern proc_macro2 \
+    $(quote-cfgs)
+
+syn-cfgs := \
+    --cfg 'feature="clone-impls"' \
+    --cfg 'feature="derive"' \
+    --cfg 'feature="extra-traits"' \
+    --cfg 'feature="fold"' \
+    --cfg 'feature="full"' \
+    --cfg 'feature="parsing"' \
+    --cfg 'feature="printing"' \
+    --cfg 'feature="proc-macro"' \
+    --cfg 'feature="quote"' \
+    --cfg 'feature="visit"' \
+    --cfg 'feature="visit-mut"'
+
+syn-skip_flags := \
+    -Wrust_2018_idioms \
+    -Wunreachable_pub
+
+syn-flags := \
+    -Amissing_docs \
+    --extern proc_macro2 \
+    --extern quote \
+    $(syn-cfgs)
+
 quiet_cmd_rustdoc = RUSTDOC $(if $(rustdoc_host),H, ) $<
       cmd_rustdoc = \
 	OBJTREE=$(abspath $(objtree)) \
 	$(RUSTDOC) $(if $(rustdoc_host),$(rust_common_flags),$(rust_flags)) \
 		$(rustc_target_flags) -L$(objtree)/$(obj) \
 		-Zunstable-options --generate-link-to-definition \
+		--extern proc_macro2 --extern quote --extern syn \
 		--output $(rustdoc_output) \
 		--crate-name $(subst rustdoc-,,$@) \
 		$(if $(rustdoc_host),,--sysroot=/dev/null) \
@@ -125,8 +175,9 @@ rustdoc-kernel: $(src)/kernel/lib.rs rustdoc-core rustdoc-macros \
 quiet_cmd_rustc_test_library = RUSTC TL $<
       cmd_rustc_test_library = \
 	OBJTREE=$(abspath $(objtree)) \
-	$(RUSTC) $(rust_common_flags) \
-		@$(objtree)/include/generated/rustc_cfg $(rustc_target_flags) \
+	$(RUSTC) \
+		$(filter-out $(skip_flags),$(rust_common_flags) $(rustc_target_flags)) \
+		@$(objtree)/include/generated/rustc_cfg \
 		--crate-type $(if $(rustc_test_library_proc),proc-macro,rlib) \
 		--out-dir $(objtree)/$(obj)/test --cfg testlib \
 		-L$(objtree)/$(obj)/test \
@@ -135,9 +186,25 @@ quiet_cmd_rustc_test_library = RUSTC TL $<
 rusttestlib-build_error: $(src)/build_error.rs FORCE
 	+$(call if_changed,rustc_test_library)
 
-rusttestlib-macros: private rustc_target_flags = --extern proc_macro
+rusttestlib-proc_macro2: private skip_flags = $(proc_macro2-skip_flags)
+rusttestlib-proc_macro2: private rustc_target_flags = $(proc_macro2-flags)
+rusttestlib-proc_macro2: $(src)/proc-macro2/lib.rs rusttest-prepare FORCE
+	+$(call if_changed,rustc_test_library)
+
+rusttestlib-quote: private skip_flags = $(quote-skip_flags)
+rusttestlib-quote: private rustc_target_flags = $(quote-flags)
+rusttestlib-quote: $(src)/quote/lib.rs rusttestlib-proc_macro2 FORCE
+	+$(call if_changed,rustc_test_library)
+
+rusttestlib-syn: private skip_flags = $(syn-skip_flags)
+rusttestlib-syn: private rustc_target_flags = $(syn-flags)
+rusttestlib-syn: $(src)/syn/lib.rs rusttestlib-quote FORCE
+	+$(call if_changed,rustc_test_library)
+
+rusttestlib-macros: private rustc_target_flags = --extern proc_macro \
+    --extern proc_macro2 --extern quote --extern syn
 rusttestlib-macros: private rustc_test_library_proc = yes
-rusttestlib-macros: $(src)/macros/lib.rs FORCE
+rusttestlib-macros: $(src)/macros/lib.rs rusttestlib-syn FORCE
 	+$(call if_changed,rustc_test_library)
 
 rusttestlib-bindings: $(src)/bindings/lib.rs FORCE
@@ -192,9 +259,10 @@ quiet_cmd_rustc_test = RUSTC T  $<
 
 rusttest: rusttest-macros rusttest-kernel
 
-rusttest-macros: private rustc_target_flags = --extern proc_macro
+rusttest-macros: private rustc_target_flags = --extern proc_macro \
+    --extern proc_macro2 --extern quote --extern syn
 rusttest-macros: private rustdoc_test_target_flags = --crate-type proc-macro
-rusttest-macros: $(src)/macros/lib.rs FORCE
+rusttest-macros: $(src)/macros/lib.rs rusttestlib-syn FORCE
 	+$(call if_changed,rustc_test)
 	+$(call if_changed,rustdoc_test)
 
@@ -332,17 +400,46 @@ $(obj)/exports_bindings_generated.h: $(obj)/bindings.o FORCE
 $(obj)/exports_kernel_generated.h: $(obj)/kernel.o FORCE
 	$(call if_changed,exports)
 
+quiet_cmd_rustc_hostlibrary = $(RUSTC_OR_CLIPPY_QUIET) H $@
+      cmd_rustc_hostlibrary = \
+	$(if $(skip_clippy),$(RUSTC),$(RUSTC_OR_CLIPPY)) \
+		$(filter-out $(skip_flags),$(KBUILD_HOSTRUSTFLAGS) $(rustc_target_flags)) \
+		-Clinker-flavor=gcc -Clinker=$(HOSTCC) \
+		-Clink-args='$(call escsq,$(KBUILD_HOSTLDFLAGS))' \
+		--emit=dep-info=$(depfile) --emit=link=$@ --crate-type rlib \
+		--out-dir $(objtree)/$(obj) -L$(objtree)/$(obj) \
+		--crate-name $(patsubst lib%.rlib,%,$(notdir $@)) $<
+
+$(obj)/libproc_macro2.rlib: private skip_clippy = 1
+$(obj)/libproc_macro2.rlib: private skip_flags = $(proc_macro2-skip_flags)
+$(obj)/libproc_macro2.rlib: private rustc_target_flags = $(proc_macro2-flags)
+$(obj)/libproc_macro2.rlib: $(src)/proc-macro2/lib.rs FORCE
+	+$(call if_changed_dep,rustc_hostlibrary)
+
+$(obj)/libquote.rlib: private skip_clippy = 1
+$(obj)/libquote.rlib: private skip_flags = $(quote-skip_flags)
+$(obj)/libquote.rlib: private rustc_target_flags = $(quote-flags)
+$(obj)/libquote.rlib: $(src)/quote/lib.rs $(obj)/libproc_macro2.rlib FORCE
+	+$(call if_changed_dep,rustc_hostlibrary)
+
+$(obj)/libsyn.rlib: private skip_clippy = 1
+$(obj)/libsyn.rlib: private skip_flags = $(syn-skip_flags)
+$(obj)/libsyn.rlib: private rustc_target_flags = $(syn-flags)
+$(obj)/libsyn.rlib: $(src)/syn/lib.rs $(obj)/libquote.rlib FORCE
+	+$(call if_changed_dep,rustc_hostlibrary)
+
 quiet_cmd_rustc_procmacro = $(RUSTC_OR_CLIPPY_QUIET) P $@
       cmd_rustc_procmacro = \
-	$(RUSTC_OR_CLIPPY) $(rust_common_flags) \
+	$(RUSTC_OR_CLIPPY) $(KBUILD_HOSTRUSTFLAGS) \
 		-Clinker-flavor=gcc -Clinker=$(HOSTCC) \
 		-Clink-args='$(call escsq,$(KBUILD_HOSTLDFLAGS))' \
 		--emit=dep-info=$(depfile) --emit=link=$@ --extern proc_macro \
+		--extern proc_macro2 --extern quote --extern syn \
 		--crate-type proc-macro \
-		--crate-name $(patsubst lib%.so,%,$(notdir $@)) $<
+		-L$(objtree)/$(obj) --crate-name $(patsubst lib%.so,%,$(notdir $@)) $<
 
 # Procedural macros can only be used with the `rustc` that compiled it.
-$(obj)/libmacros.so: $(src)/macros/lib.rs FORCE
+$(obj)/libmacros.so: $(src)/macros/lib.rs $(obj)/libsyn.rlib FORCE
 	+$(call if_changed_dep,rustc_procmacro)
 
 quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L $@
@@ -360,7 +457,11 @@ quiet_cmd_rustc_library = $(if $(skip_clippy),RUSTC,$(RUSTC_OR_CLIPPY_QUIET)) L
 
 rust-analyzer:
 	$(Q)$(srctree)/scripts/generate_rust_analyzer.py \
-		--cfgs='core=$(core-cfgs)' --cfgs='alloc=$(alloc-cfgs)' \
+		--cfgs='core=$(call escsq,$(core-cfgs))' \
+		--cfgs='alloc=$(call escsq,$(alloc-cfgs))' \
+		--cfgs='proc_macro2=$(call escsq,$(proc_macro2-cfgs))' \
+		--cfgs='quote=$(call escsq,$(quote-cfgs))' \
+		--cfgs='syn=$(call escsq,$(syn-cfgs))' \
 		$(realpath $(srctree)) $(realpath $(objtree)) \
 		$(rustc_sysroot) $(RUST_LIB_SRC) $(KBUILD_EXTMOD) > \
 		$(if $(KBUILD_EXTMOD),$(extmod_prefix),$(objtree))/rust-project.json
diff --git a/rust/macros/lib.rs b/rust/macros/lib.rs
index a626b1145e5c4ff00692e9d4e11fdb93500db1a8..17f2365d2ca162e74bbc21b0c36d738a2d0960a1 100644
--- a/rust/macros/lib.rs
+++ b/rust/macros/lib.rs
@@ -19,6 +19,8 @@ mod zeroable;
 
 use proc_macro::TokenStream;
 
+use syn::parse_macro_input;
+
 /// Declares a kernel module.
 ///
 /// The `type` argument should be a type which implements the [`Module`]
@@ -175,8 +177,11 @@ pub fn module(ts: TokenStream) -> TokenStream {
 ///
 /// [`kernel::error::VTABLE_DEFAULT_ERROR`]: ../kernel/error/constant.VTABLE_DEFAULT_ERROR.html
 #[proc_macro_attribute]
-pub fn vtable(attr: TokenStream, ts: TokenStream) -> TokenStream {
-    vtable::vtable(attr, ts)
+pub fn vtable(attr: TokenStream, input: TokenStream) -> TokenStream {
+    parse_macro_input!(attr as syn::parse::Nothing);
+    vtable::vtable(parse_macro_input!(input))
+        .unwrap_or_else(|e| e.into_compile_error())
+        .into()
 }
 
 /// Concatenate two identifiers.
diff --git a/rust/macros/vtable.rs b/rust/macros/vtable.rs
index ee06044fcd4f35cdb40be79c16d9c5b5995841a5..5783c74f6f30766f098fa80cb10b96043cbdd673 100644
--- a/rust/macros/vtable.rs
+++ b/rust/macros/vtable.rs
@@ -1,96 +1,284 @@
 // SPDX-License-Identifier: GPL-2.0
 
-use proc_macro::{Delimiter, Group, TokenStream, TokenTree};
 use std::collections::HashSet;
-use std::fmt::Write;
-
-pub(crate) fn vtable(_attr: TokenStream, ts: TokenStream) -> TokenStream {
-    let mut tokens: Vec<_> = ts.into_iter().collect();
-
-    // Scan for the `trait` or `impl` keyword.
-    let is_trait = tokens
-        .iter()
-        .find_map(|token| match token {
-            TokenTree::Ident(ident) => match ident.to_string().as_str() {
-                "trait" => Some(true),
-                "impl" => Some(false),
-                _ => None,
-            },
-            _ => None,
-        })
-        .expect("#[vtable] attribute should only be applied to trait or impl block");
-
-    // Retrieve the main body. The main body should be the last token tree.
-    let body = match tokens.pop() {
-        Some(TokenTree::Group(group)) if group.delimiter() == Delimiter::Brace => group,
-        _ => panic!("cannot locate main body of trait or impl block"),
-    };
 
-    let mut body_it = body.stream().into_iter();
+use proc_macro2::{Ident, TokenStream, Span};
+use quote::ToTokens;
+use syn::{
+    parse_quote, Error, ImplItem, ImplItemConst, Item, ItemImpl, ItemTrait, Result, Token,
+    TraitItem, TraitItemConst, Visibility,
+};
+
+fn handle_trait(mut item: ItemTrait) -> Result<ItemTrait> {
     let mut functions = Vec::new();
     let mut consts = HashSet::new();
-    while let Some(token) = body_it.next() {
-        match token {
-            TokenTree::Ident(ident) if ident.to_string() == "fn" => {
-                let fn_name = match body_it.next() {
-                    Some(TokenTree::Ident(ident)) => ident.to_string(),
-                    // Possibly we've encountered a fn pointer type instead.
-                    _ => continue,
-                };
-                functions.push(fn_name);
+
+    let mut items = Vec::new();
+
+    for mut item in item.items.into_iter() {
+        match item {
+            TraitItem::Fn(ref fn_item) => {
+                functions.push(fn_item.sig.ident.clone());
             }
-            TokenTree::Ident(ident) if ident.to_string() == "const" => {
-                let const_name = match body_it.next() {
-                    Some(TokenTree::Ident(ident)) => ident.to_string(),
-                    // Possibly we've encountered an inline const block instead.
-                    _ => continue,
-                };
-                consts.insert(const_name);
+            TraitItem::Const(ref mut const_item) => {
+                consts.insert(const_item.ident.clone());
+
+                // Check for `#[unique]` constants, we have special treatment.
+                if const_item
+                    .attrs
+                    .iter()
+                    .any(|attr| attr.path().is_ident("unique"))
+                {
+                    // Remove the attribute.
+                    const_item
+                        .attrs
+                        .retain(|attr| !attr.path().is_ident("unique"));
+
+                    let syn::Type::Reference(syn::TypeReference {
+                        lifetime: Some(lifetime),
+                        mutability: None,
+                        elem: ty,
+                        ..
+                    }) = &const_item.ty
+                    else {
+                        Err(Error::new_spanned(
+                            &const_item.ty,
+                            "`#[unique]` item must have a `&'static` type",
+                        ))?
+                    };
+
+                    if lifetime.ident != "static" {
+                        Err(Error::new_spanned(
+                            &const_item.ty,
+                            "`#[unique]` item must have a `&'static` type",
+                        ))?
+                    }
+
+                    let Some((
+                        _,
+                        syn::Expr::Reference(syn::ExprReference {
+                            mutability: None,
+                            expr: default,
+                            ..
+                        }),
+                    )) = const_item.default.take()
+                    else {
+                        Err(Error::new_spanned(
+                            const_item,
+                            "`#[unique]` item must have a default value and it must be a reference",
+                        ))?
+                    };
+
+                    let gen_const_impl_name = Ident::new(
+                        &format!("{}_IMPL", const_item.ident.clone()),
+                        const_item.ident.span(),
+                    );
+                    let gen_const_use_unique_attr_name = Ident::new(
+                        &format!("{}_USE_UNIQUE_ATTR", const_item.ident.clone()),
+                        const_item.ident.span(),
+                    );
+
+                    items.push(parse_quote! {
+                         /// A marker to prevent implementors from forgetting to use `#[unique]`
+                         /// attribute when implementing this trait.
+                         const #gen_const_use_unique_attr_name: ();
+                    });
+                    items.push(parse_quote! {
+                        /// TODO
+                        const #gen_const_impl_name: #ty = #default;
+                    });
+                }
             }
-            _ => (),
+            _ => {}
         }
+        items.push(item);
     }
 
-    let mut const_items;
-    if is_trait {
-        const_items = "
-                /// A marker to prevent implementors from forgetting to use [`#[vtable]`](vtable)
-                /// attribute when implementing this trait.
-                const USE_VTABLE_ATTR: ();
-        "
-        .to_owned();
-
-        for f in functions {
-            let gen_const_name = format!("HAS_{}", f.to_uppercase());
-            // Skip if it's declared already -- this allows user override.
-            if consts.contains(&gen_const_name) {
-                continue;
-            }
-            // We don't know on the implementation-site whether a method is required or provided
-            // so we have to generate a const for all methods.
-            write!(
-                const_items,
-                "/// Indicates if the `{f}` method is overridden by the implementor.
-                const {gen_const_name}: bool = false;",
-            )
-            .unwrap();
-            consts.insert(gen_const_name);
+    items.push(parse_quote! {
+         /// A marker to prevent implementors from forgetting to use [`#[vtable]`](vtable)
+         /// attribute when implementing this trait.
+         const USE_VTABLE_ATTR: ();
+    });
+
+    for name in functions {
+        let gen_const_name = Ident::new(
+            &format!("HAS_{}", name.to_string().to_uppercase()),
+            name.span(),
+        );
+        // Skip if it's declared already -- this allows user override.
+        if consts.contains(&gen_const_name) {
+            continue;
         }
-    } else {
-        const_items = "const USE_VTABLE_ATTR: () = ();".to_owned();
+        // We don't know on the implementation-site whether a method is required or provided
+        // so we have to generate a const for all methods.
+        let comment = format!("Indicates if the `{name}` method is overridden by the implementor.");
+        items.push(parse_quote! {
+           #[doc = #comment]
+            const #gen_const_name: bool = false;
+        });
+        consts.insert(gen_const_name);
+    }
+
+    item.items = items;
+    Ok(item)
+}
+
+fn handle_impl(mut impl_: ItemImpl) -> Result<ItemImpl> {
+    // `#[vtable]` must be used on a trait impl.
+    let Some((_, trait_, _)) = &impl_.trait_ else {
+        Err(Error::new_spanned(
+            impl_,
+            "`#[vtable]` cannot be used on inherent impl",
+        ))?
+    };
+
+    let mut functions = Vec::new();
+    let mut consts = HashSet::new();
 
-        for f in functions {
-            let gen_const_name = format!("HAS_{}", f.to_uppercase());
-            if consts.contains(&gen_const_name) {
+    let mut items = Vec::new();
+
+    for mut item in impl_.items.into_iter() {
+        match item {
+            ImplItem::Fn(ref fn_item) => {
+                functions.push(fn_item.sig.ident.clone());
+            }
+            ImplItem::Const(ref mut const_item) => {
+                consts.insert(const_item.ident.clone());
+
+                // Check for `#[unique]` constants, we have special treatment.
+                if const_item
+                    .attrs
+                    .iter()
+                    .any(|attr| attr.path().is_ident("unique"))
+                {
+                    // If the item is parsed as const, it means it have a value (e.g.
+                    // `const NAME: Ty = value;` rather than `const NAME: Ty;`.
+                    //
+                    // Raise an error in this case.
+                    Err(Error::new_spanned(
+                        &const_item.expr,
+                        "`#[unique]` item must not have a value",
+                    ))?
+                }
+            }
+            ImplItem::Verbatim(item) => {
+                // `const NAME: Ty;` is not a valid impl item (but still accepted by the parser).
+                // Which cause it to be given to us as verbatim. Parse it as trait item instead.
+                let mut const_item: TraitItemConst = syn::parse2(item)?;
+
+                consts.insert(const_item.ident.clone());
+
+                // Check for `#[unique]` constants, we have special treatment.
+                if const_item
+                    .attrs
+                    .iter()
+                    .any(|attr| attr.path().is_ident("unique"))
+                {
+                    // Remove the attribute.
+                    const_item
+                        .attrs
+                        .retain(|attr| !attr.path().is_ident("unique"));
+
+                    let syn::Type::Reference(syn::TypeReference {
+                        lifetime: Some(lifetime),
+                        mutability: None,
+                        elem: ty,
+                        ..
+                    }) = &const_item.ty
+                    else {
+                        Err(Error::new_spanned(
+                            &const_item.ty,
+                            "`#[unique]` item must have a `&'static` type",
+                        ))?
+                    };
+
+                    if lifetime.ident != "static" {
+                        Err(Error::new_spanned(
+                            &const_item.ty,
+                            "`#[unique]` item must have a `&'static` type",
+                        ))?
+                    }
+
+                    let gen_const_impl_name = Ident::new(
+                        &format!("{}_IMPL", const_item.ident.clone()),
+                        const_item.ident.span(),
+                    );
+                    let gen_const_use_unique_attr_name = Ident::new(
+                        &format!("{}_USE_UNIQUE_ATTR", const_item.ident.clone()),
+                        const_item.ident.span(),
+                    );
+
+                    if !impl_.generics.params.is_empty() {
+                        return Err(Error::new_spanned(
+                            impl_.generics,
+                            "`#[unique]` cannot be used when impl is generic",
+                        ));
+                    }
+                    let self_ty = &impl_.self_ty;
+
+                    let expr = parse_quote! {{
+                        static IMPL: #ty = <#self_ty as #trait_>::#gen_const_impl_name;
+                        &IMPL
+                    }};
+
+                    // Turn the TraitItemConst to ImplItemConst.
+                    items.push(ImplItem::Const(ImplItemConst {
+                        attrs: const_item.attrs,
+                        vis: Visibility::Inherited,
+                        defaultness: None,
+                        const_token: const_item.const_token,
+                        ident: const_item.ident,
+                        generics: const_item.generics,
+                        colon_token: const_item.colon_token,
+                        ty: const_item.ty,
+                        eq_token: Token![=](Span::mixed_site()),
+                        expr,
+                        semi_token: const_item.semi_token,
+                    }));
+
+                    items.push(parse_quote! {
+                         const #gen_const_use_unique_attr_name: () = ();
+                    });
+                }
+
+                // Don't push the verbatim item as is.
                 continue;
             }
-            write!(const_items, "const {gen_const_name}: bool = true;").unwrap();
+            _ => {}
+        }
+        items.push(item);
+    }
+
+    items.push(parse_quote! {
+         const USE_VTABLE_ATTR: () = ();
+    });
+
+    for name in functions {
+        let gen_const_name = Ident::new(
+            &format!("HAS_{}", name.to_string().to_uppercase()),
+            name.span(),
+        );
+        // Skip if it's declared already -- this allows user override.
+        if consts.contains(&gen_const_name) {
+            continue;
         }
+        items.push(parse_quote! {
+            const #gen_const_name: bool = true;
+        });
+        consts.insert(gen_const_name);
     }
 
-    let new_body = vec![const_items.parse().unwrap(), body.stream()]
-        .into_iter()
-        .collect();
-    tokens.push(TokenTree::Group(Group::new(Delimiter::Brace, new_body)));
-    tokens.into_iter().collect()
+    impl_.items = items;
+    Ok(impl_)
+}
+
+pub(crate) fn vtable(input: Item) -> Result<TokenStream> {
+    match input {
+        Item::Trait(item) => Ok(handle_trait(item)?.into_token_stream()),
+        Item::Impl(item) => Ok(handle_impl(item)?.into_token_stream()),
+        _ => Err(Error::new_spanned(
+            input,
+            "`#[vtable]` expects a `trait` or `impl`.",
+        ))?,
+    }
 }
diff --git a/rust/proc-macro2/detection.rs b/rust/proc-macro2/detection.rs
new file mode 100644
index 0000000000000000000000000000000000000000..3de448cb2ddeb279a692f6afc8d848dae7b2135d
--- /dev/null
+++ b/rust/proc-macro2/detection.rs
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use core::sync::atomic::{AtomicUsize, Ordering};
+use std::sync::Once;
+
+static WORKS: AtomicUsize = AtomicUsize::new(0);
+static INIT: Once = Once::new();
+
+pub(crate) fn inside_proc_macro() -> bool {
+    match WORKS.load(Ordering::Relaxed) {
+        1 => return false,
+        2 => return true,
+        _ => {}
+    }
+
+    INIT.call_once(initialize);
+    inside_proc_macro()
+}
+
+pub(crate) fn force_fallback() {
+    WORKS.store(1, Ordering::Relaxed);
+}
+
+pub(crate) fn unforce_fallback() {
+    initialize();
+}
+
+#[cfg(not(no_is_available))]
+fn initialize() {
+    let available = proc_macro::is_available();
+    WORKS.store(available as usize + 1, Ordering::Relaxed);
+}
+
+// Swap in a null panic hook to avoid printing "thread panicked" to stderr,
+// then use catch_unwind to determine whether the compiler's proc_macro is
+// working. When proc-macro2 is used from outside of a procedural macro all
+// of the proc_macro crate's APIs currently panic.
+//
+// The Once is to prevent the possibility of this ordering:
+//
+//     thread 1 calls take_hook, gets the user's original hook
+//     thread 1 calls set_hook with the null hook
+//     thread 2 calls take_hook, thinks null hook is the original hook
+//     thread 2 calls set_hook with the null hook
+//     thread 1 calls set_hook with the actual original hook
+//     thread 2 calls set_hook with what it thinks is the original hook
+//
+// in which the user's hook has been lost.
+//
+// There is still a race condition where a panic in a different thread can
+// happen during the interval that the user's original panic hook is
+// unregistered such that their hook is incorrectly not called. This is
+// sufficiently unlikely and less bad than printing panic messages to stderr
+// on correct use of this crate. Maybe there is a libstd feature request
+// here. For now, if a user needs to guarantee that this failure mode does
+// not occur, they need to call e.g. `proc_macro2::Span::call_site()` from
+// the main thread before launching any other threads.
+#[cfg(no_is_available)]
+fn initialize() {
+    use std::panic::{self, PanicInfo};
+
+    type PanicHook = dyn Fn(&PanicInfo) + Sync + Send + 'static;
+
+    let null_hook: Box<PanicHook> = Box::new(|_panic_info| { /* ignore */ });
+    let sanity_check = &*null_hook as *const PanicHook;
+    let original_hook = panic::take_hook();
+    panic::set_hook(null_hook);
+
+    let works = panic::catch_unwind(proc_macro::Span::call_site).is_ok();
+    WORKS.store(works as usize + 1, Ordering::Relaxed);
+
+    let hopefully_null_hook = panic::take_hook();
+    panic::set_hook(original_hook);
+    if sanity_check != &*hopefully_null_hook {
+        panic!("observed race condition in proc_macro2::inside_proc_macro");
+    }
+}
diff --git a/rust/proc-macro2/extra.rs b/rust/proc-macro2/extra.rs
new file mode 100644
index 0000000000000000000000000000000000000000..4e6d22f16913e8532e2f9fc8c3b55bb218d908f3
--- /dev/null
+++ b/rust/proc-macro2/extra.rs
@@ -0,0 +1,153 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! Items which do not have a correspondence to any API in the proc_macro crate,
+//! but are necessary to include in proc-macro2.
+
+use crate::fallback;
+use crate::imp;
+use crate::marker::{ProcMacroAutoTraits, MARKER};
+use crate::Span;
+use core::fmt::{self, Debug};
+
+/// Invalidate any `proc_macro2::Span` that exist on the current thread.
+///
+/// The implementation of `Span` uses thread-local data structures and this
+/// function clears them. Calling any method on a `Span` on the current thread
+/// created prior to the invalidation will return incorrect values or crash.
+///
+/// This function is useful for programs that process more than 2<sup>32</sup>
+/// bytes of Rust source code on the same thread. Just like rustc, proc-macro2
+/// uses 32-bit source locations, and these wrap around when the total source
+/// code processed by the same thread exceeds 2<sup>32</sup> bytes (4
+/// gigabytes). After a wraparound, `Span` methods such as `source_text()` can
+/// return wrong data.
+///
+/// # Example
+///
+/// As of late 2023, there is 200 GB of Rust code published on crates.io.
+/// Looking at just the newest version of every crate, it is 16 GB of code. So a
+/// workload that involves parsing it all would overflow a 32-bit source
+/// location unless spans are being invalidated.
+///
+/// ```
+/// use flate2::read::GzDecoder;
+/// use std::ffi::OsStr;
+/// use std::io::{BufReader, Read};
+/// use std::str::FromStr;
+/// use tar::Archive;
+///
+/// rayon::scope(|s| {
+///     for krate in every_version_of_every_crate() {
+///         s.spawn(move |_| {
+///             proc_macro2::extra::invalidate_current_thread_spans();
+///
+///             let reader = BufReader::new(krate);
+///             let tar = GzDecoder::new(reader);
+///             let mut archive = Archive::new(tar);
+///             for entry in archive.entries().unwrap() {
+///                 let mut entry = entry.unwrap();
+///                 let path = entry.path().unwrap();
+///                 if path.extension() != Some(OsStr::new("rs")) {
+///                     continue;
+///                 }
+///                 let mut content = String::new();
+///                 entry.read_to_string(&mut content).unwrap();
+///                 match proc_macro2::TokenStream::from_str(&content) {
+///                     Ok(tokens) => {/* ... */},
+///                     Err(_) => continue,
+///                 }
+///             }
+///         });
+///     }
+/// });
+/// #
+/// # fn every_version_of_every_crate() -> Vec<std::fs::File> {
+/// #     Vec::new()
+/// # }
+/// ```
+///
+/// # Panics
+///
+/// This function is not applicable to and will panic if called from a
+/// procedural macro.
+#[cfg(span_locations)]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "span-locations")))]
+pub fn invalidate_current_thread_spans() {
+    crate::imp::invalidate_current_thread_spans();
+}
+
+/// An object that holds a [`Group`]'s `span_open()` and `span_close()` together
+/// in a more compact representation than holding those 2 spans individually.
+///
+/// [`Group`]: crate::Group
+#[derive(Copy, Clone)]
+pub struct DelimSpan {
+    inner: DelimSpanEnum,
+    _marker: ProcMacroAutoTraits,
+}
+
+#[derive(Copy, Clone)]
+enum DelimSpanEnum {
+    #[cfg(wrap_proc_macro)]
+    Compiler {
+        join: proc_macro::Span,
+        open: proc_macro::Span,
+        close: proc_macro::Span,
+    },
+    Fallback(fallback::Span),
+}
+
+impl DelimSpan {
+    pub(crate) fn new(group: &imp::Group) -> Self {
+        #[cfg(wrap_proc_macro)]
+        let inner = match group {
+            imp::Group::Compiler(group) => DelimSpanEnum::Compiler {
+                join: group.span(),
+                open: group.span_open(),
+                close: group.span_close(),
+            },
+            imp::Group::Fallback(group) => DelimSpanEnum::Fallback(group.span()),
+        };
+
+        #[cfg(not(wrap_proc_macro))]
+        let inner = DelimSpanEnum::Fallback(group.span());
+
+        DelimSpan {
+            inner,
+            _marker: MARKER,
+        }
+    }
+
+    /// Returns a span covering the entire delimited group.
+    pub fn join(&self) -> Span {
+        match &self.inner {
+            #[cfg(wrap_proc_macro)]
+            DelimSpanEnum::Compiler { join, .. } => Span::_new(imp::Span::Compiler(*join)),
+            DelimSpanEnum::Fallback(span) => Span::_new_fallback(*span),
+        }
+    }
+
+    /// Returns a span for the opening punctuation of the group only.
+    pub fn open(&self) -> Span {
+        match &self.inner {
+            #[cfg(wrap_proc_macro)]
+            DelimSpanEnum::Compiler { open, .. } => Span::_new(imp::Span::Compiler(*open)),
+            DelimSpanEnum::Fallback(span) => Span::_new_fallback(span.first_byte()),
+        }
+    }
+
+    /// Returns a span for the closing punctuation of the group only.
+    pub fn close(&self) -> Span {
+        match &self.inner {
+            #[cfg(wrap_proc_macro)]
+            DelimSpanEnum::Compiler { close, .. } => Span::_new(imp::Span::Compiler(*close)),
+            DelimSpanEnum::Fallback(span) => Span::_new_fallback(span.last_byte()),
+        }
+    }
+}
+
+impl Debug for DelimSpan {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.join(), f)
+    }
+}
diff --git a/rust/proc-macro2/fallback.rs b/rust/proc-macro2/fallback.rs
new file mode 100644
index 0000000000000000000000000000000000000000..142ab99a8f4df943e02230ac44234f5b9c08cb75
--- /dev/null
+++ b/rust/proc-macro2/fallback.rs
@@ -0,0 +1,1176 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(span_locations)]
+use crate::location::LineColumn;
+use crate::parse::{self, Cursor};
+use crate::rcvec::{RcVec, RcVecBuilder, RcVecIntoIter, RcVecMut};
+use crate::{Delimiter, Spacing, TokenTree};
+#[cfg(all(span_locations, not(fuzzing)))]
+use alloc::collections::BTreeMap;
+#[cfg(all(span_locations, not(fuzzing)))]
+use core::cell::RefCell;
+#[cfg(span_locations)]
+use core::cmp;
+use core::fmt::{self, Debug, Display, Write};
+use core::mem::ManuallyDrop;
+#[cfg(span_locations)]
+use core::ops::Range;
+use core::ops::RangeBounds;
+use core::ptr;
+use core::str::FromStr;
+#[cfg(procmacro2_semver_exempt)]
+use std::path::PathBuf;
+
+/// Force use of proc-macro2's fallback implementation of the API for now, even
+/// if the compiler's implementation is available.
+pub fn force() {
+    #[cfg(wrap_proc_macro)]
+    crate::detection::force_fallback();
+}
+
+/// Resume using the compiler's implementation of the proc macro API if it is
+/// available.
+pub fn unforce() {
+    #[cfg(wrap_proc_macro)]
+    crate::detection::unforce_fallback();
+}
+
+#[derive(Clone)]
+pub(crate) struct TokenStream {
+    inner: RcVec<TokenTree>,
+}
+
+#[derive(Debug)]
+pub(crate) struct LexError {
+    pub(crate) span: Span,
+}
+
+impl LexError {
+    pub(crate) fn span(&self) -> Span {
+        self.span
+    }
+
+    pub(crate) fn call_site() -> Self {
+        LexError {
+            span: Span::call_site(),
+        }
+    }
+}
+
+impl TokenStream {
+    pub fn new() -> Self {
+        TokenStream {
+            inner: RcVecBuilder::new().build(),
+        }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.inner.len() == 0
+    }
+
+    fn take_inner(self) -> RcVecBuilder<TokenTree> {
+        let nodrop = ManuallyDrop::new(self);
+        unsafe { ptr::read(&nodrop.inner) }.make_owned()
+    }
+}
+
+fn push_token_from_proc_macro(mut vec: RcVecMut<TokenTree>, token: TokenTree) {
+    // https://github.com/dtolnay/proc-macro2/issues/235
+    match token {
+        TokenTree::Literal(crate::Literal {
+            #[cfg(wrap_proc_macro)]
+                inner: crate::imp::Literal::Fallback(literal),
+            #[cfg(not(wrap_proc_macro))]
+                inner: literal,
+            ..
+        }) if literal.repr.starts_with('-') => {
+            push_negative_literal(vec, literal);
+        }
+        _ => vec.push(token),
+    }
+
+    #[cold]
+    fn push_negative_literal(mut vec: RcVecMut<TokenTree>, mut literal: Literal) {
+        literal.repr.remove(0);
+        let mut punct = crate::Punct::new('-', Spacing::Alone);
+        punct.set_span(crate::Span::_new_fallback(literal.span));
+        vec.push(TokenTree::Punct(punct));
+        vec.push(TokenTree::Literal(crate::Literal::_new_fallback(literal)));
+    }
+}
+
+// Nonrecursive to prevent stack overflow.
+impl Drop for TokenStream {
+    fn drop(&mut self) {
+        let mut inner = match self.inner.get_mut() {
+            Some(inner) => inner,
+            None => return,
+        };
+        while let Some(token) = inner.pop() {
+            let group = match token {
+                TokenTree::Group(group) => group.inner,
+                _ => continue,
+            };
+            #[cfg(wrap_proc_macro)]
+            let group = match group {
+                crate::imp::Group::Fallback(group) => group,
+                crate::imp::Group::Compiler(_) => continue,
+            };
+            inner.extend(group.stream.take_inner());
+        }
+    }
+}
+
+pub(crate) struct TokenStreamBuilder {
+    inner: RcVecBuilder<TokenTree>,
+}
+
+impl TokenStreamBuilder {
+    pub fn new() -> Self {
+        TokenStreamBuilder {
+            inner: RcVecBuilder::new(),
+        }
+    }
+
+    pub fn with_capacity(cap: usize) -> Self {
+        TokenStreamBuilder {
+            inner: RcVecBuilder::with_capacity(cap),
+        }
+    }
+
+    pub fn push_token_from_parser(&mut self, tt: TokenTree) {
+        self.inner.push(tt);
+    }
+
+    pub fn build(self) -> TokenStream {
+        TokenStream {
+            inner: self.inner.build(),
+        }
+    }
+}
+
+#[cfg(span_locations)]
+fn get_cursor(src: &str) -> Cursor {
+    #[cfg(fuzzing)]
+    return Cursor { rest: src, off: 1 };
+
+    // Create a dummy file & add it to the source map
+    #[cfg(not(fuzzing))]
+    SOURCE_MAP.with(|sm| {
+        let mut sm = sm.borrow_mut();
+        let span = sm.add_file(src);
+        Cursor {
+            rest: src,
+            off: span.lo,
+        }
+    })
+}
+
+#[cfg(not(span_locations))]
+fn get_cursor(src: &str) -> Cursor {
+    Cursor { rest: src }
+}
+
+impl FromStr for TokenStream {
+    type Err = LexError;
+
+    fn from_str(src: &str) -> Result<TokenStream, LexError> {
+        // Create a dummy file & add it to the source map
+        let mut cursor = get_cursor(src);
+
+        // Strip a byte order mark if present
+        const BYTE_ORDER_MARK: &str = "\u{feff}";
+        if cursor.starts_with(BYTE_ORDER_MARK) {
+            cursor = cursor.advance(BYTE_ORDER_MARK.len());
+        }
+
+        parse::token_stream(cursor)
+    }
+}
+
+impl Display for LexError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("cannot parse string into token stream")
+    }
+}
+
+impl Display for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut joint = false;
+        for (i, tt) in self.inner.iter().enumerate() {
+            if i != 0 && !joint {
+                write!(f, " ")?;
+            }
+            joint = false;
+            match tt {
+                TokenTree::Group(tt) => Display::fmt(tt, f),
+                TokenTree::Ident(tt) => Display::fmt(tt, f),
+                TokenTree::Punct(tt) => {
+                    joint = tt.spacing() == Spacing::Joint;
+                    Display::fmt(tt, f)
+                }
+                TokenTree::Literal(tt) => Display::fmt(tt, f),
+            }?;
+        }
+
+        Ok(())
+    }
+}
+
+impl Debug for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("TokenStream ")?;
+        f.debug_list().entries(self.clone()).finish()
+    }
+}
+
+#[cfg(feature = "proc-macro")]
+impl From<proc_macro::TokenStream> for TokenStream {
+    fn from(inner: proc_macro::TokenStream) -> Self {
+        inner
+            .to_string()
+            .parse()
+            .expect("compiler token stream parse failed")
+    }
+}
+
+#[cfg(feature = "proc-macro")]
+impl From<TokenStream> for proc_macro::TokenStream {
+    fn from(inner: TokenStream) -> Self {
+        inner
+            .to_string()
+            .parse()
+            .expect("failed to parse to compiler tokens")
+    }
+}
+
+impl From<TokenTree> for TokenStream {
+    fn from(tree: TokenTree) -> Self {
+        let mut stream = RcVecBuilder::new();
+        push_token_from_proc_macro(stream.as_mut(), tree);
+        TokenStream {
+            inner: stream.build(),
+        }
+    }
+}
+
+impl FromIterator<TokenTree> for TokenStream {
+    fn from_iter<I: IntoIterator<Item = TokenTree>>(tokens: I) -> Self {
+        let mut stream = TokenStream::new();
+        stream.extend(tokens);
+        stream
+    }
+}
+
+impl FromIterator<TokenStream> for TokenStream {
+    fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
+        let mut v = RcVecBuilder::new();
+
+        for stream in streams {
+            v.extend(stream.take_inner());
+        }
+
+        TokenStream { inner: v.build() }
+    }
+}
+
+impl Extend<TokenTree> for TokenStream {
+    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, tokens: I) {
+        let mut vec = self.inner.make_mut();
+        tokens
+            .into_iter()
+            .for_each(|token| push_token_from_proc_macro(vec.as_mut(), token));
+    }
+}
+
+impl Extend<TokenStream> for TokenStream {
+    fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
+        self.inner.make_mut().extend(streams.into_iter().flatten());
+    }
+}
+
+pub(crate) type TokenTreeIter = RcVecIntoIter<TokenTree>;
+
+impl IntoIterator for TokenStream {
+    type Item = TokenTree;
+    type IntoIter = TokenTreeIter;
+
+    fn into_iter(self) -> TokenTreeIter {
+        self.take_inner().into_iter()
+    }
+}
+
+#[cfg(procmacro2_semver_exempt)]
+#[derive(Clone, PartialEq, Eq)]
+pub(crate) struct SourceFile {
+    path: PathBuf,
+}
+
+#[cfg(procmacro2_semver_exempt)]
+impl SourceFile {
+    /// Get the path to this source file as a string.
+    pub fn path(&self) -> PathBuf {
+        self.path.clone()
+    }
+
+    pub fn is_real(&self) -> bool {
+        false
+    }
+}
+
+#[cfg(procmacro2_semver_exempt)]
+impl Debug for SourceFile {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.debug_struct("SourceFile")
+            .field("path", &self.path())
+            .field("is_real", &self.is_real())
+            .finish()
+    }
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+thread_local! {
+    static SOURCE_MAP: RefCell<SourceMap> = RefCell::new(SourceMap {
+        // Start with a single dummy file which all call_site() and def_site()
+        // spans reference.
+        files: vec![FileInfo {
+            source_text: String::new(),
+            span: Span { lo: 0, hi: 0 },
+            lines: vec![0],
+            char_index_to_byte_offset: BTreeMap::new(),
+        }],
+    });
+}
+
+#[cfg(span_locations)]
+pub(crate) fn invalidate_current_thread_spans() {
+    #[cfg(not(fuzzing))]
+    SOURCE_MAP.with(|sm| sm.borrow_mut().files.truncate(1));
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+struct FileInfo {
+    source_text: String,
+    span: Span,
+    lines: Vec<usize>,
+    char_index_to_byte_offset: BTreeMap<usize, usize>,
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+impl FileInfo {
+    fn offset_line_column(&self, offset: usize) -> LineColumn {
+        assert!(self.span_within(Span {
+            lo: offset as u32,
+            hi: offset as u32,
+        }));
+        let offset = offset - self.span.lo as usize;
+        match self.lines.binary_search(&offset) {
+            Ok(found) => LineColumn {
+                line: found + 1,
+                column: 0,
+            },
+            Err(idx) => LineColumn {
+                line: idx,
+                column: offset - self.lines[idx - 1],
+            },
+        }
+    }
+
+    fn span_within(&self, span: Span) -> bool {
+        span.lo >= self.span.lo && span.hi <= self.span.hi
+    }
+
+    fn byte_range(&mut self, span: Span) -> Range<usize> {
+        let lo_char = (span.lo - self.span.lo) as usize;
+
+        // Look up offset of the largest already-computed char index that is
+        // less than or equal to the current requested one. We resume counting
+        // chars from that point.
+        let (&last_char_index, &last_byte_offset) = self
+            .char_index_to_byte_offset
+            .range(..=lo_char)
+            .next_back()
+            .unwrap_or((&0, &0));
+
+        let lo_byte = if last_char_index == lo_char {
+            last_byte_offset
+        } else {
+            let total_byte_offset = match self.source_text[last_byte_offset..]
+                .char_indices()
+                .nth(lo_char - last_char_index)
+            {
+                Some((additional_offset, _ch)) => last_byte_offset + additional_offset,
+                None => self.source_text.len(),
+            };
+            self.char_index_to_byte_offset
+                .insert(lo_char, total_byte_offset);
+            total_byte_offset
+        };
+
+        let trunc_lo = &self.source_text[lo_byte..];
+        let char_len = (span.hi - span.lo) as usize;
+        lo_byte..match trunc_lo.char_indices().nth(char_len) {
+            Some((offset, _ch)) => lo_byte + offset,
+            None => self.source_text.len(),
+        }
+    }
+
+    fn source_text(&mut self, span: Span) -> String {
+        let byte_range = self.byte_range(span);
+        self.source_text[byte_range].to_owned()
+    }
+}
+
+/// Computes the offsets of each line in the given source string
+/// and the total number of characters
+#[cfg(all(span_locations, not(fuzzing)))]
+fn lines_offsets(s: &str) -> (usize, Vec<usize>) {
+    let mut lines = vec![0];
+    let mut total = 0;
+
+    for ch in s.chars() {
+        total += 1;
+        if ch == '\n' {
+            lines.push(total);
+        }
+    }
+
+    (total, lines)
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+struct SourceMap {
+    files: Vec<FileInfo>,
+}
+
+#[cfg(all(span_locations, not(fuzzing)))]
+impl SourceMap {
+    fn next_start_pos(&self) -> u32 {
+        // Add 1 so there's always space between files.
+        //
+        // We'll always have at least 1 file, as we initialize our files list
+        // with a dummy file.
+        self.files.last().unwrap().span.hi + 1
+    }
+
+    fn add_file(&mut self, src: &str) -> Span {
+        let (len, lines) = lines_offsets(src);
+        let lo = self.next_start_pos();
+        let span = Span {
+            lo,
+            hi: lo + (len as u32),
+        };
+
+        self.files.push(FileInfo {
+            source_text: src.to_owned(),
+            span,
+            lines,
+            // Populated lazily by source_text().
+            char_index_to_byte_offset: BTreeMap::new(),
+        });
+
+        span
+    }
+
+    #[cfg(procmacro2_semver_exempt)]
+    fn filepath(&self, span: Span) -> PathBuf {
+        for (i, file) in self.files.iter().enumerate() {
+            if file.span_within(span) {
+                return PathBuf::from(if i == 0 {
+                    "<unspecified>".to_owned()
+                } else {
+                    format!("<parsed string {}>", i)
+                });
+            }
+        }
+        unreachable!("Invalid span with no related FileInfo!");
+    }
+
+    fn fileinfo(&self, span: Span) -> &FileInfo {
+        for file in &self.files {
+            if file.span_within(span) {
+                return file;
+            }
+        }
+        unreachable!("Invalid span with no related FileInfo!");
+    }
+
+    fn fileinfo_mut(&mut self, span: Span) -> &mut FileInfo {
+        for file in &mut self.files {
+            if file.span_within(span) {
+                return file;
+            }
+        }
+        unreachable!("Invalid span with no related FileInfo!");
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq)]
+pub(crate) struct Span {
+    #[cfg(span_locations)]
+    pub(crate) lo: u32,
+    #[cfg(span_locations)]
+    pub(crate) hi: u32,
+}
+
+impl Span {
+    #[cfg(not(span_locations))]
+    pub fn call_site() -> Self {
+        Span {}
+    }
+
+    #[cfg(span_locations)]
+    pub fn call_site() -> Self {
+        Span { lo: 0, hi: 0 }
+    }
+
+    pub fn mixed_site() -> Self {
+        Span::call_site()
+    }
+
+    #[cfg(procmacro2_semver_exempt)]
+    pub fn def_site() -> Self {
+        Span::call_site()
+    }
+
+    pub fn resolved_at(&self, _other: Span) -> Span {
+        // Stable spans consist only of line/column information, so
+        // `resolved_at` and `located_at` only select which span the
+        // caller wants line/column information from.
+        *self
+    }
+
+    pub fn located_at(&self, other: Span) -> Span {
+        other
+    }
+
+    #[cfg(procmacro2_semver_exempt)]
+    pub fn source_file(&self) -> SourceFile {
+        #[cfg(fuzzing)]
+        return SourceFile {
+            path: PathBuf::from("<unspecified>"),
+        };
+
+        #[cfg(not(fuzzing))]
+        SOURCE_MAP.with(|sm| {
+            let sm = sm.borrow();
+            let path = sm.filepath(*self);
+            SourceFile { path }
+        })
+    }
+
+    #[cfg(span_locations)]
+    pub fn byte_range(&self) -> Range<usize> {
+        #[cfg(fuzzing)]
+        return 0..0;
+
+        #[cfg(not(fuzzing))]
+        {
+            if self.is_call_site() {
+                0..0
+            } else {
+                SOURCE_MAP.with(|sm| sm.borrow_mut().fileinfo_mut(*self).byte_range(*self))
+            }
+        }
+    }
+
+    #[cfg(span_locations)]
+    pub fn start(&self) -> LineColumn {
+        #[cfg(fuzzing)]
+        return LineColumn { line: 0, column: 0 };
+
+        #[cfg(not(fuzzing))]
+        SOURCE_MAP.with(|sm| {
+            let sm = sm.borrow();
+            let fi = sm.fileinfo(*self);
+            fi.offset_line_column(self.lo as usize)
+        })
+    }
+
+    #[cfg(span_locations)]
+    pub fn end(&self) -> LineColumn {
+        #[cfg(fuzzing)]
+        return LineColumn { line: 0, column: 0 };
+
+        #[cfg(not(fuzzing))]
+        SOURCE_MAP.with(|sm| {
+            let sm = sm.borrow();
+            let fi = sm.fileinfo(*self);
+            fi.offset_line_column(self.hi as usize)
+        })
+    }
+
+    #[cfg(not(span_locations))]
+    pub fn join(&self, _other: Span) -> Option<Span> {
+        Some(Span {})
+    }
+
+    #[cfg(span_locations)]
+    pub fn join(&self, other: Span) -> Option<Span> {
+        #[cfg(fuzzing)]
+        return {
+            let _ = other;
+            None
+        };
+
+        #[cfg(not(fuzzing))]
+        SOURCE_MAP.with(|sm| {
+            let sm = sm.borrow();
+            // If `other` is not within the same FileInfo as us, return None.
+            if !sm.fileinfo(*self).span_within(other) {
+                return None;
+            }
+            Some(Span {
+                lo: cmp::min(self.lo, other.lo),
+                hi: cmp::max(self.hi, other.hi),
+            })
+        })
+    }
+
+    #[cfg(not(span_locations))]
+    pub fn source_text(&self) -> Option<String> {
+        None
+    }
+
+    #[cfg(span_locations)]
+    pub fn source_text(&self) -> Option<String> {
+        #[cfg(fuzzing)]
+        return None;
+
+        #[cfg(not(fuzzing))]
+        {
+            if self.is_call_site() {
+                None
+            } else {
+                Some(SOURCE_MAP.with(|sm| sm.borrow_mut().fileinfo_mut(*self).source_text(*self)))
+            }
+        }
+    }
+
+    #[cfg(not(span_locations))]
+    pub(crate) fn first_byte(self) -> Self {
+        self
+    }
+
+    #[cfg(span_locations)]
+    pub(crate) fn first_byte(self) -> Self {
+        Span {
+            lo: self.lo,
+            hi: cmp::min(self.lo.saturating_add(1), self.hi),
+        }
+    }
+
+    #[cfg(not(span_locations))]
+    pub(crate) fn last_byte(self) -> Self {
+        self
+    }
+
+    #[cfg(span_locations)]
+    pub(crate) fn last_byte(self) -> Self {
+        Span {
+            lo: cmp::max(self.hi.saturating_sub(1), self.lo),
+            hi: self.hi,
+        }
+    }
+
+    #[cfg(span_locations)]
+    fn is_call_site(&self) -> bool {
+        self.lo == 0 && self.hi == 0
+    }
+}
+
+impl Debug for Span {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        #[cfg(span_locations)]
+        return write!(f, "bytes({}..{})", self.lo, self.hi);
+
+        #[cfg(not(span_locations))]
+        write!(f, "Span")
+    }
+}
+
+pub(crate) fn debug_span_field_if_nontrivial(debug: &mut fmt::DebugStruct, span: Span) {
+    #[cfg(span_locations)]
+    {
+        if span.is_call_site() {
+            return;
+        }
+    }
+
+    if cfg!(span_locations) {
+        debug.field("span", &span);
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Group {
+    delimiter: Delimiter,
+    stream: TokenStream,
+    span: Span,
+}
+
+impl Group {
+    pub fn new(delimiter: Delimiter, stream: TokenStream) -> Self {
+        Group {
+            delimiter,
+            stream,
+            span: Span::call_site(),
+        }
+    }
+
+    pub fn delimiter(&self) -> Delimiter {
+        self.delimiter
+    }
+
+    pub fn stream(&self) -> TokenStream {
+        self.stream.clone()
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    pub fn span_open(&self) -> Span {
+        self.span.first_byte()
+    }
+
+    pub fn span_close(&self) -> Span {
+        self.span.last_byte()
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.span = span;
+    }
+}
+
+impl Display for Group {
+    // We attempt to match libproc_macro's formatting.
+    // Empty parens: ()
+    // Nonempty parens: (...)
+    // Empty brackets: []
+    // Nonempty brackets: [...]
+    // Empty braces: { }
+    // Nonempty braces: { ... }
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let (open, close) = match self.delimiter {
+            Delimiter::Parenthesis => ("(", ")"),
+            Delimiter::Brace => ("{ ", "}"),
+            Delimiter::Bracket => ("[", "]"),
+            Delimiter::None => ("", ""),
+        };
+
+        f.write_str(open)?;
+        Display::fmt(&self.stream, f)?;
+        if self.delimiter == Delimiter::Brace && !self.stream.inner.is_empty() {
+            f.write_str(" ")?;
+        }
+        f.write_str(close)?;
+
+        Ok(())
+    }
+}
+
+impl Debug for Group {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = fmt.debug_struct("Group");
+        debug.field("delimiter", &self.delimiter);
+        debug.field("stream", &self.stream);
+        debug_span_field_if_nontrivial(&mut debug, self.span);
+        debug.finish()
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Ident {
+    sym: String,
+    span: Span,
+    raw: bool,
+}
+
+impl Ident {
+    #[track_caller]
+    pub fn new_checked(string: &str, span: Span) -> Self {
+        validate_ident(string);
+        Ident::new_unchecked(string, span)
+    }
+
+    pub fn new_unchecked(string: &str, span: Span) -> Self {
+        Ident {
+            sym: string.to_owned(),
+            span,
+            raw: false,
+        }
+    }
+
+    #[track_caller]
+    pub fn new_raw_checked(string: &str, span: Span) -> Self {
+        validate_ident_raw(string);
+        Ident::new_raw_unchecked(string, span)
+    }
+
+    pub fn new_raw_unchecked(string: &str, span: Span) -> Self {
+        Ident {
+            sym: string.to_owned(),
+            span,
+            raw: true,
+        }
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.span = span;
+    }
+}
+
+pub(crate) fn is_ident_start(c: char) -> bool {
+    c == '_' || c.is_ascii_alphabetic()
+}
+
+pub(crate) fn is_ident_continue(c: char) -> bool {
+    c == '_' || c.is_ascii_alphanumeric()
+}
+
+#[track_caller]
+fn validate_ident(string: &str) {
+    if string.is_empty() {
+        panic!("Ident is not allowed to be empty; use Option<Ident>");
+    }
+
+    if string.bytes().all(|digit| b'0' <= digit && digit <= b'9') {
+        panic!("Ident cannot be a number; use Literal instead");
+    }
+
+    fn ident_ok(string: &str) -> bool {
+        let mut chars = string.chars();
+        let first = chars.next().unwrap();
+        if !is_ident_start(first) {
+            return false;
+        }
+        for ch in chars {
+            if !is_ident_continue(ch) {
+                return false;
+            }
+        }
+        true
+    }
+
+    if !ident_ok(string) {
+        panic!("{:?} is not a valid Ident", string);
+    }
+}
+
+#[track_caller]
+fn validate_ident_raw(string: &str) {
+    validate_ident(string);
+
+    match string {
+        "_" | "super" | "self" | "Self" | "crate" => {
+            panic!("`r#{}` cannot be a raw identifier", string);
+        }
+        _ => {}
+    }
+}
+
+impl PartialEq for Ident {
+    fn eq(&self, other: &Ident) -> bool {
+        self.sym == other.sym && self.raw == other.raw
+    }
+}
+
+impl<T> PartialEq<T> for Ident
+where
+    T: ?Sized + AsRef<str>,
+{
+    fn eq(&self, other: &T) -> bool {
+        let other = other.as_ref();
+        if self.raw {
+            other.starts_with("r#") && self.sym == other[2..]
+        } else {
+            self.sym == other
+        }
+    }
+}
+
+impl Display for Ident {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        if self.raw {
+            f.write_str("r#")?;
+        }
+        Display::fmt(&self.sym, f)
+    }
+}
+
+#[allow(clippy::missing_fields_in_debug)]
+impl Debug for Ident {
+    // Ident(proc_macro), Ident(r#union)
+    #[cfg(not(span_locations))]
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = f.debug_tuple("Ident");
+        debug.field(&format_args!("{}", self));
+        debug.finish()
+    }
+
+    // Ident {
+    //     sym: proc_macro,
+    //     span: bytes(128..138)
+    // }
+    #[cfg(span_locations)]
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = f.debug_struct("Ident");
+        debug.field("sym", &format_args!("{}", self));
+        debug_span_field_if_nontrivial(&mut debug, self.span);
+        debug.finish()
+    }
+}
+
+#[derive(Clone)]
+pub(crate) struct Literal {
+    repr: String,
+    span: Span,
+}
+
+macro_rules! suffixed_numbers {
+    ($($name:ident => $kind:ident,)*) => ($(
+        pub fn $name(n: $kind) -> Literal {
+            Literal::_new(format!(concat!("{}", stringify!($kind)), n))
+        }
+    )*)
+}
+
+macro_rules! unsuffixed_numbers {
+    ($($name:ident => $kind:ident,)*) => ($(
+        pub fn $name(n: $kind) -> Literal {
+            Literal::_new(n.to_string())
+        }
+    )*)
+}
+
+impl Literal {
+    pub(crate) fn _new(repr: String) -> Self {
+        Literal {
+            repr,
+            span: Span::call_site(),
+        }
+    }
+
+    pub(crate) unsafe fn from_str_unchecked(repr: &str) -> Self {
+        Literal::_new(repr.to_owned())
+    }
+
+    suffixed_numbers! {
+        u8_suffixed => u8,
+        u16_suffixed => u16,
+        u32_suffixed => u32,
+        u64_suffixed => u64,
+        u128_suffixed => u128,
+        usize_suffixed => usize,
+        i8_suffixed => i8,
+        i16_suffixed => i16,
+        i32_suffixed => i32,
+        i64_suffixed => i64,
+        i128_suffixed => i128,
+        isize_suffixed => isize,
+
+        f32_suffixed => f32,
+        f64_suffixed => f64,
+    }
+
+    unsuffixed_numbers! {
+        u8_unsuffixed => u8,
+        u16_unsuffixed => u16,
+        u32_unsuffixed => u32,
+        u64_unsuffixed => u64,
+        u128_unsuffixed => u128,
+        usize_unsuffixed => usize,
+        i8_unsuffixed => i8,
+        i16_unsuffixed => i16,
+        i32_unsuffixed => i32,
+        i64_unsuffixed => i64,
+        i128_unsuffixed => i128,
+        isize_unsuffixed => isize,
+    }
+
+    pub fn f32_unsuffixed(f: f32) -> Literal {
+        let mut s = f.to_string();
+        if !s.contains('.') {
+            s.push_str(".0");
+        }
+        Literal::_new(s)
+    }
+
+    pub fn f64_unsuffixed(f: f64) -> Literal {
+        let mut s = f.to_string();
+        if !s.contains('.') {
+            s.push_str(".0");
+        }
+        Literal::_new(s)
+    }
+
+    pub fn string(t: &str) -> Literal {
+        let mut repr = String::with_capacity(t.len() + 2);
+        repr.push('"');
+        let mut chars = t.chars();
+        while let Some(ch) = chars.next() {
+            if ch == '\0' {
+                repr.push_str(
+                    if chars
+                        .as_str()
+                        .starts_with(|next| '0' <= next && next <= '7')
+                    {
+                        // circumvent clippy::octal_escapes lint
+                        "\\x00"
+                    } else {
+                        "\\0"
+                    },
+                );
+            } else if ch == '\'' {
+                // escape_debug turns this into "\'" which is unnecessary.
+                repr.push(ch);
+            } else {
+                repr.extend(ch.escape_debug());
+            }
+        }
+        repr.push('"');
+        Literal::_new(repr)
+    }
+
+    pub fn character(t: char) -> Literal {
+        let mut repr = String::new();
+        repr.push('\'');
+        if t == '"' {
+            // escape_debug turns this into '\"' which is unnecessary.
+            repr.push(t);
+        } else {
+            repr.extend(t.escape_debug());
+        }
+        repr.push('\'');
+        Literal::_new(repr)
+    }
+
+    pub fn byte_string(bytes: &[u8]) -> Literal {
+        let mut escaped = "b\"".to_string();
+        let mut bytes = bytes.iter();
+        while let Some(&b) = bytes.next() {
+            #[allow(clippy::match_overlapping_arm)]
+            match b {
+                b'\0' => escaped.push_str(match bytes.as_slice().first() {
+                    // circumvent clippy::octal_escapes lint
+                    Some(b'0'..=b'7') => r"\x00",
+                    _ => r"\0",
+                }),
+                b'\t' => escaped.push_str(r"\t"),
+                b'\n' => escaped.push_str(r"\n"),
+                b'\r' => escaped.push_str(r"\r"),
+                b'"' => escaped.push_str("\\\""),
+                b'\\' => escaped.push_str("\\\\"),
+                b'\x20'..=b'\x7E' => escaped.push(b as char),
+                _ => {
+                    let _ = write!(escaped, "\\x{:02X}", b);
+                }
+            }
+        }
+        escaped.push('"');
+        Literal::_new(escaped)
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.span = span;
+    }
+
+    pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
+        #[cfg(not(span_locations))]
+        {
+            let _ = range;
+            None
+        }
+
+        #[cfg(span_locations)]
+        {
+            use core::ops::Bound;
+
+            let lo = match range.start_bound() {
+                Bound::Included(start) => {
+                    let start = u32::try_from(*start).ok()?;
+                    self.span.lo.checked_add(start)?
+                }
+                Bound::Excluded(start) => {
+                    let start = u32::try_from(*start).ok()?;
+                    self.span.lo.checked_add(start)?.checked_add(1)?
+                }
+                Bound::Unbounded => self.span.lo,
+            };
+            let hi = match range.end_bound() {
+                Bound::Included(end) => {
+                    let end = u32::try_from(*end).ok()?;
+                    self.span.lo.checked_add(end)?.checked_add(1)?
+                }
+                Bound::Excluded(end) => {
+                    let end = u32::try_from(*end).ok()?;
+                    self.span.lo.checked_add(end)?
+                }
+                Bound::Unbounded => self.span.hi,
+            };
+            if lo <= hi && hi <= self.span.hi {
+                Some(Span { lo, hi })
+            } else {
+                None
+            }
+        }
+    }
+}
+
+impl FromStr for Literal {
+    type Err = LexError;
+
+    fn from_str(repr: &str) -> Result<Self, Self::Err> {
+        let mut cursor = get_cursor(repr);
+        #[cfg(span_locations)]
+        let lo = cursor.off;
+
+        let negative = cursor.starts_with_char('-');
+        if negative {
+            cursor = cursor.advance(1);
+            if !cursor.starts_with_fn(|ch| ch.is_ascii_digit()) {
+                return Err(LexError::call_site());
+            }
+        }
+
+        if let Ok((rest, mut literal)) = parse::literal(cursor) {
+            if rest.is_empty() {
+                if negative {
+                    literal.repr.insert(0, '-');
+                }
+                literal.span = Span {
+                    #[cfg(span_locations)]
+                    lo,
+                    #[cfg(span_locations)]
+                    hi: rest.off,
+                };
+                return Ok(literal);
+            }
+        }
+        Err(LexError::call_site())
+    }
+}
+
+impl Display for Literal {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.repr, f)
+    }
+}
+
+impl Debug for Literal {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = fmt.debug_struct("Literal");
+        debug.field("lit", &format_args!("{}", self.repr));
+        debug_span_field_if_nontrivial(&mut debug, self.span);
+        debug.finish()
+    }
+}
diff --git a/rust/proc-macro2/lib.rs b/rust/proc-macro2/lib.rs
new file mode 100644
index 0000000000000000000000000000000000000000..e962ca2eebf538c5f1caaa17a4c74f0b85adcc00
--- /dev/null
+++ b/rust/proc-macro2/lib.rs
@@ -0,0 +1,1348 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! [![github]](https://github.com/dtolnay/proc-macro2)&ensp;[![crates-io]](https://crates.io/crates/proc-macro2)&ensp;[![docs-rs]](crate)
+//!
+//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
+//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
+//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs
+//!
+//! <br>
+//!
+//! A wrapper around the procedural macro API of the compiler's [`proc_macro`]
+//! crate. This library serves two purposes:
+//!
+//! [`proc_macro`]: https://doc.rust-lang.org/proc_macro/
+//!
+//! - **Bring proc-macro-like functionality to other contexts like build.rs and
+//!   main.rs.** Types from `proc_macro` are entirely specific to procedural
+//!   macros and cannot ever exist in code outside of a procedural macro.
+//!   Meanwhile `proc_macro2` types may exist anywhere including non-macro code.
+//!   By developing foundational libraries like [syn] and [quote] against
+//!   `proc_macro2` rather than `proc_macro`, the procedural macro ecosystem
+//!   becomes easily applicable to many other use cases and we avoid
+//!   reimplementing non-macro equivalents of those libraries.
+//!
+//! - **Make procedural macros unit testable.** As a consequence of being
+//!   specific to procedural macros, nothing that uses `proc_macro` can be
+//!   executed from a unit test. In order for helper libraries or components of
+//!   a macro to be testable in isolation, they must be implemented using
+//!   `proc_macro2`.
+//!
+//! [syn]: https://github.com/dtolnay/syn
+//! [quote]: https://github.com/dtolnay/quote
+//!
+//! # Usage
+//!
+//! The skeleton of a typical procedural macro typically looks like this:
+//!
+//! ```
+//! extern crate proc_macro;
+//!
+//! # const IGNORE: &str = stringify! {
+//! #[proc_macro_derive(MyDerive)]
+//! # };
+//! # #[cfg(wrap_proc_macro)]
+//! pub fn my_derive(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+//!     let input = proc_macro2::TokenStream::from(input);
+//!
+//!     let output: proc_macro2::TokenStream = {
+//!         /* transform input */
+//!         # input
+//!     };
+//!
+//!     proc_macro::TokenStream::from(output)
+//! }
+//! ```
+//!
+//! If parsing with [Syn], you'll use [`parse_macro_input!`] instead to
+//! propagate parse errors correctly back to the compiler when parsing fails.
+//!
+//! [`parse_macro_input!`]: https://docs.rs/syn/2.0/syn/macro.parse_macro_input.html
+//!
+//! # Unstable features
+//!
+//! The default feature set of proc-macro2 tracks the most recent stable
+//! compiler API. Functionality in `proc_macro` that is not yet stable is not
+//! exposed by proc-macro2 by default.
+//!
+//! To opt into the additional APIs available in the most recent nightly
+//! compiler, the `procmacro2_semver_exempt` config flag must be passed to
+//! rustc. We will polyfill those nightly-only APIs back to Rust 1.56.0. As
+//! these are unstable APIs that track the nightly compiler, minor versions of
+//! proc-macro2 may make breaking changes to them at any time.
+//!
+//! ```sh
+//! RUSTFLAGS='--cfg procmacro2_semver_exempt' cargo build
+//! ```
+//!
+//! Note that this must not only be done for your crate, but for any crate that
+//! depends on your crate. This infectious nature is intentional, as it serves
+//! as a reminder that you are outside of the normal semver guarantees.
+//!
+//! Semver exempt methods are marked as such in the proc-macro2 documentation.
+//!
+//! # Thread-Safety
+//!
+//! Most types in this crate are `!Sync` because the underlying compiler
+//! types make use of thread-local memory, meaning they cannot be accessed from
+//! a different thread.
+
+// Proc-macro2 types in rustdoc of other crates get linked to here.
+#![doc(html_root_url = "https://docs.rs/proc-macro2/1.0.79")]
+#![cfg_attr(any(proc_macro_span, super_unstable), feature(proc_macro_span))]
+#![cfg_attr(super_unstable, feature(proc_macro_def_site))]
+#![cfg_attr(doc_cfg, feature(doc_cfg))]
+#![deny(unsafe_op_in_unsafe_fn)]
+#![allow(
+    clippy::cast_lossless,
+    clippy::cast_possible_truncation,
+    clippy::checked_conversions,
+    clippy::doc_markdown,
+    clippy::incompatible_msrv,
+    clippy::items_after_statements,
+    clippy::iter_without_into_iter,
+    clippy::let_underscore_untyped,
+    clippy::manual_assert,
+    clippy::manual_range_contains,
+    clippy::missing_safety_doc,
+    clippy::must_use_candidate,
+    clippy::needless_doctest_main,
+    clippy::new_without_default,
+    clippy::return_self_not_must_use,
+    clippy::shadow_unrelated,
+    clippy::trivially_copy_pass_by_ref,
+    clippy::unnecessary_wraps,
+    clippy::unused_self,
+    clippy::used_underscore_binding,
+    clippy::vec_init_then_push
+)]
+
+#[cfg(all(procmacro2_semver_exempt, wrap_proc_macro, not(super_unstable)))]
+compile_error! {"\
+    Something is not right. If you've tried to turn on \
+    procmacro2_semver_exempt, you need to ensure that it \
+    is turned on for the compilation of the proc-macro2 \
+    build script as well.
+"}
+
+#[cfg(all(
+    procmacro2_nightly_testing,
+    feature = "proc-macro",
+    not(proc_macro_span)
+))]
+compile_error! {"\
+    Build script probe failed to compile.
+"}
+
+extern crate alloc;
+
+#[cfg(feature = "proc-macro")]
+extern crate proc_macro;
+
+mod marker;
+mod parse;
+mod rcvec;
+
+#[cfg(wrap_proc_macro)]
+mod detection;
+
+// Public for proc_macro2::fallback::force() and unforce(), but those are quite
+// a niche use case so we omit it from rustdoc.
+#[doc(hidden)]
+pub mod fallback;
+
+pub mod extra;
+
+#[cfg(not(wrap_proc_macro))]
+use crate::fallback as imp;
+#[path = "wrapper.rs"]
+#[cfg(wrap_proc_macro)]
+mod imp;
+
+#[cfg(span_locations)]
+mod location;
+
+use crate::extra::DelimSpan;
+use crate::marker::{ProcMacroAutoTraits, MARKER};
+use core::cmp::Ordering;
+use core::fmt::{self, Debug, Display};
+use core::hash::{Hash, Hasher};
+#[cfg(span_locations)]
+use core::ops::Range;
+use core::ops::RangeBounds;
+use core::str::FromStr;
+use std::error::Error;
+#[cfg(procmacro2_semver_exempt)]
+use std::path::PathBuf;
+
+#[cfg(span_locations)]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "span-locations")))]
+pub use crate::location::LineColumn;
+
+/// An abstract stream of tokens, or more concretely a sequence of token trees.
+///
+/// This type provides interfaces for iterating over token trees and for
+/// collecting token trees into one stream.
+///
+/// Token stream is both the input and output of `#[proc_macro]`,
+/// `#[proc_macro_attribute]` and `#[proc_macro_derive]` definitions.
+#[derive(Clone)]
+pub struct TokenStream {
+    inner: imp::TokenStream,
+    _marker: ProcMacroAutoTraits,
+}
+
+/// Error returned from `TokenStream::from_str`.
+pub struct LexError {
+    inner: imp::LexError,
+    _marker: ProcMacroAutoTraits,
+}
+
+impl TokenStream {
+    fn _new(inner: imp::TokenStream) -> Self {
+        TokenStream {
+            inner,
+            _marker: MARKER,
+        }
+    }
+
+    fn _new_fallback(inner: fallback::TokenStream) -> Self {
+        TokenStream {
+            inner: inner.into(),
+            _marker: MARKER,
+        }
+    }
+
+    /// Returns an empty `TokenStream` containing no token trees.
+    pub fn new() -> Self {
+        TokenStream::_new(imp::TokenStream::new())
+    }
+
+    /// Checks if this `TokenStream` is empty.
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+}
+
+/// `TokenStream::default()` returns an empty stream,
+/// i.e. this is equivalent with `TokenStream::new()`.
+impl Default for TokenStream {
+    fn default() -> Self {
+        TokenStream::new()
+    }
+}
+
+/// Attempts to break the string into tokens and parse those tokens into a token
+/// stream.
+///
+/// May fail for a number of reasons, for example, if the string contains
+/// unbalanced delimiters or characters not existing in the language.
+///
+/// NOTE: Some errors may cause panics instead of returning `LexError`. We
+/// reserve the right to change these errors into `LexError`s later.
+impl FromStr for TokenStream {
+    type Err = LexError;
+
+    fn from_str(src: &str) -> Result<TokenStream, LexError> {
+        let e = src.parse().map_err(|e| LexError {
+            inner: e,
+            _marker: MARKER,
+        })?;
+        Ok(TokenStream::_new(e))
+    }
+}
+
+#[cfg(feature = "proc-macro")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "proc-macro")))]
+impl From<proc_macro::TokenStream> for TokenStream {
+    fn from(inner: proc_macro::TokenStream) -> Self {
+        TokenStream::_new(inner.into())
+    }
+}
+
+#[cfg(feature = "proc-macro")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "proc-macro")))]
+impl From<TokenStream> for proc_macro::TokenStream {
+    fn from(inner: TokenStream) -> Self {
+        inner.inner.into()
+    }
+}
+
+impl From<TokenTree> for TokenStream {
+    fn from(token: TokenTree) -> Self {
+        TokenStream::_new(imp::TokenStream::from(token))
+    }
+}
+
+impl Extend<TokenTree> for TokenStream {
+    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, streams: I) {
+        self.inner.extend(streams);
+    }
+}
+
+impl Extend<TokenStream> for TokenStream {
+    fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
+        self.inner
+            .extend(streams.into_iter().map(|stream| stream.inner));
+    }
+}
+
+/// Collects a number of token trees into a single stream.
+impl FromIterator<TokenTree> for TokenStream {
+    fn from_iter<I: IntoIterator<Item = TokenTree>>(streams: I) -> Self {
+        TokenStream::_new(streams.into_iter().collect())
+    }
+}
+impl FromIterator<TokenStream> for TokenStream {
+    fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
+        TokenStream::_new(streams.into_iter().map(|i| i.inner).collect())
+    }
+}
+
+/// Prints the token stream as a string that is supposed to be losslessly
+/// convertible back into the same token stream (modulo spans), except for
+/// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
+/// numeric literals.
+impl Display for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.inner, f)
+    }
+}
+
+/// Prints token in a form convenient for debugging.
+impl Debug for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.inner, f)
+    }
+}
+
+impl LexError {
+    pub fn span(&self) -> Span {
+        Span::_new(self.inner.span())
+    }
+}
+
+impl Debug for LexError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.inner, f)
+    }
+}
+
+impl Display for LexError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.inner, f)
+    }
+}
+
+impl Error for LexError {}
+
+/// The source file of a given `Span`.
+///
+/// This type is semver exempt and not exposed by default.
+#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
+#[cfg_attr(doc_cfg, doc(cfg(procmacro2_semver_exempt)))]
+#[derive(Clone, PartialEq, Eq)]
+pub struct SourceFile {
+    inner: imp::SourceFile,
+    _marker: ProcMacroAutoTraits,
+}
+
+#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
+impl SourceFile {
+    fn _new(inner: imp::SourceFile) -> Self {
+        SourceFile {
+            inner,
+            _marker: MARKER,
+        }
+    }
+
+    /// Get the path to this source file.
+    ///
+    /// ### Note
+    ///
+    /// If the code span associated with this `SourceFile` was generated by an
+    /// external macro, this may not be an actual path on the filesystem. Use
+    /// [`is_real`] to check.
+    ///
+    /// Also note that even if `is_real` returns `true`, if
+    /// `--remap-path-prefix` was passed on the command line, the path as given
+    /// may not actually be valid.
+    ///
+    /// [`is_real`]: #method.is_real
+    pub fn path(&self) -> PathBuf {
+        self.inner.path()
+    }
+
+    /// Returns `true` if this source file is a real source file, and not
+    /// generated by an external macro's expansion.
+    pub fn is_real(&self) -> bool {
+        self.inner.is_real()
+    }
+}
+
+#[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
+impl Debug for SourceFile {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.inner, f)
+    }
+}
+
+/// A region of source code, along with macro expansion information.
+#[derive(Copy, Clone)]
+pub struct Span {
+    inner: imp::Span,
+    _marker: ProcMacroAutoTraits,
+}
+
+impl Span {
+    fn _new(inner: imp::Span) -> Self {
+        Span {
+            inner,
+            _marker: MARKER,
+        }
+    }
+
+    fn _new_fallback(inner: fallback::Span) -> Self {
+        Span {
+            inner: inner.into(),
+            _marker: MARKER,
+        }
+    }
+
+    /// The span of the invocation of the current procedural macro.
+    ///
+    /// Identifiers created with this span will be resolved as if they were
+    /// written directly at the macro call location (call-site hygiene) and
+    /// other code at the macro call site will be able to refer to them as well.
+    pub fn call_site() -> Self {
+        Span::_new(imp::Span::call_site())
+    }
+
+    /// The span located at the invocation of the procedural macro, but with
+    /// local variables, labels, and `$crate` resolved at the definition site
+    /// of the macro. This is the same hygiene behavior as `macro_rules`.
+    pub fn mixed_site() -> Self {
+        Span::_new(imp::Span::mixed_site())
+    }
+
+    /// A span that resolves at the macro definition site.
+    ///
+    /// This method is semver exempt and not exposed by default.
+    #[cfg(procmacro2_semver_exempt)]
+    #[cfg_attr(doc_cfg, doc(cfg(procmacro2_semver_exempt)))]
+    pub fn def_site() -> Self {
+        Span::_new(imp::Span::def_site())
+    }
+
+    /// Creates a new span with the same line/column information as `self` but
+    /// that resolves symbols as though it were at `other`.
+    pub fn resolved_at(&self, other: Span) -> Span {
+        Span::_new(self.inner.resolved_at(other.inner))
+    }
+
+    /// Creates a new span with the same name resolution behavior as `self` but
+    /// with the line/column information of `other`.
+    pub fn located_at(&self, other: Span) -> Span {
+        Span::_new(self.inner.located_at(other.inner))
+    }
+
+    /// Convert `proc_macro2::Span` to `proc_macro::Span`.
+    ///
+    /// This method is available when building with a nightly compiler, or when
+    /// building with rustc 1.29+ *without* semver exempt features.
+    ///
+    /// # Panics
+    ///
+    /// Panics if called from outside of a procedural macro. Unlike
+    /// `proc_macro2::Span`, the `proc_macro::Span` type can only exist within
+    /// the context of a procedural macro invocation.
+    #[cfg(wrap_proc_macro)]
+    pub fn unwrap(self) -> proc_macro::Span {
+        self.inner.unwrap()
+    }
+
+    // Soft deprecated. Please use Span::unwrap.
+    #[cfg(wrap_proc_macro)]
+    #[doc(hidden)]
+    pub fn unstable(self) -> proc_macro::Span {
+        self.unwrap()
+    }
+
+    /// The original source file into which this span points.
+    ///
+    /// This method is semver exempt and not exposed by default.
+    #[cfg(all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)))]
+    #[cfg_attr(doc_cfg, doc(cfg(procmacro2_semver_exempt)))]
+    pub fn source_file(&self) -> SourceFile {
+        SourceFile::_new(self.inner.source_file())
+    }
+
+    /// Returns the span's byte position range in the source file.
+    ///
+    /// This method requires the `"span-locations"` feature to be enabled.
+    ///
+    /// When executing in a procedural macro context, the returned range is only
+    /// accurate if compiled with a nightly toolchain. The stable toolchain does
+    /// not have this information available. When executing outside of a
+    /// procedural macro, such as main.rs or build.rs, the byte range is always
+    /// accurate regardless of toolchain.
+    #[cfg(span_locations)]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "span-locations")))]
+    pub fn byte_range(&self) -> Range<usize> {
+        self.inner.byte_range()
+    }
+
+    /// Get the starting line/column in the source file for this span.
+    ///
+    /// This method requires the `"span-locations"` feature to be enabled.
+    ///
+    /// When executing in a procedural macro context, the returned line/column
+    /// are only meaningful if compiled with a nightly toolchain. The stable
+    /// toolchain does not have this information available. When executing
+    /// outside of a procedural macro, such as main.rs or build.rs, the
+    /// line/column are always meaningful regardless of toolchain.
+    #[cfg(span_locations)]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "span-locations")))]
+    pub fn start(&self) -> LineColumn {
+        self.inner.start()
+    }
+
+    /// Get the ending line/column in the source file for this span.
+    ///
+    /// This method requires the `"span-locations"` feature to be enabled.
+    ///
+    /// When executing in a procedural macro context, the returned line/column
+    /// are only meaningful if compiled with a nightly toolchain. The stable
+    /// toolchain does not have this information available. When executing
+    /// outside of a procedural macro, such as main.rs or build.rs, the
+    /// line/column are always meaningful regardless of toolchain.
+    #[cfg(span_locations)]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "span-locations")))]
+    pub fn end(&self) -> LineColumn {
+        self.inner.end()
+    }
+
+    /// Create a new span encompassing `self` and `other`.
+    ///
+    /// Returns `None` if `self` and `other` are from different files.
+    ///
+    /// Warning: the underlying [`proc_macro::Span::join`] method is
+    /// nightly-only. When called from within a procedural macro not using a
+    /// nightly compiler, this method will always return `None`.
+    ///
+    /// [`proc_macro::Span::join`]: https://doc.rust-lang.org/proc_macro/struct.Span.html#method.join
+    pub fn join(&self, other: Span) -> Option<Span> {
+        self.inner.join(other.inner).map(Span::_new)
+    }
+
+    /// Compares two spans to see if they're equal.
+    ///
+    /// This method is semver exempt and not exposed by default.
+    #[cfg(procmacro2_semver_exempt)]
+    #[cfg_attr(doc_cfg, doc(cfg(procmacro2_semver_exempt)))]
+    pub fn eq(&self, other: &Span) -> bool {
+        self.inner.eq(&other.inner)
+    }
+
+    /// Returns the source text behind a span. This preserves the original
+    /// source code, including spaces and comments. It only returns a result if
+    /// the span corresponds to real source code.
+    ///
+    /// Note: The observable result of a macro should only rely on the tokens
+    /// and not on this source text. The result of this function is a best
+    /// effort to be used for diagnostics only.
+    pub fn source_text(&self) -> Option<String> {
+        self.inner.source_text()
+    }
+}
+
+/// Prints a span in a form convenient for debugging.
+impl Debug for Span {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.inner, f)
+    }
+}
+
+/// A single token or a delimited sequence of token trees (e.g. `[1, (), ..]`).
+#[derive(Clone)]
+pub enum TokenTree {
+    /// A token stream surrounded by bracket delimiters.
+    Group(Group),
+    /// An identifier.
+    Ident(Ident),
+    /// A single punctuation character (`+`, `,`, `$`, etc.).
+    Punct(Punct),
+    /// A literal character (`'a'`), string (`"hello"`), number (`2.3`), etc.
+    Literal(Literal),
+}
+
+impl TokenTree {
+    /// Returns the span of this tree, delegating to the `span` method of
+    /// the contained token or a delimited stream.
+    pub fn span(&self) -> Span {
+        match self {
+            TokenTree::Group(t) => t.span(),
+            TokenTree::Ident(t) => t.span(),
+            TokenTree::Punct(t) => t.span(),
+            TokenTree::Literal(t) => t.span(),
+        }
+    }
+
+    /// Configures the span for *only this token*.
+    ///
+    /// Note that if this token is a `Group` then this method will not configure
+    /// the span of each of the internal tokens, this will simply delegate to
+    /// the `set_span` method of each variant.
+    pub fn set_span(&mut self, span: Span) {
+        match self {
+            TokenTree::Group(t) => t.set_span(span),
+            TokenTree::Ident(t) => t.set_span(span),
+            TokenTree::Punct(t) => t.set_span(span),
+            TokenTree::Literal(t) => t.set_span(span),
+        }
+    }
+}
+
+impl From<Group> for TokenTree {
+    fn from(g: Group) -> Self {
+        TokenTree::Group(g)
+    }
+}
+
+impl From<Ident> for TokenTree {
+    fn from(g: Ident) -> Self {
+        TokenTree::Ident(g)
+    }
+}
+
+impl From<Punct> for TokenTree {
+    fn from(g: Punct) -> Self {
+        TokenTree::Punct(g)
+    }
+}
+
+impl From<Literal> for TokenTree {
+    fn from(g: Literal) -> Self {
+        TokenTree::Literal(g)
+    }
+}
+
+/// Prints the token tree as a string that is supposed to be losslessly
+/// convertible back into the same token tree (modulo spans), except for
+/// possibly `TokenTree::Group`s with `Delimiter::None` delimiters and negative
+/// numeric literals.
+impl Display for TokenTree {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            TokenTree::Group(t) => Display::fmt(t, f),
+            TokenTree::Ident(t) => Display::fmt(t, f),
+            TokenTree::Punct(t) => Display::fmt(t, f),
+            TokenTree::Literal(t) => Display::fmt(t, f),
+        }
+    }
+}
+
+/// Prints token tree in a form convenient for debugging.
+impl Debug for TokenTree {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        // Each of these has the name in the struct type in the derived debug,
+        // so don't bother with an extra layer of indirection
+        match self {
+            TokenTree::Group(t) => Debug::fmt(t, f),
+            TokenTree::Ident(t) => {
+                let mut debug = f.debug_struct("Ident");
+                debug.field("sym", &format_args!("{}", t));
+                imp::debug_span_field_if_nontrivial(&mut debug, t.span().inner);
+                debug.finish()
+            }
+            TokenTree::Punct(t) => Debug::fmt(t, f),
+            TokenTree::Literal(t) => Debug::fmt(t, f),
+        }
+    }
+}
+
+/// A delimited token stream.
+///
+/// A `Group` internally contains a `TokenStream` which is surrounded by
+/// `Delimiter`s.
+#[derive(Clone)]
+pub struct Group {
+    inner: imp::Group,
+}
+
+/// Describes how a sequence of token trees is delimited.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum Delimiter {
+    /// `( ... )`
+    Parenthesis,
+    /// `{ ... }`
+    Brace,
+    /// `[ ... ]`
+    Bracket,
+    /// `Ø ... Ø`
+    ///
+    /// An implicit delimiter, that may, for example, appear around tokens
+    /// coming from a "macro variable" `$var`. It is important to preserve
+    /// operator priorities in cases like `$var * 3` where `$var` is `1 + 2`.
+    /// Implicit delimiters may not survive roundtrip of a token stream through
+    /// a string.
+    None,
+}
+
+impl Group {
+    fn _new(inner: imp::Group) -> Self {
+        Group { inner }
+    }
+
+    fn _new_fallback(inner: fallback::Group) -> Self {
+        Group {
+            inner: inner.into(),
+        }
+    }
+
+    /// Creates a new `Group` with the given delimiter and token stream.
+    ///
+    /// This constructor will set the span for this group to
+    /// `Span::call_site()`. To change the span you can use the `set_span`
+    /// method below.
+    pub fn new(delimiter: Delimiter, stream: TokenStream) -> Self {
+        Group {
+            inner: imp::Group::new(delimiter, stream.inner),
+        }
+    }
+
+    /// Returns the punctuation used as the delimiter for this group: a set of
+    /// parentheses, square brackets, or curly braces.
+    pub fn delimiter(&self) -> Delimiter {
+        self.inner.delimiter()
+    }
+
+    /// Returns the `TokenStream` of tokens that are delimited in this `Group`.
+    ///
+    /// Note that the returned token stream does not include the delimiter
+    /// returned above.
+    pub fn stream(&self) -> TokenStream {
+        TokenStream::_new(self.inner.stream())
+    }
+
+    /// Returns the span for the delimiters of this token stream, spanning the
+    /// entire `Group`.
+    ///
+    /// ```text
+    /// pub fn span(&self) -> Span {
+    ///            ^^^^^^^
+    /// ```
+    pub fn span(&self) -> Span {
+        Span::_new(self.inner.span())
+    }
+
+    /// Returns the span pointing to the opening delimiter of this group.
+    ///
+    /// ```text
+    /// pub fn span_open(&self) -> Span {
+    ///                 ^
+    /// ```
+    pub fn span_open(&self) -> Span {
+        Span::_new(self.inner.span_open())
+    }
+
+    /// Returns the span pointing to the closing delimiter of this group.
+    ///
+    /// ```text
+    /// pub fn span_close(&self) -> Span {
+    ///                        ^
+    /// ```
+    pub fn span_close(&self) -> Span {
+        Span::_new(self.inner.span_close())
+    }
+
+    /// Returns an object that holds this group's `span_open()` and
+    /// `span_close()` together (in a more compact representation than holding
+    /// those 2 spans individually).
+    pub fn delim_span(&self) -> DelimSpan {
+        DelimSpan::new(&self.inner)
+    }
+
+    /// Configures the span for this `Group`'s delimiters, but not its internal
+    /// tokens.
+    ///
+    /// This method will **not** set the span of all the internal tokens spanned
+    /// by this group, but rather it will only set the span of the delimiter
+    /// tokens at the level of the `Group`.
+    pub fn set_span(&mut self, span: Span) {
+        self.inner.set_span(span.inner);
+    }
+}
+
+/// Prints the group as a string that should be losslessly convertible back
+/// into the same group (modulo spans), except for possibly `TokenTree::Group`s
+/// with `Delimiter::None` delimiters.
+impl Display for Group {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.inner, formatter)
+    }
+}
+
+impl Debug for Group {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.inner, formatter)
+    }
+}
+
+/// A `Punct` is a single punctuation character like `+`, `-` or `#`.
+///
+/// Multicharacter operators like `+=` are represented as two instances of
+/// `Punct` with different forms of `Spacing` returned.
+#[derive(Clone)]
+pub struct Punct {
+    ch: char,
+    spacing: Spacing,
+    span: Span,
+}
+
+/// Whether a `Punct` is followed immediately by another `Punct` or followed by
+/// another token or whitespace.
+#[derive(Copy, Clone, Debug, Eq, PartialEq)]
+pub enum Spacing {
+    /// E.g. `+` is `Alone` in `+ =`, `+ident` or `+()`.
+    Alone,
+    /// E.g. `+` is `Joint` in `+=` or `'` is `Joint` in `'#`.
+    ///
+    /// Additionally, single quote `'` can join with identifiers to form
+    /// lifetimes `'ident`.
+    Joint,
+}
+
+impl Punct {
+    /// Creates a new `Punct` from the given character and spacing.
+    ///
+    /// The `ch` argument must be a valid punctuation character permitted by the
+    /// language, otherwise the function will panic.
+    ///
+    /// The returned `Punct` will have the default span of `Span::call_site()`
+    /// which can be further configured with the `set_span` method below.
+    pub fn new(ch: char, spacing: Spacing) -> Self {
+        Punct {
+            ch,
+            spacing,
+            span: Span::call_site(),
+        }
+    }
+
+    /// Returns the value of this punctuation character as `char`.
+    pub fn as_char(&self) -> char {
+        self.ch
+    }
+
+    /// Returns the spacing of this punctuation character, indicating whether
+    /// it's immediately followed by another `Punct` in the token stream, so
+    /// they can potentially be combined into a multicharacter operator
+    /// (`Joint`), or it's followed by some other token or whitespace (`Alone`)
+    /// so the operator has certainly ended.
+    pub fn spacing(&self) -> Spacing {
+        self.spacing
+    }
+
+    /// Returns the span for this punctuation character.
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    /// Configure the span for this punctuation character.
+    pub fn set_span(&mut self, span: Span) {
+        self.span = span;
+    }
+}
+
+/// Prints the punctuation character as a string that should be losslessly
+/// convertible back into the same character.
+impl Display for Punct {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.ch, f)
+    }
+}
+
+impl Debug for Punct {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        let mut debug = fmt.debug_struct("Punct");
+        debug.field("char", &self.ch);
+        debug.field("spacing", &self.spacing);
+        imp::debug_span_field_if_nontrivial(&mut debug, self.span.inner);
+        debug.finish()
+    }
+}
+
+/// A word of Rust code, which may be a keyword or legal variable name.
+///
+/// An identifier consists of at least one Unicode code point, the first of
+/// which has the XID_Start property and the rest of which have the XID_Continue
+/// property.
+///
+/// - The empty string is not an identifier. Use `Option<Ident>`.
+/// - A lifetime is not an identifier. Use `syn::Lifetime` instead.
+///
+/// An identifier constructed with `Ident::new` is permitted to be a Rust
+/// keyword, though parsing one through its [`Parse`] implementation rejects
+/// Rust keywords. Use `input.call(Ident::parse_any)` when parsing to match the
+/// behaviour of `Ident::new`.
+///
+/// [`Parse`]: https://docs.rs/syn/2.0/syn/parse/trait.Parse.html
+///
+/// # Examples
+///
+/// A new ident can be created from a string using the `Ident::new` function.
+/// A span must be provided explicitly which governs the name resolution
+/// behavior of the resulting identifier.
+///
+/// ```
+/// use proc_macro2::{Ident, Span};
+///
+/// fn main() {
+///     let call_ident = Ident::new("calligraphy", Span::call_site());
+///
+///     println!("{}", call_ident);
+/// }
+/// ```
+///
+/// An ident can be interpolated into a token stream using the `quote!` macro.
+///
+/// ```
+/// use proc_macro2::{Ident, Span};
+/// use quote::quote;
+///
+/// fn main() {
+///     let ident = Ident::new("demo", Span::call_site());
+///
+///     // Create a variable binding whose name is this ident.
+///     let expanded = quote! { let #ident = 10; };
+///
+///     // Create a variable binding with a slightly different name.
+///     let temp_ident = Ident::new(&format!("new_{}", ident), Span::call_site());
+///     let expanded = quote! { let #temp_ident = 10; };
+/// }
+/// ```
+///
+/// A string representation of the ident is available through the `to_string()`
+/// method.
+///
+/// ```
+/// # use proc_macro2::{Ident, Span};
+/// #
+/// # let ident = Ident::new("another_identifier", Span::call_site());
+/// #
+/// // Examine the ident as a string.
+/// let ident_string = ident.to_string();
+/// if ident_string.len() > 60 {
+///     println!("Very long identifier: {}", ident_string)
+/// }
+/// ```
+#[derive(Clone)]
+pub struct Ident {
+    inner: imp::Ident,
+    _marker: ProcMacroAutoTraits,
+}
+
+impl Ident {
+    fn _new(inner: imp::Ident) -> Self {
+        Ident {
+            inner,
+            _marker: MARKER,
+        }
+    }
+
+    /// Creates a new `Ident` with the given `string` as well as the specified
+    /// `span`.
+    ///
+    /// The `string` argument must be a valid identifier permitted by the
+    /// language, otherwise the function will panic.
+    ///
+    /// Note that `span`, currently in rustc, configures the hygiene information
+    /// for this identifier.
+    ///
+    /// As of this time `Span::call_site()` explicitly opts-in to "call-site"
+    /// hygiene meaning that identifiers created with this span will be resolved
+    /// as if they were written directly at the location of the macro call, and
+    /// other code at the macro call site will be able to refer to them as well.
+    ///
+    /// Later spans like `Span::def_site()` will allow to opt-in to
+    /// "definition-site" hygiene meaning that identifiers created with this
+    /// span will be resolved at the location of the macro definition and other
+    /// code at the macro call site will not be able to refer to them.
+    ///
+    /// Due to the current importance of hygiene this constructor, unlike other
+    /// tokens, requires a `Span` to be specified at construction.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the input string is neither a keyword nor a legal variable
+    /// name. If you are not sure whether the string contains an identifier and
+    /// need to handle an error case, use
+    /// <a href="https://docs.rs/syn/2.0/syn/fn.parse_str.html"><code
+    ///   style="padding-right:0;">syn::parse_str</code></a><code
+    ///   style="padding-left:0;">::&lt;Ident&gt;</code>
+    /// rather than `Ident::new`.
+    #[track_caller]
+    pub fn new(string: &str, span: Span) -> Self {
+        Ident::_new(imp::Ident::new_checked(string, span.inner))
+    }
+
+    /// Same as `Ident::new`, but creates a raw identifier (`r#ident`). The
+    /// `string` argument must be a valid identifier permitted by the language
+    /// (including keywords, e.g. `fn`). Keywords which are usable in path
+    /// segments (e.g. `self`, `super`) are not supported, and will cause a
+    /// panic.
+    #[track_caller]
+    pub fn new_raw(string: &str, span: Span) -> Self {
+        Ident::_new(imp::Ident::new_raw_checked(string, span.inner))
+    }
+
+    /// Returns the span of this `Ident`.
+    pub fn span(&self) -> Span {
+        Span::_new(self.inner.span())
+    }
+
+    /// Configures the span of this `Ident`, possibly changing its hygiene
+    /// context.
+    pub fn set_span(&mut self, span: Span) {
+        self.inner.set_span(span.inner);
+    }
+}
+
+impl PartialEq for Ident {
+    fn eq(&self, other: &Ident) -> bool {
+        self.inner == other.inner
+    }
+}
+
+impl<T> PartialEq<T> for Ident
+where
+    T: ?Sized + AsRef<str>,
+{
+    fn eq(&self, other: &T) -> bool {
+        self.inner == other
+    }
+}
+
+impl Eq for Ident {}
+
+impl PartialOrd for Ident {
+    fn partial_cmp(&self, other: &Ident) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Ident {
+    fn cmp(&self, other: &Ident) -> Ordering {
+        self.to_string().cmp(&other.to_string())
+    }
+}
+
+impl Hash for Ident {
+    fn hash<H: Hasher>(&self, hasher: &mut H) {
+        self.to_string().hash(hasher);
+    }
+}
+
+/// Prints the identifier as a string that should be losslessly convertible back
+/// into the same identifier.
+impl Display for Ident {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.inner, f)
+    }
+}
+
+impl Debug for Ident {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.inner, f)
+    }
+}
+
+/// A literal string (`"hello"`), byte string (`b"hello"`), character (`'a'`),
+/// byte character (`b'a'`), an integer or floating point number with or without
+/// a suffix (`1`, `1u8`, `2.3`, `2.3f32`).
+///
+/// Boolean literals like `true` and `false` do not belong here, they are
+/// `Ident`s.
+#[derive(Clone)]
+pub struct Literal {
+    inner: imp::Literal,
+    _marker: ProcMacroAutoTraits,
+}
+
+macro_rules! suffixed_int_literals {
+    ($($name:ident => $kind:ident,)*) => ($(
+        /// Creates a new suffixed integer literal with the specified value.
+        ///
+        /// This function will create an integer like `1u32` where the integer
+        /// value specified is the first part of the token and the integral is
+        /// also suffixed at the end. Literals created from negative numbers may
+        /// not survive roundtrips through `TokenStream` or strings and may be
+        /// broken into two tokens (`-` and positive literal).
+        ///
+        /// Literals created through this method have the `Span::call_site()`
+        /// span by default, which can be configured with the `set_span` method
+        /// below.
+        pub fn $name(n: $kind) -> Literal {
+            Literal::_new(imp::Literal::$name(n))
+        }
+    )*)
+}
+
+macro_rules! unsuffixed_int_literals {
+    ($($name:ident => $kind:ident,)*) => ($(
+        /// Creates a new unsuffixed integer literal with the specified value.
+        ///
+        /// This function will create an integer like `1` where the integer
+        /// value specified is the first part of the token. No suffix is
+        /// specified on this token, meaning that invocations like
+        /// `Literal::i8_unsuffixed(1)` are equivalent to
+        /// `Literal::u32_unsuffixed(1)`. Literals created from negative numbers
+        /// may not survive roundtrips through `TokenStream` or strings and may
+        /// be broken into two tokens (`-` and positive literal).
+        ///
+        /// Literals created through this method have the `Span::call_site()`
+        /// span by default, which can be configured with the `set_span` method
+        /// below.
+        pub fn $name(n: $kind) -> Literal {
+            Literal::_new(imp::Literal::$name(n))
+        }
+    )*)
+}
+
+impl Literal {
+    fn _new(inner: imp::Literal) -> Self {
+        Literal {
+            inner,
+            _marker: MARKER,
+        }
+    }
+
+    fn _new_fallback(inner: fallback::Literal) -> Self {
+        Literal {
+            inner: inner.into(),
+            _marker: MARKER,
+        }
+    }
+
+    suffixed_int_literals! {
+        u8_suffixed => u8,
+        u16_suffixed => u16,
+        u32_suffixed => u32,
+        u64_suffixed => u64,
+        u128_suffixed => u128,
+        usize_suffixed => usize,
+        i8_suffixed => i8,
+        i16_suffixed => i16,
+        i32_suffixed => i32,
+        i64_suffixed => i64,
+        i128_suffixed => i128,
+        isize_suffixed => isize,
+    }
+
+    unsuffixed_int_literals! {
+        u8_unsuffixed => u8,
+        u16_unsuffixed => u16,
+        u32_unsuffixed => u32,
+        u64_unsuffixed => u64,
+        u128_unsuffixed => u128,
+        usize_unsuffixed => usize,
+        i8_unsuffixed => i8,
+        i16_unsuffixed => i16,
+        i32_unsuffixed => i32,
+        i64_unsuffixed => i64,
+        i128_unsuffixed => i128,
+        isize_unsuffixed => isize,
+    }
+
+    /// Creates a new unsuffixed floating-point literal.
+    ///
+    /// This constructor is similar to those like `Literal::i8_unsuffixed` where
+    /// the float's value is emitted directly into the token but no suffix is
+    /// used, so it may be inferred to be a `f64` later in the compiler.
+    /// Literals created from negative numbers may not survive round-trips
+    /// through `TokenStream` or strings and may be broken into two tokens (`-`
+    /// and positive literal).
+    ///
+    /// # Panics
+    ///
+    /// This function requires that the specified float is finite, for example
+    /// if it is infinity or NaN this function will panic.
+    pub fn f64_unsuffixed(f: f64) -> Literal {
+        assert!(f.is_finite());
+        Literal::_new(imp::Literal::f64_unsuffixed(f))
+    }
+
+    /// Creates a new suffixed floating-point literal.
+    ///
+    /// This constructor will create a literal like `1.0f64` where the value
+    /// specified is the preceding part of the token and `f64` is the suffix of
+    /// the token. This token will always be inferred to be an `f64` in the
+    /// compiler. Literals created from negative numbers may not survive
+    /// round-trips through `TokenStream` or strings and may be broken into two
+    /// tokens (`-` and positive literal).
+    ///
+    /// # Panics
+    ///
+    /// This function requires that the specified float is finite, for example
+    /// if it is infinity or NaN this function will panic.
+    pub fn f64_suffixed(f: f64) -> Literal {
+        assert!(f.is_finite());
+        Literal::_new(imp::Literal::f64_suffixed(f))
+    }
+
+    /// Creates a new unsuffixed floating-point literal.
+    ///
+    /// This constructor is similar to those like `Literal::i8_unsuffixed` where
+    /// the float's value is emitted directly into the token but no suffix is
+    /// used, so it may be inferred to be a `f64` later in the compiler.
+    /// Literals created from negative numbers may not survive round-trips
+    /// through `TokenStream` or strings and may be broken into two tokens (`-`
+    /// and positive literal).
+    ///
+    /// # Panics
+    ///
+    /// This function requires that the specified float is finite, for example
+    /// if it is infinity or NaN this function will panic.
+    pub fn f32_unsuffixed(f: f32) -> Literal {
+        assert!(f.is_finite());
+        Literal::_new(imp::Literal::f32_unsuffixed(f))
+    }
+
+    /// Creates a new suffixed floating-point literal.
+    ///
+    /// This constructor will create a literal like `1.0f32` where the value
+    /// specified is the preceding part of the token and `f32` is the suffix of
+    /// the token. This token will always be inferred to be an `f32` in the
+    /// compiler. Literals created from negative numbers may not survive
+    /// round-trips through `TokenStream` or strings and may be broken into two
+    /// tokens (`-` and positive literal).
+    ///
+    /// # Panics
+    ///
+    /// This function requires that the specified float is finite, for example
+    /// if it is infinity or NaN this function will panic.
+    pub fn f32_suffixed(f: f32) -> Literal {
+        assert!(f.is_finite());
+        Literal::_new(imp::Literal::f32_suffixed(f))
+    }
+
+    /// String literal.
+    pub fn string(string: &str) -> Literal {
+        Literal::_new(imp::Literal::string(string))
+    }
+
+    /// Character literal.
+    pub fn character(ch: char) -> Literal {
+        Literal::_new(imp::Literal::character(ch))
+    }
+
+    /// Byte string literal.
+    pub fn byte_string(s: &[u8]) -> Literal {
+        Literal::_new(imp::Literal::byte_string(s))
+    }
+
+    /// Returns the span encompassing this literal.
+    pub fn span(&self) -> Span {
+        Span::_new(self.inner.span())
+    }
+
+    /// Configures the span associated for this literal.
+    pub fn set_span(&mut self, span: Span) {
+        self.inner.set_span(span.inner);
+    }
+
+    /// Returns a `Span` that is a subset of `self.span()` containing only
+    /// the source bytes in range `range`. Returns `None` if the would-be
+    /// trimmed span is outside the bounds of `self`.
+    ///
+    /// Warning: the underlying [`proc_macro::Literal::subspan`] method is
+    /// nightly-only. When called from within a procedural macro not using a
+    /// nightly compiler, this method will always return `None`.
+    ///
+    /// [`proc_macro::Literal::subspan`]: https://doc.rust-lang.org/proc_macro/struct.Literal.html#method.subspan
+    pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
+        self.inner.subspan(range).map(Span::_new)
+    }
+
+    // Intended for the `quote!` macro to use when constructing a proc-macro2
+    // token out of a macro_rules $:literal token, which is already known to be
+    // a valid literal. This avoids reparsing/validating the literal's string
+    // representation. This is not public API other than for quote.
+    #[doc(hidden)]
+    pub unsafe fn from_str_unchecked(repr: &str) -> Self {
+        Literal::_new(unsafe { imp::Literal::from_str_unchecked(repr) })
+    }
+}
+
+impl FromStr for Literal {
+    type Err = LexError;
+
+    fn from_str(repr: &str) -> Result<Self, LexError> {
+        repr.parse().map(Literal::_new).map_err(|inner| LexError {
+            inner,
+            _marker: MARKER,
+        })
+    }
+}
+
+impl Debug for Literal {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.inner, f)
+    }
+}
+
+impl Display for Literal {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.inner, f)
+    }
+}
+
+/// Public implementation details for the `TokenStream` type, such as iterators.
+pub mod token_stream {
+    use crate::marker::{ProcMacroAutoTraits, MARKER};
+    use crate::{imp, TokenTree};
+    use core::fmt::{self, Debug};
+
+    pub use crate::TokenStream;
+
+    /// An iterator over `TokenStream`'s `TokenTree`s.
+    ///
+    /// The iteration is "shallow", e.g. the iterator doesn't recurse into
+    /// delimited groups, and returns whole groups as token trees.
+    #[derive(Clone)]
+    pub struct IntoIter {
+        inner: imp::TokenTreeIter,
+        _marker: ProcMacroAutoTraits,
+    }
+
+    impl Iterator for IntoIter {
+        type Item = TokenTree;
+
+        fn next(&mut self) -> Option<TokenTree> {
+            self.inner.next()
+        }
+
+        fn size_hint(&self) -> (usize, Option<usize>) {
+            self.inner.size_hint()
+        }
+    }
+
+    impl Debug for IntoIter {
+        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+            f.write_str("TokenStream ")?;
+            f.debug_list().entries(self.clone()).finish()
+        }
+    }
+
+    impl IntoIterator for TokenStream {
+        type Item = TokenTree;
+        type IntoIter = IntoIter;
+
+        fn into_iter(self) -> IntoIter {
+            IntoIter {
+                inner: self.inner.into_iter(),
+                _marker: MARKER,
+            }
+        }
+    }
+}
diff --git a/rust/proc-macro2/location.rs b/rust/proc-macro2/location.rs
new file mode 100644
index 0000000000000000000000000000000000000000..04ef1ad0e904f5034552002ccadaea4999aa853a
--- /dev/null
+++ b/rust/proc-macro2/location.rs
@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use core::cmp::Ordering;
+
+/// A line-column pair representing the start or end of a `Span`.
+///
+/// This type is semver exempt and not exposed by default.
+#[cfg_attr(doc_cfg, doc(cfg(feature = "span-locations")))]
+#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash)]
+pub struct LineColumn {
+    /// The 1-indexed line in the source file on which the span starts or ends
+    /// (inclusive).
+    pub line: usize,
+    /// The 0-indexed column (in UTF-8 characters) in the source file on which
+    /// the span starts or ends (inclusive).
+    pub column: usize,
+}
+
+impl Ord for LineColumn {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.line
+            .cmp(&other.line)
+            .then(self.column.cmp(&other.column))
+    }
+}
+
+impl PartialOrd for LineColumn {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
diff --git a/rust/proc-macro2/marker.rs b/rust/proc-macro2/marker.rs
new file mode 100644
index 0000000000000000000000000000000000000000..6f322424808c3add2aefaff942d46cdd5d0ae83a
--- /dev/null
+++ b/rust/proc-macro2/marker.rs
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use alloc::rc::Rc;
+use core::marker::PhantomData;
+use core::panic::{RefUnwindSafe, UnwindSafe};
+
+// Zero sized marker with the correct set of autotrait impls we want all proc
+// macro types to have.
+#[derive(Copy, Clone)]
+#[cfg_attr(
+    all(procmacro2_semver_exempt, any(not(wrap_proc_macro), super_unstable)),
+    derive(PartialEq, Eq)
+)]
+pub(crate) struct ProcMacroAutoTraits(PhantomData<Rc<()>>);
+
+pub(crate) const MARKER: ProcMacroAutoTraits = ProcMacroAutoTraits(PhantomData);
+
+impl UnwindSafe for ProcMacroAutoTraits {}
+impl RefUnwindSafe for ProcMacroAutoTraits {}
diff --git a/rust/proc-macro2/parse.rs b/rust/proc-macro2/parse.rs
new file mode 100644
index 0000000000000000000000000000000000000000..aeb4413e0a46797fdf32dc0933687394f1365d4b
--- /dev/null
+++ b/rust/proc-macro2/parse.rs
@@ -0,0 +1,998 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::fallback::{
+    self, is_ident_continue, is_ident_start, Group, LexError, Literal, Span, TokenStream,
+    TokenStreamBuilder,
+};
+use crate::{Delimiter, Punct, Spacing, TokenTree};
+use core::char;
+use core::str::{Bytes, CharIndices, Chars};
+
+#[derive(Copy, Clone, Eq, PartialEq)]
+pub(crate) struct Cursor<'a> {
+    pub rest: &'a str,
+    #[cfg(span_locations)]
+    pub off: u32,
+}
+
+impl<'a> Cursor<'a> {
+    pub fn advance(&self, bytes: usize) -> Cursor<'a> {
+        let (_front, rest) = self.rest.split_at(bytes);
+        Cursor {
+            rest,
+            #[cfg(span_locations)]
+            off: self.off + _front.chars().count() as u32,
+        }
+    }
+
+    pub fn starts_with(&self, s: &str) -> bool {
+        self.rest.starts_with(s)
+    }
+
+    pub fn starts_with_char(&self, ch: char) -> bool {
+        self.rest.starts_with(ch)
+    }
+
+    pub fn starts_with_fn<Pattern>(&self, f: Pattern) -> bool
+    where
+        Pattern: FnMut(char) -> bool,
+    {
+        self.rest.starts_with(f)
+    }
+
+    pub fn is_empty(&self) -> bool {
+        self.rest.is_empty()
+    }
+
+    fn len(&self) -> usize {
+        self.rest.len()
+    }
+
+    fn as_bytes(&self) -> &'a [u8] {
+        self.rest.as_bytes()
+    }
+
+    fn bytes(&self) -> Bytes<'a> {
+        self.rest.bytes()
+    }
+
+    fn chars(&self) -> Chars<'a> {
+        self.rest.chars()
+    }
+
+    fn char_indices(&self) -> CharIndices<'a> {
+        self.rest.char_indices()
+    }
+
+    fn parse(&self, tag: &str) -> Result<Cursor<'a>, Reject> {
+        if self.starts_with(tag) {
+            Ok(self.advance(tag.len()))
+        } else {
+            Err(Reject)
+        }
+    }
+}
+
+pub(crate) struct Reject;
+type PResult<'a, O> = Result<(Cursor<'a>, O), Reject>;
+
+fn skip_whitespace(input: Cursor) -> Cursor {
+    let mut s = input;
+
+    while !s.is_empty() {
+        let byte = s.as_bytes()[0];
+        if byte == b'/' {
+            if s.starts_with("//")
+                && (!s.starts_with("///") || s.starts_with("////"))
+                && !s.starts_with("//!")
+            {
+                let (cursor, _) = take_until_newline_or_eof(s);
+                s = cursor;
+                continue;
+            } else if s.starts_with("/**/") {
+                s = s.advance(4);
+                continue;
+            } else if s.starts_with("/*")
+                && (!s.starts_with("/**") || s.starts_with("/***"))
+                && !s.starts_with("/*!")
+            {
+                match block_comment(s) {
+                    Ok((rest, _)) => {
+                        s = rest;
+                        continue;
+                    }
+                    Err(Reject) => return s,
+                }
+            }
+        }
+        match byte {
+            b' ' | 0x09..=0x0d => {
+                s = s.advance(1);
+                continue;
+            }
+            b if b.is_ascii() => {}
+            _ => {
+                let ch = s.chars().next().unwrap();
+                if is_whitespace(ch) {
+                    s = s.advance(ch.len_utf8());
+                    continue;
+                }
+            }
+        }
+        return s;
+    }
+    s
+}
+
+fn block_comment(input: Cursor) -> PResult<&str> {
+    if !input.starts_with("/*") {
+        return Err(Reject);
+    }
+
+    let mut depth = 0usize;
+    let bytes = input.as_bytes();
+    let mut i = 0usize;
+    let upper = bytes.len() - 1;
+
+    while i < upper {
+        if bytes[i] == b'/' && bytes[i + 1] == b'*' {
+            depth += 1;
+            i += 1; // eat '*'
+        } else if bytes[i] == b'*' && bytes[i + 1] == b'/' {
+            depth -= 1;
+            if depth == 0 {
+                return Ok((input.advance(i + 2), &input.rest[..i + 2]));
+            }
+            i += 1; // eat '/'
+        }
+        i += 1;
+    }
+
+    Err(Reject)
+}
+
+fn is_whitespace(ch: char) -> bool {
+    // Rust treats left-to-right mark and right-to-left mark as whitespace
+    ch.is_whitespace() || ch == '\u{200e}' || ch == '\u{200f}'
+}
+
+fn word_break(input: Cursor) -> Result<Cursor, Reject> {
+    match input.chars().next() {
+        Some(ch) if is_ident_continue(ch) => Err(Reject),
+        Some(_) | None => Ok(input),
+    }
+}
+
+// Rustc's representation of a macro expansion error in expression position or
+// type position.
+const ERROR: &str = "(/*ERROR*/)";
+
+pub(crate) fn token_stream(mut input: Cursor) -> Result<TokenStream, LexError> {
+    let mut trees = TokenStreamBuilder::new();
+    let mut stack = Vec::new();
+
+    loop {
+        input = skip_whitespace(input);
+
+        if let Ok((rest, ())) = doc_comment(input, &mut trees) {
+            input = rest;
+            continue;
+        }
+
+        #[cfg(span_locations)]
+        let lo = input.off;
+
+        let first = match input.bytes().next() {
+            Some(first) => first,
+            None => match stack.last() {
+                None => return Ok(trees.build()),
+                #[cfg(span_locations)]
+                Some((lo, _frame)) => {
+                    return Err(LexError {
+                        span: Span { lo: *lo, hi: *lo },
+                    })
+                }
+                #[cfg(not(span_locations))]
+                Some(_frame) => return Err(LexError { span: Span {} }),
+            },
+        };
+
+        if let Some(open_delimiter) = match first {
+            b'(' if !input.starts_with(ERROR) => Some(Delimiter::Parenthesis),
+            b'[' => Some(Delimiter::Bracket),
+            b'{' => Some(Delimiter::Brace),
+            _ => None,
+        } {
+            input = input.advance(1);
+            let frame = (open_delimiter, trees);
+            #[cfg(span_locations)]
+            let frame = (lo, frame);
+            stack.push(frame);
+            trees = TokenStreamBuilder::new();
+        } else if let Some(close_delimiter) = match first {
+            b')' => Some(Delimiter::Parenthesis),
+            b']' => Some(Delimiter::Bracket),
+            b'}' => Some(Delimiter::Brace),
+            _ => None,
+        } {
+            let frame = match stack.pop() {
+                Some(frame) => frame,
+                None => return Err(lex_error(input)),
+            };
+            #[cfg(span_locations)]
+            let (lo, frame) = frame;
+            let (open_delimiter, outer) = frame;
+            if open_delimiter != close_delimiter {
+                return Err(lex_error(input));
+            }
+            input = input.advance(1);
+            let mut g = Group::new(open_delimiter, trees.build());
+            g.set_span(Span {
+                #[cfg(span_locations)]
+                lo,
+                #[cfg(span_locations)]
+                hi: input.off,
+            });
+            trees = outer;
+            trees.push_token_from_parser(TokenTree::Group(crate::Group::_new_fallback(g)));
+        } else {
+            let (rest, mut tt) = match leaf_token(input) {
+                Ok((rest, tt)) => (rest, tt),
+                Err(Reject) => return Err(lex_error(input)),
+            };
+            tt.set_span(crate::Span::_new_fallback(Span {
+                #[cfg(span_locations)]
+                lo,
+                #[cfg(span_locations)]
+                hi: rest.off,
+            }));
+            trees.push_token_from_parser(tt);
+            input = rest;
+        }
+    }
+}
+
+fn lex_error(cursor: Cursor) -> LexError {
+    #[cfg(not(span_locations))]
+    let _ = cursor;
+    LexError {
+        span: Span {
+            #[cfg(span_locations)]
+            lo: cursor.off,
+            #[cfg(span_locations)]
+            hi: cursor.off,
+        },
+    }
+}
+
+fn leaf_token(input: Cursor) -> PResult<TokenTree> {
+    if let Ok((input, l)) = literal(input) {
+        // must be parsed before ident
+        Ok((input, TokenTree::Literal(crate::Literal::_new_fallback(l))))
+    } else if let Ok((input, p)) = punct(input) {
+        Ok((input, TokenTree::Punct(p)))
+    } else if let Ok((input, i)) = ident(input) {
+        Ok((input, TokenTree::Ident(i)))
+    } else if input.starts_with(ERROR) {
+        let rest = input.advance(ERROR.len());
+        let repr = crate::Literal::_new_fallback(Literal::_new(ERROR.to_owned()));
+        Ok((rest, TokenTree::Literal(repr)))
+    } else {
+        Err(Reject)
+    }
+}
+
+fn ident(input: Cursor) -> PResult<crate::Ident> {
+    if [
+        "r\"", "r#\"", "r##", "b\"", "b\'", "br\"", "br#", "c\"", "cr\"", "cr#",
+    ]
+    .iter()
+    .any(|prefix| input.starts_with(prefix))
+    {
+        Err(Reject)
+    } else {
+        ident_any(input)
+    }
+}
+
+fn ident_any(input: Cursor) -> PResult<crate::Ident> {
+    let raw = input.starts_with("r#");
+    let rest = input.advance((raw as usize) << 1);
+
+    let (rest, sym) = ident_not_raw(rest)?;
+
+    if !raw {
+        let ident = crate::Ident::_new(crate::imp::Ident::new_unchecked(
+            sym,
+            fallback::Span::call_site(),
+        ));
+        return Ok((rest, ident));
+    }
+
+    match sym {
+        "_" | "super" | "self" | "Self" | "crate" => return Err(Reject),
+        _ => {}
+    }
+
+    let ident = crate::Ident::_new(crate::imp::Ident::new_raw_unchecked(
+        sym,
+        fallback::Span::call_site(),
+    ));
+    Ok((rest, ident))
+}
+
+fn ident_not_raw(input: Cursor) -> PResult<&str> {
+    let mut chars = input.char_indices();
+
+    match chars.next() {
+        Some((_, ch)) if is_ident_start(ch) => {}
+        _ => return Err(Reject),
+    }
+
+    let mut end = input.len();
+    for (i, ch) in chars {
+        if !is_ident_continue(ch) {
+            end = i;
+            break;
+        }
+    }
+
+    Ok((input.advance(end), &input.rest[..end]))
+}
+
+pub(crate) fn literal(input: Cursor) -> PResult<Literal> {
+    let rest = literal_nocapture(input)?;
+    let end = input.len() - rest.len();
+    Ok((rest, Literal::_new(input.rest[..end].to_string())))
+}
+
+fn literal_nocapture(input: Cursor) -> Result<Cursor, Reject> {
+    if let Ok(ok) = string(input) {
+        Ok(ok)
+    } else if let Ok(ok) = byte_string(input) {
+        Ok(ok)
+    } else if let Ok(ok) = c_string(input) {
+        Ok(ok)
+    } else if let Ok(ok) = byte(input) {
+        Ok(ok)
+    } else if let Ok(ok) = character(input) {
+        Ok(ok)
+    } else if let Ok(ok) = float(input) {
+        Ok(ok)
+    } else if let Ok(ok) = int(input) {
+        Ok(ok)
+    } else {
+        Err(Reject)
+    }
+}
+
+fn literal_suffix(input: Cursor) -> Cursor {
+    match ident_not_raw(input) {
+        Ok((input, _)) => input,
+        Err(Reject) => input,
+    }
+}
+
+fn string(input: Cursor) -> Result<Cursor, Reject> {
+    if let Ok(input) = input.parse("\"") {
+        cooked_string(input)
+    } else if let Ok(input) = input.parse("r") {
+        raw_string(input)
+    } else {
+        Err(Reject)
+    }
+}
+
+fn cooked_string(mut input: Cursor) -> Result<Cursor, Reject> {
+    let mut chars = input.char_indices();
+
+    while let Some((i, ch)) = chars.next() {
+        match ch {
+            '"' => {
+                let input = input.advance(i + 1);
+                return Ok(literal_suffix(input));
+            }
+            '\r' => match chars.next() {
+                Some((_, '\n')) => {}
+                _ => break,
+            },
+            '\\' => match chars.next() {
+                Some((_, 'x')) => {
+                    backslash_x_char(&mut chars)?;
+                }
+                Some((_, 'n' | 'r' | 't' | '\\' | '\'' | '"' | '0')) => {}
+                Some((_, 'u')) => {
+                    backslash_u(&mut chars)?;
+                }
+                Some((newline, ch @ ('\n' | '\r'))) => {
+                    input = input.advance(newline + 1);
+                    trailing_backslash(&mut input, ch as u8)?;
+                    chars = input.char_indices();
+                }
+                _ => break,
+            },
+            _ch => {}
+        }
+    }
+    Err(Reject)
+}
+
+fn raw_string(input: Cursor) -> Result<Cursor, Reject> {
+    let (input, delimiter) = delimiter_of_raw_string(input)?;
+    let mut bytes = input.bytes().enumerate();
+    while let Some((i, byte)) = bytes.next() {
+        match byte {
+            b'"' if input.rest[i + 1..].starts_with(delimiter) => {
+                let rest = input.advance(i + 1 + delimiter.len());
+                return Ok(literal_suffix(rest));
+            }
+            b'\r' => match bytes.next() {
+                Some((_, b'\n')) => {}
+                _ => break,
+            },
+            _ => {}
+        }
+    }
+    Err(Reject)
+}
+
+fn byte_string(input: Cursor) -> Result<Cursor, Reject> {
+    if let Ok(input) = input.parse("b\"") {
+        cooked_byte_string(input)
+    } else if let Ok(input) = input.parse("br") {
+        raw_byte_string(input)
+    } else {
+        Err(Reject)
+    }
+}
+
+fn cooked_byte_string(mut input: Cursor) -> Result<Cursor, Reject> {
+    let mut bytes = input.bytes().enumerate();
+    while let Some((offset, b)) = bytes.next() {
+        match b {
+            b'"' => {
+                let input = input.advance(offset + 1);
+                return Ok(literal_suffix(input));
+            }
+            b'\r' => match bytes.next() {
+                Some((_, b'\n')) => {}
+                _ => break,
+            },
+            b'\\' => match bytes.next() {
+                Some((_, b'x')) => {
+                    backslash_x_byte(&mut bytes)?;
+                }
+                Some((_, b'n' | b'r' | b't' | b'\\' | b'0' | b'\'' | b'"')) => {}
+                Some((newline, b @ (b'\n' | b'\r'))) => {
+                    input = input.advance(newline + 1);
+                    trailing_backslash(&mut input, b)?;
+                    bytes = input.bytes().enumerate();
+                }
+                _ => break,
+            },
+            b if b.is_ascii() => {}
+            _ => break,
+        }
+    }
+    Err(Reject)
+}
+
+fn delimiter_of_raw_string(input: Cursor) -> PResult<&str> {
+    for (i, byte) in input.bytes().enumerate() {
+        match byte {
+            b'"' => {
+                if i > 255 {
+                    // https://github.com/rust-lang/rust/pull/95251
+                    return Err(Reject);
+                }
+                return Ok((input.advance(i + 1), &input.rest[..i]));
+            }
+            b'#' => {}
+            _ => break,
+        }
+    }
+    Err(Reject)
+}
+
+fn raw_byte_string(input: Cursor) -> Result<Cursor, Reject> {
+    let (input, delimiter) = delimiter_of_raw_string(input)?;
+    let mut bytes = input.bytes().enumerate();
+    while let Some((i, byte)) = bytes.next() {
+        match byte {
+            b'"' if input.rest[i + 1..].starts_with(delimiter) => {
+                let rest = input.advance(i + 1 + delimiter.len());
+                return Ok(literal_suffix(rest));
+            }
+            b'\r' => match bytes.next() {
+                Some((_, b'\n')) => {}
+                _ => break,
+            },
+            other => {
+                if !other.is_ascii() {
+                    break;
+                }
+            }
+        }
+    }
+    Err(Reject)
+}
+
+fn c_string(input: Cursor) -> Result<Cursor, Reject> {
+    if let Ok(input) = input.parse("c\"") {
+        cooked_c_string(input)
+    } else if let Ok(input) = input.parse("cr") {
+        raw_c_string(input)
+    } else {
+        Err(Reject)
+    }
+}
+
+fn raw_c_string(input: Cursor) -> Result<Cursor, Reject> {
+    let (input, delimiter) = delimiter_of_raw_string(input)?;
+    let mut bytes = input.bytes().enumerate();
+    while let Some((i, byte)) = bytes.next() {
+        match byte {
+            b'"' if input.rest[i + 1..].starts_with(delimiter) => {
+                let rest = input.advance(i + 1 + delimiter.len());
+                return Ok(literal_suffix(rest));
+            }
+            b'\r' => match bytes.next() {
+                Some((_, b'\n')) => {}
+                _ => break,
+            },
+            b'\0' => break,
+            _ => {}
+        }
+    }
+    Err(Reject)
+}
+
+fn cooked_c_string(mut input: Cursor) -> Result<Cursor, Reject> {
+    let mut chars = input.char_indices();
+
+    while let Some((i, ch)) = chars.next() {
+        match ch {
+            '"' => {
+                let input = input.advance(i + 1);
+                return Ok(literal_suffix(input));
+            }
+            '\r' => match chars.next() {
+                Some((_, '\n')) => {}
+                _ => break,
+            },
+            '\\' => match chars.next() {
+                Some((_, 'x')) => {
+                    backslash_x_nonzero(&mut chars)?;
+                }
+                Some((_, 'n' | 'r' | 't' | '\\' | '\'' | '"')) => {}
+                Some((_, 'u')) => {
+                    if backslash_u(&mut chars)? == '\0' {
+                        break;
+                    }
+                }
+                Some((newline, ch @ ('\n' | '\r'))) => {
+                    input = input.advance(newline + 1);
+                    trailing_backslash(&mut input, ch as u8)?;
+                    chars = input.char_indices();
+                }
+                _ => break,
+            },
+            '\0' => break,
+            _ch => {}
+        }
+    }
+    Err(Reject)
+}
+
+fn byte(input: Cursor) -> Result<Cursor, Reject> {
+    let input = input.parse("b'")?;
+    let mut bytes = input.bytes().enumerate();
+    let ok = match bytes.next().map(|(_, b)| b) {
+        Some(b'\\') => match bytes.next().map(|(_, b)| b) {
+            Some(b'x') => backslash_x_byte(&mut bytes).is_ok(),
+            Some(b'n' | b'r' | b't' | b'\\' | b'0' | b'\'' | b'"') => true,
+            _ => false,
+        },
+        b => b.is_some(),
+    };
+    if !ok {
+        return Err(Reject);
+    }
+    let (offset, _) = bytes.next().ok_or(Reject)?;
+    if !input.chars().as_str().is_char_boundary(offset) {
+        return Err(Reject);
+    }
+    let input = input.advance(offset).parse("'")?;
+    Ok(literal_suffix(input))
+}
+
+fn character(input: Cursor) -> Result<Cursor, Reject> {
+    let input = input.parse("'")?;
+    let mut chars = input.char_indices();
+    let ok = match chars.next().map(|(_, ch)| ch) {
+        Some('\\') => match chars.next().map(|(_, ch)| ch) {
+            Some('x') => backslash_x_char(&mut chars).is_ok(),
+            Some('u') => backslash_u(&mut chars).is_ok(),
+            Some('n' | 'r' | 't' | '\\' | '0' | '\'' | '"') => true,
+            _ => false,
+        },
+        ch => ch.is_some(),
+    };
+    if !ok {
+        return Err(Reject);
+    }
+    let (idx, _) = chars.next().ok_or(Reject)?;
+    let input = input.advance(idx).parse("'")?;
+    Ok(literal_suffix(input))
+}
+
+macro_rules! next_ch {
+    ($chars:ident @ $pat:pat) => {
+        match $chars.next() {
+            Some((_, ch)) => match ch {
+                $pat => ch,
+                _ => return Err(Reject),
+            },
+            None => return Err(Reject),
+        }
+    };
+}
+
+fn backslash_x_char<I>(chars: &mut I) -> Result<(), Reject>
+where
+    I: Iterator<Item = (usize, char)>,
+{
+    next_ch!(chars @ '0'..='7');
+    next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F');
+    Ok(())
+}
+
+fn backslash_x_byte<I>(chars: &mut I) -> Result<(), Reject>
+where
+    I: Iterator<Item = (usize, u8)>,
+{
+    next_ch!(chars @ b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F');
+    next_ch!(chars @ b'0'..=b'9' | b'a'..=b'f' | b'A'..=b'F');
+    Ok(())
+}
+
+fn backslash_x_nonzero<I>(chars: &mut I) -> Result<(), Reject>
+where
+    I: Iterator<Item = (usize, char)>,
+{
+    let first = next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F');
+    let second = next_ch!(chars @ '0'..='9' | 'a'..='f' | 'A'..='F');
+    if first == '0' && second == '0' {
+        Err(Reject)
+    } else {
+        Ok(())
+    }
+}
+
+fn backslash_u<I>(chars: &mut I) -> Result<char, Reject>
+where
+    I: Iterator<Item = (usize, char)>,
+{
+    next_ch!(chars @ '{');
+    let mut value = 0;
+    let mut len = 0;
+    for (_, ch) in chars {
+        let digit = match ch {
+            '0'..='9' => ch as u8 - b'0',
+            'a'..='f' => 10 + ch as u8 - b'a',
+            'A'..='F' => 10 + ch as u8 - b'A',
+            '_' if len > 0 => continue,
+            '}' if len > 0 => return char::from_u32(value).ok_or(Reject),
+            _ => break,
+        };
+        if len == 6 {
+            break;
+        }
+        value *= 0x10;
+        value += u32::from(digit);
+        len += 1;
+    }
+    Err(Reject)
+}
+
+fn trailing_backslash(input: &mut Cursor, mut last: u8) -> Result<(), Reject> {
+    let mut whitespace = input.bytes().enumerate();
+    loop {
+        if last == b'\r' && whitespace.next().map_or(true, |(_, b)| b != b'\n') {
+            return Err(Reject);
+        }
+        match whitespace.next() {
+            Some((_, b @ (b' ' | b'\t' | b'\n' | b'\r'))) => {
+                last = b;
+            }
+            Some((offset, _)) => {
+                *input = input.advance(offset);
+                return Ok(());
+            }
+            None => return Err(Reject),
+        }
+    }
+}
+
+fn float(input: Cursor) -> Result<Cursor, Reject> {
+    let mut rest = float_digits(input)?;
+    if let Some(ch) = rest.chars().next() {
+        if is_ident_start(ch) {
+            rest = ident_not_raw(rest)?.0;
+        }
+    }
+    word_break(rest)
+}
+
+fn float_digits(input: Cursor) -> Result<Cursor, Reject> {
+    let mut chars = input.chars().peekable();
+    match chars.next() {
+        Some(ch) if '0' <= ch && ch <= '9' => {}
+        _ => return Err(Reject),
+    }
+
+    let mut len = 1;
+    let mut has_dot = false;
+    let mut has_exp = false;
+    while let Some(&ch) = chars.peek() {
+        match ch {
+            '0'..='9' | '_' => {
+                chars.next();
+                len += 1;
+            }
+            '.' => {
+                if has_dot {
+                    break;
+                }
+                chars.next();
+                if chars
+                    .peek()
+                    .map_or(false, |&ch| ch == '.' || is_ident_start(ch))
+                {
+                    return Err(Reject);
+                }
+                len += 1;
+                has_dot = true;
+            }
+            'e' | 'E' => {
+                chars.next();
+                len += 1;
+                has_exp = true;
+                break;
+            }
+            _ => break,
+        }
+    }
+
+    if !(has_dot || has_exp) {
+        return Err(Reject);
+    }
+
+    if has_exp {
+        let token_before_exp = if has_dot {
+            Ok(input.advance(len - 1))
+        } else {
+            Err(Reject)
+        };
+        let mut has_sign = false;
+        let mut has_exp_value = false;
+        while let Some(&ch) = chars.peek() {
+            match ch {
+                '+' | '-' => {
+                    if has_exp_value {
+                        break;
+                    }
+                    if has_sign {
+                        return token_before_exp;
+                    }
+                    chars.next();
+                    len += 1;
+                    has_sign = true;
+                }
+                '0'..='9' => {
+                    chars.next();
+                    len += 1;
+                    has_exp_value = true;
+                }
+                '_' => {
+                    chars.next();
+                    len += 1;
+                }
+                _ => break,
+            }
+        }
+        if !has_exp_value {
+            return token_before_exp;
+        }
+    }
+
+    Ok(input.advance(len))
+}
+
+fn int(input: Cursor) -> Result<Cursor, Reject> {
+    let mut rest = digits(input)?;
+    if let Some(ch) = rest.chars().next() {
+        if is_ident_start(ch) {
+            rest = ident_not_raw(rest)?.0;
+        }
+    }
+    word_break(rest)
+}
+
+fn digits(mut input: Cursor) -> Result<Cursor, Reject> {
+    let base = if input.starts_with("0x") {
+        input = input.advance(2);
+        16
+    } else if input.starts_with("0o") {
+        input = input.advance(2);
+        8
+    } else if input.starts_with("0b") {
+        input = input.advance(2);
+        2
+    } else {
+        10
+    };
+
+    let mut len = 0;
+    let mut empty = true;
+    for b in input.bytes() {
+        match b {
+            b'0'..=b'9' => {
+                let digit = (b - b'0') as u64;
+                if digit >= base {
+                    return Err(Reject);
+                }
+            }
+            b'a'..=b'f' => {
+                let digit = 10 + (b - b'a') as u64;
+                if digit >= base {
+                    break;
+                }
+            }
+            b'A'..=b'F' => {
+                let digit = 10 + (b - b'A') as u64;
+                if digit >= base {
+                    break;
+                }
+            }
+            b'_' => {
+                if empty && base == 10 {
+                    return Err(Reject);
+                }
+                len += 1;
+                continue;
+            }
+            _ => break,
+        };
+        len += 1;
+        empty = false;
+    }
+    if empty {
+        Err(Reject)
+    } else {
+        Ok(input.advance(len))
+    }
+}
+
+fn punct(input: Cursor) -> PResult<Punct> {
+    let (rest, ch) = punct_char(input)?;
+    if ch == '\'' {
+        if ident_any(rest)?.0.starts_with_char('\'') {
+            Err(Reject)
+        } else {
+            Ok((rest, Punct::new('\'', Spacing::Joint)))
+        }
+    } else {
+        let kind = match punct_char(rest) {
+            Ok(_) => Spacing::Joint,
+            Err(Reject) => Spacing::Alone,
+        };
+        Ok((rest, Punct::new(ch, kind)))
+    }
+}
+
+fn punct_char(input: Cursor) -> PResult<char> {
+    if input.starts_with("//") || input.starts_with("/*") {
+        // Do not accept `/` of a comment as a punct.
+        return Err(Reject);
+    }
+
+    let mut chars = input.chars();
+    let first = match chars.next() {
+        Some(ch) => ch,
+        None => {
+            return Err(Reject);
+        }
+    };
+    let recognized = "~!@#$%^&*-=+|;:,<.>/?'";
+    if recognized.contains(first) {
+        Ok((input.advance(first.len_utf8()), first))
+    } else {
+        Err(Reject)
+    }
+}
+
+fn doc_comment<'a>(input: Cursor<'a>, trees: &mut TokenStreamBuilder) -> PResult<'a, ()> {
+    #[cfg(span_locations)]
+    let lo = input.off;
+    let (rest, (comment, inner)) = doc_comment_contents(input)?;
+    let fallback_span = Span {
+        #[cfg(span_locations)]
+        lo,
+        #[cfg(span_locations)]
+        hi: rest.off,
+    };
+    let span = crate::Span::_new_fallback(fallback_span);
+
+    let mut scan_for_bare_cr = comment;
+    while let Some(cr) = scan_for_bare_cr.find('\r') {
+        let rest = &scan_for_bare_cr[cr + 1..];
+        if !rest.starts_with('\n') {
+            return Err(Reject);
+        }
+        scan_for_bare_cr = rest;
+    }
+
+    let mut pound = Punct::new('#', Spacing::Alone);
+    pound.set_span(span);
+    trees.push_token_from_parser(TokenTree::Punct(pound));
+
+    if inner {
+        let mut bang = Punct::new('!', Spacing::Alone);
+        bang.set_span(span);
+        trees.push_token_from_parser(TokenTree::Punct(bang));
+    }
+
+    let doc_ident = crate::Ident::_new(crate::imp::Ident::new_unchecked("doc", fallback_span));
+    let mut equal = Punct::new('=', Spacing::Alone);
+    equal.set_span(span);
+    let mut literal = crate::Literal::string(comment);
+    literal.set_span(span);
+    let mut bracketed = TokenStreamBuilder::with_capacity(3);
+    bracketed.push_token_from_parser(TokenTree::Ident(doc_ident));
+    bracketed.push_token_from_parser(TokenTree::Punct(equal));
+    bracketed.push_token_from_parser(TokenTree::Literal(literal));
+    let group = Group::new(Delimiter::Bracket, bracketed.build());
+    let mut group = crate::Group::_new_fallback(group);
+    group.set_span(span);
+    trees.push_token_from_parser(TokenTree::Group(group));
+
+    Ok((rest, ()))
+}
+
+fn doc_comment_contents(input: Cursor) -> PResult<(&str, bool)> {
+    if input.starts_with("//!") {
+        let input = input.advance(3);
+        let (input, s) = take_until_newline_or_eof(input);
+        Ok((input, (s, true)))
+    } else if input.starts_with("/*!") {
+        let (input, s) = block_comment(input)?;
+        Ok((input, (&s[3..s.len() - 2], true)))
+    } else if input.starts_with("///") {
+        let input = input.advance(3);
+        if input.starts_with_char('/') {
+            return Err(Reject);
+        }
+        let (input, s) = take_until_newline_or_eof(input);
+        Ok((input, (s, false)))
+    } else if input.starts_with("/**") && !input.rest[3..].starts_with('*') {
+        let (input, s) = block_comment(input)?;
+        Ok((input, (&s[3..s.len() - 2], false)))
+    } else {
+        Err(Reject)
+    }
+}
+
+fn take_until_newline_or_eof(input: Cursor) -> (Cursor, &str) {
+    let chars = input.char_indices();
+
+    for (i, ch) in chars {
+        if ch == '\n' {
+            return (input.advance(i), &input.rest[..i]);
+        } else if ch == '\r' && input.rest[i + 1..].starts_with('\n') {
+            return (input.advance(i + 1), &input.rest[..i]);
+        }
+    }
+
+    (input.advance(input.len()), input.rest)
+}
diff --git a/rust/proc-macro2/rcvec.rs b/rust/proc-macro2/rcvec.rs
new file mode 100644
index 0000000000000000000000000000000000000000..c52d519e00b8f5a31bd6324f078ba248d4ed72dd
--- /dev/null
+++ b/rust/proc-macro2/rcvec.rs
@@ -0,0 +1,147 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use alloc::rc::Rc;
+use alloc::vec;
+use core::mem;
+use core::panic::RefUnwindSafe;
+use core::slice;
+
+pub(crate) struct RcVec<T> {
+    inner: Rc<Vec<T>>,
+}
+
+pub(crate) struct RcVecBuilder<T> {
+    inner: Vec<T>,
+}
+
+pub(crate) struct RcVecMut<'a, T> {
+    inner: &'a mut Vec<T>,
+}
+
+#[derive(Clone)]
+pub(crate) struct RcVecIntoIter<T> {
+    inner: vec::IntoIter<T>,
+}
+
+impl<T> RcVec<T> {
+    pub fn is_empty(&self) -> bool {
+        self.inner.is_empty()
+    }
+
+    pub fn len(&self) -> usize {
+        self.inner.len()
+    }
+
+    pub fn iter(&self) -> slice::Iter<T> {
+        self.inner.iter()
+    }
+
+    pub fn make_mut(&mut self) -> RcVecMut<T>
+    where
+        T: Clone,
+    {
+        RcVecMut {
+            inner: Rc::make_mut(&mut self.inner),
+        }
+    }
+
+    pub fn get_mut(&mut self) -> Option<RcVecMut<T>> {
+        let inner = Rc::get_mut(&mut self.inner)?;
+        Some(RcVecMut { inner })
+    }
+
+    pub fn make_owned(mut self) -> RcVecBuilder<T>
+    where
+        T: Clone,
+    {
+        let vec = if let Some(owned) = Rc::get_mut(&mut self.inner) {
+            mem::take(owned)
+        } else {
+            Vec::clone(&self.inner)
+        };
+        RcVecBuilder { inner: vec }
+    }
+}
+
+impl<T> RcVecBuilder<T> {
+    pub fn new() -> Self {
+        RcVecBuilder { inner: Vec::new() }
+    }
+
+    pub fn with_capacity(cap: usize) -> Self {
+        RcVecBuilder {
+            inner: Vec::with_capacity(cap),
+        }
+    }
+
+    pub fn push(&mut self, element: T) {
+        self.inner.push(element);
+    }
+
+    pub fn extend(&mut self, iter: impl IntoIterator<Item = T>) {
+        self.inner.extend(iter);
+    }
+
+    pub fn as_mut(&mut self) -> RcVecMut<T> {
+        RcVecMut {
+            inner: &mut self.inner,
+        }
+    }
+
+    pub fn build(self) -> RcVec<T> {
+        RcVec {
+            inner: Rc::new(self.inner),
+        }
+    }
+}
+
+impl<'a, T> RcVecMut<'a, T> {
+    pub fn push(&mut self, element: T) {
+        self.inner.push(element);
+    }
+
+    pub fn extend(&mut self, iter: impl IntoIterator<Item = T>) {
+        self.inner.extend(iter);
+    }
+
+    pub fn pop(&mut self) -> Option<T> {
+        self.inner.pop()
+    }
+
+    pub fn as_mut(&mut self) -> RcVecMut<T> {
+        RcVecMut { inner: self.inner }
+    }
+}
+
+impl<T> Clone for RcVec<T> {
+    fn clone(&self) -> Self {
+        RcVec {
+            inner: Rc::clone(&self.inner),
+        }
+    }
+}
+
+impl<T> IntoIterator for RcVecBuilder<T> {
+    type Item = T;
+    type IntoIter = RcVecIntoIter<T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        RcVecIntoIter {
+            inner: self.inner.into_iter(),
+        }
+    }
+}
+
+impl<T> Iterator for RcVecIntoIter<T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next()
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        self.inner.size_hint()
+    }
+}
+
+impl<T> RefUnwindSafe for RcVec<T> where T: RefUnwindSafe {}
diff --git a/rust/proc-macro2/wrapper.rs b/rust/proc-macro2/wrapper.rs
new file mode 100644
index 0000000000000000000000000000000000000000..d1bba27b6068dc619ebe7c6d424c5b2aee211169
--- /dev/null
+++ b/rust/proc-macro2/wrapper.rs
@@ -0,0 +1,956 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::detection::inside_proc_macro;
+#[cfg(span_locations)]
+use crate::location::LineColumn;
+use crate::{fallback, Delimiter, Punct, Spacing, TokenTree};
+use core::fmt::{self, Debug, Display};
+#[cfg(span_locations)]
+use core::ops::Range;
+use core::ops::RangeBounds;
+use core::str::FromStr;
+use std::panic;
+#[cfg(super_unstable)]
+use std::path::PathBuf;
+
+#[derive(Clone)]
+pub(crate) enum TokenStream {
+    Compiler(DeferredTokenStream),
+    Fallback(fallback::TokenStream),
+}
+
+// Work around https://github.com/rust-lang/rust/issues/65080.
+// In `impl Extend<TokenTree> for TokenStream` which is used heavily by quote,
+// we hold on to the appended tokens and do proc_macro::TokenStream::extend as
+// late as possible to batch together consecutive uses of the Extend impl.
+#[derive(Clone)]
+pub(crate) struct DeferredTokenStream {
+    stream: proc_macro::TokenStream,
+    extra: Vec<proc_macro::TokenTree>,
+}
+
+pub(crate) enum LexError {
+    Compiler(proc_macro::LexError),
+    Fallback(fallback::LexError),
+
+    // Rustc was supposed to return a LexError, but it panicked instead.
+    // https://github.com/rust-lang/rust/issues/58736
+    CompilerPanic,
+}
+
+#[cold]
+fn mismatch(line: u32) -> ! {
+    #[cfg(procmacro2_backtrace)]
+    {
+        let backtrace = std::backtrace::Backtrace::force_capture();
+        panic!("compiler/fallback mismatch #{}\n\n{}", line, backtrace)
+    }
+    #[cfg(not(procmacro2_backtrace))]
+    {
+        panic!("compiler/fallback mismatch #{}", line)
+    }
+}
+
+impl DeferredTokenStream {
+    fn new(stream: proc_macro::TokenStream) -> Self {
+        DeferredTokenStream {
+            stream,
+            extra: Vec::new(),
+        }
+    }
+
+    fn is_empty(&self) -> bool {
+        self.stream.is_empty() && self.extra.is_empty()
+    }
+
+    fn evaluate_now(&mut self) {
+        // If-check provides a fast short circuit for the common case of `extra`
+        // being empty, which saves a round trip over the proc macro bridge.
+        // Improves macro expansion time in winrt by 6% in debug mode.
+        if !self.extra.is_empty() {
+            self.stream.extend(self.extra.drain(..));
+        }
+    }
+
+    fn into_token_stream(mut self) -> proc_macro::TokenStream {
+        self.evaluate_now();
+        self.stream
+    }
+}
+
+impl TokenStream {
+    pub fn new() -> Self {
+        if inside_proc_macro() {
+            TokenStream::Compiler(DeferredTokenStream::new(proc_macro::TokenStream::new()))
+        } else {
+            TokenStream::Fallback(fallback::TokenStream::new())
+        }
+    }
+
+    pub fn is_empty(&self) -> bool {
+        match self {
+            TokenStream::Compiler(tts) => tts.is_empty(),
+            TokenStream::Fallback(tts) => tts.is_empty(),
+        }
+    }
+
+    fn unwrap_nightly(self) -> proc_macro::TokenStream {
+        match self {
+            TokenStream::Compiler(s) => s.into_token_stream(),
+            TokenStream::Fallback(_) => mismatch(line!()),
+        }
+    }
+
+    fn unwrap_stable(self) -> fallback::TokenStream {
+        match self {
+            TokenStream::Compiler(_) => mismatch(line!()),
+            TokenStream::Fallback(s) => s,
+        }
+    }
+}
+
+impl FromStr for TokenStream {
+    type Err = LexError;
+
+    fn from_str(src: &str) -> Result<TokenStream, LexError> {
+        if inside_proc_macro() {
+            Ok(TokenStream::Compiler(DeferredTokenStream::new(
+                proc_macro_parse(src)?,
+            )))
+        } else {
+            Ok(TokenStream::Fallback(src.parse()?))
+        }
+    }
+}
+
+// Work around https://github.com/rust-lang/rust/issues/58736.
+fn proc_macro_parse(src: &str) -> Result<proc_macro::TokenStream, LexError> {
+    let result = panic::catch_unwind(|| src.parse().map_err(LexError::Compiler));
+    result.unwrap_or_else(|_| Err(LexError::CompilerPanic))
+}
+
+impl Display for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            TokenStream::Compiler(tts) => Display::fmt(&tts.clone().into_token_stream(), f),
+            TokenStream::Fallback(tts) => Display::fmt(tts, f),
+        }
+    }
+}
+
+impl From<proc_macro::TokenStream> for TokenStream {
+    fn from(inner: proc_macro::TokenStream) -> Self {
+        TokenStream::Compiler(DeferredTokenStream::new(inner))
+    }
+}
+
+impl From<TokenStream> for proc_macro::TokenStream {
+    fn from(inner: TokenStream) -> Self {
+        match inner {
+            TokenStream::Compiler(inner) => inner.into_token_stream(),
+            TokenStream::Fallback(inner) => inner.to_string().parse().unwrap(),
+        }
+    }
+}
+
+impl From<fallback::TokenStream> for TokenStream {
+    fn from(inner: fallback::TokenStream) -> Self {
+        TokenStream::Fallback(inner)
+    }
+}
+
+// Assumes inside_proc_macro().
+fn into_compiler_token(token: TokenTree) -> proc_macro::TokenTree {
+    match token {
+        TokenTree::Group(tt) => tt.inner.unwrap_nightly().into(),
+        TokenTree::Punct(tt) => {
+            let spacing = match tt.spacing() {
+                Spacing::Joint => proc_macro::Spacing::Joint,
+                Spacing::Alone => proc_macro::Spacing::Alone,
+            };
+            let mut punct = proc_macro::Punct::new(tt.as_char(), spacing);
+            punct.set_span(tt.span().inner.unwrap_nightly());
+            punct.into()
+        }
+        TokenTree::Ident(tt) => tt.inner.unwrap_nightly().into(),
+        TokenTree::Literal(tt) => tt.inner.unwrap_nightly().into(),
+    }
+}
+
+impl From<TokenTree> for TokenStream {
+    fn from(token: TokenTree) -> Self {
+        if inside_proc_macro() {
+            TokenStream::Compiler(DeferredTokenStream::new(into_compiler_token(token).into()))
+        } else {
+            TokenStream::Fallback(token.into())
+        }
+    }
+}
+
+impl FromIterator<TokenTree> for TokenStream {
+    fn from_iter<I: IntoIterator<Item = TokenTree>>(trees: I) -> Self {
+        if inside_proc_macro() {
+            TokenStream::Compiler(DeferredTokenStream::new(
+                trees.into_iter().map(into_compiler_token).collect(),
+            ))
+        } else {
+            TokenStream::Fallback(trees.into_iter().collect())
+        }
+    }
+}
+
+impl FromIterator<TokenStream> for TokenStream {
+    fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
+        let mut streams = streams.into_iter();
+        match streams.next() {
+            Some(TokenStream::Compiler(mut first)) => {
+                first.evaluate_now();
+                first.stream.extend(streams.map(|s| match s {
+                    TokenStream::Compiler(s) => s.into_token_stream(),
+                    TokenStream::Fallback(_) => mismatch(line!()),
+                }));
+                TokenStream::Compiler(first)
+            }
+            Some(TokenStream::Fallback(mut first)) => {
+                first.extend(streams.map(|s| match s {
+                    TokenStream::Fallback(s) => s,
+                    TokenStream::Compiler(_) => mismatch(line!()),
+                }));
+                TokenStream::Fallback(first)
+            }
+            None => TokenStream::new(),
+        }
+    }
+}
+
+impl Extend<TokenTree> for TokenStream {
+    fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, stream: I) {
+        match self {
+            TokenStream::Compiler(tts) => {
+                // Here is the reason for DeferredTokenStream.
+                for token in stream {
+                    tts.extra.push(into_compiler_token(token));
+                }
+            }
+            TokenStream::Fallback(tts) => tts.extend(stream),
+        }
+    }
+}
+
+impl Extend<TokenStream> for TokenStream {
+    fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
+        match self {
+            TokenStream::Compiler(tts) => {
+                tts.evaluate_now();
+                tts.stream
+                    .extend(streams.into_iter().map(TokenStream::unwrap_nightly));
+            }
+            TokenStream::Fallback(tts) => {
+                tts.extend(streams.into_iter().map(TokenStream::unwrap_stable));
+            }
+        }
+    }
+}
+
+impl Debug for TokenStream {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            TokenStream::Compiler(tts) => Debug::fmt(&tts.clone().into_token_stream(), f),
+            TokenStream::Fallback(tts) => Debug::fmt(tts, f),
+        }
+    }
+}
+
+impl LexError {
+    pub(crate) fn span(&self) -> Span {
+        match self {
+            LexError::Compiler(_) | LexError::CompilerPanic => Span::call_site(),
+            LexError::Fallback(e) => Span::Fallback(e.span()),
+        }
+    }
+}
+
+impl From<proc_macro::LexError> for LexError {
+    fn from(e: proc_macro::LexError) -> Self {
+        LexError::Compiler(e)
+    }
+}
+
+impl From<fallback::LexError> for LexError {
+    fn from(e: fallback::LexError) -> Self {
+        LexError::Fallback(e)
+    }
+}
+
+impl Debug for LexError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            LexError::Compiler(e) => Debug::fmt(e, f),
+            LexError::Fallback(e) => Debug::fmt(e, f),
+            LexError::CompilerPanic => {
+                let fallback = fallback::LexError::call_site();
+                Debug::fmt(&fallback, f)
+            }
+        }
+    }
+}
+
+impl Display for LexError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            LexError::Compiler(e) => Display::fmt(e, f),
+            LexError::Fallback(e) => Display::fmt(e, f),
+            LexError::CompilerPanic => {
+                let fallback = fallback::LexError::call_site();
+                Display::fmt(&fallback, f)
+            }
+        }
+    }
+}
+
+#[derive(Clone)]
+pub(crate) enum TokenTreeIter {
+    Compiler(proc_macro::token_stream::IntoIter),
+    Fallback(fallback::TokenTreeIter),
+}
+
+impl IntoIterator for TokenStream {
+    type Item = TokenTree;
+    type IntoIter = TokenTreeIter;
+
+    fn into_iter(self) -> TokenTreeIter {
+        match self {
+            TokenStream::Compiler(tts) => {
+                TokenTreeIter::Compiler(tts.into_token_stream().into_iter())
+            }
+            TokenStream::Fallback(tts) => TokenTreeIter::Fallback(tts.into_iter()),
+        }
+    }
+}
+
+impl Iterator for TokenTreeIter {
+    type Item = TokenTree;
+
+    fn next(&mut self) -> Option<TokenTree> {
+        let token = match self {
+            TokenTreeIter::Compiler(iter) => iter.next()?,
+            TokenTreeIter::Fallback(iter) => return iter.next(),
+        };
+        Some(match token {
+            proc_macro::TokenTree::Group(tt) => crate::Group::_new(Group::Compiler(tt)).into(),
+            proc_macro::TokenTree::Punct(tt) => {
+                let spacing = match tt.spacing() {
+                    proc_macro::Spacing::Joint => Spacing::Joint,
+                    proc_macro::Spacing::Alone => Spacing::Alone,
+                };
+                let mut o = Punct::new(tt.as_char(), spacing);
+                o.set_span(crate::Span::_new(Span::Compiler(tt.span())));
+                o.into()
+            }
+            proc_macro::TokenTree::Ident(s) => crate::Ident::_new(Ident::Compiler(s)).into(),
+            proc_macro::TokenTree::Literal(l) => crate::Literal::_new(Literal::Compiler(l)).into(),
+        })
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        match self {
+            TokenTreeIter::Compiler(tts) => tts.size_hint(),
+            TokenTreeIter::Fallback(tts) => tts.size_hint(),
+        }
+    }
+}
+
+#[derive(Clone, PartialEq, Eq)]
+#[cfg(super_unstable)]
+pub(crate) enum SourceFile {
+    Compiler(proc_macro::SourceFile),
+    Fallback(fallback::SourceFile),
+}
+
+#[cfg(super_unstable)]
+impl SourceFile {
+    fn nightly(sf: proc_macro::SourceFile) -> Self {
+        SourceFile::Compiler(sf)
+    }
+
+    /// Get the path to this source file as a string.
+    pub fn path(&self) -> PathBuf {
+        match self {
+            SourceFile::Compiler(a) => a.path(),
+            SourceFile::Fallback(a) => a.path(),
+        }
+    }
+
+    pub fn is_real(&self) -> bool {
+        match self {
+            SourceFile::Compiler(a) => a.is_real(),
+            SourceFile::Fallback(a) => a.is_real(),
+        }
+    }
+}
+
+#[cfg(super_unstable)]
+impl Debug for SourceFile {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            SourceFile::Compiler(a) => Debug::fmt(a, f),
+            SourceFile::Fallback(a) => Debug::fmt(a, f),
+        }
+    }
+}
+
+#[derive(Copy, Clone)]
+pub(crate) enum Span {
+    Compiler(proc_macro::Span),
+    Fallback(fallback::Span),
+}
+
+impl Span {
+    pub fn call_site() -> Self {
+        if inside_proc_macro() {
+            Span::Compiler(proc_macro::Span::call_site())
+        } else {
+            Span::Fallback(fallback::Span::call_site())
+        }
+    }
+
+    pub fn mixed_site() -> Self {
+        if inside_proc_macro() {
+            Span::Compiler(proc_macro::Span::mixed_site())
+        } else {
+            Span::Fallback(fallback::Span::mixed_site())
+        }
+    }
+
+    #[cfg(super_unstable)]
+    pub fn def_site() -> Self {
+        if inside_proc_macro() {
+            Span::Compiler(proc_macro::Span::def_site())
+        } else {
+            Span::Fallback(fallback::Span::def_site())
+        }
+    }
+
+    pub fn resolved_at(&self, other: Span) -> Span {
+        match (self, other) {
+            (Span::Compiler(a), Span::Compiler(b)) => Span::Compiler(a.resolved_at(b)),
+            (Span::Fallback(a), Span::Fallback(b)) => Span::Fallback(a.resolved_at(b)),
+            (Span::Compiler(_), Span::Fallback(_)) => mismatch(line!()),
+            (Span::Fallback(_), Span::Compiler(_)) => mismatch(line!()),
+        }
+    }
+
+    pub fn located_at(&self, other: Span) -> Span {
+        match (self, other) {
+            (Span::Compiler(a), Span::Compiler(b)) => Span::Compiler(a.located_at(b)),
+            (Span::Fallback(a), Span::Fallback(b)) => Span::Fallback(a.located_at(b)),
+            (Span::Compiler(_), Span::Fallback(_)) => mismatch(line!()),
+            (Span::Fallback(_), Span::Compiler(_)) => mismatch(line!()),
+        }
+    }
+
+    pub fn unwrap(self) -> proc_macro::Span {
+        match self {
+            Span::Compiler(s) => s,
+            Span::Fallback(_) => panic!("proc_macro::Span is only available in procedural macros"),
+        }
+    }
+
+    #[cfg(super_unstable)]
+    pub fn source_file(&self) -> SourceFile {
+        match self {
+            Span::Compiler(s) => SourceFile::nightly(s.source_file()),
+            Span::Fallback(s) => SourceFile::Fallback(s.source_file()),
+        }
+    }
+
+    #[cfg(span_locations)]
+    pub fn byte_range(&self) -> Range<usize> {
+        match self {
+            #[cfg(proc_macro_span)]
+            Span::Compiler(s) => s.byte_range(),
+            #[cfg(not(proc_macro_span))]
+            Span::Compiler(_) => 0..0,
+            Span::Fallback(s) => s.byte_range(),
+        }
+    }
+
+    #[cfg(span_locations)]
+    pub fn start(&self) -> LineColumn {
+        match self {
+            Span::Compiler(_) => LineColumn { line: 0, column: 0 },
+            Span::Fallback(s) => s.start(),
+        }
+    }
+
+    #[cfg(span_locations)]
+    pub fn end(&self) -> LineColumn {
+        match self {
+            Span::Compiler(_) => LineColumn { line: 0, column: 0 },
+            Span::Fallback(s) => s.end(),
+        }
+    }
+
+    pub fn join(&self, other: Span) -> Option<Span> {
+        let ret = match (self, other) {
+            #[cfg(proc_macro_span)]
+            (Span::Compiler(a), Span::Compiler(b)) => Span::Compiler(a.join(b)?),
+            (Span::Fallback(a), Span::Fallback(b)) => Span::Fallback(a.join(b)?),
+            _ => return None,
+        };
+        Some(ret)
+    }
+
+    #[cfg(super_unstable)]
+    pub fn eq(&self, other: &Span) -> bool {
+        match (self, other) {
+            (Span::Compiler(a), Span::Compiler(b)) => a.eq(b),
+            (Span::Fallback(a), Span::Fallback(b)) => a.eq(b),
+            _ => false,
+        }
+    }
+
+    pub fn source_text(&self) -> Option<String> {
+        match self {
+            #[cfg(not(no_source_text))]
+            Span::Compiler(s) => s.source_text(),
+            #[cfg(no_source_text)]
+            Span::Compiler(_) => None,
+            Span::Fallback(s) => s.source_text(),
+        }
+    }
+
+    fn unwrap_nightly(self) -> proc_macro::Span {
+        match self {
+            Span::Compiler(s) => s,
+            Span::Fallback(_) => mismatch(line!()),
+        }
+    }
+}
+
+impl From<proc_macro::Span> for crate::Span {
+    fn from(proc_span: proc_macro::Span) -> Self {
+        crate::Span::_new(Span::Compiler(proc_span))
+    }
+}
+
+impl From<fallback::Span> for Span {
+    fn from(inner: fallback::Span) -> Self {
+        Span::Fallback(inner)
+    }
+}
+
+impl Debug for Span {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Span::Compiler(s) => Debug::fmt(s, f),
+            Span::Fallback(s) => Debug::fmt(s, f),
+        }
+    }
+}
+
+pub(crate) fn debug_span_field_if_nontrivial(debug: &mut fmt::DebugStruct, span: Span) {
+    match span {
+        Span::Compiler(s) => {
+            debug.field("span", &s);
+        }
+        Span::Fallback(s) => fallback::debug_span_field_if_nontrivial(debug, s),
+    }
+}
+
+#[derive(Clone)]
+pub(crate) enum Group {
+    Compiler(proc_macro::Group),
+    Fallback(fallback::Group),
+}
+
+impl Group {
+    pub fn new(delimiter: Delimiter, stream: TokenStream) -> Self {
+        match stream {
+            TokenStream::Compiler(tts) => {
+                let delimiter = match delimiter {
+                    Delimiter::Parenthesis => proc_macro::Delimiter::Parenthesis,
+                    Delimiter::Bracket => proc_macro::Delimiter::Bracket,
+                    Delimiter::Brace => proc_macro::Delimiter::Brace,
+                    Delimiter::None => proc_macro::Delimiter::None,
+                };
+                Group::Compiler(proc_macro::Group::new(delimiter, tts.into_token_stream()))
+            }
+            TokenStream::Fallback(stream) => {
+                Group::Fallback(fallback::Group::new(delimiter, stream))
+            }
+        }
+    }
+
+    pub fn delimiter(&self) -> Delimiter {
+        match self {
+            Group::Compiler(g) => match g.delimiter() {
+                proc_macro::Delimiter::Parenthesis => Delimiter::Parenthesis,
+                proc_macro::Delimiter::Bracket => Delimiter::Bracket,
+                proc_macro::Delimiter::Brace => Delimiter::Brace,
+                proc_macro::Delimiter::None => Delimiter::None,
+            },
+            Group::Fallback(g) => g.delimiter(),
+        }
+    }
+
+    pub fn stream(&self) -> TokenStream {
+        match self {
+            Group::Compiler(g) => TokenStream::Compiler(DeferredTokenStream::new(g.stream())),
+            Group::Fallback(g) => TokenStream::Fallback(g.stream()),
+        }
+    }
+
+    pub fn span(&self) -> Span {
+        match self {
+            Group::Compiler(g) => Span::Compiler(g.span()),
+            Group::Fallback(g) => Span::Fallback(g.span()),
+        }
+    }
+
+    pub fn span_open(&self) -> Span {
+        match self {
+            Group::Compiler(g) => Span::Compiler(g.span_open()),
+            Group::Fallback(g) => Span::Fallback(g.span_open()),
+        }
+    }
+
+    pub fn span_close(&self) -> Span {
+        match self {
+            Group::Compiler(g) => Span::Compiler(g.span_close()),
+            Group::Fallback(g) => Span::Fallback(g.span_close()),
+        }
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        match (self, span) {
+            (Group::Compiler(g), Span::Compiler(s)) => g.set_span(s),
+            (Group::Fallback(g), Span::Fallback(s)) => g.set_span(s),
+            (Group::Compiler(_), Span::Fallback(_)) => mismatch(line!()),
+            (Group::Fallback(_), Span::Compiler(_)) => mismatch(line!()),
+        }
+    }
+
+    fn unwrap_nightly(self) -> proc_macro::Group {
+        match self {
+            Group::Compiler(g) => g,
+            Group::Fallback(_) => mismatch(line!()),
+        }
+    }
+}
+
+impl From<fallback::Group> for Group {
+    fn from(g: fallback::Group) -> Self {
+        Group::Fallback(g)
+    }
+}
+
+impl Display for Group {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Group::Compiler(group) => Display::fmt(group, formatter),
+            Group::Fallback(group) => Display::fmt(group, formatter),
+        }
+    }
+}
+
+impl Debug for Group {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Group::Compiler(group) => Debug::fmt(group, formatter),
+            Group::Fallback(group) => Debug::fmt(group, formatter),
+        }
+    }
+}
+
+#[derive(Clone)]
+pub(crate) enum Ident {
+    Compiler(proc_macro::Ident),
+    Fallback(fallback::Ident),
+}
+
+impl Ident {
+    #[track_caller]
+    pub fn new_checked(string: &str, span: Span) -> Self {
+        match span {
+            Span::Compiler(s) => Ident::Compiler(proc_macro::Ident::new(string, s)),
+            Span::Fallback(s) => Ident::Fallback(fallback::Ident::new_checked(string, s)),
+        }
+    }
+
+    pub fn new_unchecked(string: &str, span: fallback::Span) -> Self {
+        Ident::Fallback(fallback::Ident::new_unchecked(string, span))
+    }
+
+    #[track_caller]
+    pub fn new_raw_checked(string: &str, span: Span) -> Self {
+        match span {
+            Span::Compiler(s) => Ident::Compiler(proc_macro::Ident::new_raw(string, s)),
+            Span::Fallback(s) => Ident::Fallback(fallback::Ident::new_raw_checked(string, s)),
+        }
+    }
+
+    pub fn new_raw_unchecked(string: &str, span: fallback::Span) -> Self {
+        Ident::Fallback(fallback::Ident::new_raw_unchecked(string, span))
+    }
+
+    pub fn span(&self) -> Span {
+        match self {
+            Ident::Compiler(t) => Span::Compiler(t.span()),
+            Ident::Fallback(t) => Span::Fallback(t.span()),
+        }
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        match (self, span) {
+            (Ident::Compiler(t), Span::Compiler(s)) => t.set_span(s),
+            (Ident::Fallback(t), Span::Fallback(s)) => t.set_span(s),
+            (Ident::Compiler(_), Span::Fallback(_)) => mismatch(line!()),
+            (Ident::Fallback(_), Span::Compiler(_)) => mismatch(line!()),
+        }
+    }
+
+    fn unwrap_nightly(self) -> proc_macro::Ident {
+        match self {
+            Ident::Compiler(s) => s,
+            Ident::Fallback(_) => mismatch(line!()),
+        }
+    }
+}
+
+impl PartialEq for Ident {
+    fn eq(&self, other: &Ident) -> bool {
+        match (self, other) {
+            (Ident::Compiler(t), Ident::Compiler(o)) => t.to_string() == o.to_string(),
+            (Ident::Fallback(t), Ident::Fallback(o)) => t == o,
+            (Ident::Compiler(_), Ident::Fallback(_)) => mismatch(line!()),
+            (Ident::Fallback(_), Ident::Compiler(_)) => mismatch(line!()),
+        }
+    }
+}
+
+impl<T> PartialEq<T> for Ident
+where
+    T: ?Sized + AsRef<str>,
+{
+    fn eq(&self, other: &T) -> bool {
+        let other = other.as_ref();
+        match self {
+            Ident::Compiler(t) => t.to_string() == other,
+            Ident::Fallback(t) => t == other,
+        }
+    }
+}
+
+impl Display for Ident {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Ident::Compiler(t) => Display::fmt(t, f),
+            Ident::Fallback(t) => Display::fmt(t, f),
+        }
+    }
+}
+
+impl Debug for Ident {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Ident::Compiler(t) => Debug::fmt(t, f),
+            Ident::Fallback(t) => Debug::fmt(t, f),
+        }
+    }
+}
+
+#[derive(Clone)]
+pub(crate) enum Literal {
+    Compiler(proc_macro::Literal),
+    Fallback(fallback::Literal),
+}
+
+macro_rules! suffixed_numbers {
+    ($($name:ident => $kind:ident,)*) => ($(
+        pub fn $name(n: $kind) -> Literal {
+            if inside_proc_macro() {
+                Literal::Compiler(proc_macro::Literal::$name(n))
+            } else {
+                Literal::Fallback(fallback::Literal::$name(n))
+            }
+        }
+    )*)
+}
+
+macro_rules! unsuffixed_integers {
+    ($($name:ident => $kind:ident,)*) => ($(
+        pub fn $name(n: $kind) -> Literal {
+            if inside_proc_macro() {
+                Literal::Compiler(proc_macro::Literal::$name(n))
+            } else {
+                Literal::Fallback(fallback::Literal::$name(n))
+            }
+        }
+    )*)
+}
+
+impl Literal {
+    pub unsafe fn from_str_unchecked(repr: &str) -> Self {
+        if inside_proc_macro() {
+            Literal::Compiler(proc_macro::Literal::from_str(repr).expect("invalid literal"))
+        } else {
+            Literal::Fallback(unsafe { fallback::Literal::from_str_unchecked(repr) })
+        }
+    }
+
+    suffixed_numbers! {
+        u8_suffixed => u8,
+        u16_suffixed => u16,
+        u32_suffixed => u32,
+        u64_suffixed => u64,
+        u128_suffixed => u128,
+        usize_suffixed => usize,
+        i8_suffixed => i8,
+        i16_suffixed => i16,
+        i32_suffixed => i32,
+        i64_suffixed => i64,
+        i128_suffixed => i128,
+        isize_suffixed => isize,
+
+        f32_suffixed => f32,
+        f64_suffixed => f64,
+    }
+
+    unsuffixed_integers! {
+        u8_unsuffixed => u8,
+        u16_unsuffixed => u16,
+        u32_unsuffixed => u32,
+        u64_unsuffixed => u64,
+        u128_unsuffixed => u128,
+        usize_unsuffixed => usize,
+        i8_unsuffixed => i8,
+        i16_unsuffixed => i16,
+        i32_unsuffixed => i32,
+        i64_unsuffixed => i64,
+        i128_unsuffixed => i128,
+        isize_unsuffixed => isize,
+    }
+
+    pub fn f32_unsuffixed(f: f32) -> Literal {
+        if inside_proc_macro() {
+            Literal::Compiler(proc_macro::Literal::f32_unsuffixed(f))
+        } else {
+            Literal::Fallback(fallback::Literal::f32_unsuffixed(f))
+        }
+    }
+
+    pub fn f64_unsuffixed(f: f64) -> Literal {
+        if inside_proc_macro() {
+            Literal::Compiler(proc_macro::Literal::f64_unsuffixed(f))
+        } else {
+            Literal::Fallback(fallback::Literal::f64_unsuffixed(f))
+        }
+    }
+
+    pub fn string(t: &str) -> Literal {
+        if inside_proc_macro() {
+            Literal::Compiler(proc_macro::Literal::string(t))
+        } else {
+            Literal::Fallback(fallback::Literal::string(t))
+        }
+    }
+
+    pub fn character(t: char) -> Literal {
+        if inside_proc_macro() {
+            Literal::Compiler(proc_macro::Literal::character(t))
+        } else {
+            Literal::Fallback(fallback::Literal::character(t))
+        }
+    }
+
+    pub fn byte_string(bytes: &[u8]) -> Literal {
+        if inside_proc_macro() {
+            Literal::Compiler(proc_macro::Literal::byte_string(bytes))
+        } else {
+            Literal::Fallback(fallback::Literal::byte_string(bytes))
+        }
+    }
+
+    pub fn span(&self) -> Span {
+        match self {
+            Literal::Compiler(lit) => Span::Compiler(lit.span()),
+            Literal::Fallback(lit) => Span::Fallback(lit.span()),
+        }
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        match (self, span) {
+            (Literal::Compiler(lit), Span::Compiler(s)) => lit.set_span(s),
+            (Literal::Fallback(lit), Span::Fallback(s)) => lit.set_span(s),
+            (Literal::Compiler(_), Span::Fallback(_)) => mismatch(line!()),
+            (Literal::Fallback(_), Span::Compiler(_)) => mismatch(line!()),
+        }
+    }
+
+    pub fn subspan<R: RangeBounds<usize>>(&self, range: R) -> Option<Span> {
+        match self {
+            #[cfg(proc_macro_span)]
+            Literal::Compiler(lit) => lit.subspan(range).map(Span::Compiler),
+            #[cfg(not(proc_macro_span))]
+            Literal::Compiler(_lit) => None,
+            Literal::Fallback(lit) => lit.subspan(range).map(Span::Fallback),
+        }
+    }
+
+    fn unwrap_nightly(self) -> proc_macro::Literal {
+        match self {
+            Literal::Compiler(s) => s,
+            Literal::Fallback(_) => mismatch(line!()),
+        }
+    }
+}
+
+impl From<fallback::Literal> for Literal {
+    fn from(s: fallback::Literal) -> Self {
+        Literal::Fallback(s)
+    }
+}
+
+impl FromStr for Literal {
+    type Err = LexError;
+
+    fn from_str(repr: &str) -> Result<Self, Self::Err> {
+        if inside_proc_macro() {
+            let literal = proc_macro::Literal::from_str(repr)?;
+            Ok(Literal::Compiler(literal))
+        } else {
+            let literal = fallback::Literal::from_str(repr)?;
+            Ok(Literal::Fallback(literal))
+        }
+    }
+}
+
+impl Display for Literal {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Literal::Compiler(t) => Display::fmt(t, f),
+            Literal::Fallback(t) => Display::fmt(t, f),
+        }
+    }
+}
+
+impl Debug for Literal {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Literal::Compiler(t) => Debug::fmt(t, f),
+            Literal::Fallback(t) => Debug::fmt(t, f),
+        }
+    }
+}
+
+#[cfg(span_locations)]
+pub(crate) fn invalidate_current_thread_spans() {
+    if inside_proc_macro() {
+        panic!(
+            "proc_macro2::extra::invalidate_current_thread_spans is not available in procedural macros"
+        );
+    } else {
+        crate::fallback::invalidate_current_thread_spans();
+    }
+}
diff --git a/rust/quote/ext.rs b/rust/quote/ext.rs
new file mode 100644
index 0000000000000000000000000000000000000000..977d2f0c59192445f58b5d5f20fca6184e51c9ae
--- /dev/null
+++ b/rust/quote/ext.rs
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use super::ToTokens;
+use core::iter;
+use proc_macro2::{TokenStream, TokenTree};
+
+/// TokenStream extension trait with methods for appending tokens.
+///
+/// This trait is sealed and cannot be implemented outside of the `quote` crate.
+pub trait TokenStreamExt: private::Sealed {
+    /// For use by `ToTokens` implementations.
+    ///
+    /// Appends the token specified to this list of tokens.
+    fn append<U>(&mut self, token: U)
+    where
+        U: Into<TokenTree>;
+
+    /// For use by `ToTokens` implementations.
+    ///
+    /// ```
+    /// # use quote::{quote, TokenStreamExt, ToTokens};
+    /// # use proc_macro2::TokenStream;
+    /// #
+    /// struct X;
+    ///
+    /// impl ToTokens for X {
+    ///     fn to_tokens(&self, tokens: &mut TokenStream) {
+    ///         tokens.append_all(&[true, false]);
+    ///     }
+    /// }
+    ///
+    /// let tokens = quote!(#X);
+    /// assert_eq!(tokens.to_string(), "true false");
+    /// ```
+    fn append_all<I>(&mut self, iter: I)
+    where
+        I: IntoIterator,
+        I::Item: ToTokens;
+
+    /// For use by `ToTokens` implementations.
+    ///
+    /// Appends all of the items in the iterator `I`, separated by the tokens
+    /// `U`.
+    fn append_separated<I, U>(&mut self, iter: I, op: U)
+    where
+        I: IntoIterator,
+        I::Item: ToTokens,
+        U: ToTokens;
+
+    /// For use by `ToTokens` implementations.
+    ///
+    /// Appends all tokens in the iterator `I`, appending `U` after each
+    /// element, including after the last element of the iterator.
+    fn append_terminated<I, U>(&mut self, iter: I, term: U)
+    where
+        I: IntoIterator,
+        I::Item: ToTokens,
+        U: ToTokens;
+}
+
+impl TokenStreamExt for TokenStream {
+    fn append<U>(&mut self, token: U)
+    where
+        U: Into<TokenTree>,
+    {
+        self.extend(iter::once(token.into()));
+    }
+
+    fn append_all<I>(&mut self, iter: I)
+    where
+        I: IntoIterator,
+        I::Item: ToTokens,
+    {
+        for token in iter {
+            token.to_tokens(self);
+        }
+    }
+
+    fn append_separated<I, U>(&mut self, iter: I, op: U)
+    where
+        I: IntoIterator,
+        I::Item: ToTokens,
+        U: ToTokens,
+    {
+        for (i, token) in iter.into_iter().enumerate() {
+            if i > 0 {
+                op.to_tokens(self);
+            }
+            token.to_tokens(self);
+        }
+    }
+
+    fn append_terminated<I, U>(&mut self, iter: I, term: U)
+    where
+        I: IntoIterator,
+        I::Item: ToTokens,
+        U: ToTokens,
+    {
+        for token in iter {
+            token.to_tokens(self);
+            term.to_tokens(self);
+        }
+    }
+}
+
+mod private {
+    use proc_macro2::TokenStream;
+
+    pub trait Sealed {}
+
+    impl Sealed for TokenStream {}
+}
diff --git a/rust/quote/format.rs b/rust/quote/format.rs
new file mode 100644
index 0000000000000000000000000000000000000000..9fbf9c5949a9f0e9728c8a3ed33d7dd2545da627
--- /dev/null
+++ b/rust/quote/format.rs
@@ -0,0 +1,170 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+/// Formatting macro for constructing `Ident`s.
+///
+/// <br>
+///
+/// # Syntax
+///
+/// Syntax is copied from the [`format!`] macro, supporting both positional and
+/// named arguments.
+///
+/// Only a limited set of formatting traits are supported. The current mapping
+/// of format types to traits is:
+///
+/// * `{}` ⇒ [`IdentFragment`]
+/// * `{:o}` ⇒ [`Octal`](std::fmt::Octal)
+/// * `{:x}` ⇒ [`LowerHex`](std::fmt::LowerHex)
+/// * `{:X}` ⇒ [`UpperHex`](std::fmt::UpperHex)
+/// * `{:b}` ⇒ [`Binary`](std::fmt::Binary)
+///
+/// See [`std::fmt`] for more information.
+///
+/// <br>
+///
+/// # IdentFragment
+///
+/// Unlike `format!`, this macro uses the [`IdentFragment`] formatting trait by
+/// default. This trait is like `Display`, with a few differences:
+///
+/// * `IdentFragment` is only implemented for a limited set of types, such as
+///    unsigned integers and strings.
+/// * [`Ident`] arguments will have their `r#` prefixes stripped, if present.
+///
+/// [`IdentFragment`]: crate::IdentFragment
+/// [`Ident`]: proc_macro2::Ident
+///
+/// <br>
+///
+/// # Hygiene
+///
+/// The [`Span`] of the first `Ident` argument is used as the span of the final
+/// identifier, falling back to [`Span::call_site`] when no identifiers are
+/// provided.
+///
+/// ```
+/// # use quote::format_ident;
+/// # let ident = format_ident!("Ident");
+/// // If `ident` is an Ident, the span of `my_ident` will be inherited from it.
+/// let my_ident = format_ident!("My{}{}", ident, "IsCool");
+/// assert_eq!(my_ident, "MyIdentIsCool");
+/// ```
+///
+/// Alternatively, the span can be overridden by passing the `span` named
+/// argument.
+///
+/// ```
+/// # use quote::format_ident;
+/// # const IGNORE_TOKENS: &'static str = stringify! {
+/// let my_span = /* ... */;
+/// # };
+/// # let my_span = proc_macro2::Span::call_site();
+/// format_ident!("MyIdent", span = my_span);
+/// ```
+///
+/// [`Span`]: proc_macro2::Span
+/// [`Span::call_site`]: proc_macro2::Span::call_site
+///
+/// <p><br></p>
+///
+/// # Panics
+///
+/// This method will panic if the resulting formatted string is not a valid
+/// identifier.
+///
+/// <br>
+///
+/// # Examples
+///
+/// Composing raw and non-raw identifiers:
+/// ```
+/// # use quote::format_ident;
+/// let my_ident = format_ident!("My{}", "Ident");
+/// assert_eq!(my_ident, "MyIdent");
+///
+/// let raw = format_ident!("r#Raw");
+/// assert_eq!(raw, "r#Raw");
+///
+/// let my_ident_raw = format_ident!("{}Is{}", my_ident, raw);
+/// assert_eq!(my_ident_raw, "MyIdentIsRaw");
+/// ```
+///
+/// Integer formatting options:
+/// ```
+/// # use quote::format_ident;
+/// let num: u32 = 10;
+///
+/// let decimal = format_ident!("Id_{}", num);
+/// assert_eq!(decimal, "Id_10");
+///
+/// let octal = format_ident!("Id_{:o}", num);
+/// assert_eq!(octal, "Id_12");
+///
+/// let binary = format_ident!("Id_{:b}", num);
+/// assert_eq!(binary, "Id_1010");
+///
+/// let lower_hex = format_ident!("Id_{:x}", num);
+/// assert_eq!(lower_hex, "Id_a");
+///
+/// let upper_hex = format_ident!("Id_{:X}", num);
+/// assert_eq!(upper_hex, "Id_A");
+/// ```
+#[macro_export]
+macro_rules! format_ident {
+    ($fmt:expr) => {
+        $crate::format_ident_impl!([
+            $crate::__private::Option::None,
+            $fmt
+        ])
+    };
+
+    ($fmt:expr, $($rest:tt)*) => {
+        $crate::format_ident_impl!([
+            $crate::__private::Option::None,
+            $fmt
+        ] $($rest)*)
+    };
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! format_ident_impl {
+    // Final state
+    ([$span:expr, $($fmt:tt)*]) => {
+        $crate::__private::mk_ident(
+            &$crate::__private::format!($($fmt)*),
+            $span,
+        )
+    };
+
+    // Span argument
+    ([$old:expr, $($fmt:tt)*] span = $span:expr) => {
+        $crate::format_ident_impl!([$old, $($fmt)*] span = $span,)
+    };
+    ([$old:expr, $($fmt:tt)*] span = $span:expr, $($rest:tt)*) => {
+        $crate::format_ident_impl!([
+            $crate::__private::Option::Some::<$crate::__private::Span>($span),
+            $($fmt)*
+        ] $($rest)*)
+    };
+
+    // Named argument
+    ([$span:expr, $($fmt:tt)*] $name:ident = $arg:expr) => {
+        $crate::format_ident_impl!([$span, $($fmt)*] $name = $arg,)
+    };
+    ([$span:expr, $($fmt:tt)*] $name:ident = $arg:expr, $($rest:tt)*) => {
+        match $crate::__private::IdentFragmentAdapter(&$arg) {
+            arg => $crate::format_ident_impl!([$span.or(arg.span()), $($fmt)*, $name = arg] $($rest)*),
+        }
+    };
+
+    // Positional argument
+    ([$span:expr, $($fmt:tt)*] $arg:expr) => {
+        $crate::format_ident_impl!([$span, $($fmt)*] $arg,)
+    };
+    ([$span:expr, $($fmt:tt)*] $arg:expr, $($rest:tt)*) => {
+        match $crate::__private::IdentFragmentAdapter(&$arg) {
+            arg => $crate::format_ident_impl!([$span.or(arg.span()), $($fmt)*, arg] $($rest)*),
+        }
+    };
+}
diff --git a/rust/quote/ident_fragment.rs b/rust/quote/ident_fragment.rs
new file mode 100644
index 0000000000000000000000000000000000000000..d98106f17666207d8bd0ac48ad0fee3b2cd8f93b
--- /dev/null
+++ b/rust/quote/ident_fragment.rs
@@ -0,0 +1,90 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use alloc::borrow::Cow;
+use core::fmt;
+use proc_macro2::{Ident, Span};
+
+/// Specialized formatting trait used by `format_ident!`.
+///
+/// [`Ident`] arguments formatted using this trait will have their `r#` prefix
+/// stripped, if present.
+///
+/// See [`format_ident!`] for more information.
+///
+/// [`format_ident!`]: crate::format_ident
+pub trait IdentFragment {
+    /// Format this value as an identifier fragment.
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result;
+
+    /// Span associated with this `IdentFragment`.
+    ///
+    /// If non-`None`, may be inherited by formatted identifiers.
+    fn span(&self) -> Option<Span> {
+        None
+    }
+}
+
+impl<T: IdentFragment + ?Sized> IdentFragment for &T {
+    fn span(&self) -> Option<Span> {
+        <T as IdentFragment>::span(*self)
+    }
+
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        IdentFragment::fmt(*self, f)
+    }
+}
+
+impl<T: IdentFragment + ?Sized> IdentFragment for &mut T {
+    fn span(&self) -> Option<Span> {
+        <T as IdentFragment>::span(*self)
+    }
+
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        IdentFragment::fmt(*self, f)
+    }
+}
+
+impl IdentFragment for Ident {
+    fn span(&self) -> Option<Span> {
+        Some(self.span())
+    }
+
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let id = self.to_string();
+        if let Some(id) = id.strip_prefix("r#") {
+            fmt::Display::fmt(id, f)
+        } else {
+            fmt::Display::fmt(&id[..], f)
+        }
+    }
+}
+
+impl<T> IdentFragment for Cow<'_, T>
+where
+    T: IdentFragment + ToOwned + ?Sized,
+{
+    fn span(&self) -> Option<Span> {
+        T::span(self)
+    }
+
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        T::fmt(self, f)
+    }
+}
+
+// Limited set of types which this is implemented for, as we want to avoid types
+// which will often include non-identifier characters in their `Display` impl.
+macro_rules! ident_fragment_display {
+    ($($T:ty),*) => {
+        $(
+            impl IdentFragment for $T {
+                fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                    fmt::Display::fmt(self, f)
+                }
+            }
+        )*
+    };
+}
+
+ident_fragment_display!(bool, str, String, char);
+ident_fragment_display!(u8, u16, u32, u64, u128, usize);
diff --git a/rust/quote/lib.rs b/rust/quote/lib.rs
new file mode 100644
index 0000000000000000000000000000000000000000..8fc1a8320ae5e9106080ecb5a20e8b4e42da5d8d
--- /dev/null
+++ b/rust/quote/lib.rs
@@ -0,0 +1,1446 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! [![github]](https://github.com/dtolnay/quote)&ensp;[![crates-io]](https://crates.io/crates/quote)&ensp;[![docs-rs]](https://docs.rs/quote)
+//!
+//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
+//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
+//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs
+//!
+//! <br>
+//!
+//! This crate provides the [`quote!`] macro for turning Rust syntax tree data
+//! structures into tokens of source code.
+//!
+//! [`quote!`]: macro.quote.html
+//!
+//! Procedural macros in Rust receive a stream of tokens as input, execute
+//! arbitrary Rust code to determine how to manipulate those tokens, and produce
+//! a stream of tokens to hand back to the compiler to compile into the caller's
+//! crate. Quasi-quoting is a solution to one piece of that &mdash; producing
+//! tokens to return to the compiler.
+//!
+//! The idea of quasi-quoting is that we write *code* that we treat as *data*.
+//! Within the `quote!` macro, we can write what looks like code to our text
+//! editor or IDE. We get all the benefits of the editor's brace matching,
+//! syntax highlighting, indentation, and maybe autocompletion. But rather than
+//! compiling that as code into the current crate, we can treat it as data, pass
+//! it around, mutate it, and eventually hand it back to the compiler as tokens
+//! to compile into the macro caller's crate.
+//!
+//! This crate is motivated by the procedural macro use case, but is a
+//! general-purpose Rust quasi-quoting library and is not specific to procedural
+//! macros.
+//!
+//! ```toml
+//! [dependencies]
+//! quote = "1.0"
+//! ```
+//!
+//! <br>
+//!
+//! # Example
+//!
+//! The following quasi-quoted block of code is something you might find in [a]
+//! procedural macro having to do with data structure serialization. The `#var`
+//! syntax performs interpolation of runtime variables into the quoted tokens.
+//! Check out the documentation of the [`quote!`] macro for more detail about
+//! the syntax. See also the [`quote_spanned!`] macro which is important for
+//! implementing hygienic procedural macros.
+//!
+//! [a]: https://serde.rs/
+//! [`quote_spanned!`]: macro.quote_spanned.html
+//!
+//! ```
+//! # use quote::quote;
+//! #
+//! # let generics = "";
+//! # let where_clause = "";
+//! # let field_ty = "";
+//! # let item_ty = "";
+//! # let path = "";
+//! # let value = "";
+//! #
+//! let tokens = quote! {
+//!     struct SerializeWith #generics #where_clause {
+//!         value: &'a #field_ty,
+//!         phantom: core::marker::PhantomData<#item_ty>,
+//!     }
+//!
+//!     impl #generics serde::Serialize for SerializeWith #generics #where_clause {
+//!         fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+//!         where
+//!             S: serde::Serializer,
+//!         {
+//!             #path(self.value, serializer)
+//!         }
+//!     }
+//!
+//!     SerializeWith {
+//!         value: #value,
+//!         phantom: core::marker::PhantomData::<#item_ty>,
+//!     }
+//! };
+//! ```
+//!
+//! <br>
+//!
+//! # Non-macro code generators
+//!
+//! When using `quote` in a build.rs or main.rs and writing the output out to a
+//! file, consider having the code generator pass the tokens through
+//! [prettyplease] before writing. This way if an error occurs in the generated
+//! code it is convenient for a human to read and debug.
+//!
+//! [prettyplease]: https://github.com/dtolnay/prettyplease
+
+// Quote types in rustdoc of other crates get linked to here.
+#![doc(html_root_url = "https://docs.rs/quote/1.0.35")]
+#![allow(
+    clippy::doc_markdown,
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    // false positive https://github.com/rust-lang/rust-clippy/issues/6983
+    clippy::wrong_self_convention,
+)]
+
+extern crate alloc;
+
+#[cfg(feature = "proc-macro")]
+extern crate proc_macro;
+
+mod ext;
+mod format;
+mod ident_fragment;
+mod to_tokens;
+
+// Not public API.
+#[doc(hidden)]
+#[path = "runtime.rs"]
+pub mod __private;
+
+pub use crate::ext::TokenStreamExt;
+pub use crate::ident_fragment::IdentFragment;
+pub use crate::to_tokens::ToTokens;
+
+// Not public API.
+#[doc(hidden)]
+pub mod spanned;
+
+/// The whole point.
+///
+/// Performs variable interpolation against the input and produces it as
+/// [`proc_macro2::TokenStream`].
+///
+/// Note: for returning tokens to the compiler in a procedural macro, use
+/// `.into()` on the result to convert to [`proc_macro::TokenStream`].
+///
+/// [`TokenStream`]: https://docs.rs/proc-macro2/1.0/proc_macro2/struct.TokenStream.html
+///
+/// <br>
+///
+/// # Interpolation
+///
+/// Variable interpolation is done with `#var` (similar to `$var` in
+/// `macro_rules!` macros). This grabs the `var` variable that is currently in
+/// scope and inserts it in that location in the output tokens. Any type
+/// implementing the [`ToTokens`] trait can be interpolated. This includes most
+/// Rust primitive types as well as most of the syntax tree types from the [Syn]
+/// crate.
+///
+/// [`ToTokens`]: trait.ToTokens.html
+/// [Syn]: https://github.com/dtolnay/syn
+///
+/// Repetition is done using `#(...)*` or `#(...),*` again similar to
+/// `macro_rules!`. This iterates through the elements of any variable
+/// interpolated within the repetition and inserts a copy of the repetition body
+/// for each one. The variables in an interpolation may be a `Vec`, slice,
+/// `BTreeSet`, or any `Iterator`.
+///
+/// - `#(#var)*` — no separators
+/// - `#(#var),*` — the character before the asterisk is used as a separator
+/// - `#( struct #var; )*` — the repetition can contain other tokens
+/// - `#( #k => println!("{}", #v), )*` — even multiple interpolations
+///
+/// <br>
+///
+/// # Hygiene
+///
+/// Any interpolated tokens preserve the `Span` information provided by their
+/// `ToTokens` implementation. Tokens that originate within the `quote!`
+/// invocation are spanned with [`Span::call_site()`].
+///
+/// [`Span::call_site()`]: https://docs.rs/proc-macro2/1.0/proc_macro2/struct.Span.html#method.call_site
+///
+/// A different span can be provided through the [`quote_spanned!`] macro.
+///
+/// [`quote_spanned!`]: macro.quote_spanned.html
+///
+/// <br>
+///
+/// # Return type
+///
+/// The macro evaluates to an expression of type `proc_macro2::TokenStream`.
+/// Meanwhile Rust procedural macros are expected to return the type
+/// `proc_macro::TokenStream`.
+///
+/// The difference between the two types is that `proc_macro` types are entirely
+/// specific to procedural macros and cannot ever exist in code outside of a
+/// procedural macro, while `proc_macro2` types may exist anywhere including
+/// tests and non-macro code like main.rs and build.rs. This is why even the
+/// procedural macro ecosystem is largely built around `proc_macro2`, because
+/// that ensures the libraries are unit testable and accessible in non-macro
+/// contexts.
+///
+/// There is a [`From`]-conversion in both directions so returning the output of
+/// `quote!` from a procedural macro usually looks like `tokens.into()` or
+/// `proc_macro::TokenStream::from(tokens)`.
+///
+/// [`From`]: https://doc.rust-lang.org/std/convert/trait.From.html
+///
+/// <br>
+///
+/// # Examples
+///
+/// ### Procedural macro
+///
+/// The structure of a basic procedural macro is as follows. Refer to the [Syn]
+/// crate for further useful guidance on using `quote!` as part of a procedural
+/// macro.
+///
+/// [Syn]: https://github.com/dtolnay/syn
+///
+/// ```
+/// # #[cfg(any())]
+/// extern crate proc_macro;
+/// # extern crate proc_macro2;
+///
+/// # #[cfg(any())]
+/// use proc_macro::TokenStream;
+/// # use proc_macro2::TokenStream;
+/// use quote::quote;
+///
+/// # const IGNORE_TOKENS: &'static str = stringify! {
+/// #[proc_macro_derive(HeapSize)]
+/// # };
+/// pub fn derive_heap_size(input: TokenStream) -> TokenStream {
+///     // Parse the input and figure out what implementation to generate...
+///     # const IGNORE_TOKENS: &'static str = stringify! {
+///     let name = /* ... */;
+///     let expr = /* ... */;
+///     # };
+///     #
+///     # let name = 0;
+///     # let expr = 0;
+///
+///     let expanded = quote! {
+///         // The generated impl.
+///         impl heapsize::HeapSize for #name {
+///             fn heap_size_of_children(&self) -> usize {
+///                 #expr
+///             }
+///         }
+///     };
+///
+///     // Hand the output tokens back to the compiler.
+///     TokenStream::from(expanded)
+/// }
+/// ```
+///
+/// <p><br></p>
+///
+/// ### Combining quoted fragments
+///
+/// Usually you don't end up constructing an entire final `TokenStream` in one
+/// piece. Different parts may come from different helper functions. The tokens
+/// produced by `quote!` themselves implement `ToTokens` and so can be
+/// interpolated into later `quote!` invocations to build up a final result.
+///
+/// ```
+/// # use quote::quote;
+/// #
+/// let type_definition = quote! {...};
+/// let methods = quote! {...};
+///
+/// let tokens = quote! {
+///     #type_definition
+///     #methods
+/// };
+/// ```
+///
+/// <p><br></p>
+///
+/// ### Constructing identifiers
+///
+/// Suppose we have an identifier `ident` which came from somewhere in a macro
+/// input and we need to modify it in some way for the macro output. Let's
+/// consider prepending the identifier with an underscore.
+///
+/// Simply interpolating the identifier next to an underscore will not have the
+/// behavior of concatenating them. The underscore and the identifier will
+/// continue to be two separate tokens as if you had written `_ x`.
+///
+/// ```
+/// # use proc_macro2::{self as syn, Span};
+/// # use quote::quote;
+/// #
+/// # let ident = syn::Ident::new("i", Span::call_site());
+/// #
+/// // incorrect
+/// quote! {
+///     let mut _#ident = 0;
+/// }
+/// # ;
+/// ```
+///
+/// The solution is to build a new identifier token with the correct value. As
+/// this is such a common case, the [`format_ident!`] macro provides a
+/// convenient utility for doing so correctly.
+///
+/// ```
+/// # use proc_macro2::{Ident, Span};
+/// # use quote::{format_ident, quote};
+/// #
+/// # let ident = Ident::new("i", Span::call_site());
+/// #
+/// let varname = format_ident!("_{}", ident);
+/// quote! {
+///     let mut #varname = 0;
+/// }
+/// # ;
+/// ```
+///
+/// Alternatively, the APIs provided by Syn and proc-macro2 can be used to
+/// directly build the identifier. This is roughly equivalent to the above, but
+/// will not handle `ident` being a raw identifier.
+///
+/// ```
+/// # use proc_macro2::{self as syn, Span};
+/// # use quote::quote;
+/// #
+/// # let ident = syn::Ident::new("i", Span::call_site());
+/// #
+/// let concatenated = format!("_{}", ident);
+/// let varname = syn::Ident::new(&concatenated, ident.span());
+/// quote! {
+///     let mut #varname = 0;
+/// }
+/// # ;
+/// ```
+///
+/// <p><br></p>
+///
+/// ### Making method calls
+///
+/// Let's say our macro requires some type specified in the macro input to have
+/// a constructor called `new`. We have the type in a variable called
+/// `field_type` of type `syn::Type` and want to invoke the constructor.
+///
+/// ```
+/// # use quote::quote;
+/// #
+/// # let field_type = quote!(...);
+/// #
+/// // incorrect
+/// quote! {
+///     let value = #field_type::new();
+/// }
+/// # ;
+/// ```
+///
+/// This works only sometimes. If `field_type` is `String`, the expanded code
+/// contains `String::new()` which is fine. But if `field_type` is something
+/// like `Vec<i32>` then the expanded code is `Vec<i32>::new()` which is invalid
+/// syntax. Ordinarily in handwritten Rust we would write `Vec::<i32>::new()`
+/// but for macros often the following is more convenient.
+///
+/// ```
+/// # use quote::quote;
+/// #
+/// # let field_type = quote!(...);
+/// #
+/// quote! {
+///     let value = <#field_type>::new();
+/// }
+/// # ;
+/// ```
+///
+/// This expands to `<Vec<i32>>::new()` which behaves correctly.
+///
+/// A similar pattern is appropriate for trait methods.
+///
+/// ```
+/// # use quote::quote;
+/// #
+/// # let field_type = quote!(...);
+/// #
+/// quote! {
+///     let value = <#field_type as core::default::Default>::default();
+/// }
+/// # ;
+/// ```
+///
+/// <p><br></p>
+///
+/// ### Interpolating text inside of doc comments
+///
+/// Neither doc comments nor string literals get interpolation behavior in
+/// quote:
+///
+/// ```compile_fail
+/// quote! {
+///     /// try to interpolate: #ident
+///     ///
+///     /// ...
+/// }
+/// ```
+///
+/// ```compile_fail
+/// quote! {
+///     #[doc = "try to interpolate: #ident"]
+/// }
+/// ```
+///
+/// Instead the best way to build doc comments that involve variables is by
+/// formatting the doc string literal outside of quote.
+///
+/// ```rust
+/// # use proc_macro2::{Ident, Span};
+/// # use quote::quote;
+/// #
+/// # const IGNORE: &str = stringify! {
+/// let msg = format!(...);
+/// # };
+/// #
+/// # let ident = Ident::new("var", Span::call_site());
+/// # let msg = format!("try to interpolate: {}", ident);
+/// quote! {
+///     #[doc = #msg]
+///     ///
+///     /// ...
+/// }
+/// # ;
+/// ```
+///
+/// <p><br></p>
+///
+/// ### Indexing into a tuple struct
+///
+/// When interpolating indices of a tuple or tuple struct, we need them not to
+/// appears suffixed as integer literals by interpolating them as [`syn::Index`]
+/// instead.
+///
+/// [`syn::Index`]: https://docs.rs/syn/2.0/syn/struct.Index.html
+///
+/// ```compile_fail
+/// let i = 0usize..self.fields.len();
+///
+/// // expands to 0 + self.0usize.heap_size() + self.1usize.heap_size() + ...
+/// // which is not valid syntax
+/// quote! {
+///     0 #( + self.#i.heap_size() )*
+/// }
+/// ```
+///
+/// ```
+/// # use proc_macro2::{Ident, TokenStream};
+/// # use quote::quote;
+/// #
+/// # mod syn {
+/// #     use proc_macro2::{Literal, TokenStream};
+/// #     use quote::{ToTokens, TokenStreamExt};
+/// #
+/// #     pub struct Index(usize);
+/// #
+/// #     impl From<usize> for Index {
+/// #         fn from(i: usize) -> Self {
+/// #             Index(i)
+/// #         }
+/// #     }
+/// #
+/// #     impl ToTokens for Index {
+/// #         fn to_tokens(&self, tokens: &mut TokenStream) {
+/// #             tokens.append(Literal::usize_unsuffixed(self.0));
+/// #         }
+/// #     }
+/// # }
+/// #
+/// # struct Struct {
+/// #     fields: Vec<Ident>,
+/// # }
+/// #
+/// # impl Struct {
+/// #     fn example(&self) -> TokenStream {
+/// let i = (0..self.fields.len()).map(syn::Index::from);
+///
+/// // expands to 0 + self.0.heap_size() + self.1.heap_size() + ...
+/// quote! {
+///     0 #( + self.#i.heap_size() )*
+/// }
+/// #     }
+/// # }
+/// ```
+#[cfg(doc)]
+#[macro_export]
+macro_rules! quote {
+    ($($tt:tt)*) => {
+        ...
+    };
+}
+
+#[cfg(not(doc))]
+#[macro_export]
+macro_rules! quote {
+    () => {
+        $crate::__private::TokenStream::new()
+    };
+
+    // Special case rule for a single tt, for performance.
+    ($tt:tt) => {{
+        let mut _s = $crate::__private::TokenStream::new();
+        $crate::quote_token!{$tt _s}
+        _s
+    }};
+
+    // Special case rules for two tts, for performance.
+    (# $var:ident) => {{
+        let mut _s = $crate::__private::TokenStream::new();
+        $crate::ToTokens::to_tokens(&$var, &mut _s);
+        _s
+    }};
+    ($tt1:tt $tt2:tt) => {{
+        let mut _s = $crate::__private::TokenStream::new();
+        $crate::quote_token!{$tt1 _s}
+        $crate::quote_token!{$tt2 _s}
+        _s
+    }};
+
+    // Rule for any other number of tokens.
+    ($($tt:tt)*) => {{
+        let mut _s = $crate::__private::TokenStream::new();
+        $crate::quote_each_token!{_s $($tt)*}
+        _s
+    }};
+}
+
+/// Same as `quote!`, but applies a given span to all tokens originating within
+/// the macro invocation.
+///
+/// <br>
+///
+/// # Syntax
+///
+/// A span expression of type [`Span`], followed by `=>`, followed by the tokens
+/// to quote. The span expression should be brief &mdash; use a variable for
+/// anything more than a few characters. There should be no space before the
+/// `=>` token.
+///
+/// [`Span`]: https://docs.rs/proc-macro2/1.0/proc_macro2/struct.Span.html
+///
+/// ```
+/// # use proc_macro2::Span;
+/// # use quote::quote_spanned;
+/// #
+/// # const IGNORE_TOKENS: &'static str = stringify! {
+/// let span = /* ... */;
+/// # };
+/// # let span = Span::call_site();
+/// # let init = 0;
+///
+/// // On one line, use parentheses.
+/// let tokens = quote_spanned!(span=> Box::into_raw(Box::new(#init)));
+///
+/// // On multiple lines, place the span at the top and use braces.
+/// let tokens = quote_spanned! {span=>
+///     Box::into_raw(Box::new(#init))
+/// };
+/// ```
+///
+/// The lack of space before the `=>` should look jarring to Rust programmers
+/// and this is intentional. The formatting is designed to be visibly
+/// off-balance and draw the eye a particular way, due to the span expression
+/// being evaluated in the context of the procedural macro and the remaining
+/// tokens being evaluated in the generated code.
+///
+/// <br>
+///
+/// # Hygiene
+///
+/// Any interpolated tokens preserve the `Span` information provided by their
+/// `ToTokens` implementation. Tokens that originate within the `quote_spanned!`
+/// invocation are spanned with the given span argument.
+///
+/// <br>
+///
+/// # Example
+///
+/// The following procedural macro code uses `quote_spanned!` to assert that a
+/// particular Rust type implements the [`Sync`] trait so that references can be
+/// safely shared between threads.
+///
+/// [`Sync`]: https://doc.rust-lang.org/std/marker/trait.Sync.html
+///
+/// ```
+/// # use quote::{quote_spanned, TokenStreamExt, ToTokens};
+/// # use proc_macro2::{Span, TokenStream};
+/// #
+/// # struct Type;
+/// #
+/// # impl Type {
+/// #     fn span(&self) -> Span {
+/// #         Span::call_site()
+/// #     }
+/// # }
+/// #
+/// # impl ToTokens for Type {
+/// #     fn to_tokens(&self, _tokens: &mut TokenStream) {}
+/// # }
+/// #
+/// # let ty = Type;
+/// # let call_site = Span::call_site();
+/// #
+/// let ty_span = ty.span();
+/// let assert_sync = quote_spanned! {ty_span=>
+///     struct _AssertSync where #ty: Sync;
+/// };
+/// ```
+///
+/// If the assertion fails, the user will see an error like the following. The
+/// input span of their type is highlighted in the error.
+///
+/// ```text
+/// error[E0277]: the trait bound `*const (): std::marker::Sync` is not satisfied
+///   --> src/main.rs:10:21
+///    |
+/// 10 |     static ref PTR: *const () = &();
+///    |                     ^^^^^^^^^ `*const ()` cannot be shared between threads safely
+/// ```
+///
+/// In this example it is important for the where-clause to be spanned with the
+/// line/column information of the user's input type so that error messages are
+/// placed appropriately by the compiler.
+#[cfg(doc)]
+#[macro_export]
+macro_rules! quote_spanned {
+    ($span:expr=> $($tt:tt)*) => {
+        ...
+    };
+}
+
+#[cfg(not(doc))]
+#[macro_export]
+macro_rules! quote_spanned {
+    ($span:expr=>) => {{
+        let _: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
+        $crate::__private::TokenStream::new()
+    }};
+
+    // Special case rule for a single tt, for performance.
+    ($span:expr=> $tt:tt) => {{
+        let mut _s = $crate::__private::TokenStream::new();
+        let _span: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
+        $crate::quote_token_spanned!{$tt _s _span}
+        _s
+    }};
+
+    // Special case rules for two tts, for performance.
+    ($span:expr=> # $var:ident) => {{
+        let mut _s = $crate::__private::TokenStream::new();
+        let _: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
+        $crate::ToTokens::to_tokens(&$var, &mut _s);
+        _s
+    }};
+    ($span:expr=> $tt1:tt $tt2:tt) => {{
+        let mut _s = $crate::__private::TokenStream::new();
+        let _span: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
+        $crate::quote_token_spanned!{$tt1 _s _span}
+        $crate::quote_token_spanned!{$tt2 _s _span}
+        _s
+    }};
+
+    // Rule for any other number of tokens.
+    ($span:expr=> $($tt:tt)*) => {{
+        let mut _s = $crate::__private::TokenStream::new();
+        let _span: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
+        $crate::quote_each_token_spanned!{_s _span $($tt)*}
+        _s
+    }};
+}
+
+// Extract the names of all #metavariables and pass them to the $call macro.
+//
+// in:   pounded_var_names!(then!(...) a #b c #( #d )* #e)
+// out:  then!(... b);
+//       then!(... d);
+//       then!(... e);
+#[macro_export]
+#[doc(hidden)]
+macro_rules! pounded_var_names {
+    ($call:ident! $extra:tt $($tts:tt)*) => {
+        $crate::pounded_var_names_with_context!{$call! $extra
+            (@ $($tts)*)
+            ($($tts)* @)
+        }
+    };
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! pounded_var_names_with_context {
+    ($call:ident! $extra:tt ($($b1:tt)*) ($($curr:tt)*)) => {
+        $(
+            $crate::pounded_var_with_context!{$call! $extra $b1 $curr}
+        )*
+    };
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! pounded_var_with_context {
+    ($call:ident! $extra:tt $b1:tt ( $($inner:tt)* )) => {
+        $crate::pounded_var_names!{$call! $extra $($inner)*}
+    };
+
+    ($call:ident! $extra:tt $b1:tt [ $($inner:tt)* ]) => {
+        $crate::pounded_var_names!{$call! $extra $($inner)*}
+    };
+
+    ($call:ident! $extra:tt $b1:tt { $($inner:tt)* }) => {
+        $crate::pounded_var_names!{$call! $extra $($inner)*}
+    };
+
+    ($call:ident!($($extra:tt)*) # $var:ident) => {
+        $crate::$call!($($extra)* $var);
+    };
+
+    ($call:ident! $extra:tt $b1:tt $curr:tt) => {};
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_bind_into_iter {
+    ($has_iter:ident $var:ident) => {
+        // `mut` may be unused if $var occurs multiple times in the list.
+        #[allow(unused_mut)]
+        let (mut $var, i) = $var.quote_into_iter();
+        let $has_iter = $has_iter | i;
+    };
+}
+
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_bind_next_or_break {
+    ($var:ident) => {
+        let $var = match $var.next() {
+            Some(_x) => $crate::__private::RepInterp(_x),
+            None => break,
+        };
+    };
+}
+
+// The obvious way to write this macro is as a tt muncher. This implementation
+// does something more complex for two reasons.
+//
+//   - With a tt muncher it's easy to hit Rust's built-in recursion_limit, which
+//     this implementation avoids because it isn't tail recursive.
+//
+//   - Compile times for a tt muncher are quadratic relative to the length of
+//     the input. This implementation is linear, so it will be faster
+//     (potentially much faster) for big inputs. However, the constant factors
+//     of this implementation are higher than that of a tt muncher, so it is
+//     somewhat slower than a tt muncher if there are many invocations with
+//     short inputs.
+//
+// An invocation like this:
+//
+//     quote_each_token!(_s a b c d e f g h i j);
+//
+// expands to this:
+//
+//     quote_tokens_with_context!(_s
+//         (@  @  @  @   @   @   a   b   c   d   e   f   g  h  i  j)
+//         (@  @  @  @   @   a   b   c   d   e   f   g   h  i  j  @)
+//         (@  @  @  @   a   b   c   d   e   f   g   h   i  j  @  @)
+//         (@  @  @ (a) (b) (c) (d) (e) (f) (g) (h) (i) (j) @  @  @)
+//         (@  @  a  b   c   d   e   f   g   h   i   j   @  @  @  @)
+//         (@  a  b  c   d   e   f   g   h   i   j   @   @  @  @  @)
+//         (a  b  c  d   e   f   g   h   i   j   @   @   @  @  @  @)
+//     );
+//
+// which gets transposed and expanded to this:
+//
+//     quote_token_with_context!(_s @ @ @  @  @ @ a);
+//     quote_token_with_context!(_s @ @ @  @  @ a b);
+//     quote_token_with_context!(_s @ @ @  @  a b c);
+//     quote_token_with_context!(_s @ @ @ (a) b c d);
+//     quote_token_with_context!(_s @ @ a (b) c d e);
+//     quote_token_with_context!(_s @ a b (c) d e f);
+//     quote_token_with_context!(_s a b c (d) e f g);
+//     quote_token_with_context!(_s b c d (e) f g h);
+//     quote_token_with_context!(_s c d e (f) g h i);
+//     quote_token_with_context!(_s d e f (g) h i j);
+//     quote_token_with_context!(_s e f g (h) i j @);
+//     quote_token_with_context!(_s f g h (i) j @ @);
+//     quote_token_with_context!(_s g h i (j) @ @ @);
+//     quote_token_with_context!(_s h i j  @  @ @ @);
+//     quote_token_with_context!(_s i j @  @  @ @ @);
+//     quote_token_with_context!(_s j @ @  @  @ @ @);
+//
+// Without having used muncher-style recursion, we get one invocation of
+// quote_token_with_context for each original tt, with three tts of context on
+// either side. This is enough for the longest possible interpolation form (a
+// repetition with separator, as in `# (#var) , *`) to be fully represented with
+// the first or last tt in the middle.
+//
+// The middle tt (surrounded by parentheses) is the tt being processed.
+//
+//   - When it is a `#`, quote_token_with_context can do an interpolation. The
+//     interpolation kind will depend on the three subsequent tts.
+//
+//   - When it is within a later part of an interpolation, it can be ignored
+//     because the interpolation has already been done.
+//
+//   - When it is not part of an interpolation it can be pushed as a single
+//     token into the output.
+//
+//   - When the middle token is an unparenthesized `@`, that call is one of the
+//     first 3 or last 3 calls of quote_token_with_context and does not
+//     correspond to one of the original input tokens, so turns into nothing.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_each_token {
+    ($tokens:ident $($tts:tt)*) => {
+        $crate::quote_tokens_with_context!{$tokens
+            (@ @ @ @ @ @ $($tts)*)
+            (@ @ @ @ @ $($tts)* @)
+            (@ @ @ @ $($tts)* @ @)
+            (@ @ @ $(($tts))* @ @ @)
+            (@ @ $($tts)* @ @ @ @)
+            (@ $($tts)* @ @ @ @ @)
+            ($($tts)* @ @ @ @ @ @)
+        }
+    };
+}
+
+// See the explanation on quote_each_token.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_each_token_spanned {
+    ($tokens:ident $span:ident $($tts:tt)*) => {
+        $crate::quote_tokens_with_context_spanned!{$tokens $span
+            (@ @ @ @ @ @ $($tts)*)
+            (@ @ @ @ @ $($tts)* @)
+            (@ @ @ @ $($tts)* @ @)
+            (@ @ @ $(($tts))* @ @ @)
+            (@ @ $($tts)* @ @ @ @)
+            (@ $($tts)* @ @ @ @ @)
+            ($($tts)* @ @ @ @ @ @)
+        }
+    };
+}
+
+// See the explanation on quote_each_token.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_tokens_with_context {
+    ($tokens:ident
+        ($($b3:tt)*) ($($b2:tt)*) ($($b1:tt)*)
+        ($($curr:tt)*)
+        ($($a1:tt)*) ($($a2:tt)*) ($($a3:tt)*)
+    ) => {
+        $(
+            $crate::quote_token_with_context!{$tokens $b3 $b2 $b1 $curr $a1 $a2 $a3}
+        )*
+    };
+}
+
+// See the explanation on quote_each_token.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_tokens_with_context_spanned {
+    ($tokens:ident $span:ident
+        ($($b3:tt)*) ($($b2:tt)*) ($($b1:tt)*)
+        ($($curr:tt)*)
+        ($($a1:tt)*) ($($a2:tt)*) ($($a3:tt)*)
+    ) => {
+        $(
+            $crate::quote_token_with_context_spanned!{$tokens $span $b3 $b2 $b1 $curr $a1 $a2 $a3}
+        )*
+    };
+}
+
+// See the explanation on quote_each_token.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_token_with_context {
+    // Unparenthesized `@` indicates this call does not correspond to one of the
+    // original input tokens. Ignore it.
+    ($tokens:ident $b3:tt $b2:tt $b1:tt @ $a1:tt $a2:tt $a3:tt) => {};
+
+    // A repetition with no separator.
+    ($tokens:ident $b3:tt $b2:tt $b1:tt (#) ( $($inner:tt)* ) * $a3:tt) => {{
+        use $crate::__private::ext::*;
+        let has_iter = $crate::__private::ThereIsNoIteratorInRepetition;
+        $crate::pounded_var_names!{quote_bind_into_iter!(has_iter) () $($inner)*}
+        let _: $crate::__private::HasIterator = has_iter;
+        // This is `while true` instead of `loop` because if there are no
+        // iterators used inside of this repetition then the body would not
+        // contain any `break`, so the compiler would emit unreachable code
+        // warnings on anything below the loop. We use has_iter to detect and
+        // fail to compile when there are no iterators, so here we just work
+        // around the unneeded extra warning.
+        while true {
+            $crate::pounded_var_names!{quote_bind_next_or_break!() () $($inner)*}
+            $crate::quote_each_token!{$tokens $($inner)*}
+        }
+    }};
+    // ... and one step later.
+    ($tokens:ident $b3:tt $b2:tt # (( $($inner:tt)* )) * $a2:tt $a3:tt) => {};
+    // ... and one step later.
+    ($tokens:ident $b3:tt # ( $($inner:tt)* ) (*) $a1:tt $a2:tt $a3:tt) => {};
+
+    // A repetition with separator.
+    ($tokens:ident $b3:tt $b2:tt $b1:tt (#) ( $($inner:tt)* ) $sep:tt *) => {{
+        use $crate::__private::ext::*;
+        let mut _i = 0usize;
+        let has_iter = $crate::__private::ThereIsNoIteratorInRepetition;
+        $crate::pounded_var_names!{quote_bind_into_iter!(has_iter) () $($inner)*}
+        let _: $crate::__private::HasIterator = has_iter;
+        while true {
+            $crate::pounded_var_names!{quote_bind_next_or_break!() () $($inner)*}
+            if _i > 0 {
+                $crate::quote_token!{$sep $tokens}
+            }
+            _i += 1;
+            $crate::quote_each_token!{$tokens $($inner)*}
+        }
+    }};
+    // ... and one step later.
+    ($tokens:ident $b3:tt $b2:tt # (( $($inner:tt)* )) $sep:tt * $a3:tt) => {};
+    // ... and one step later.
+    ($tokens:ident $b3:tt # ( $($inner:tt)* ) ($sep:tt) * $a2:tt $a3:tt) => {};
+    // (A special case for `#(var)**`, where the first `*` is treated as the
+    // repetition symbol and the second `*` is treated as an ordinary token.)
+    ($tokens:ident # ( $($inner:tt)* ) * (*) $a1:tt $a2:tt $a3:tt) => {
+        // https://github.com/dtolnay/quote/issues/130
+        $crate::quote_token!{* $tokens}
+    };
+    // ... and one step later.
+    ($tokens:ident # ( $($inner:tt)* ) $sep:tt (*) $a1:tt $a2:tt $a3:tt) => {};
+
+    // A non-repetition interpolation.
+    ($tokens:ident $b3:tt $b2:tt $b1:tt (#) $var:ident $a2:tt $a3:tt) => {
+        $crate::ToTokens::to_tokens(&$var, &mut $tokens);
+    };
+    // ... and one step later.
+    ($tokens:ident $b3:tt $b2:tt # ($var:ident) $a1:tt $a2:tt $a3:tt) => {};
+
+    // An ordinary token, not part of any interpolation.
+    ($tokens:ident $b3:tt $b2:tt $b1:tt ($curr:tt) $a1:tt $a2:tt $a3:tt) => {
+        $crate::quote_token!{$curr $tokens}
+    };
+}
+
+// See the explanation on quote_each_token, and on the individual rules of
+// quote_token_with_context.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_token_with_context_spanned {
+    ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt @ $a1:tt $a2:tt $a3:tt) => {};
+
+    ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt (#) ( $($inner:tt)* ) * $a3:tt) => {{
+        use $crate::__private::ext::*;
+        let has_iter = $crate::__private::ThereIsNoIteratorInRepetition;
+        $crate::pounded_var_names!{quote_bind_into_iter!(has_iter) () $($inner)*}
+        let _: $crate::__private::HasIterator = has_iter;
+        while true {
+            $crate::pounded_var_names!{quote_bind_next_or_break!() () $($inner)*}
+            $crate::quote_each_token_spanned!{$tokens $span $($inner)*}
+        }
+    }};
+    ($tokens:ident $span:ident $b3:tt $b2:tt # (( $($inner:tt)* )) * $a2:tt $a3:tt) => {};
+    ($tokens:ident $span:ident $b3:tt # ( $($inner:tt)* ) (*) $a1:tt $a2:tt $a3:tt) => {};
+
+    ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt (#) ( $($inner:tt)* ) $sep:tt *) => {{
+        use $crate::__private::ext::*;
+        let mut _i = 0usize;
+        let has_iter = $crate::__private::ThereIsNoIteratorInRepetition;
+        $crate::pounded_var_names!{quote_bind_into_iter!(has_iter) () $($inner)*}
+        let _: $crate::__private::HasIterator = has_iter;
+        while true {
+            $crate::pounded_var_names!{quote_bind_next_or_break!() () $($inner)*}
+            if _i > 0 {
+                $crate::quote_token_spanned!{$sep $tokens $span}
+            }
+            _i += 1;
+            $crate::quote_each_token_spanned!{$tokens $span $($inner)*}
+        }
+    }};
+    ($tokens:ident $span:ident $b3:tt $b2:tt # (( $($inner:tt)* )) $sep:tt * $a3:tt) => {};
+    ($tokens:ident $span:ident $b3:tt # ( $($inner:tt)* ) ($sep:tt) * $a2:tt $a3:tt) => {};
+    ($tokens:ident $span:ident # ( $($inner:tt)* ) * (*) $a1:tt $a2:tt $a3:tt) => {
+        // https://github.com/dtolnay/quote/issues/130
+        $crate::quote_token_spanned!{* $tokens $span}
+    };
+    ($tokens:ident $span:ident # ( $($inner:tt)* ) $sep:tt (*) $a1:tt $a2:tt $a3:tt) => {};
+
+    ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt (#) $var:ident $a2:tt $a3:tt) => {
+        $crate::ToTokens::to_tokens(&$var, &mut $tokens);
+    };
+    ($tokens:ident $span:ident $b3:tt $b2:tt # ($var:ident) $a1:tt $a2:tt $a3:tt) => {};
+
+    ($tokens:ident $span:ident $b3:tt $b2:tt $b1:tt ($curr:tt) $a1:tt $a2:tt $a3:tt) => {
+        $crate::quote_token_spanned!{$curr $tokens $span}
+    };
+}
+
+// These rules are ordered by approximate token frequency, at least for the
+// first 10 or so, to improve compile times. Having `ident` first is by far the
+// most important because it's typically 2-3x more common than the next most
+// common token.
+//
+// Separately, we put the token being matched in the very front so that failing
+// rules may fail to match as quickly as possible.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_token {
+    ($ident:ident $tokens:ident) => {
+        $crate::__private::push_ident(&mut $tokens, stringify!($ident));
+    };
+
+    (:: $tokens:ident) => {
+        $crate::__private::push_colon2(&mut $tokens);
+    };
+
+    (( $($inner:tt)* ) $tokens:ident) => {
+        $crate::__private::push_group(
+            &mut $tokens,
+            $crate::__private::Delimiter::Parenthesis,
+            $crate::quote!($($inner)*),
+        );
+    };
+
+    ([ $($inner:tt)* ] $tokens:ident) => {
+        $crate::__private::push_group(
+            &mut $tokens,
+            $crate::__private::Delimiter::Bracket,
+            $crate::quote!($($inner)*),
+        );
+    };
+
+    ({ $($inner:tt)* } $tokens:ident) => {
+        $crate::__private::push_group(
+            &mut $tokens,
+            $crate::__private::Delimiter::Brace,
+            $crate::quote!($($inner)*),
+        );
+    };
+
+    (# $tokens:ident) => {
+        $crate::__private::push_pound(&mut $tokens);
+    };
+
+    (, $tokens:ident) => {
+        $crate::__private::push_comma(&mut $tokens);
+    };
+
+    (. $tokens:ident) => {
+        $crate::__private::push_dot(&mut $tokens);
+    };
+
+    (; $tokens:ident) => {
+        $crate::__private::push_semi(&mut $tokens);
+    };
+
+    (: $tokens:ident) => {
+        $crate::__private::push_colon(&mut $tokens);
+    };
+
+    (+ $tokens:ident) => {
+        $crate::__private::push_add(&mut $tokens);
+    };
+
+    (+= $tokens:ident) => {
+        $crate::__private::push_add_eq(&mut $tokens);
+    };
+
+    (& $tokens:ident) => {
+        $crate::__private::push_and(&mut $tokens);
+    };
+
+    (&& $tokens:ident) => {
+        $crate::__private::push_and_and(&mut $tokens);
+    };
+
+    (&= $tokens:ident) => {
+        $crate::__private::push_and_eq(&mut $tokens);
+    };
+
+    (@ $tokens:ident) => {
+        $crate::__private::push_at(&mut $tokens);
+    };
+
+    (! $tokens:ident) => {
+        $crate::__private::push_bang(&mut $tokens);
+    };
+
+    (^ $tokens:ident) => {
+        $crate::__private::push_caret(&mut $tokens);
+    };
+
+    (^= $tokens:ident) => {
+        $crate::__private::push_caret_eq(&mut $tokens);
+    };
+
+    (/ $tokens:ident) => {
+        $crate::__private::push_div(&mut $tokens);
+    };
+
+    (/= $tokens:ident) => {
+        $crate::__private::push_div_eq(&mut $tokens);
+    };
+
+    (.. $tokens:ident) => {
+        $crate::__private::push_dot2(&mut $tokens);
+    };
+
+    (... $tokens:ident) => {
+        $crate::__private::push_dot3(&mut $tokens);
+    };
+
+    (..= $tokens:ident) => {
+        $crate::__private::push_dot_dot_eq(&mut $tokens);
+    };
+
+    (= $tokens:ident) => {
+        $crate::__private::push_eq(&mut $tokens);
+    };
+
+    (== $tokens:ident) => {
+        $crate::__private::push_eq_eq(&mut $tokens);
+    };
+
+    (>= $tokens:ident) => {
+        $crate::__private::push_ge(&mut $tokens);
+    };
+
+    (> $tokens:ident) => {
+        $crate::__private::push_gt(&mut $tokens);
+    };
+
+    (<= $tokens:ident) => {
+        $crate::__private::push_le(&mut $tokens);
+    };
+
+    (< $tokens:ident) => {
+        $crate::__private::push_lt(&mut $tokens);
+    };
+
+    (*= $tokens:ident) => {
+        $crate::__private::push_mul_eq(&mut $tokens);
+    };
+
+    (!= $tokens:ident) => {
+        $crate::__private::push_ne(&mut $tokens);
+    };
+
+    (| $tokens:ident) => {
+        $crate::__private::push_or(&mut $tokens);
+    };
+
+    (|= $tokens:ident) => {
+        $crate::__private::push_or_eq(&mut $tokens);
+    };
+
+    (|| $tokens:ident) => {
+        $crate::__private::push_or_or(&mut $tokens);
+    };
+
+    (? $tokens:ident) => {
+        $crate::__private::push_question(&mut $tokens);
+    };
+
+    (-> $tokens:ident) => {
+        $crate::__private::push_rarrow(&mut $tokens);
+    };
+
+    (<- $tokens:ident) => {
+        $crate::__private::push_larrow(&mut $tokens);
+    };
+
+    (% $tokens:ident) => {
+        $crate::__private::push_rem(&mut $tokens);
+    };
+
+    (%= $tokens:ident) => {
+        $crate::__private::push_rem_eq(&mut $tokens);
+    };
+
+    (=> $tokens:ident) => {
+        $crate::__private::push_fat_arrow(&mut $tokens);
+    };
+
+    (<< $tokens:ident) => {
+        $crate::__private::push_shl(&mut $tokens);
+    };
+
+    (<<= $tokens:ident) => {
+        $crate::__private::push_shl_eq(&mut $tokens);
+    };
+
+    (>> $tokens:ident) => {
+        $crate::__private::push_shr(&mut $tokens);
+    };
+
+    (>>= $tokens:ident) => {
+        $crate::__private::push_shr_eq(&mut $tokens);
+    };
+
+    (* $tokens:ident) => {
+        $crate::__private::push_star(&mut $tokens);
+    };
+
+    (- $tokens:ident) => {
+        $crate::__private::push_sub(&mut $tokens);
+    };
+
+    (-= $tokens:ident) => {
+        $crate::__private::push_sub_eq(&mut $tokens);
+    };
+
+    ($lifetime:lifetime $tokens:ident) => {
+        $crate::__private::push_lifetime(&mut $tokens, stringify!($lifetime));
+    };
+
+    (_ $tokens:ident) => {
+        $crate::__private::push_underscore(&mut $tokens);
+    };
+
+    ($other:tt $tokens:ident) => {
+        $crate::__private::parse(&mut $tokens, stringify!($other));
+    };
+}
+
+// See the comment above `quote_token!` about the rule ordering.
+#[macro_export]
+#[doc(hidden)]
+macro_rules! quote_token_spanned {
+    ($ident:ident $tokens:ident $span:ident) => {
+        $crate::__private::push_ident_spanned(&mut $tokens, $span, stringify!($ident));
+    };
+
+    (:: $tokens:ident $span:ident) => {
+        $crate::__private::push_colon2_spanned(&mut $tokens, $span);
+    };
+
+    (( $($inner:tt)* ) $tokens:ident $span:ident) => {
+        $crate::__private::push_group_spanned(
+            &mut $tokens,
+            $span,
+            $crate::__private::Delimiter::Parenthesis,
+            $crate::quote_spanned!($span=> $($inner)*),
+        );
+    };
+
+    ([ $($inner:tt)* ] $tokens:ident $span:ident) => {
+        $crate::__private::push_group_spanned(
+            &mut $tokens,
+            $span,
+            $crate::__private::Delimiter::Bracket,
+            $crate::quote_spanned!($span=> $($inner)*),
+        );
+    };
+
+    ({ $($inner:tt)* } $tokens:ident $span:ident) => {
+        $crate::__private::push_group_spanned(
+            &mut $tokens,
+            $span,
+            $crate::__private::Delimiter::Brace,
+            $crate::quote_spanned!($span=> $($inner)*),
+        );
+    };
+
+    (# $tokens:ident $span:ident) => {
+        $crate::__private::push_pound_spanned(&mut $tokens, $span);
+    };
+
+    (, $tokens:ident $span:ident) => {
+        $crate::__private::push_comma_spanned(&mut $tokens, $span);
+    };
+
+    (. $tokens:ident $span:ident) => {
+        $crate::__private::push_dot_spanned(&mut $tokens, $span);
+    };
+
+    (; $tokens:ident $span:ident) => {
+        $crate::__private::push_semi_spanned(&mut $tokens, $span);
+    };
+
+    (: $tokens:ident $span:ident) => {
+        $crate::__private::push_colon_spanned(&mut $tokens, $span);
+    };
+
+    (+ $tokens:ident $span:ident) => {
+        $crate::__private::push_add_spanned(&mut $tokens, $span);
+    };
+
+    (+= $tokens:ident $span:ident) => {
+        $crate::__private::push_add_eq_spanned(&mut $tokens, $span);
+    };
+
+    (& $tokens:ident $span:ident) => {
+        $crate::__private::push_and_spanned(&mut $tokens, $span);
+    };
+
+    (&& $tokens:ident $span:ident) => {
+        $crate::__private::push_and_and_spanned(&mut $tokens, $span);
+    };
+
+    (&= $tokens:ident $span:ident) => {
+        $crate::__private::push_and_eq_spanned(&mut $tokens, $span);
+    };
+
+    (@ $tokens:ident $span:ident) => {
+        $crate::__private::push_at_spanned(&mut $tokens, $span);
+    };
+
+    (! $tokens:ident $span:ident) => {
+        $crate::__private::push_bang_spanned(&mut $tokens, $span);
+    };
+
+    (^ $tokens:ident $span:ident) => {
+        $crate::__private::push_caret_spanned(&mut $tokens, $span);
+    };
+
+    (^= $tokens:ident $span:ident) => {
+        $crate::__private::push_caret_eq_spanned(&mut $tokens, $span);
+    };
+
+    (/ $tokens:ident $span:ident) => {
+        $crate::__private::push_div_spanned(&mut $tokens, $span);
+    };
+
+    (/= $tokens:ident $span:ident) => {
+        $crate::__private::push_div_eq_spanned(&mut $tokens, $span);
+    };
+
+    (.. $tokens:ident $span:ident) => {
+        $crate::__private::push_dot2_spanned(&mut $tokens, $span);
+    };
+
+    (... $tokens:ident $span:ident) => {
+        $crate::__private::push_dot3_spanned(&mut $tokens, $span);
+    };
+
+    (..= $tokens:ident $span:ident) => {
+        $crate::__private::push_dot_dot_eq_spanned(&mut $tokens, $span);
+    };
+
+    (= $tokens:ident $span:ident) => {
+        $crate::__private::push_eq_spanned(&mut $tokens, $span);
+    };
+
+    (== $tokens:ident $span:ident) => {
+        $crate::__private::push_eq_eq_spanned(&mut $tokens, $span);
+    };
+
+    (>= $tokens:ident $span:ident) => {
+        $crate::__private::push_ge_spanned(&mut $tokens, $span);
+    };
+
+    (> $tokens:ident $span:ident) => {
+        $crate::__private::push_gt_spanned(&mut $tokens, $span);
+    };
+
+    (<= $tokens:ident $span:ident) => {
+        $crate::__private::push_le_spanned(&mut $tokens, $span);
+    };
+
+    (< $tokens:ident $span:ident) => {
+        $crate::__private::push_lt_spanned(&mut $tokens, $span);
+    };
+
+    (*= $tokens:ident $span:ident) => {
+        $crate::__private::push_mul_eq_spanned(&mut $tokens, $span);
+    };
+
+    (!= $tokens:ident $span:ident) => {
+        $crate::__private::push_ne_spanned(&mut $tokens, $span);
+    };
+
+    (| $tokens:ident $span:ident) => {
+        $crate::__private::push_or_spanned(&mut $tokens, $span);
+    };
+
+    (|= $tokens:ident $span:ident) => {
+        $crate::__private::push_or_eq_spanned(&mut $tokens, $span);
+    };
+
+    (|| $tokens:ident $span:ident) => {
+        $crate::__private::push_or_or_spanned(&mut $tokens, $span);
+    };
+
+    (? $tokens:ident $span:ident) => {
+        $crate::__private::push_question_spanned(&mut $tokens, $span);
+    };
+
+    (-> $tokens:ident $span:ident) => {
+        $crate::__private::push_rarrow_spanned(&mut $tokens, $span);
+    };
+
+    (<- $tokens:ident $span:ident) => {
+        $crate::__private::push_larrow_spanned(&mut $tokens, $span);
+    };
+
+    (% $tokens:ident $span:ident) => {
+        $crate::__private::push_rem_spanned(&mut $tokens, $span);
+    };
+
+    (%= $tokens:ident $span:ident) => {
+        $crate::__private::push_rem_eq_spanned(&mut $tokens, $span);
+    };
+
+    (=> $tokens:ident $span:ident) => {
+        $crate::__private::push_fat_arrow_spanned(&mut $tokens, $span);
+    };
+
+    (<< $tokens:ident $span:ident) => {
+        $crate::__private::push_shl_spanned(&mut $tokens, $span);
+    };
+
+    (<<= $tokens:ident $span:ident) => {
+        $crate::__private::push_shl_eq_spanned(&mut $tokens, $span);
+    };
+
+    (>> $tokens:ident $span:ident) => {
+        $crate::__private::push_shr_spanned(&mut $tokens, $span);
+    };
+
+    (>>= $tokens:ident $span:ident) => {
+        $crate::__private::push_shr_eq_spanned(&mut $tokens, $span);
+    };
+
+    (* $tokens:ident $span:ident) => {
+        $crate::__private::push_star_spanned(&mut $tokens, $span);
+    };
+
+    (- $tokens:ident $span:ident) => {
+        $crate::__private::push_sub_spanned(&mut $tokens, $span);
+    };
+
+    (-= $tokens:ident $span:ident) => {
+        $crate::__private::push_sub_eq_spanned(&mut $tokens, $span);
+    };
+
+    ($lifetime:lifetime $tokens:ident $span:ident) => {
+        $crate::__private::push_lifetime_spanned(&mut $tokens, $span, stringify!($lifetime));
+    };
+
+    (_ $tokens:ident $span:ident) => {
+        $crate::__private::push_underscore_spanned(&mut $tokens, $span);
+    };
+
+    ($other:tt $tokens:ident $span:ident) => {
+        $crate::__private::parse_spanned(&mut $tokens, $span, stringify!($other));
+    };
+}
diff --git a/rust/quote/runtime.rs b/rust/quote/runtime.rs
new file mode 100644
index 0000000000000000000000000000000000000000..63aab7d93cd151602563c7c1f9ccd4901f2d4d27
--- /dev/null
+++ b/rust/quote/runtime.rs
@@ -0,0 +1,532 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use self::get_span::{GetSpan, GetSpanBase, GetSpanInner};
+use crate::{IdentFragment, ToTokens, TokenStreamExt};
+use core::fmt;
+use core::iter;
+use core::ops::BitOr;
+use proc_macro2::{Group, Ident, Punct, Spacing, TokenTree};
+
+#[doc(hidden)]
+pub use alloc::format;
+#[doc(hidden)]
+pub use core::option::Option;
+
+#[doc(hidden)]
+pub type Delimiter = proc_macro2::Delimiter;
+#[doc(hidden)]
+pub type Span = proc_macro2::Span;
+#[doc(hidden)]
+pub type TokenStream = proc_macro2::TokenStream;
+
+#[doc(hidden)]
+pub struct HasIterator; // True
+#[doc(hidden)]
+pub struct ThereIsNoIteratorInRepetition; // False
+
+impl BitOr<ThereIsNoIteratorInRepetition> for ThereIsNoIteratorInRepetition {
+    type Output = ThereIsNoIteratorInRepetition;
+    fn bitor(self, _rhs: ThereIsNoIteratorInRepetition) -> ThereIsNoIteratorInRepetition {
+        ThereIsNoIteratorInRepetition
+    }
+}
+
+impl BitOr<ThereIsNoIteratorInRepetition> for HasIterator {
+    type Output = HasIterator;
+    fn bitor(self, _rhs: ThereIsNoIteratorInRepetition) -> HasIterator {
+        HasIterator
+    }
+}
+
+impl BitOr<HasIterator> for ThereIsNoIteratorInRepetition {
+    type Output = HasIterator;
+    fn bitor(self, _rhs: HasIterator) -> HasIterator {
+        HasIterator
+    }
+}
+
+impl BitOr<HasIterator> for HasIterator {
+    type Output = HasIterator;
+    fn bitor(self, _rhs: HasIterator) -> HasIterator {
+        HasIterator
+    }
+}
+
+/// Extension traits used by the implementation of `quote!`. These are defined
+/// in separate traits, rather than as a single trait due to ambiguity issues.
+///
+/// These traits expose a `quote_into_iter` method which should allow calling
+/// whichever impl happens to be applicable. Calling that method repeatedly on
+/// the returned value should be idempotent.
+#[doc(hidden)]
+pub mod ext {
+    use super::RepInterp;
+    use super::{HasIterator as HasIter, ThereIsNoIteratorInRepetition as DoesNotHaveIter};
+    use crate::ToTokens;
+    use alloc::collections::btree_set::{self, BTreeSet};
+    use core::slice;
+
+    /// Extension trait providing the `quote_into_iter` method on iterators.
+    #[doc(hidden)]
+    pub trait RepIteratorExt: Iterator + Sized {
+        fn quote_into_iter(self) -> (Self, HasIter) {
+            (self, HasIter)
+        }
+    }
+
+    impl<T: Iterator> RepIteratorExt for T {}
+
+    /// Extension trait providing the `quote_into_iter` method for
+    /// non-iterable types. These types interpolate the same value in each
+    /// iteration of the repetition.
+    #[doc(hidden)]
+    pub trait RepToTokensExt {
+        /// Pretend to be an iterator for the purposes of `quote_into_iter`.
+        /// This allows repeated calls to `quote_into_iter` to continue
+        /// correctly returning DoesNotHaveIter.
+        fn next(&self) -> Option<&Self> {
+            Some(self)
+        }
+
+        fn quote_into_iter(&self) -> (&Self, DoesNotHaveIter) {
+            (self, DoesNotHaveIter)
+        }
+    }
+
+    impl<T: ToTokens + ?Sized> RepToTokensExt for T {}
+
+    /// Extension trait providing the `quote_into_iter` method for types that
+    /// can be referenced as an iterator.
+    #[doc(hidden)]
+    pub trait RepAsIteratorExt<'q> {
+        type Iter: Iterator;
+
+        fn quote_into_iter(&'q self) -> (Self::Iter, HasIter);
+    }
+
+    impl<'q, 'a, T: RepAsIteratorExt<'q> + ?Sized> RepAsIteratorExt<'q> for &'a T {
+        type Iter = T::Iter;
+
+        fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) {
+            <T as RepAsIteratorExt>::quote_into_iter(*self)
+        }
+    }
+
+    impl<'q, 'a, T: RepAsIteratorExt<'q> + ?Sized> RepAsIteratorExt<'q> for &'a mut T {
+        type Iter = T::Iter;
+
+        fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) {
+            <T as RepAsIteratorExt>::quote_into_iter(*self)
+        }
+    }
+
+    impl<'q, T: 'q> RepAsIteratorExt<'q> for [T] {
+        type Iter = slice::Iter<'q, T>;
+
+        fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) {
+            (self.iter(), HasIter)
+        }
+    }
+
+    impl<'q, T: 'q> RepAsIteratorExt<'q> for Vec<T> {
+        type Iter = slice::Iter<'q, T>;
+
+        fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) {
+            (self.iter(), HasIter)
+        }
+    }
+
+    impl<'q, T: 'q> RepAsIteratorExt<'q> for BTreeSet<T> {
+        type Iter = btree_set::Iter<'q, T>;
+
+        fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) {
+            (self.iter(), HasIter)
+        }
+    }
+
+    impl<'q, T: RepAsIteratorExt<'q>> RepAsIteratorExt<'q> for RepInterp<T> {
+        type Iter = T::Iter;
+
+        fn quote_into_iter(&'q self) -> (Self::Iter, HasIter) {
+            self.0.quote_into_iter()
+        }
+    }
+}
+
+// Helper type used within interpolations to allow for repeated binding names.
+// Implements the relevant traits, and exports a dummy `next()` method.
+#[derive(Copy, Clone)]
+#[doc(hidden)]
+pub struct RepInterp<T>(pub T);
+
+impl<T> RepInterp<T> {
+    // This method is intended to look like `Iterator::next`, and is called when
+    // a name is bound multiple times, as the previous binding will shadow the
+    // original `Iterator` object. This allows us to avoid advancing the
+    // iterator multiple times per iteration.
+    pub fn next(self) -> Option<T> {
+        Some(self.0)
+    }
+}
+
+impl<T: Iterator> Iterator for RepInterp<T> {
+    type Item = T::Item;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.0.next()
+    }
+}
+
+impl<T: ToTokens> ToTokens for RepInterp<T> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        self.0.to_tokens(tokens);
+    }
+}
+
+#[doc(hidden)]
+#[inline]
+pub fn get_span<T>(span: T) -> GetSpan<T> {
+    GetSpan(GetSpanInner(GetSpanBase(span)))
+}
+
+mod get_span {
+    use core::ops::Deref;
+    use proc_macro2::extra::DelimSpan;
+    use proc_macro2::Span;
+
+    pub struct GetSpan<T>(pub(crate) GetSpanInner<T>);
+
+    pub struct GetSpanInner<T>(pub(crate) GetSpanBase<T>);
+
+    pub struct GetSpanBase<T>(pub(crate) T);
+
+    impl GetSpan<Span> {
+        #[inline]
+        pub fn __into_span(self) -> Span {
+            ((self.0).0).0
+        }
+    }
+
+    impl GetSpanInner<DelimSpan> {
+        #[inline]
+        pub fn __into_span(&self) -> Span {
+            (self.0).0.join()
+        }
+    }
+
+    impl<T> GetSpanBase<T> {
+        #[allow(clippy::unused_self)]
+        pub fn __into_span(&self) -> T {
+            unreachable!()
+        }
+    }
+
+    impl<T> Deref for GetSpan<T> {
+        type Target = GetSpanInner<T>;
+
+        #[inline]
+        fn deref(&self) -> &Self::Target {
+            &self.0
+        }
+    }
+
+    impl<T> Deref for GetSpanInner<T> {
+        type Target = GetSpanBase<T>;
+
+        #[inline]
+        fn deref(&self) -> &Self::Target {
+            &self.0
+        }
+    }
+}
+
+#[doc(hidden)]
+pub fn push_group(tokens: &mut TokenStream, delimiter: Delimiter, inner: TokenStream) {
+    tokens.append(Group::new(delimiter, inner));
+}
+
+#[doc(hidden)]
+pub fn push_group_spanned(
+    tokens: &mut TokenStream,
+    span: Span,
+    delimiter: Delimiter,
+    inner: TokenStream,
+) {
+    let mut g = Group::new(delimiter, inner);
+    g.set_span(span);
+    tokens.append(g);
+}
+
+#[doc(hidden)]
+pub fn parse(tokens: &mut TokenStream, s: &str) {
+    let s: TokenStream = s.parse().expect("invalid token stream");
+    tokens.extend(iter::once(s));
+}
+
+#[doc(hidden)]
+pub fn parse_spanned(tokens: &mut TokenStream, span: Span, s: &str) {
+    let s: TokenStream = s.parse().expect("invalid token stream");
+    tokens.extend(s.into_iter().map(|t| respan_token_tree(t, span)));
+}
+
+// Token tree with every span replaced by the given one.
+fn respan_token_tree(mut token: TokenTree, span: Span) -> TokenTree {
+    match &mut token {
+        TokenTree::Group(g) => {
+            let stream = g
+                .stream()
+                .into_iter()
+                .map(|token| respan_token_tree(token, span))
+                .collect();
+            *g = Group::new(g.delimiter(), stream);
+            g.set_span(span);
+        }
+        other => other.set_span(span),
+    }
+    token
+}
+
+#[doc(hidden)]
+pub fn push_ident(tokens: &mut TokenStream, s: &str) {
+    let span = Span::call_site();
+    push_ident_spanned(tokens, span, s);
+}
+
+#[doc(hidden)]
+pub fn push_ident_spanned(tokens: &mut TokenStream, span: Span, s: &str) {
+    tokens.append(ident_maybe_raw(s, span));
+}
+
+#[doc(hidden)]
+pub fn push_lifetime(tokens: &mut TokenStream, lifetime: &str) {
+    struct Lifetime<'a> {
+        name: &'a str,
+        state: u8,
+    }
+
+    impl<'a> Iterator for Lifetime<'a> {
+        type Item = TokenTree;
+
+        fn next(&mut self) -> Option<Self::Item> {
+            match self.state {
+                0 => {
+                    self.state = 1;
+                    Some(TokenTree::Punct(Punct::new('\'', Spacing::Joint)))
+                }
+                1 => {
+                    self.state = 2;
+                    Some(TokenTree::Ident(Ident::new(self.name, Span::call_site())))
+                }
+                _ => None,
+            }
+        }
+    }
+
+    tokens.extend(Lifetime {
+        name: &lifetime[1..],
+        state: 0,
+    });
+}
+
+#[doc(hidden)]
+pub fn push_lifetime_spanned(tokens: &mut TokenStream, span: Span, lifetime: &str) {
+    struct Lifetime<'a> {
+        name: &'a str,
+        span: Span,
+        state: u8,
+    }
+
+    impl<'a> Iterator for Lifetime<'a> {
+        type Item = TokenTree;
+
+        fn next(&mut self) -> Option<Self::Item> {
+            match self.state {
+                0 => {
+                    self.state = 1;
+                    let mut apostrophe = Punct::new('\'', Spacing::Joint);
+                    apostrophe.set_span(self.span);
+                    Some(TokenTree::Punct(apostrophe))
+                }
+                1 => {
+                    self.state = 2;
+                    Some(TokenTree::Ident(Ident::new(self.name, self.span)))
+                }
+                _ => None,
+            }
+        }
+    }
+
+    tokens.extend(Lifetime {
+        name: &lifetime[1..],
+        span,
+        state: 0,
+    });
+}
+
+macro_rules! push_punct {
+    ($name:ident $spanned:ident $char1:tt) => {
+        #[doc(hidden)]
+        pub fn $name(tokens: &mut TokenStream) {
+            tokens.append(Punct::new($char1, Spacing::Alone));
+        }
+        #[doc(hidden)]
+        pub fn $spanned(tokens: &mut TokenStream, span: Span) {
+            let mut punct = Punct::new($char1, Spacing::Alone);
+            punct.set_span(span);
+            tokens.append(punct);
+        }
+    };
+    ($name:ident $spanned:ident $char1:tt $char2:tt) => {
+        #[doc(hidden)]
+        pub fn $name(tokens: &mut TokenStream) {
+            tokens.append(Punct::new($char1, Spacing::Joint));
+            tokens.append(Punct::new($char2, Spacing::Alone));
+        }
+        #[doc(hidden)]
+        pub fn $spanned(tokens: &mut TokenStream, span: Span) {
+            let mut punct = Punct::new($char1, Spacing::Joint);
+            punct.set_span(span);
+            tokens.append(punct);
+            let mut punct = Punct::new($char2, Spacing::Alone);
+            punct.set_span(span);
+            tokens.append(punct);
+        }
+    };
+    ($name:ident $spanned:ident $char1:tt $char2:tt $char3:tt) => {
+        #[doc(hidden)]
+        pub fn $name(tokens: &mut TokenStream) {
+            tokens.append(Punct::new($char1, Spacing::Joint));
+            tokens.append(Punct::new($char2, Spacing::Joint));
+            tokens.append(Punct::new($char3, Spacing::Alone));
+        }
+        #[doc(hidden)]
+        pub fn $spanned(tokens: &mut TokenStream, span: Span) {
+            let mut punct = Punct::new($char1, Spacing::Joint);
+            punct.set_span(span);
+            tokens.append(punct);
+            let mut punct = Punct::new($char2, Spacing::Joint);
+            punct.set_span(span);
+            tokens.append(punct);
+            let mut punct = Punct::new($char3, Spacing::Alone);
+            punct.set_span(span);
+            tokens.append(punct);
+        }
+    };
+}
+
+push_punct!(push_add push_add_spanned '+');
+push_punct!(push_add_eq push_add_eq_spanned '+' '=');
+push_punct!(push_and push_and_spanned '&');
+push_punct!(push_and_and push_and_and_spanned '&' '&');
+push_punct!(push_and_eq push_and_eq_spanned '&' '=');
+push_punct!(push_at push_at_spanned '@');
+push_punct!(push_bang push_bang_spanned '!');
+push_punct!(push_caret push_caret_spanned '^');
+push_punct!(push_caret_eq push_caret_eq_spanned '^' '=');
+push_punct!(push_colon push_colon_spanned ':');
+push_punct!(push_colon2 push_colon2_spanned ':' ':');
+push_punct!(push_comma push_comma_spanned ',');
+push_punct!(push_div push_div_spanned '/');
+push_punct!(push_div_eq push_div_eq_spanned '/' '=');
+push_punct!(push_dot push_dot_spanned '.');
+push_punct!(push_dot2 push_dot2_spanned '.' '.');
+push_punct!(push_dot3 push_dot3_spanned '.' '.' '.');
+push_punct!(push_dot_dot_eq push_dot_dot_eq_spanned '.' '.' '=');
+push_punct!(push_eq push_eq_spanned '=');
+push_punct!(push_eq_eq push_eq_eq_spanned '=' '=');
+push_punct!(push_ge push_ge_spanned '>' '=');
+push_punct!(push_gt push_gt_spanned '>');
+push_punct!(push_le push_le_spanned '<' '=');
+push_punct!(push_lt push_lt_spanned '<');
+push_punct!(push_mul_eq push_mul_eq_spanned '*' '=');
+push_punct!(push_ne push_ne_spanned '!' '=');
+push_punct!(push_or push_or_spanned '|');
+push_punct!(push_or_eq push_or_eq_spanned '|' '=');
+push_punct!(push_or_or push_or_or_spanned '|' '|');
+push_punct!(push_pound push_pound_spanned '#');
+push_punct!(push_question push_question_spanned '?');
+push_punct!(push_rarrow push_rarrow_spanned '-' '>');
+push_punct!(push_larrow push_larrow_spanned '<' '-');
+push_punct!(push_rem push_rem_spanned '%');
+push_punct!(push_rem_eq push_rem_eq_spanned '%' '=');
+push_punct!(push_fat_arrow push_fat_arrow_spanned '=' '>');
+push_punct!(push_semi push_semi_spanned ';');
+push_punct!(push_shl push_shl_spanned '<' '<');
+push_punct!(push_shl_eq push_shl_eq_spanned '<' '<' '=');
+push_punct!(push_shr push_shr_spanned '>' '>');
+push_punct!(push_shr_eq push_shr_eq_spanned '>' '>' '=');
+push_punct!(push_star push_star_spanned '*');
+push_punct!(push_sub push_sub_spanned '-');
+push_punct!(push_sub_eq push_sub_eq_spanned '-' '=');
+
+#[doc(hidden)]
+pub fn push_underscore(tokens: &mut TokenStream) {
+    push_underscore_spanned(tokens, Span::call_site());
+}
+
+#[doc(hidden)]
+pub fn push_underscore_spanned(tokens: &mut TokenStream, span: Span) {
+    tokens.append(Ident::new("_", span));
+}
+
+// Helper method for constructing identifiers from the `format_ident!` macro,
+// handling `r#` prefixes.
+#[doc(hidden)]
+pub fn mk_ident(id: &str, span: Option<Span>) -> Ident {
+    let span = span.unwrap_or_else(Span::call_site);
+    ident_maybe_raw(id, span)
+}
+
+fn ident_maybe_raw(id: &str, span: Span) -> Ident {
+    if let Some(id) = id.strip_prefix("r#") {
+        Ident::new_raw(id, span)
+    } else {
+        Ident::new(id, span)
+    }
+}
+
+// Adapts from `IdentFragment` to `fmt::Display` for use by the `format_ident!`
+// macro, and exposes span information from these fragments.
+//
+// This struct also has forwarding implementations of the formatting traits
+// `Octal`, `LowerHex`, `UpperHex`, and `Binary` to allow for their use within
+// `format_ident!`.
+#[derive(Copy, Clone)]
+#[doc(hidden)]
+pub struct IdentFragmentAdapter<T: IdentFragment>(pub T);
+
+impl<T: IdentFragment> IdentFragmentAdapter<T> {
+    pub fn span(&self) -> Option<Span> {
+        self.0.span()
+    }
+}
+
+impl<T: IdentFragment> fmt::Display for IdentFragmentAdapter<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        IdentFragment::fmt(&self.0, f)
+    }
+}
+
+impl<T: IdentFragment + fmt::Octal> fmt::Octal for IdentFragmentAdapter<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Octal::fmt(&self.0, f)
+    }
+}
+
+impl<T: IdentFragment + fmt::LowerHex> fmt::LowerHex for IdentFragmentAdapter<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::LowerHex::fmt(&self.0, f)
+    }
+}
+
+impl<T: IdentFragment + fmt::UpperHex> fmt::UpperHex for IdentFragmentAdapter<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::UpperHex::fmt(&self.0, f)
+    }
+}
+
+impl<T: IdentFragment + fmt::Binary> fmt::Binary for IdentFragmentAdapter<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        fmt::Binary::fmt(&self.0, f)
+    }
+}
diff --git a/rust/quote/spanned.rs b/rust/quote/spanned.rs
new file mode 100644
index 0000000000000000000000000000000000000000..54ce9177f45ea345ed28e5f139544059e07d7a19
--- /dev/null
+++ b/rust/quote/spanned.rs
@@ -0,0 +1,52 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::ToTokens;
+use proc_macro2::extra::DelimSpan;
+use proc_macro2::{Span, TokenStream};
+
+// Not public API other than via the syn crate. Use syn::spanned::Spanned.
+pub trait Spanned: private::Sealed {
+    fn __span(&self) -> Span;
+}
+
+impl Spanned for Span {
+    fn __span(&self) -> Span {
+        *self
+    }
+}
+
+impl Spanned for DelimSpan {
+    fn __span(&self) -> Span {
+        self.join()
+    }
+}
+
+impl<T: ?Sized + ToTokens> Spanned for T {
+    fn __span(&self) -> Span {
+        join_spans(self.into_token_stream())
+    }
+}
+
+fn join_spans(tokens: TokenStream) -> Span {
+    let mut iter = tokens.into_iter().map(|tt| tt.span());
+
+    let first = match iter.next() {
+        Some(span) => span,
+        None => return Span::call_site(),
+    };
+
+    iter.fold(None, |_prev, next| Some(next))
+        .and_then(|last| first.join(last))
+        .unwrap_or(first)
+}
+
+mod private {
+    use crate::ToTokens;
+    use proc_macro2::extra::DelimSpan;
+    use proc_macro2::Span;
+
+    pub trait Sealed {}
+    impl Sealed for Span {}
+    impl Sealed for DelimSpan {}
+    impl<T: ?Sized + ToTokens> Sealed for T {}
+}
diff --git a/rust/quote/to_tokens.rs b/rust/quote/to_tokens.rs
new file mode 100644
index 0000000000000000000000000000000000000000..67b18485e8e015902cf841257c3d49a16763cc19
--- /dev/null
+++ b/rust/quote/to_tokens.rs
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use super::TokenStreamExt;
+use alloc::borrow::Cow;
+use alloc::rc::Rc;
+use core::iter;
+use proc_macro2::{Group, Ident, Literal, Punct, Span, TokenStream, TokenTree};
+
+/// Types that can be interpolated inside a `quote!` invocation.
+///
+/// [`quote!`]: macro.quote.html
+pub trait ToTokens {
+    /// Write `self` to the given `TokenStream`.
+    ///
+    /// The token append methods provided by the [`TokenStreamExt`] extension
+    /// trait may be useful for implementing `ToTokens`.
+    ///
+    /// [`TokenStreamExt`]: trait.TokenStreamExt.html
+    ///
+    /// # Example
+    ///
+    /// Example implementation for a struct representing Rust paths like
+    /// `std::cmp::PartialEq`:
+    ///
+    /// ```
+    /// use proc_macro2::{TokenTree, Spacing, Span, Punct, TokenStream};
+    /// use quote::{TokenStreamExt, ToTokens};
+    ///
+    /// pub struct Path {
+    ///     pub global: bool,
+    ///     pub segments: Vec<PathSegment>,
+    /// }
+    ///
+    /// impl ToTokens for Path {
+    ///     fn to_tokens(&self, tokens: &mut TokenStream) {
+    ///         for (i, segment) in self.segments.iter().enumerate() {
+    ///             if i > 0 || self.global {
+    ///                 // Double colon `::`
+    ///                 tokens.append(Punct::new(':', Spacing::Joint));
+    ///                 tokens.append(Punct::new(':', Spacing::Alone));
+    ///             }
+    ///             segment.to_tokens(tokens);
+    ///         }
+    ///     }
+    /// }
+    /// #
+    /// # pub struct PathSegment;
+    /// #
+    /// # impl ToTokens for PathSegment {
+    /// #     fn to_tokens(&self, tokens: &mut TokenStream) {
+    /// #         unimplemented!()
+    /// #     }
+    /// # }
+    /// ```
+    fn to_tokens(&self, tokens: &mut TokenStream);
+
+    /// Convert `self` directly into a `TokenStream` object.
+    ///
+    /// This method is implicitly implemented using `to_tokens`, and acts as a
+    /// convenience method for consumers of the `ToTokens` trait.
+    fn to_token_stream(&self) -> TokenStream {
+        let mut tokens = TokenStream::new();
+        self.to_tokens(&mut tokens);
+        tokens
+    }
+
+    /// Convert `self` directly into a `TokenStream` object.
+    ///
+    /// This method is implicitly implemented using `to_tokens`, and acts as a
+    /// convenience method for consumers of the `ToTokens` trait.
+    fn into_token_stream(self) -> TokenStream
+    where
+        Self: Sized,
+    {
+        self.to_token_stream()
+    }
+}
+
+impl<'a, T: ?Sized + ToTokens> ToTokens for &'a T {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        (**self).to_tokens(tokens);
+    }
+}
+
+impl<'a, T: ?Sized + ToTokens> ToTokens for &'a mut T {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        (**self).to_tokens(tokens);
+    }
+}
+
+impl<'a, T: ?Sized + ToOwned + ToTokens> ToTokens for Cow<'a, T> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        (**self).to_tokens(tokens);
+    }
+}
+
+impl<T: ?Sized + ToTokens> ToTokens for Box<T> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        (**self).to_tokens(tokens);
+    }
+}
+
+impl<T: ?Sized + ToTokens> ToTokens for Rc<T> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        (**self).to_tokens(tokens);
+    }
+}
+
+impl<T: ToTokens> ToTokens for Option<T> {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        if let Some(ref t) = *self {
+            t.to_tokens(tokens);
+        }
+    }
+}
+
+impl ToTokens for str {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.append(Literal::string(self));
+    }
+}
+
+impl ToTokens for String {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        self.as_str().to_tokens(tokens);
+    }
+}
+
+macro_rules! primitive {
+    ($($t:ident => $name:ident)*) => {
+        $(
+            impl ToTokens for $t {
+                fn to_tokens(&self, tokens: &mut TokenStream) {
+                    tokens.append(Literal::$name(*self));
+                }
+            }
+        )*
+    };
+}
+
+primitive! {
+    i8 => i8_suffixed
+    i16 => i16_suffixed
+    i32 => i32_suffixed
+    i64 => i64_suffixed
+    i128 => i128_suffixed
+    isize => isize_suffixed
+
+    u8 => u8_suffixed
+    u16 => u16_suffixed
+    u32 => u32_suffixed
+    u64 => u64_suffixed
+    u128 => u128_suffixed
+    usize => usize_suffixed
+
+    f32 => f32_suffixed
+    f64 => f64_suffixed
+}
+
+impl ToTokens for char {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.append(Literal::character(*self));
+    }
+}
+
+impl ToTokens for bool {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let word = if *self { "true" } else { "false" };
+        tokens.append(Ident::new(word, Span::call_site()));
+    }
+}
+
+impl ToTokens for Group {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.append(self.clone());
+    }
+}
+
+impl ToTokens for Ident {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.append(self.clone());
+    }
+}
+
+impl ToTokens for Punct {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.append(self.clone());
+    }
+}
+
+impl ToTokens for Literal {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.append(self.clone());
+    }
+}
+
+impl ToTokens for TokenTree {
+    fn to_tokens(&self, dst: &mut TokenStream) {
+        dst.append(self.clone());
+    }
+}
+
+impl ToTokens for TokenStream {
+    fn to_tokens(&self, dst: &mut TokenStream) {
+        dst.extend(iter::once(self.clone()));
+    }
+
+    fn into_token_stream(self) -> TokenStream {
+        self
+    }
+}
diff --git a/rust/syn/attr.rs b/rust/syn/attr.rs
new file mode 100644
index 0000000000000000000000000000000000000000..a052f10c8c320f996046fc8d5e2fb07e9850eb2c
--- /dev/null
+++ b/rust/syn/attr.rs
@@ -0,0 +1,795 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "parsing")]
+use crate::error::Error;
+#[cfg(feature = "parsing")]
+use crate::error::Result;
+use crate::expr::Expr;
+use crate::mac::MacroDelimiter;
+#[cfg(feature = "parsing")]
+use crate::meta::{self, ParseNestedMeta};
+#[cfg(feature = "parsing")]
+use crate::parse::{Parse, ParseStream, Parser};
+use crate::path::Path;
+use crate::token;
+use proc_macro2::TokenStream;
+#[cfg(feature = "printing")]
+use std::iter;
+#[cfg(feature = "printing")]
+use std::slice;
+
+ast_struct! {
+    /// An attribute, like `#[repr(transparent)]`.
+    ///
+    /// <br>
+    ///
+    /// # Syntax
+    ///
+    /// Rust has six types of attributes.
+    ///
+    /// - Outer attributes like `#[repr(transparent)]`. These appear outside or
+    ///   in front of the item they describe.
+    ///
+    /// - Inner attributes like `#![feature(proc_macro)]`. These appear inside
+    ///   of the item they describe, usually a module.
+    ///
+    /// - Outer one-line doc comments like `/// Example`.
+    ///
+    /// - Inner one-line doc comments like `//! Please file an issue`.
+    ///
+    /// - Outer documentation blocks `/** Example */`.
+    ///
+    /// - Inner documentation blocks `/*! Please file an issue */`.
+    ///
+    /// The `style` field of type `AttrStyle` distinguishes whether an attribute
+    /// is outer or inner.
+    ///
+    /// Every attribute has a `path` that indicates the intended interpretation
+    /// of the rest of the attribute's contents. The path and the optional
+    /// additional contents are represented together in the `meta` field of the
+    /// attribute in three possible varieties:
+    ///
+    /// - Meta::Path &mdash; attributes whose information content conveys just a
+    ///   path, for example the `#[test]` attribute.
+    ///
+    /// - Meta::List &mdash; attributes that carry arbitrary tokens after the
+    ///   path, surrounded by a delimiter (parenthesis, bracket, or brace). For
+    ///   example `#[derive(Copy)]` or `#[precondition(x < 5)]`.
+    ///
+    /// - Meta::NameValue &mdash; attributes with an `=` sign after the path,
+    ///   followed by a Rust expression. For example `#[path =
+    ///   "sys/windows.rs"]`.
+    ///
+    /// All doc comments are represented in the NameValue style with a path of
+    /// "doc", as this is how they are processed by the compiler and by
+    /// `macro_rules!` macros.
+    ///
+    /// ```text
+    /// #[derive(Copy, Clone)]
+    ///   ~~~~~~Path
+    ///   ^^^^^^^^^^^^^^^^^^^Meta::List
+    ///
+    /// #[path = "sys/windows.rs"]
+    ///   ~~~~Path
+    ///   ^^^^^^^^^^^^^^^^^^^^^^^Meta::NameValue
+    ///
+    /// #[test]
+    ///   ^^^^Meta::Path
+    /// ```
+    ///
+    /// <br>
+    ///
+    /// # Parsing from tokens to Attribute
+    ///
+    /// This type does not implement the [`Parse`] trait and thus cannot be
+    /// parsed directly by [`ParseStream::parse`]. Instead use
+    /// [`ParseStream::call`] with one of the two parser functions
+    /// [`Attribute::parse_outer`] or [`Attribute::parse_inner`] depending on
+    /// which you intend to parse.
+    ///
+    /// [`Parse`]: crate::parse::Parse
+    /// [`ParseStream::parse`]: crate::parse::ParseBuffer::parse
+    /// [`ParseStream::call`]: crate::parse::ParseBuffer::call
+    ///
+    /// ```
+    /// use syn::{Attribute, Ident, Result, Token};
+    /// use syn::parse::{Parse, ParseStream};
+    ///
+    /// // Parses a unit struct with attributes.
+    /// //
+    /// //     #[path = "s.tmpl"]
+    /// //     struct S;
+    /// struct UnitStruct {
+    ///     attrs: Vec<Attribute>,
+    ///     struct_token: Token![struct],
+    ///     name: Ident,
+    ///     semi_token: Token![;],
+    /// }
+    ///
+    /// impl Parse for UnitStruct {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         Ok(UnitStruct {
+    ///             attrs: input.call(Attribute::parse_outer)?,
+    ///             struct_token: input.parse()?,
+    ///             name: input.parse()?,
+    ///             semi_token: input.parse()?,
+    ///         })
+    ///     }
+    /// }
+    /// ```
+    ///
+    /// <p><br></p>
+    ///
+    /// # Parsing from Attribute to structured arguments
+    ///
+    /// The grammar of attributes in Rust is very flexible, which makes the
+    /// syntax tree not that useful on its own. In particular, arguments of the
+    /// `Meta::List` variety of attribute are held in an arbitrary `tokens:
+    /// TokenStream`. Macros are expected to check the `path` of the attribute,
+    /// decide whether they recognize it, and then parse the remaining tokens
+    /// according to whatever grammar they wish to require for that kind of
+    /// attribute. Use [`parse_args()`] to parse those tokens into the expected
+    /// data structure.
+    ///
+    /// [`parse_args()`]: Attribute::parse_args
+    ///
+    /// <p><br></p>
+    ///
+    /// # Doc comments
+    ///
+    /// The compiler transforms doc comments, such as `/// comment` and `/*!
+    /// comment */`, into attributes before macros are expanded. Each comment is
+    /// expanded into an attribute of the form `#[doc = r"comment"]`.
+    ///
+    /// As an example, the following `mod` items are expanded identically:
+    ///
+    /// ```
+    /// # use syn::{ItemMod, parse_quote};
+    /// let doc: ItemMod = parse_quote! {
+    ///     /// Single line doc comments
+    ///     /// We write so many!
+    ///     /**
+    ///      * Multi-line comments...
+    ///      * May span many lines
+    ///      */
+    ///     mod example {
+    ///         //! Of course, they can be inner too
+    ///         /*! And fit in a single line */
+    ///     }
+    /// };
+    /// let attr: ItemMod = parse_quote! {
+    ///     #[doc = r" Single line doc comments"]
+    ///     #[doc = r" We write so many!"]
+    ///     #[doc = r"
+    ///      * Multi-line comments...
+    ///      * May span many lines
+    ///      "]
+    ///     mod example {
+    ///         #![doc = r" Of course, they can be inner too"]
+    ///         #![doc = r" And fit in a single line "]
+    ///     }
+    /// };
+    /// assert_eq!(doc, attr);
+    /// ```
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct Attribute {
+        pub pound_token: Token![#],
+        pub style: AttrStyle,
+        pub bracket_token: token::Bracket,
+        pub meta: Meta,
+    }
+}
+
+impl Attribute {
+    /// Returns the path that identifies the interpretation of this attribute.
+    ///
+    /// For example this would return the `test` in `#[test]`, the `derive` in
+    /// `#[derive(Copy)]`, and the `path` in `#[path = "sys/windows.rs"]`.
+    pub fn path(&self) -> &Path {
+        self.meta.path()
+    }
+
+    /// Parse the arguments to the attribute as a syntax tree.
+    ///
+    /// This is similar to pulling out the `TokenStream` from `Meta::List` and
+    /// doing `syn::parse2::<T>(meta_list.tokens)`, except that using
+    /// `parse_args` the error message has a more useful span when `tokens` is
+    /// empty.
+    ///
+    /// The surrounding delimiters are *not* included in the input to the
+    /// parser.
+    ///
+    /// ```text
+    /// #[my_attr(value < 5)]
+    ///           ^^^^^^^^^ what gets parsed
+    /// ```
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{parse_quote, Attribute, Expr};
+    ///
+    /// let attr: Attribute = parse_quote! {
+    ///     #[precondition(value < 5)]
+    /// };
+    ///
+    /// if attr.path().is_ident("precondition") {
+    ///     let precondition: Expr = attr.parse_args()?;
+    ///     // ...
+    /// }
+    /// # anyhow::Ok(())
+    /// ```
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_args<T: Parse>(&self) -> Result<T> {
+        self.parse_args_with(T::parse)
+    }
+
+    /// Parse the arguments to the attribute using the given parser.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{parse_quote, Attribute};
+    ///
+    /// let attr: Attribute = parse_quote! {
+    ///     #[inception { #[brrrrrrraaaaawwwwrwrrrmrmrmmrmrmmmmm] }]
+    /// };
+    ///
+    /// let bwom = attr.parse_args_with(Attribute::parse_outer)?;
+    ///
+    /// // Attribute does not have a Parse impl, so we couldn't directly do:
+    /// // let bwom: Attribute = attr.parse_args()?;
+    /// # anyhow::Ok(())
+    /// ```
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_args_with<F: Parser>(&self, parser: F) -> Result<F::Output> {
+        match &self.meta {
+            Meta::Path(path) => Err(crate::error::new2(
+                path.segments.first().unwrap().ident.span(),
+                path.segments.last().unwrap().ident.span(),
+                format!(
+                    "expected attribute arguments in parentheses: {}[{}(...)]",
+                    parsing::DisplayAttrStyle(&self.style),
+                    parsing::DisplayPath(path),
+                ),
+            )),
+            Meta::NameValue(meta) => Err(Error::new(
+                meta.eq_token.span,
+                format_args!(
+                    "expected parentheses: {}[{}(...)]",
+                    parsing::DisplayAttrStyle(&self.style),
+                    parsing::DisplayPath(&meta.path),
+                ),
+            )),
+            Meta::List(meta) => meta.parse_args_with(parser),
+        }
+    }
+
+    /// Parse the arguments to the attribute, expecting it to follow the
+    /// conventional structure used by most of Rust's built-in attributes.
+    ///
+    /// The [*Meta Item Attribute Syntax*][syntax] section in the Rust reference
+    /// explains the convention in more detail. Not all attributes follow this
+    /// convention, so [`parse_args()`][Self::parse_args] is available if you
+    /// need to parse arbitrarily goofy attribute syntax.
+    ///
+    /// [syntax]: https://doc.rust-lang.org/reference/attributes.html#meta-item-attribute-syntax
+    ///
+    /// # Example
+    ///
+    /// We'll parse a struct, and then parse some of Rust's `#[repr]` attribute
+    /// syntax.
+    ///
+    /// ```
+    /// use syn::{parenthesized, parse_quote, token, ItemStruct, LitInt};
+    ///
+    /// let input: ItemStruct = parse_quote! {
+    ///     #[repr(C, align(4))]
+    ///     pub struct MyStruct(u16, u32);
+    /// };
+    ///
+    /// let mut repr_c = false;
+    /// let mut repr_transparent = false;
+    /// let mut repr_align = None::<usize>;
+    /// let mut repr_packed = None::<usize>;
+    /// for attr in &input.attrs {
+    ///     if attr.path().is_ident("repr") {
+    ///         attr.parse_nested_meta(|meta| {
+    ///             // #[repr(C)]
+    ///             if meta.path.is_ident("C") {
+    ///                 repr_c = true;
+    ///                 return Ok(());
+    ///             }
+    ///
+    ///             // #[repr(transparent)]
+    ///             if meta.path.is_ident("transparent") {
+    ///                 repr_transparent = true;
+    ///                 return Ok(());
+    ///             }
+    ///
+    ///             // #[repr(align(N))]
+    ///             if meta.path.is_ident("align") {
+    ///                 let content;
+    ///                 parenthesized!(content in meta.input);
+    ///                 let lit: LitInt = content.parse()?;
+    ///                 let n: usize = lit.base10_parse()?;
+    ///                 repr_align = Some(n);
+    ///                 return Ok(());
+    ///             }
+    ///
+    ///             // #[repr(packed)] or #[repr(packed(N))], omitted N means 1
+    ///             if meta.path.is_ident("packed") {
+    ///                 if meta.input.peek(token::Paren) {
+    ///                     let content;
+    ///                     parenthesized!(content in meta.input);
+    ///                     let lit: LitInt = content.parse()?;
+    ///                     let n: usize = lit.base10_parse()?;
+    ///                     repr_packed = Some(n);
+    ///                 } else {
+    ///                     repr_packed = Some(1);
+    ///                 }
+    ///                 return Ok(());
+    ///             }
+    ///
+    ///             Err(meta.error("unrecognized repr"))
+    ///         })?;
+    ///     }
+    /// }
+    /// # anyhow::Ok(())
+    /// ```
+    ///
+    /// # Alternatives
+    ///
+    /// In some cases, for attributes which have nested layers of structured
+    /// content, the following less flexible approach might be more convenient:
+    ///
+    /// ```
+    /// # use syn::{parse_quote, ItemStruct};
+    /// #
+    /// # let input: ItemStruct = parse_quote! {
+    /// #     #[repr(C, align(4))]
+    /// #     pub struct MyStruct(u16, u32);
+    /// # };
+    /// #
+    /// use syn::punctuated::Punctuated;
+    /// use syn::{parenthesized, token, Error, LitInt, Meta, Token};
+    ///
+    /// let mut repr_c = false;
+    /// let mut repr_transparent = false;
+    /// let mut repr_align = None::<usize>;
+    /// let mut repr_packed = None::<usize>;
+    /// for attr in &input.attrs {
+    ///     if attr.path().is_ident("repr") {
+    ///         let nested = attr.parse_args_with(Punctuated::<Meta, Token![,]>::parse_terminated)?;
+    ///         for meta in nested {
+    ///             match meta {
+    ///                 // #[repr(C)]
+    ///                 Meta::Path(path) if path.is_ident("C") => {
+    ///                     repr_c = true;
+    ///                 }
+    ///
+    ///                 // #[repr(align(N))]
+    ///                 Meta::List(meta) if meta.path.is_ident("align") => {
+    ///                     let lit: LitInt = meta.parse_args()?;
+    ///                     let n: usize = lit.base10_parse()?;
+    ///                     repr_align = Some(n);
+    ///                 }
+    ///
+    ///                 /* ... */
+    ///
+    ///                 _ => {
+    ///                     return Err(Error::new_spanned(meta, "unrecognized repr"));
+    ///                 }
+    ///             }
+    ///         }
+    ///     }
+    /// }
+    /// # Ok(())
+    /// ```
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_nested_meta(
+        &self,
+        logic: impl FnMut(ParseNestedMeta) -> Result<()>,
+    ) -> Result<()> {
+        self.parse_args_with(meta::parser(logic))
+    }
+
+    /// Parses zero or more outer attributes from the stream.
+    ///
+    /// # Example
+    ///
+    /// See
+    /// [*Parsing from tokens to Attribute*](#parsing-from-tokens-to-attribute).
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_outer(input: ParseStream) -> Result<Vec<Self>> {
+        let mut attrs = Vec::new();
+        while input.peek(Token![#]) {
+            attrs.push(input.call(parsing::single_parse_outer)?);
+        }
+        Ok(attrs)
+    }
+
+    /// Parses zero or more inner attributes from the stream.
+    ///
+    /// # Example
+    ///
+    /// See
+    /// [*Parsing from tokens to Attribute*](#parsing-from-tokens-to-attribute).
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_inner(input: ParseStream) -> Result<Vec<Self>> {
+        let mut attrs = Vec::new();
+        parsing::parse_inner(input, &mut attrs)?;
+        Ok(attrs)
+    }
+}
+
+ast_enum! {
+    /// Distinguishes between attributes that decorate an item and attributes
+    /// that are contained within an item.
+    ///
+    /// # Outer attributes
+    ///
+    /// - `#[repr(transparent)]`
+    /// - `/// # Example`
+    /// - `/** Please file an issue */`
+    ///
+    /// # Inner attributes
+    ///
+    /// - `#![feature(proc_macro)]`
+    /// - `//! # Example`
+    /// - `/*! Please file an issue */`
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum AttrStyle {
+        Outer,
+        Inner(Token![!]),
+    }
+}
+
+ast_enum_of_structs! {
+    /// Content of a compile-time structured attribute.
+    ///
+    /// ## Path
+    ///
+    /// A meta path is like the `test` in `#[test]`.
+    ///
+    /// ## List
+    ///
+    /// A meta list is like the `derive(Copy)` in `#[derive(Copy)]`.
+    ///
+    /// ## NameValue
+    ///
+    /// A name-value meta is like the `path = "..."` in `#[path =
+    /// "sys/windows.rs"]`.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum Meta {
+        Path(Path),
+
+        /// A structured list within an attribute, like `derive(Copy, Clone)`.
+        List(MetaList),
+
+        /// A name-value pair within an attribute, like `feature = "nightly"`.
+        NameValue(MetaNameValue),
+    }
+}
+
+ast_struct! {
+    /// A structured list within an attribute, like `derive(Copy, Clone)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct MetaList {
+        pub path: Path,
+        pub delimiter: MacroDelimiter,
+        pub tokens: TokenStream,
+    }
+}
+
+ast_struct! {
+    /// A name-value pair within an attribute, like `feature = "nightly"`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct MetaNameValue {
+        pub path: Path,
+        pub eq_token: Token![=],
+        pub value: Expr,
+    }
+}
+
+impl Meta {
+    /// Returns the path that begins this structured meta item.
+    ///
+    /// For example this would return the `test` in `#[test]`, the `derive` in
+    /// `#[derive(Copy)]`, and the `path` in `#[path = "sys/windows.rs"]`.
+    pub fn path(&self) -> &Path {
+        match self {
+            Meta::Path(path) => path,
+            Meta::List(meta) => &meta.path,
+            Meta::NameValue(meta) => &meta.path,
+        }
+    }
+
+    /// Error if this is a `Meta::List` or `Meta::NameValue`.
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn require_path_only(&self) -> Result<&Path> {
+        let error_span = match self {
+            Meta::Path(path) => return Ok(path),
+            Meta::List(meta) => meta.delimiter.span().open(),
+            Meta::NameValue(meta) => meta.eq_token.span,
+        };
+        Err(Error::new(error_span, "unexpected token in attribute"))
+    }
+
+    /// Error if this is a `Meta::Path` or `Meta::NameValue`.
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn require_list(&self) -> Result<&MetaList> {
+        match self {
+            Meta::List(meta) => Ok(meta),
+            Meta::Path(path) => Err(crate::error::new2(
+                path.segments.first().unwrap().ident.span(),
+                path.segments.last().unwrap().ident.span(),
+                format!(
+                    "expected attribute arguments in parentheses: `{}(...)`",
+                    parsing::DisplayPath(path),
+                ),
+            )),
+            Meta::NameValue(meta) => Err(Error::new(meta.eq_token.span, "expected `(`")),
+        }
+    }
+
+    /// Error if this is a `Meta::Path` or `Meta::List`.
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn require_name_value(&self) -> Result<&MetaNameValue> {
+        match self {
+            Meta::NameValue(meta) => Ok(meta),
+            Meta::Path(path) => Err(crate::error::new2(
+                path.segments.first().unwrap().ident.span(),
+                path.segments.last().unwrap().ident.span(),
+                format!(
+                    "expected a value for this attribute: `{} = ...`",
+                    parsing::DisplayPath(path),
+                ),
+            )),
+            Meta::List(meta) => Err(Error::new(meta.delimiter.span().open(), "expected `=`")),
+        }
+    }
+}
+
+impl MetaList {
+    /// See [`Attribute::parse_args`].
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_args<T: Parse>(&self) -> Result<T> {
+        self.parse_args_with(T::parse)
+    }
+
+    /// See [`Attribute::parse_args_with`].
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_args_with<F: Parser>(&self, parser: F) -> Result<F::Output> {
+        let scope = self.delimiter.span().close();
+        crate::parse::parse_scoped(parser, scope, self.tokens.clone())
+    }
+
+    /// See [`Attribute::parse_nested_meta`].
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_nested_meta(
+        &self,
+        logic: impl FnMut(ParseNestedMeta) -> Result<()>,
+    ) -> Result<()> {
+        self.parse_args_with(meta::parser(logic))
+    }
+}
+
+#[cfg(feature = "printing")]
+pub(crate) trait FilterAttrs<'a> {
+    type Ret: Iterator<Item = &'a Attribute>;
+
+    fn outer(self) -> Self::Ret;
+    #[cfg(feature = "full")]
+    fn inner(self) -> Self::Ret;
+}
+
+#[cfg(feature = "printing")]
+impl<'a> FilterAttrs<'a> for &'a [Attribute] {
+    type Ret = iter::Filter<slice::Iter<'a, Attribute>, fn(&&Attribute) -> bool>;
+
+    fn outer(self) -> Self::Ret {
+        fn is_outer(attr: &&Attribute) -> bool {
+            match attr.style {
+                AttrStyle::Outer => true,
+                AttrStyle::Inner(_) => false,
+            }
+        }
+        self.iter().filter(is_outer)
+    }
+
+    #[cfg(feature = "full")]
+    fn inner(self) -> Self::Ret {
+        fn is_inner(attr: &&Attribute) -> bool {
+            match attr.style {
+                AttrStyle::Inner(_) => true,
+                AttrStyle::Outer => false,
+            }
+        }
+        self.iter().filter(is_inner)
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::{AttrStyle, Attribute, Meta, MetaList, MetaNameValue};
+    use crate::error::Result;
+    use crate::expr::{Expr, ExprLit};
+    use crate::lit::Lit;
+    use crate::parse::discouraged::Speculative as _;
+    use crate::parse::{Parse, ParseStream};
+    use crate::path::Path;
+    use crate::{mac, token};
+    use std::fmt::{self, Display};
+
+    pub(crate) fn parse_inner(input: ParseStream, attrs: &mut Vec<Attribute>) -> Result<()> {
+        while input.peek(Token![#]) && input.peek2(Token![!]) {
+            attrs.push(input.call(single_parse_inner)?);
+        }
+        Ok(())
+    }
+
+    pub(crate) fn single_parse_inner(input: ParseStream) -> Result<Attribute> {
+        let content;
+        Ok(Attribute {
+            pound_token: input.parse()?,
+            style: AttrStyle::Inner(input.parse()?),
+            bracket_token: bracketed!(content in input),
+            meta: content.parse()?,
+        })
+    }
+
+    pub(crate) fn single_parse_outer(input: ParseStream) -> Result<Attribute> {
+        let content;
+        Ok(Attribute {
+            pound_token: input.parse()?,
+            style: AttrStyle::Outer,
+            bracket_token: bracketed!(content in input),
+            meta: content.parse()?,
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Meta {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let path = input.call(Path::parse_mod_style)?;
+            parse_meta_after_path(path, input)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for MetaList {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let path = input.call(Path::parse_mod_style)?;
+            parse_meta_list_after_path(path, input)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for MetaNameValue {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let path = input.call(Path::parse_mod_style)?;
+            parse_meta_name_value_after_path(path, input)
+        }
+    }
+
+    pub(crate) fn parse_meta_after_path(path: Path, input: ParseStream) -> Result<Meta> {
+        if input.peek(token::Paren) || input.peek(token::Bracket) || input.peek(token::Brace) {
+            parse_meta_list_after_path(path, input).map(Meta::List)
+        } else if input.peek(Token![=]) {
+            parse_meta_name_value_after_path(path, input).map(Meta::NameValue)
+        } else {
+            Ok(Meta::Path(path))
+        }
+    }
+
+    fn parse_meta_list_after_path(path: Path, input: ParseStream) -> Result<MetaList> {
+        let (delimiter, tokens) = mac::parse_delimiter(input)?;
+        Ok(MetaList {
+            path,
+            delimiter,
+            tokens,
+        })
+    }
+
+    fn parse_meta_name_value_after_path(path: Path, input: ParseStream) -> Result<MetaNameValue> {
+        let eq_token: Token![=] = input.parse()?;
+        let ahead = input.fork();
+        let lit: Option<Lit> = ahead.parse()?;
+        let value = if let (Some(lit), true) = (lit, ahead.is_empty()) {
+            input.advance_to(&ahead);
+            Expr::Lit(ExprLit {
+                attrs: Vec::new(),
+                lit,
+            })
+        } else if input.peek(Token![#]) && input.peek2(token::Bracket) {
+            return Err(input.error("unexpected attribute inside of attribute"));
+        } else {
+            input.parse()?
+        };
+        Ok(MetaNameValue {
+            path,
+            eq_token,
+            value,
+        })
+    }
+
+    pub(super) struct DisplayAttrStyle<'a>(pub &'a AttrStyle);
+
+    impl<'a> Display for DisplayAttrStyle<'a> {
+        fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            formatter.write_str(match self.0 {
+                AttrStyle::Outer => "#",
+                AttrStyle::Inner(_) => "#!",
+            })
+        }
+    }
+
+    pub(super) struct DisplayPath<'a>(pub &'a Path);
+
+    impl<'a> Display for DisplayPath<'a> {
+        fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            for (i, segment) in self.0.segments.iter().enumerate() {
+                if i > 0 || self.0.leading_colon.is_some() {
+                    formatter.write_str("::")?;
+                }
+                write!(formatter, "{}", segment.ident)?;
+            }
+            Ok(())
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::attr::{AttrStyle, Attribute, MetaList, MetaNameValue};
+    use proc_macro2::TokenStream;
+    use quote::ToTokens;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Attribute {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.pound_token.to_tokens(tokens);
+            if let AttrStyle::Inner(b) = &self.style {
+                b.to_tokens(tokens);
+            }
+            self.bracket_token.surround(tokens, |tokens| {
+                self.meta.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for MetaList {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.path.to_tokens(tokens);
+            self.delimiter.surround(tokens, self.tokens.clone());
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for MetaNameValue {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.path.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.value.to_tokens(tokens);
+        }
+    }
+}
diff --git a/rust/syn/bigint.rs b/rust/syn/bigint.rs
new file mode 100644
index 0000000000000000000000000000000000000000..d706f9f515e9cace5bb3feeca536493609a3353b
--- /dev/null
+++ b/rust/syn/bigint.rs
@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use std::ops::{AddAssign, MulAssign};
+
+// For implementing base10_digits() accessor on LitInt.
+pub(crate) struct BigInt {
+    digits: Vec<u8>,
+}
+
+impl BigInt {
+    pub(crate) fn new() -> Self {
+        BigInt { digits: Vec::new() }
+    }
+
+    pub(crate) fn to_string(&self) -> String {
+        let mut repr = String::with_capacity(self.digits.len());
+
+        let mut has_nonzero = false;
+        for digit in self.digits.iter().rev() {
+            has_nonzero |= *digit != 0;
+            if has_nonzero {
+                repr.push((*digit + b'0') as char);
+            }
+        }
+
+        if repr.is_empty() {
+            repr.push('0');
+        }
+
+        repr
+    }
+
+    fn reserve_two_digits(&mut self) {
+        let len = self.digits.len();
+        let desired =
+            len + !self.digits.ends_with(&[0, 0]) as usize + !self.digits.ends_with(&[0]) as usize;
+        self.digits.resize(desired, 0);
+    }
+}
+
+impl AddAssign<u8> for BigInt {
+    // Assumes increment <16.
+    fn add_assign(&mut self, mut increment: u8) {
+        self.reserve_two_digits();
+
+        let mut i = 0;
+        while increment > 0 {
+            let sum = self.digits[i] + increment;
+            self.digits[i] = sum % 10;
+            increment = sum / 10;
+            i += 1;
+        }
+    }
+}
+
+impl MulAssign<u8> for BigInt {
+    // Assumes base <=16.
+    fn mul_assign(&mut self, base: u8) {
+        self.reserve_two_digits();
+
+        let mut carry = 0;
+        for digit in &mut self.digits {
+            let prod = *digit * base + carry;
+            *digit = prod % 10;
+            carry = prod / 10;
+        }
+    }
+}
diff --git a/rust/syn/buffer.rs b/rust/syn/buffer.rs
new file mode 100644
index 0000000000000000000000000000000000000000..440e13e7a78aa0fadab7cd02535926f6a339ef83
--- /dev/null
+++ b/rust/syn/buffer.rs
@@ -0,0 +1,434 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! A stably addressed token buffer supporting efficient traversal based on a
+//! cheaply copyable cursor.
+
+// This module is heavily commented as it contains most of the unsafe code in
+// Syn, and caution should be used when editing it. The public-facing interface
+// is 100% safe but the implementation is fragile internally.
+
+use crate::Lifetime;
+use proc_macro2::extra::DelimSpan;
+use proc_macro2::{Delimiter, Group, Ident, Literal, Punct, Spacing, Span, TokenStream, TokenTree};
+use std::cmp::Ordering;
+use std::marker::PhantomData;
+
+/// Internal type which is used instead of `TokenTree` to represent a token tree
+/// within a `TokenBuffer`.
+enum Entry {
+    // Mimicking types from proc-macro.
+    // Group entries contain the offset to the matching End entry.
+    Group(Group, usize),
+    Ident(Ident),
+    Punct(Punct),
+    Literal(Literal),
+    // End entries contain the offset (negative) to the start of the buffer.
+    End(isize),
+}
+
+/// A buffer that can be efficiently traversed multiple times, unlike
+/// `TokenStream` which requires a deep copy in order to traverse more than
+/// once.
+pub struct TokenBuffer {
+    // NOTE: Do not implement clone on this - while the current design could be
+    // cloned, other designs which could be desirable may not be cloneable.
+    entries: Box<[Entry]>,
+}
+
+impl TokenBuffer {
+    fn recursive_new(entries: &mut Vec<Entry>, stream: TokenStream) {
+        for tt in stream {
+            match tt {
+                TokenTree::Ident(ident) => entries.push(Entry::Ident(ident)),
+                TokenTree::Punct(punct) => entries.push(Entry::Punct(punct)),
+                TokenTree::Literal(literal) => entries.push(Entry::Literal(literal)),
+                TokenTree::Group(group) => {
+                    let group_start_index = entries.len();
+                    entries.push(Entry::End(0)); // we replace this below
+                    Self::recursive_new(entries, group.stream());
+                    let group_end_index = entries.len();
+                    entries.push(Entry::End(-(group_end_index as isize)));
+                    let group_end_offset = group_end_index - group_start_index;
+                    entries[group_start_index] = Entry::Group(group, group_end_offset);
+                }
+            }
+        }
+    }
+
+    /// Creates a `TokenBuffer` containing all the tokens from the input
+    /// `proc_macro::TokenStream`.
+    #[cfg(feature = "proc-macro")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "proc-macro")))]
+    pub fn new(stream: proc_macro::TokenStream) -> Self {
+        Self::new2(stream.into())
+    }
+
+    /// Creates a `TokenBuffer` containing all the tokens from the input
+    /// `proc_macro2::TokenStream`.
+    pub fn new2(stream: TokenStream) -> Self {
+        let mut entries = Vec::new();
+        Self::recursive_new(&mut entries, stream);
+        entries.push(Entry::End(-(entries.len() as isize)));
+        Self {
+            entries: entries.into_boxed_slice(),
+        }
+    }
+
+    /// Creates a cursor referencing the first token in the buffer and able to
+    /// traverse until the end of the buffer.
+    pub fn begin(&self) -> Cursor {
+        let ptr = self.entries.as_ptr();
+        unsafe { Cursor::create(ptr, ptr.add(self.entries.len() - 1)) }
+    }
+}
+
+/// A cheaply copyable cursor into a `TokenBuffer`.
+///
+/// This cursor holds a shared reference into the immutable data which is used
+/// internally to represent a `TokenStream`, and can be efficiently manipulated
+/// and copied around.
+///
+/// An empty `Cursor` can be created directly, or one may create a `TokenBuffer`
+/// object and get a cursor to its first token with `begin()`.
+pub struct Cursor<'a> {
+    // The current entry which the `Cursor` is pointing at.
+    ptr: *const Entry,
+    // This is the only `Entry::End` object which this cursor is allowed to
+    // point at. All other `End` objects are skipped over in `Cursor::create`.
+    scope: *const Entry,
+    // Cursor is covariant in 'a. This field ensures that our pointers are still
+    // valid.
+    marker: PhantomData<&'a Entry>,
+}
+
+impl<'a> Cursor<'a> {
+    /// Creates a cursor referencing a static empty TokenStream.
+    pub fn empty() -> Self {
+        // It's safe in this situation for us to put an `Entry` object in global
+        // storage, despite it not actually being safe to send across threads
+        // (`Ident` is a reference into a thread-local table). This is because
+        // this entry never includes a `Ident` object.
+        //
+        // This wrapper struct allows us to break the rules and put a `Sync`
+        // object in global storage.
+        struct UnsafeSyncEntry(Entry);
+        unsafe impl Sync for UnsafeSyncEntry {}
+        static EMPTY_ENTRY: UnsafeSyncEntry = UnsafeSyncEntry(Entry::End(0));
+
+        Cursor {
+            ptr: &EMPTY_ENTRY.0,
+            scope: &EMPTY_ENTRY.0,
+            marker: PhantomData,
+        }
+    }
+
+    /// This create method intelligently exits non-explicitly-entered
+    /// `None`-delimited scopes when the cursor reaches the end of them,
+    /// allowing for them to be treated transparently.
+    unsafe fn create(mut ptr: *const Entry, scope: *const Entry) -> Self {
+        // NOTE: If we're looking at a `End`, we want to advance the cursor
+        // past it, unless `ptr == scope`, which means that we're at the edge of
+        // our cursor's scope. We should only have `ptr != scope` at the exit
+        // from None-delimited groups entered with `ignore_none`.
+        while let Entry::End(_) = unsafe { &*ptr } {
+            if ptr == scope {
+                break;
+            }
+            ptr = unsafe { ptr.add(1) };
+        }
+
+        Cursor {
+            ptr,
+            scope,
+            marker: PhantomData,
+        }
+    }
+
+    /// Get the current entry.
+    fn entry(self) -> &'a Entry {
+        unsafe { &*self.ptr }
+    }
+
+    /// Bump the cursor to point at the next token after the current one. This
+    /// is undefined behavior if the cursor is currently looking at an
+    /// `Entry::End`.
+    ///
+    /// If the cursor is looking at an `Entry::Group`, the bumped cursor will
+    /// point at the first token in the group (with the same scope end).
+    unsafe fn bump_ignore_group(self) -> Cursor<'a> {
+        unsafe { Cursor::create(self.ptr.offset(1), self.scope) }
+    }
+
+    /// While the cursor is looking at a `None`-delimited group, move it to look
+    /// at the first token inside instead. If the group is empty, this will move
+    /// the cursor past the `None`-delimited group.
+    ///
+    /// WARNING: This mutates its argument.
+    fn ignore_none(&mut self) {
+        while let Entry::Group(group, _) = self.entry() {
+            if group.delimiter() == Delimiter::None {
+                unsafe { *self = self.bump_ignore_group() };
+            } else {
+                break;
+            }
+        }
+    }
+
+    /// Checks whether the cursor is currently pointing at the end of its valid
+    /// scope.
+    pub fn eof(self) -> bool {
+        // We're at eof if we're at the end of our scope.
+        self.ptr == self.scope
+    }
+
+    /// If the cursor is pointing at a `Group` with the given delimiter, returns
+    /// a cursor into that group and one pointing to the next `TokenTree`.
+    pub fn group(mut self, delim: Delimiter) -> Option<(Cursor<'a>, DelimSpan, Cursor<'a>)> {
+        // If we're not trying to enter a none-delimited group, we want to
+        // ignore them. We have to make sure to _not_ ignore them when we want
+        // to enter them, of course. For obvious reasons.
+        if delim != Delimiter::None {
+            self.ignore_none();
+        }
+
+        if let Entry::Group(group, end_offset) = self.entry() {
+            if group.delimiter() == delim {
+                let span = group.delim_span();
+                let end_of_group = unsafe { self.ptr.add(*end_offset) };
+                let inside_of_group = unsafe { Cursor::create(self.ptr.add(1), end_of_group) };
+                let after_group = unsafe { Cursor::create(end_of_group, self.scope) };
+                return Some((inside_of_group, span, after_group));
+            }
+        }
+
+        None
+    }
+
+    pub(crate) fn any_group(self) -> Option<(Cursor<'a>, Delimiter, DelimSpan, Cursor<'a>)> {
+        if let Entry::Group(group, end_offset) = self.entry() {
+            let delimiter = group.delimiter();
+            let span = group.delim_span();
+            let end_of_group = unsafe { self.ptr.add(*end_offset) };
+            let inside_of_group = unsafe { Cursor::create(self.ptr.add(1), end_of_group) };
+            let after_group = unsafe { Cursor::create(end_of_group, self.scope) };
+            return Some((inside_of_group, delimiter, span, after_group));
+        }
+
+        None
+    }
+
+    pub(crate) fn any_group_token(self) -> Option<(Group, Cursor<'a>)> {
+        if let Entry::Group(group, end_offset) = self.entry() {
+            let end_of_group = unsafe { self.ptr.add(*end_offset) };
+            let after_group = unsafe { Cursor::create(end_of_group, self.scope) };
+            return Some((group.clone(), after_group));
+        }
+
+        None
+    }
+
+    /// If the cursor is pointing at a `Ident`, returns it along with a cursor
+    /// pointing at the next `TokenTree`.
+    pub fn ident(mut self) -> Option<(Ident, Cursor<'a>)> {
+        self.ignore_none();
+        match self.entry() {
+            Entry::Ident(ident) => Some((ident.clone(), unsafe { self.bump_ignore_group() })),
+            _ => None,
+        }
+    }
+
+    /// If the cursor is pointing at a `Punct`, returns it along with a cursor
+    /// pointing at the next `TokenTree`.
+    pub fn punct(mut self) -> Option<(Punct, Cursor<'a>)> {
+        self.ignore_none();
+        match self.entry() {
+            Entry::Punct(punct) if punct.as_char() != '\'' => {
+                Some((punct.clone(), unsafe { self.bump_ignore_group() }))
+            }
+            _ => None,
+        }
+    }
+
+    /// If the cursor is pointing at a `Literal`, return it along with a cursor
+    /// pointing at the next `TokenTree`.
+    pub fn literal(mut self) -> Option<(Literal, Cursor<'a>)> {
+        self.ignore_none();
+        match self.entry() {
+            Entry::Literal(literal) => Some((literal.clone(), unsafe { self.bump_ignore_group() })),
+            _ => None,
+        }
+    }
+
+    /// If the cursor is pointing at a `Lifetime`, returns it along with a
+    /// cursor pointing at the next `TokenTree`.
+    pub fn lifetime(mut self) -> Option<(Lifetime, Cursor<'a>)> {
+        self.ignore_none();
+        match self.entry() {
+            Entry::Punct(punct) if punct.as_char() == '\'' && punct.spacing() == Spacing::Joint => {
+                let next = unsafe { self.bump_ignore_group() };
+                let (ident, rest) = next.ident()?;
+                let lifetime = Lifetime {
+                    apostrophe: punct.span(),
+                    ident,
+                };
+                Some((lifetime, rest))
+            }
+            _ => None,
+        }
+    }
+
+    /// Copies all remaining tokens visible from this cursor into a
+    /// `TokenStream`.
+    pub fn token_stream(self) -> TokenStream {
+        let mut tts = Vec::new();
+        let mut cursor = self;
+        while let Some((tt, rest)) = cursor.token_tree() {
+            tts.push(tt);
+            cursor = rest;
+        }
+        tts.into_iter().collect()
+    }
+
+    /// If the cursor is pointing at a `TokenTree`, returns it along with a
+    /// cursor pointing at the next `TokenTree`.
+    ///
+    /// Returns `None` if the cursor has reached the end of its stream.
+    ///
+    /// This method does not treat `None`-delimited groups as transparent, and
+    /// will return a `Group(None, ..)` if the cursor is looking at one.
+    pub fn token_tree(self) -> Option<(TokenTree, Cursor<'a>)> {
+        let (tree, len) = match self.entry() {
+            Entry::Group(group, end_offset) => (group.clone().into(), *end_offset),
+            Entry::Literal(literal) => (literal.clone().into(), 1),
+            Entry::Ident(ident) => (ident.clone().into(), 1),
+            Entry::Punct(punct) => (punct.clone().into(), 1),
+            Entry::End(_) => return None,
+        };
+
+        let rest = unsafe { Cursor::create(self.ptr.add(len), self.scope) };
+        Some((tree, rest))
+    }
+
+    /// Returns the `Span` of the current token, or `Span::call_site()` if this
+    /// cursor points to eof.
+    pub fn span(self) -> Span {
+        match self.entry() {
+            Entry::Group(group, _) => group.span(),
+            Entry::Literal(literal) => literal.span(),
+            Entry::Ident(ident) => ident.span(),
+            Entry::Punct(punct) => punct.span(),
+            Entry::End(_) => Span::call_site(),
+        }
+    }
+
+    /// Returns the `Span` of the token immediately prior to the position of
+    /// this cursor, or of the current token if there is no previous one.
+    #[cfg(any(feature = "full", feature = "derive"))]
+    pub(crate) fn prev_span(mut self) -> Span {
+        if start_of_buffer(self) < self.ptr {
+            self.ptr = unsafe { self.ptr.offset(-1) };
+            if let Entry::End(_) = self.entry() {
+                // Locate the matching Group begin token.
+                let mut depth = 1;
+                loop {
+                    self.ptr = unsafe { self.ptr.offset(-1) };
+                    match self.entry() {
+                        Entry::Group(group, _) => {
+                            depth -= 1;
+                            if depth == 0 {
+                                return group.span();
+                            }
+                        }
+                        Entry::End(_) => depth += 1,
+                        Entry::Literal(_) | Entry::Ident(_) | Entry::Punct(_) => {}
+                    }
+                }
+            }
+        }
+        self.span()
+    }
+
+    /// Skip over the next token without cloning it. Returns `None` if this
+    /// cursor points to eof.
+    ///
+    /// This method treats `'lifetimes` as a single token.
+    pub(crate) fn skip(self) -> Option<Cursor<'a>> {
+        let len = match self.entry() {
+            Entry::End(_) => return None,
+
+            // Treat lifetimes as a single tt for the purposes of 'skip'.
+            Entry::Punct(punct) if punct.as_char() == '\'' && punct.spacing() == Spacing::Joint => {
+                match unsafe { &*self.ptr.add(1) } {
+                    Entry::Ident(_) => 2,
+                    _ => 1,
+                }
+            }
+
+            Entry::Group(_, end_offset) => *end_offset,
+            _ => 1,
+        };
+
+        Some(unsafe { Cursor::create(self.ptr.add(len), self.scope) })
+    }
+}
+
+impl<'a> Copy for Cursor<'a> {}
+
+impl<'a> Clone for Cursor<'a> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<'a> Eq for Cursor<'a> {}
+
+impl<'a> PartialEq for Cursor<'a> {
+    fn eq(&self, other: &Self) -> bool {
+        self.ptr == other.ptr
+    }
+}
+
+impl<'a> PartialOrd for Cursor<'a> {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        if same_buffer(*self, *other) {
+            Some(cmp_assuming_same_buffer(*self, *other))
+        } else {
+            None
+        }
+    }
+}
+
+pub(crate) fn same_scope(a: Cursor, b: Cursor) -> bool {
+    a.scope == b.scope
+}
+
+pub(crate) fn same_buffer(a: Cursor, b: Cursor) -> bool {
+    start_of_buffer(a) == start_of_buffer(b)
+}
+
+fn start_of_buffer(cursor: Cursor) -> *const Entry {
+    unsafe {
+        match &*cursor.scope {
+            Entry::End(offset) => cursor.scope.offset(*offset),
+            _ => unreachable!(),
+        }
+    }
+}
+
+pub(crate) fn cmp_assuming_same_buffer(a: Cursor, b: Cursor) -> Ordering {
+    a.ptr.cmp(&b.ptr)
+}
+
+pub(crate) fn open_span_of_group(cursor: Cursor) -> Span {
+    match cursor.entry() {
+        Entry::Group(group, _) => group.span_open(),
+        _ => cursor.span(),
+    }
+}
+
+pub(crate) fn close_span_of_group(cursor: Cursor) -> Span {
+    match cursor.entry() {
+        Entry::Group(group, _) => group.span_close(),
+        _ => cursor.span(),
+    }
+}
diff --git a/rust/syn/custom_keyword.rs b/rust/syn/custom_keyword.rs
new file mode 100644
index 0000000000000000000000000000000000000000..ff2c415f1aabc11fdd5b2998a5368770da97707b
--- /dev/null
+++ b/rust/syn/custom_keyword.rs
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+/// Define a type that supports parsing and printing a given identifier as if it
+/// were a keyword.
+///
+/// # Usage
+///
+/// As a convention, it is recommended that this macro be invoked within a
+/// module called `kw` or `keyword` and that the resulting parser be invoked
+/// with a `kw::` or `keyword::` prefix.
+///
+/// ```
+/// mod kw {
+///     syn::custom_keyword!(whatever);
+/// }
+/// ```
+///
+/// The generated syntax tree node supports the following operations just like
+/// any built-in keyword token.
+///
+/// - [Peeking] — `input.peek(kw::whatever)`
+///
+/// - [Parsing] — `input.parse::<kw::whatever>()?`
+///
+/// - [Printing] — `quote!( ... #whatever_token ... )`
+///
+/// - Construction from a [`Span`] — `let whatever_token = kw::whatever(sp)`
+///
+/// - Field access to its span — `let sp = whatever_token.span`
+///
+/// [Peeking]: crate::parse::ParseBuffer::peek
+/// [Parsing]: crate::parse::ParseBuffer::parse
+/// [Printing]: quote::ToTokens
+/// [`Span`]: proc_macro2::Span
+///
+/// # Example
+///
+/// This example parses input that looks like `bool = true` or `str = "value"`.
+/// The key must be either the identifier `bool` or the identifier `str`. If
+/// `bool`, the value may be either `true` or `false`. If `str`, the value may
+/// be any string literal.
+///
+/// The symbols `bool` and `str` are not reserved keywords in Rust so these are
+/// not considered keywords in the `syn::token` module. Like any other
+/// identifier that is not a keyword, these can be declared as custom keywords
+/// by crates that need to use them as such.
+///
+/// ```
+/// use syn::{LitBool, LitStr, Result, Token};
+/// use syn::parse::{Parse, ParseStream};
+///
+/// mod kw {
+///     syn::custom_keyword!(bool);
+///     syn::custom_keyword!(str);
+/// }
+///
+/// enum Argument {
+///     Bool {
+///         bool_token: kw::bool,
+///         eq_token: Token![=],
+///         value: LitBool,
+///     },
+///     Str {
+///         str_token: kw::str,
+///         eq_token: Token![=],
+///         value: LitStr,
+///     },
+/// }
+///
+/// impl Parse for Argument {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         let lookahead = input.lookahead1();
+///         if lookahead.peek(kw::bool) {
+///             Ok(Argument::Bool {
+///                 bool_token: input.parse::<kw::bool>()?,
+///                 eq_token: input.parse()?,
+///                 value: input.parse()?,
+///             })
+///         } else if lookahead.peek(kw::str) {
+///             Ok(Argument::Str {
+///                 str_token: input.parse::<kw::str>()?,
+///                 eq_token: input.parse()?,
+///                 value: input.parse()?,
+///             })
+///         } else {
+///             Err(lookahead.error())
+///         }
+///     }
+/// }
+/// ```
+#[macro_export]
+macro_rules! custom_keyword {
+    ($ident:ident) => {
+        #[allow(non_camel_case_types)]
+        pub struct $ident {
+            #[allow(dead_code)]
+            pub span: $crate::__private::Span,
+        }
+
+        #[doc(hidden)]
+        #[allow(dead_code, non_snake_case)]
+        pub fn $ident<__S: $crate::__private::IntoSpans<$crate::__private::Span>>(
+            span: __S,
+        ) -> $ident {
+            $ident {
+                span: $crate::__private::IntoSpans::into_spans(span),
+            }
+        }
+
+        const _: () = {
+            impl $crate::__private::Default for $ident {
+                fn default() -> Self {
+                    $ident {
+                        span: $crate::__private::Span::call_site(),
+                    }
+                }
+            }
+
+            $crate::impl_parse_for_custom_keyword!($ident);
+            $crate::impl_to_tokens_for_custom_keyword!($ident);
+            $crate::impl_clone_for_custom_keyword!($ident);
+            $crate::impl_extra_traits_for_custom_keyword!($ident);
+        };
+    };
+}
+
+// Not public API.
+#[cfg(feature = "parsing")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_parse_for_custom_keyword {
+    ($ident:ident) => {
+        // For peek.
+        impl $crate::__private::CustomToken for $ident {
+            fn peek(cursor: $crate::buffer::Cursor) -> $crate::__private::bool {
+                if let $crate::__private::Some((ident, _rest)) = cursor.ident() {
+                    ident == $crate::__private::stringify!($ident)
+                } else {
+                    false
+                }
+            }
+
+            fn display() -> &'static $crate::__private::str {
+                $crate::__private::concat!("`", $crate::__private::stringify!($ident), "`")
+            }
+        }
+
+        impl $crate::parse::Parse for $ident {
+            fn parse(input: $crate::parse::ParseStream) -> $crate::parse::Result<$ident> {
+                input.step(|cursor| {
+                    if let $crate::__private::Some((ident, rest)) = cursor.ident() {
+                        if ident == $crate::__private::stringify!($ident) {
+                            return $crate::__private::Ok(($ident { span: ident.span() }, rest));
+                        }
+                    }
+                    $crate::__private::Err(cursor.error($crate::__private::concat!(
+                        "expected `",
+                        $crate::__private::stringify!($ident),
+                        "`",
+                    )))
+                })
+            }
+        }
+    };
+}
+
+// Not public API.
+#[cfg(not(feature = "parsing"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_parse_for_custom_keyword {
+    ($ident:ident) => {};
+}
+
+// Not public API.
+#[cfg(feature = "printing")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_to_tokens_for_custom_keyword {
+    ($ident:ident) => {
+        impl $crate::__private::ToTokens for $ident {
+            fn to_tokens(&self, tokens: &mut $crate::__private::TokenStream2) {
+                let ident = $crate::Ident::new($crate::__private::stringify!($ident), self.span);
+                $crate::__private::TokenStreamExt::append(tokens, ident);
+            }
+        }
+    };
+}
+
+// Not public API.
+#[cfg(not(feature = "printing"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_to_tokens_for_custom_keyword {
+    ($ident:ident) => {};
+}
+
+// Not public API.
+#[cfg(feature = "clone-impls")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_clone_for_custom_keyword {
+    ($ident:ident) => {
+        impl $crate::__private::Copy for $ident {}
+
+        #[allow(clippy::expl_impl_clone_on_copy)]
+        impl $crate::__private::Clone for $ident {
+            fn clone(&self) -> Self {
+                *self
+            }
+        }
+    };
+}
+
+// Not public API.
+#[cfg(not(feature = "clone-impls"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_clone_for_custom_keyword {
+    ($ident:ident) => {};
+}
+
+// Not public API.
+#[cfg(feature = "extra-traits")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_extra_traits_for_custom_keyword {
+    ($ident:ident) => {
+        impl $crate::__private::Debug for $ident {
+            fn fmt(&self, f: &mut $crate::__private::Formatter) -> $crate::__private::FmtResult {
+                $crate::__private::Formatter::write_str(
+                    f,
+                    $crate::__private::concat!(
+                        "Keyword [",
+                        $crate::__private::stringify!($ident),
+                        "]",
+                    ),
+                )
+            }
+        }
+
+        impl $crate::__private::Eq for $ident {}
+
+        impl $crate::__private::PartialEq for $ident {
+            fn eq(&self, _other: &Self) -> $crate::__private::bool {
+                true
+            }
+        }
+
+        impl $crate::__private::Hash for $ident {
+            fn hash<__H: $crate::__private::Hasher>(&self, _state: &mut __H) {}
+        }
+    };
+}
+
+// Not public API.
+#[cfg(not(feature = "extra-traits"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_extra_traits_for_custom_keyword {
+    ($ident:ident) => {};
+}
diff --git a/rust/syn/custom_punctuation.rs b/rust/syn/custom_punctuation.rs
new file mode 100644
index 0000000000000000000000000000000000000000..d37c0e9c3a1ed49d94f9e7186cd7b4a0eebf7ff5
--- /dev/null
+++ b/rust/syn/custom_punctuation.rs
@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+/// Define a type that supports parsing and printing a multi-character symbol
+/// as if it were a punctuation token.
+///
+/// # Usage
+///
+/// ```
+/// syn::custom_punctuation!(LeftRightArrow, <=>);
+/// ```
+///
+/// The generated syntax tree node supports the following operations just like
+/// any built-in punctuation token.
+///
+/// - [Peeking] — `input.peek(LeftRightArrow)`
+///
+/// - [Parsing] — `input.parse::<LeftRightArrow>()?`
+///
+/// - [Printing] — `quote!( ... #lrarrow ... )`
+///
+/// - Construction from a [`Span`] — `let lrarrow = LeftRightArrow(sp)`
+///
+/// - Construction from multiple [`Span`] — `let lrarrow = LeftRightArrow([sp, sp, sp])`
+///
+/// - Field access to its spans — `let spans = lrarrow.spans`
+///
+/// [Peeking]: crate::parse::ParseBuffer::peek
+/// [Parsing]: crate::parse::ParseBuffer::parse
+/// [Printing]: quote::ToTokens
+/// [`Span`]: proc_macro2::Span
+///
+/// # Example
+///
+/// ```
+/// use proc_macro2::{TokenStream, TokenTree};
+/// use syn::parse::{Parse, ParseStream, Peek, Result};
+/// use syn::punctuated::Punctuated;
+/// use syn::Expr;
+///
+/// syn::custom_punctuation!(PathSeparator, </>);
+///
+/// // expr </> expr </> expr ...
+/// struct PathSegments {
+///     segments: Punctuated<Expr, PathSeparator>,
+/// }
+///
+/// impl Parse for PathSegments {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         let mut segments = Punctuated::new();
+///
+///         let first = parse_until(input, PathSeparator)?;
+///         segments.push_value(syn::parse2(first)?);
+///
+///         while input.peek(PathSeparator) {
+///             segments.push_punct(input.parse()?);
+///
+///             let next = parse_until(input, PathSeparator)?;
+///             segments.push_value(syn::parse2(next)?);
+///         }
+///
+///         Ok(PathSegments { segments })
+///     }
+/// }
+///
+/// fn parse_until<E: Peek>(input: ParseStream, end: E) -> Result<TokenStream> {
+///     let mut tokens = TokenStream::new();
+///     while !input.is_empty() && !input.peek(end) {
+///         let next: TokenTree = input.parse()?;
+///         tokens.extend(Some(next));
+///     }
+///     Ok(tokens)
+/// }
+///
+/// fn main() {
+///     let input = r#" a::b </> c::d::e "#;
+///     let _: PathSegments = syn::parse_str(input).unwrap();
+/// }
+/// ```
+#[macro_export]
+macro_rules! custom_punctuation {
+    ($ident:ident, $($tt:tt)+) => {
+        pub struct $ident {
+            #[allow(dead_code)]
+            pub spans: $crate::custom_punctuation_repr!($($tt)+),
+        }
+
+        #[doc(hidden)]
+        #[allow(dead_code, non_snake_case)]
+        pub fn $ident<__S: $crate::__private::IntoSpans<$crate::custom_punctuation_repr!($($tt)+)>>(
+            spans: __S,
+        ) -> $ident {
+            let _validate_len = 0 $(+ $crate::custom_punctuation_len!(strict, $tt))*;
+            $ident {
+                spans: $crate::__private::IntoSpans::into_spans(spans)
+            }
+        }
+
+        const _: () = {
+            impl $crate::__private::Default for $ident {
+                fn default() -> Self {
+                    $ident($crate::__private::Span::call_site())
+                }
+            }
+
+            $crate::impl_parse_for_custom_punctuation!($ident, $($tt)+);
+            $crate::impl_to_tokens_for_custom_punctuation!($ident, $($tt)+);
+            $crate::impl_clone_for_custom_punctuation!($ident, $($tt)+);
+            $crate::impl_extra_traits_for_custom_punctuation!($ident, $($tt)+);
+        };
+    };
+}
+
+// Not public API.
+#[cfg(feature = "parsing")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_parse_for_custom_punctuation {
+    ($ident:ident, $($tt:tt)+) => {
+        impl $crate::__private::CustomToken for $ident {
+            fn peek(cursor: $crate::buffer::Cursor) -> $crate::__private::bool {
+                $crate::__private::peek_punct(cursor, $crate::stringify_punct!($($tt)+))
+            }
+
+            fn display() -> &'static $crate::__private::str {
+                $crate::__private::concat!("`", $crate::stringify_punct!($($tt)+), "`")
+            }
+        }
+
+        impl $crate::parse::Parse for $ident {
+            fn parse(input: $crate::parse::ParseStream) -> $crate::parse::Result<$ident> {
+                let spans: $crate::custom_punctuation_repr!($($tt)+) =
+                    $crate::__private::parse_punct(input, $crate::stringify_punct!($($tt)+))?;
+                Ok($ident(spans))
+            }
+        }
+    };
+}
+
+// Not public API.
+#[cfg(not(feature = "parsing"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_parse_for_custom_punctuation {
+    ($ident:ident, $($tt:tt)+) => {};
+}
+
+// Not public API.
+#[cfg(feature = "printing")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_to_tokens_for_custom_punctuation {
+    ($ident:ident, $($tt:tt)+) => {
+        impl $crate::__private::ToTokens for $ident {
+            fn to_tokens(&self, tokens: &mut $crate::__private::TokenStream2) {
+                $crate::__private::print_punct($crate::stringify_punct!($($tt)+), &self.spans, tokens)
+            }
+        }
+    };
+}
+
+// Not public API.
+#[cfg(not(feature = "printing"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_to_tokens_for_custom_punctuation {
+    ($ident:ident, $($tt:tt)+) => {};
+}
+
+// Not public API.
+#[cfg(feature = "clone-impls")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_clone_for_custom_punctuation {
+    ($ident:ident, $($tt:tt)+) => {
+        impl $crate::__private::Copy for $ident {}
+
+        #[allow(clippy::expl_impl_clone_on_copy)]
+        impl $crate::__private::Clone for $ident {
+            fn clone(&self) -> Self {
+                *self
+            }
+        }
+    };
+}
+
+// Not public API.
+#[cfg(not(feature = "clone-impls"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_clone_for_custom_punctuation {
+    ($ident:ident, $($tt:tt)+) => {};
+}
+
+// Not public API.
+#[cfg(feature = "extra-traits")]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_extra_traits_for_custom_punctuation {
+    ($ident:ident, $($tt:tt)+) => {
+        impl $crate::__private::Debug for $ident {
+            fn fmt(&self, f: &mut $crate::__private::Formatter) -> $crate::__private::FmtResult {
+                $crate::__private::Formatter::write_str(f, $crate::__private::stringify!($ident))
+            }
+        }
+
+        impl $crate::__private::Eq for $ident {}
+
+        impl $crate::__private::PartialEq for $ident {
+            fn eq(&self, _other: &Self) -> $crate::__private::bool {
+                true
+            }
+        }
+
+        impl $crate::__private::Hash for $ident {
+            fn hash<__H: $crate::__private::Hasher>(&self, _state: &mut __H) {}
+        }
+    };
+}
+
+// Not public API.
+#[cfg(not(feature = "extra-traits"))]
+#[doc(hidden)]
+#[macro_export]
+macro_rules! impl_extra_traits_for_custom_punctuation {
+    ($ident:ident, $($tt:tt)+) => {};
+}
+
+// Not public API.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! custom_punctuation_repr {
+    ($($tt:tt)+) => {
+        [$crate::__private::Span; 0 $(+ $crate::custom_punctuation_len!(lenient, $tt))+]
+    };
+}
+
+// Not public API.
+#[doc(hidden)]
+#[macro_export]
+#[rustfmt::skip]
+macro_rules! custom_punctuation_len {
+    ($mode:ident, &)     => { 1 };
+    ($mode:ident, &&)    => { 2 };
+    ($mode:ident, &=)    => { 2 };
+    ($mode:ident, @)     => { 1 };
+    ($mode:ident, ^)     => { 1 };
+    ($mode:ident, ^=)    => { 2 };
+    ($mode:ident, :)     => { 1 };
+    ($mode:ident, ,)     => { 1 };
+    ($mode:ident, $)     => { 1 };
+    ($mode:ident, .)     => { 1 };
+    ($mode:ident, ..)    => { 2 };
+    ($mode:ident, ...)   => { 3 };
+    ($mode:ident, ..=)   => { 3 };
+    ($mode:ident, =)     => { 1 };
+    ($mode:ident, ==)    => { 2 };
+    ($mode:ident, =>)    => { 2 };
+    ($mode:ident, >=)    => { 2 };
+    ($mode:ident, >)     => { 1 };
+    ($mode:ident, <-)    => { 2 };
+    ($mode:ident, <=)    => { 2 };
+    ($mode:ident, <)     => { 1 };
+    ($mode:ident, -)     => { 1 };
+    ($mode:ident, -=)    => { 2 };
+    ($mode:ident, !=)    => { 2 };
+    ($mode:ident, !)     => { 1 };
+    ($mode:ident, |)     => { 1 };
+    ($mode:ident, |=)    => { 2 };
+    ($mode:ident, ||)    => { 2 };
+    ($mode:ident, ::)    => { 2 };
+    ($mode:ident, %)     => { 1 };
+    ($mode:ident, %=)    => { 2 };
+    ($mode:ident, +)     => { 1 };
+    ($mode:ident, +=)    => { 2 };
+    ($mode:ident, #)     => { 1 };
+    ($mode:ident, ?)     => { 1 };
+    ($mode:ident, ->)    => { 2 };
+    ($mode:ident, ;)     => { 1 };
+    ($mode:ident, <<)    => { 2 };
+    ($mode:ident, <<=)   => { 3 };
+    ($mode:ident, >>)    => { 2 };
+    ($mode:ident, >>=)   => { 3 };
+    ($mode:ident, /)     => { 1 };
+    ($mode:ident, /=)    => { 2 };
+    ($mode:ident, *)     => { 1 };
+    ($mode:ident, *=)    => { 2 };
+    ($mode:ident, ~)     => { 1 };
+    (lenient, $tt:tt)    => { 0 };
+    (strict, $tt:tt)     => {{ $crate::custom_punctuation_unexpected!($tt); 0 }};
+}
+
+// Not public API.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! custom_punctuation_unexpected {
+    () => {};
+}
+
+// Not public API.
+#[doc(hidden)]
+#[macro_export]
+macro_rules! stringify_punct {
+    ($($tt:tt)+) => {
+        $crate::__private::concat!($($crate::__private::stringify!($tt)),+)
+    };
+}
diff --git a/rust/syn/data.rs b/rust/syn/data.rs
new file mode 100644
index 0000000000000000000000000000000000000000..ed513db4e63393249dd79ce270fc55698b4b4e20
--- /dev/null
+++ b/rust/syn/data.rs
@@ -0,0 +1,425 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+use crate::expr::Expr;
+use crate::ident::Ident;
+use crate::punctuated::{self, Punctuated};
+use crate::restriction::{FieldMutability, Visibility};
+use crate::token;
+use crate::ty::Type;
+
+ast_struct! {
+    /// An enum variant.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct Variant {
+        pub attrs: Vec<Attribute>,
+
+        /// Name of the variant.
+        pub ident: Ident,
+
+        /// Content stored in the variant.
+        pub fields: Fields,
+
+        /// Explicit discriminant: `Variant = 1`
+        pub discriminant: Option<(Token![=], Expr)>,
+    }
+}
+
+ast_enum_of_structs! {
+    /// Data stored within an enum variant or struct.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum Fields {
+        /// Named fields of a struct or struct variant such as `Point { x: f64,
+        /// y: f64 }`.
+        Named(FieldsNamed),
+
+        /// Unnamed fields of a tuple struct or tuple variant such as `Some(T)`.
+        Unnamed(FieldsUnnamed),
+
+        /// Unit struct or unit variant such as `None`.
+        Unit,
+    }
+}
+
+ast_struct! {
+    /// Named fields of a struct or struct variant such as `Point { x: f64,
+    /// y: f64 }`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct FieldsNamed {
+        pub brace_token: token::Brace,
+        pub named: Punctuated<Field, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// Unnamed fields of a tuple struct or tuple variant such as `Some(T)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct FieldsUnnamed {
+        pub paren_token: token::Paren,
+        pub unnamed: Punctuated<Field, Token![,]>,
+    }
+}
+
+impl Fields {
+    /// Get an iterator over the borrowed [`Field`] items in this object. This
+    /// iterator can be used to iterate over a named or unnamed struct or
+    /// variant's fields uniformly.
+    pub fn iter(&self) -> punctuated::Iter<Field> {
+        match self {
+            Fields::Unit => crate::punctuated::empty_punctuated_iter(),
+            Fields::Named(f) => f.named.iter(),
+            Fields::Unnamed(f) => f.unnamed.iter(),
+        }
+    }
+
+    /// Get an iterator over the mutably borrowed [`Field`] items in this
+    /// object. This iterator can be used to iterate over a named or unnamed
+    /// struct or variant's fields uniformly.
+    pub fn iter_mut(&mut self) -> punctuated::IterMut<Field> {
+        match self {
+            Fields::Unit => crate::punctuated::empty_punctuated_iter_mut(),
+            Fields::Named(f) => f.named.iter_mut(),
+            Fields::Unnamed(f) => f.unnamed.iter_mut(),
+        }
+    }
+
+    /// Returns the number of fields.
+    pub fn len(&self) -> usize {
+        match self {
+            Fields::Unit => 0,
+            Fields::Named(f) => f.named.len(),
+            Fields::Unnamed(f) => f.unnamed.len(),
+        }
+    }
+
+    /// Returns `true` if there are zero fields.
+    pub fn is_empty(&self) -> bool {
+        match self {
+            Fields::Unit => true,
+            Fields::Named(f) => f.named.is_empty(),
+            Fields::Unnamed(f) => f.unnamed.is_empty(),
+        }
+    }
+}
+
+impl IntoIterator for Fields {
+    type Item = Field;
+    type IntoIter = punctuated::IntoIter<Field>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        match self {
+            Fields::Unit => Punctuated::<Field, ()>::new().into_iter(),
+            Fields::Named(f) => f.named.into_iter(),
+            Fields::Unnamed(f) => f.unnamed.into_iter(),
+        }
+    }
+}
+
+impl<'a> IntoIterator for &'a Fields {
+    type Item = &'a Field;
+    type IntoIter = punctuated::Iter<'a, Field>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}
+
+impl<'a> IntoIterator for &'a mut Fields {
+    type Item = &'a mut Field;
+    type IntoIter = punctuated::IterMut<'a, Field>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter_mut()
+    }
+}
+
+ast_struct! {
+    /// A field of a struct or enum variant.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct Field {
+        pub attrs: Vec<Attribute>,
+
+        pub vis: Visibility,
+
+        pub mutability: FieldMutability,
+
+        /// Name of the field, if any.
+        ///
+        /// Fields of tuple structs have no names.
+        pub ident: Option<Ident>,
+
+        pub colon_token: Option<Token![:]>,
+
+        pub ty: Type,
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::Attribute;
+    use crate::data::{Field, Fields, FieldsNamed, FieldsUnnamed, Variant};
+    use crate::error::Result;
+    use crate::expr::Expr;
+    use crate::ext::IdentExt as _;
+    use crate::ident::Ident;
+    #[cfg(not(feature = "full"))]
+    use crate::parse::discouraged::Speculative as _;
+    use crate::parse::{Parse, ParseStream};
+    use crate::restriction::{FieldMutability, Visibility};
+    use crate::token;
+    use crate::ty::Type;
+    use crate::verbatim;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Variant {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let _visibility: Visibility = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let fields = if input.peek(token::Brace) {
+                Fields::Named(input.parse()?)
+            } else if input.peek(token::Paren) {
+                Fields::Unnamed(input.parse()?)
+            } else {
+                Fields::Unit
+            };
+            let discriminant = if input.peek(Token![=]) {
+                let eq_token: Token![=] = input.parse()?;
+                #[cfg(feature = "full")]
+                let discriminant: Expr = input.parse()?;
+                #[cfg(not(feature = "full"))]
+                let discriminant = {
+                    let begin = input.fork();
+                    let ahead = input.fork();
+                    let mut discriminant: Result<Expr> = ahead.parse();
+                    if discriminant.is_ok() {
+                        input.advance_to(&ahead);
+                    } else if scan_lenient_discriminant(input).is_ok() {
+                        discriminant = Ok(Expr::Verbatim(verbatim::between(&begin, input)));
+                    }
+                    discriminant?
+                };
+                Some((eq_token, discriminant))
+            } else {
+                None
+            };
+            Ok(Variant {
+                attrs,
+                ident,
+                fields,
+                discriminant,
+            })
+        }
+    }
+
+    #[cfg(not(feature = "full"))]
+    pub(crate) fn scan_lenient_discriminant(input: ParseStream) -> Result<()> {
+        use crate::expr::Member;
+        use crate::lifetime::Lifetime;
+        use crate::lit::Lit;
+        use crate::lit::LitFloat;
+        use crate::op::{BinOp, UnOp};
+        use crate::path::{self, AngleBracketedGenericArguments};
+        use proc_macro2::Delimiter::{self, Brace, Bracket, Parenthesis};
+
+        let consume = |delimiter: Delimiter| {
+            Result::unwrap(input.step(|cursor| match cursor.group(delimiter) {
+                Some((_inside, _span, rest)) => Ok((true, rest)),
+                None => Ok((false, *cursor)),
+            }))
+        };
+
+        macro_rules! consume {
+            [$token:tt] => {
+                input.parse::<Option<Token![$token]>>().unwrap().is_some()
+            };
+        }
+
+        let mut initial = true;
+        let mut depth = 0usize;
+        loop {
+            if initial {
+                if consume![&] {
+                    input.parse::<Option<Token![mut]>>()?;
+                } else if consume![if] || consume![match] || consume![while] {
+                    depth += 1;
+                } else if input.parse::<Option<Lit>>()?.is_some()
+                    || (consume(Brace) || consume(Bracket) || consume(Parenthesis))
+                    || (consume![async] || consume![const] || consume![loop] || consume![unsafe])
+                        && (consume(Brace) || break)
+                {
+                    initial = false;
+                } else if consume![let] {
+                    while !consume![=] {
+                        if !((consume![|] || consume![ref] || consume![mut] || consume![@])
+                            || (consume![!] || input.parse::<Option<Lit>>()?.is_some())
+                            || (consume![..=] || consume![..] || consume![&] || consume![_])
+                            || (consume(Brace) || consume(Bracket) || consume(Parenthesis)))
+                        {
+                            path::parsing::qpath(input, true)?;
+                        }
+                    }
+                } else if input.parse::<Option<Lifetime>>()?.is_some() && !consume![:] {
+                    break;
+                } else if input.parse::<UnOp>().is_err() {
+                    path::parsing::qpath(input, true)?;
+                    initial = consume![!] || depth == 0 && input.peek(token::Brace);
+                }
+            } else if input.is_empty() || input.peek(Token![,]) {
+                return Ok(());
+            } else if depth > 0 && consume(Brace) {
+                if consume![else] && !consume(Brace) {
+                    initial = consume![if] || break;
+                } else {
+                    depth -= 1;
+                }
+            } else if input.parse::<BinOp>().is_ok() || (consume![..] | consume![=]) {
+                initial = true;
+            } else if consume![.] {
+                if input.parse::<Option<LitFloat>>()?.is_none()
+                    && (input.parse::<Member>()?.is_named() && consume![::])
+                {
+                    AngleBracketedGenericArguments::do_parse(None, input)?;
+                }
+            } else if consume![as] {
+                input.parse::<Type>()?;
+            } else if !(consume(Brace) || consume(Bracket) || consume(Parenthesis)) {
+                break;
+            }
+        }
+
+        Err(input.error("unsupported expression"))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for FieldsNamed {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let content;
+            Ok(FieldsNamed {
+                brace_token: braced!(content in input),
+                named: content.parse_terminated(Field::parse_named, Token![,])?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for FieldsUnnamed {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let content;
+            Ok(FieldsUnnamed {
+                paren_token: parenthesized!(content in input),
+                unnamed: content.parse_terminated(Field::parse_unnamed, Token![,])?,
+            })
+        }
+    }
+
+    impl Field {
+        /// Parses a named (braced struct) field.
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+        pub fn parse_named(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+
+            let unnamed_field = cfg!(feature = "full") && input.peek(Token![_]);
+            let ident = if unnamed_field {
+                input.call(Ident::parse_any)
+            } else {
+                input.parse()
+            }?;
+
+            let colon_token: Token![:] = input.parse()?;
+
+            let ty: Type = if unnamed_field
+                && (input.peek(Token![struct])
+                    || input.peek(Token![union]) && input.peek2(token::Brace))
+            {
+                let begin = input.fork();
+                input.call(Ident::parse_any)?;
+                input.parse::<FieldsNamed>()?;
+                Type::Verbatim(verbatim::between(&begin, input))
+            } else {
+                input.parse()?
+            };
+
+            Ok(Field {
+                attrs,
+                vis,
+                mutability: FieldMutability::None,
+                ident: Some(ident),
+                colon_token: Some(colon_token),
+                ty,
+            })
+        }
+
+        /// Parses an unnamed (tuple struct) field.
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+        pub fn parse_unnamed(input: ParseStream) -> Result<Self> {
+            Ok(Field {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                mutability: FieldMutability::None,
+                ident: None,
+                colon_token: None,
+                ty: input.parse()?,
+            })
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::data::{Field, FieldsNamed, FieldsUnnamed, Variant};
+    use crate::print::TokensOrDefault;
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Variant {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(&self.attrs);
+            self.ident.to_tokens(tokens);
+            self.fields.to_tokens(tokens);
+            if let Some((eq_token, disc)) = &self.discriminant {
+                eq_token.to_tokens(tokens);
+                disc.to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for FieldsNamed {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.brace_token.surround(tokens, |tokens| {
+                self.named.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for FieldsUnnamed {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.paren_token.surround(tokens, |tokens| {
+                self.unnamed.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Field {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(&self.attrs);
+            self.vis.to_tokens(tokens);
+            if let Some(ident) = &self.ident {
+                ident.to_tokens(tokens);
+                TokensOrDefault(&self.colon_token).to_tokens(tokens);
+            }
+            self.ty.to_tokens(tokens);
+        }
+    }
+}
diff --git a/rust/syn/derive.rs b/rust/syn/derive.rs
new file mode 100644
index 0000000000000000000000000000000000000000..74649479f1eae56868bdc80f392669757da651c6
--- /dev/null
+++ b/rust/syn/derive.rs
@@ -0,0 +1,261 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+use crate::data::{Fields, FieldsNamed, Variant};
+use crate::generics::Generics;
+use crate::ident::Ident;
+use crate::punctuated::Punctuated;
+use crate::restriction::Visibility;
+use crate::token;
+
+ast_struct! {
+    /// Data structure sent to a `proc_macro_derive` macro.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    pub struct DeriveInput {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub ident: Ident,
+        pub generics: Generics,
+        pub data: Data,
+    }
+}
+
+ast_enum! {
+    /// The storage of a struct, enum or union data structure.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    pub enum Data {
+        Struct(DataStruct),
+        Enum(DataEnum),
+        Union(DataUnion),
+    }
+}
+
+ast_struct! {
+    /// A struct input to a `proc_macro_derive` macro.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    pub struct DataStruct {
+        pub struct_token: Token![struct],
+        pub fields: Fields,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// An enum input to a `proc_macro_derive` macro.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    pub struct DataEnum {
+        pub enum_token: Token![enum],
+        pub brace_token: token::Brace,
+        pub variants: Punctuated<Variant, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// An untagged union input to a `proc_macro_derive` macro.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    pub struct DataUnion {
+        pub union_token: Token![union],
+        pub fields: FieldsNamed,
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::Attribute;
+    use crate::data::{Fields, FieldsNamed, Variant};
+    use crate::derive::{Data, DataEnum, DataStruct, DataUnion, DeriveInput};
+    use crate::error::Result;
+    use crate::generics::{Generics, WhereClause};
+    use crate::ident::Ident;
+    use crate::parse::{Parse, ParseStream};
+    use crate::punctuated::Punctuated;
+    use crate::restriction::Visibility;
+    use crate::token;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for DeriveInput {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis = input.parse::<Visibility>()?;
+
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Token![struct]) {
+                let struct_token = input.parse::<Token![struct]>()?;
+                let ident = input.parse::<Ident>()?;
+                let generics = input.parse::<Generics>()?;
+                let (where_clause, fields, semi) = data_struct(input)?;
+                Ok(DeriveInput {
+                    attrs,
+                    vis,
+                    ident,
+                    generics: Generics {
+                        where_clause,
+                        ..generics
+                    },
+                    data: Data::Struct(DataStruct {
+                        struct_token,
+                        fields,
+                        semi_token: semi,
+                    }),
+                })
+            } else if lookahead.peek(Token![enum]) {
+                let enum_token = input.parse::<Token![enum]>()?;
+                let ident = input.parse::<Ident>()?;
+                let generics = input.parse::<Generics>()?;
+                let (where_clause, brace, variants) = data_enum(input)?;
+                Ok(DeriveInput {
+                    attrs,
+                    vis,
+                    ident,
+                    generics: Generics {
+                        where_clause,
+                        ..generics
+                    },
+                    data: Data::Enum(DataEnum {
+                        enum_token,
+                        brace_token: brace,
+                        variants,
+                    }),
+                })
+            } else if lookahead.peek(Token![union]) {
+                let union_token = input.parse::<Token![union]>()?;
+                let ident = input.parse::<Ident>()?;
+                let generics = input.parse::<Generics>()?;
+                let (where_clause, fields) = data_union(input)?;
+                Ok(DeriveInput {
+                    attrs,
+                    vis,
+                    ident,
+                    generics: Generics {
+                        where_clause,
+                        ..generics
+                    },
+                    data: Data::Union(DataUnion {
+                        union_token,
+                        fields,
+                    }),
+                })
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+
+    pub(crate) fn data_struct(
+        input: ParseStream,
+    ) -> Result<(Option<WhereClause>, Fields, Option<Token![;]>)> {
+        let mut lookahead = input.lookahead1();
+        let mut where_clause = None;
+        if lookahead.peek(Token![where]) {
+            where_clause = Some(input.parse()?);
+            lookahead = input.lookahead1();
+        }
+
+        if where_clause.is_none() && lookahead.peek(token::Paren) {
+            let fields = input.parse()?;
+
+            lookahead = input.lookahead1();
+            if lookahead.peek(Token![where]) {
+                where_clause = Some(input.parse()?);
+                lookahead = input.lookahead1();
+            }
+
+            if lookahead.peek(Token![;]) {
+                let semi = input.parse()?;
+                Ok((where_clause, Fields::Unnamed(fields), Some(semi)))
+            } else {
+                Err(lookahead.error())
+            }
+        } else if lookahead.peek(token::Brace) {
+            let fields = input.parse()?;
+            Ok((where_clause, Fields::Named(fields), None))
+        } else if lookahead.peek(Token![;]) {
+            let semi = input.parse()?;
+            Ok((where_clause, Fields::Unit, Some(semi)))
+        } else {
+            Err(lookahead.error())
+        }
+    }
+
+    pub(crate) fn data_enum(
+        input: ParseStream,
+    ) -> Result<(
+        Option<WhereClause>,
+        token::Brace,
+        Punctuated<Variant, Token![,]>,
+    )> {
+        let where_clause = input.parse()?;
+
+        let content;
+        let brace = braced!(content in input);
+        let variants = content.parse_terminated(Variant::parse, Token![,])?;
+
+        Ok((where_clause, brace, variants))
+    }
+
+    pub(crate) fn data_union(input: ParseStream) -> Result<(Option<WhereClause>, FieldsNamed)> {
+        let where_clause = input.parse()?;
+        let fields = input.parse()?;
+        Ok((where_clause, fields))
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::attr::FilterAttrs;
+    use crate::data::Fields;
+    use crate::derive::{Data, DeriveInput};
+    use crate::print::TokensOrDefault;
+    use proc_macro2::TokenStream;
+    use quote::ToTokens;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for DeriveInput {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            for attr in self.attrs.outer() {
+                attr.to_tokens(tokens);
+            }
+            self.vis.to_tokens(tokens);
+            match &self.data {
+                Data::Struct(d) => d.struct_token.to_tokens(tokens),
+                Data::Enum(d) => d.enum_token.to_tokens(tokens),
+                Data::Union(d) => d.union_token.to_tokens(tokens),
+            }
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            match &self.data {
+                Data::Struct(data) => match &data.fields {
+                    Fields::Named(fields) => {
+                        self.generics.where_clause.to_tokens(tokens);
+                        fields.to_tokens(tokens);
+                    }
+                    Fields::Unnamed(fields) => {
+                        fields.to_tokens(tokens);
+                        self.generics.where_clause.to_tokens(tokens);
+                        TokensOrDefault(&data.semi_token).to_tokens(tokens);
+                    }
+                    Fields::Unit => {
+                        self.generics.where_clause.to_tokens(tokens);
+                        TokensOrDefault(&data.semi_token).to_tokens(tokens);
+                    }
+                },
+                Data::Enum(data) => {
+                    self.generics.where_clause.to_tokens(tokens);
+                    data.brace_token.surround(tokens, |tokens| {
+                        data.variants.to_tokens(tokens);
+                    });
+                }
+                Data::Union(data) => {
+                    self.generics.where_clause.to_tokens(tokens);
+                    data.fields.to_tokens(tokens);
+                }
+            }
+        }
+    }
+}
diff --git a/rust/syn/discouraged.rs b/rust/syn/discouraged.rs
new file mode 100644
index 0000000000000000000000000000000000000000..fe02cd4b84b409bc3d65034b50cd5037f9ffaf3d
--- /dev/null
+++ b/rust/syn/discouraged.rs
@@ -0,0 +1,227 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! Extensions to the parsing API with niche applicability.
+
+use crate::buffer::Cursor;
+use crate::error::Result;
+use crate::parse::{inner_unexpected, ParseBuffer, Unexpected};
+use proc_macro2::extra::DelimSpan;
+use proc_macro2::Delimiter;
+use std::cell::Cell;
+use std::mem;
+use std::rc::Rc;
+
+/// Extensions to the `ParseStream` API to support speculative parsing.
+pub trait Speculative {
+    /// Advance this parse stream to the position of a forked parse stream.
+    ///
+    /// This is the opposite operation to [`ParseStream::fork`]. You can fork a
+    /// parse stream, perform some speculative parsing, then join the original
+    /// stream to the fork to "commit" the parsing from the fork to the main
+    /// stream.
+    ///
+    /// If you can avoid doing this, you should, as it limits the ability to
+    /// generate useful errors. That said, it is often the only way to parse
+    /// syntax of the form `A* B*` for arbitrary syntax `A` and `B`. The problem
+    /// is that when the fork fails to parse an `A`, it's impossible to tell
+    /// whether that was because of a syntax error and the user meant to provide
+    /// an `A`, or that the `A`s are finished and it's time to start parsing
+    /// `B`s. Use with care.
+    ///
+    /// Also note that if `A` is a subset of `B`, `A* B*` can be parsed by
+    /// parsing `B*` and removing the leading members of `A` from the
+    /// repetition, bypassing the need to involve the downsides associated with
+    /// speculative parsing.
+    ///
+    /// [`ParseStream::fork`]: ParseBuffer::fork
+    ///
+    /// # Example
+    ///
+    /// There has been chatter about the possibility of making the colons in the
+    /// turbofish syntax like `path::to::<T>` no longer required by accepting
+    /// `path::to<T>` in expression position. Specifically, according to [RFC
+    /// 2544], [`PathSegment`] parsing should always try to consume a following
+    /// `<` token as the start of generic arguments, and reset to the `<` if
+    /// that fails (e.g. the token is acting as a less-than operator).
+    ///
+    /// This is the exact kind of parsing behavior which requires the "fork,
+    /// try, commit" behavior that [`ParseStream::fork`] discourages. With
+    /// `advance_to`, we can avoid having to parse the speculatively parsed
+    /// content a second time.
+    ///
+    /// This change in behavior can be implemented in syn by replacing just the
+    /// `Parse` implementation for `PathSegment`:
+    ///
+    /// ```
+    /// # use syn::ext::IdentExt;
+    /// use syn::parse::discouraged::Speculative;
+    /// # use syn::parse::{Parse, ParseStream};
+    /// # use syn::{Ident, PathArguments, Result, Token};
+    ///
+    /// pub struct PathSegment {
+    ///     pub ident: Ident,
+    ///     pub arguments: PathArguments,
+    /// }
+    /// #
+    /// # impl<T> From<T> for PathSegment
+    /// # where
+    /// #     T: Into<Ident>,
+    /// # {
+    /// #     fn from(ident: T) -> Self {
+    /// #         PathSegment {
+    /// #             ident: ident.into(),
+    /// #             arguments: PathArguments::None,
+    /// #         }
+    /// #     }
+    /// # }
+    ///
+    /// impl Parse for PathSegment {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         if input.peek(Token![super])
+    ///             || input.peek(Token![self])
+    ///             || input.peek(Token![Self])
+    ///             || input.peek(Token![crate])
+    ///         {
+    ///             let ident = input.call(Ident::parse_any)?;
+    ///             return Ok(PathSegment::from(ident));
+    ///         }
+    ///
+    ///         let ident = input.parse()?;
+    ///         if input.peek(Token![::]) && input.peek3(Token![<]) {
+    ///             return Ok(PathSegment {
+    ///                 ident,
+    ///                 arguments: PathArguments::AngleBracketed(input.parse()?),
+    ///             });
+    ///         }
+    ///         if input.peek(Token![<]) && !input.peek(Token![<=]) {
+    ///             let fork = input.fork();
+    ///             if let Ok(arguments) = fork.parse() {
+    ///                 input.advance_to(&fork);
+    ///                 return Ok(PathSegment {
+    ///                     ident,
+    ///                     arguments: PathArguments::AngleBracketed(arguments),
+    ///                 });
+    ///             }
+    ///         }
+    ///         Ok(PathSegment::from(ident))
+    ///     }
+    /// }
+    ///
+    /// # syn::parse_str::<PathSegment>("a<b,c>").unwrap();
+    /// ```
+    ///
+    /// # Drawbacks
+    ///
+    /// The main drawback of this style of speculative parsing is in error
+    /// presentation. Even if the lookahead is the "correct" parse, the error
+    /// that is shown is that of the "fallback" parse. To use the same example
+    /// as the turbofish above, take the following unfinished "turbofish":
+    ///
+    /// ```text
+    /// let _ = f<&'a fn(), for<'a> serde::>();
+    /// ```
+    ///
+    /// If this is parsed as generic arguments, we can provide the error message
+    ///
+    /// ```text
+    /// error: expected identifier
+    ///  --> src.rs:L:C
+    ///   |
+    /// L | let _ = f<&'a fn(), for<'a> serde::>();
+    ///   |                                    ^
+    /// ```
+    ///
+    /// but if parsed using the above speculative parsing, it falls back to
+    /// assuming that the `<` is a less-than when it fails to parse the generic
+    /// arguments, and tries to interpret the `&'a` as the start of a labelled
+    /// loop, resulting in the much less helpful error
+    ///
+    /// ```text
+    /// error: expected `:`
+    ///  --> src.rs:L:C
+    ///   |
+    /// L | let _ = f<&'a fn(), for<'a> serde::>();
+    ///   |               ^^
+    /// ```
+    ///
+    /// This can be mitigated with various heuristics (two examples: show both
+    /// forks' parse errors, or show the one that consumed more tokens), but
+    /// when you can control the grammar, sticking to something that can be
+    /// parsed LL(3) and without the LL(*) speculative parsing this makes
+    /// possible, displaying reasonable errors becomes much more simple.
+    ///
+    /// [RFC 2544]: https://github.com/rust-lang/rfcs/pull/2544
+    /// [`PathSegment`]: crate::PathSegment
+    ///
+    /// # Performance
+    ///
+    /// This method performs a cheap fixed amount of work that does not depend
+    /// on how far apart the two streams are positioned.
+    ///
+    /// # Panics
+    ///
+    /// The forked stream in the argument of `advance_to` must have been
+    /// obtained by forking `self`. Attempting to advance to any other stream
+    /// will cause a panic.
+    fn advance_to(&self, fork: &Self);
+}
+
+impl<'a> Speculative for ParseBuffer<'a> {
+    fn advance_to(&self, fork: &Self) {
+        if !crate::buffer::same_scope(self.cursor(), fork.cursor()) {
+            panic!("Fork was not derived from the advancing parse stream");
+        }
+
+        let (self_unexp, self_sp) = inner_unexpected(self);
+        let (fork_unexp, fork_sp) = inner_unexpected(fork);
+        if !Rc::ptr_eq(&self_unexp, &fork_unexp) {
+            match (fork_sp, self_sp) {
+                // Unexpected set on the fork, but not on `self`, copy it over.
+                (Some(span), None) => {
+                    self_unexp.set(Unexpected::Some(span));
+                }
+                // Unexpected unset. Use chain to propagate errors from fork.
+                (None, None) => {
+                    fork_unexp.set(Unexpected::Chain(self_unexp));
+
+                    // Ensure toplevel 'unexpected' tokens from the fork don't
+                    // bubble up the chain by replacing the root `unexpected`
+                    // pointer, only 'unexpected' tokens from existing group
+                    // parsers should bubble.
+                    fork.unexpected
+                        .set(Some(Rc::new(Cell::new(Unexpected::None))));
+                }
+                // Unexpected has been set on `self`. No changes needed.
+                (_, Some(_)) => {}
+            }
+        }
+
+        // See comment on `cell` in the struct definition.
+        self.cell
+            .set(unsafe { mem::transmute::<Cursor, Cursor<'static>>(fork.cursor()) });
+    }
+}
+
+/// Extensions to the `ParseStream` API to support manipulating invisible
+/// delimiters the same as if they were visible.
+pub trait AnyDelimiter {
+    /// Returns the delimiter, the span of the delimiter token, and the nested
+    /// contents for further parsing.
+    fn parse_any_delimiter(&self) -> Result<(Delimiter, DelimSpan, ParseBuffer)>;
+}
+
+impl<'a> AnyDelimiter for ParseBuffer<'a> {
+    fn parse_any_delimiter(&self) -> Result<(Delimiter, DelimSpan, ParseBuffer)> {
+        self.step(|cursor| {
+            if let Some((content, delimiter, span, rest)) = cursor.any_group() {
+                let scope = crate::buffer::close_span_of_group(*cursor);
+                let nested = crate::parse::advance_step_cursor(cursor, content);
+                let unexpected = crate::parse::get_unexpected(self);
+                let content = crate::parse::new_parse_buffer(scope, nested, unexpected);
+                Ok(((delimiter, span, content), rest))
+            } else {
+                Err(cursor.error("expected any delimiter"))
+            }
+        })
+    }
+}
diff --git a/rust/syn/drops.rs b/rust/syn/drops.rs
new file mode 100644
index 0000000000000000000000000000000000000000..a6b20562e7f5cf76e70ae38920cf9d47c02e993c
--- /dev/null
+++ b/rust/syn/drops.rs
@@ -0,0 +1,60 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use std::iter;
+use std::mem::ManuallyDrop;
+use std::ops::{Deref, DerefMut};
+use std::option;
+use std::slice;
+
+#[repr(transparent)]
+pub(crate) struct NoDrop<T: ?Sized>(ManuallyDrop<T>);
+
+impl<T> NoDrop<T> {
+    pub(crate) fn new(value: T) -> Self
+    where
+        T: TrivialDrop,
+    {
+        NoDrop(ManuallyDrop::new(value))
+    }
+}
+
+impl<T: ?Sized> Deref for NoDrop<T> {
+    type Target = T;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<T: ?Sized> DerefMut for NoDrop<T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.0
+    }
+}
+
+pub(crate) trait TrivialDrop {}
+
+impl<T> TrivialDrop for iter::Empty<T> {}
+impl<'a, T> TrivialDrop for slice::Iter<'a, T> {}
+impl<'a, T> TrivialDrop for slice::IterMut<'a, T> {}
+impl<'a, T> TrivialDrop for option::IntoIter<&'a T> {}
+impl<'a, T> TrivialDrop for option::IntoIter<&'a mut T> {}
+
+#[test]
+fn test_needs_drop() {
+    use std::mem::needs_drop;
+
+    struct NeedsDrop;
+
+    impl Drop for NeedsDrop {
+        fn drop(&mut self) {}
+    }
+
+    assert!(needs_drop::<NeedsDrop>());
+
+    // Test each of the types with a handwritten TrivialDrop impl above.
+    assert!(!needs_drop::<iter::Empty<NeedsDrop>>());
+    assert!(!needs_drop::<slice::Iter<NeedsDrop>>());
+    assert!(!needs_drop::<slice::IterMut<NeedsDrop>>());
+    assert!(!needs_drop::<option::IntoIter<&NeedsDrop>>());
+    assert!(!needs_drop::<option::IntoIter<&mut NeedsDrop>>());
+}
diff --git a/rust/syn/error.rs b/rust/syn/error.rs
new file mode 100644
index 0000000000000000000000000000000000000000..4bb042b31452cf226b6a4ef3f521b82064ce8c67
--- /dev/null
+++ b/rust/syn/error.rs
@@ -0,0 +1,469 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "parsing")]
+use crate::buffer::Cursor;
+use crate::thread::ThreadBound;
+use proc_macro2::{
+    Delimiter, Group, Ident, LexError, Literal, Punct, Spacing, Span, TokenStream, TokenTree,
+};
+#[cfg(feature = "printing")]
+use quote::ToTokens;
+use std::fmt::{self, Debug, Display};
+use std::slice;
+use std::vec;
+
+/// The result of a Syn parser.
+pub type Result<T> = std::result::Result<T, Error>;
+
+/// Error returned when a Syn parser cannot parse the input tokens.
+///
+/// # Error reporting in proc macros
+///
+/// The correct way to report errors back to the compiler from a procedural
+/// macro is by emitting an appropriately spanned invocation of
+/// [`compile_error!`] in the generated code. This produces a better diagnostic
+/// message than simply panicking the macro.
+///
+/// [`compile_error!`]: std::compile_error!
+///
+/// When parsing macro input, the [`parse_macro_input!`] macro handles the
+/// conversion to `compile_error!` automatically.
+///
+/// [`parse_macro_input!`]: crate::parse_macro_input!
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// use proc_macro::TokenStream;
+/// use syn::parse::{Parse, ParseStream, Result};
+/// use syn::{parse_macro_input, ItemFn};
+///
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro_attribute]
+/// # };
+/// pub fn my_attr(args: TokenStream, input: TokenStream) -> TokenStream {
+///     let args = parse_macro_input!(args as MyAttrArgs);
+///     let input = parse_macro_input!(input as ItemFn);
+///
+///     /* ... */
+///     # TokenStream::new()
+/// }
+///
+/// struct MyAttrArgs {
+///     # _k: [(); { stringify! {
+///     ...
+///     # }; 0 }]
+/// }
+///
+/// impl Parse for MyAttrArgs {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         # stringify! {
+///         ...
+///         # };
+///         # unimplemented!()
+///     }
+/// }
+/// ```
+///
+/// For errors that arise later than the initial parsing stage, the
+/// [`.to_compile_error()`] or [`.into_compile_error()`] methods can be used to
+/// perform an explicit conversion to `compile_error!`.
+///
+/// [`.to_compile_error()`]: Error::to_compile_error
+/// [`.into_compile_error()`]: Error::into_compile_error
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// # use proc_macro::TokenStream;
+/// # use syn::{parse_macro_input, DeriveInput};
+/// #
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro_derive(MyDerive)]
+/// # };
+/// pub fn my_derive(input: TokenStream) -> TokenStream {
+///     let input = parse_macro_input!(input as DeriveInput);
+///
+///     // fn(DeriveInput) -> syn::Result<proc_macro2::TokenStream>
+///     expand::my_derive(input)
+///         .unwrap_or_else(syn::Error::into_compile_error)
+///         .into()
+/// }
+/// #
+/// # mod expand {
+/// #     use proc_macro2::TokenStream;
+/// #     use syn::{DeriveInput, Result};
+/// #
+/// #     pub fn my_derive(input: DeriveInput) -> Result<TokenStream> {
+/// #         unimplemented!()
+/// #     }
+/// # }
+/// ```
+pub struct Error {
+    messages: Vec<ErrorMessage>,
+}
+
+struct ErrorMessage {
+    // Span is implemented as an index into a thread-local interner to keep the
+    // size small. It is not safe to access from a different thread. We want
+    // errors to be Send and Sync to play nicely with ecosystem crates for error
+    // handling, so pin the span we're given to its original thread and assume
+    // it is Span::call_site if accessed from any other thread.
+    span: ThreadBound<SpanRange>,
+    message: String,
+}
+
+// Cannot use std::ops::Range<Span> because that does not implement Copy,
+// whereas ThreadBound<T> requires a Copy impl as a way to ensure no Drop impls
+// are involved.
+struct SpanRange {
+    start: Span,
+    end: Span,
+}
+
+#[cfg(test)]
+struct _Test
+where
+    Error: Send + Sync;
+
+impl Error {
+    /// Usually the [`ParseStream::error`] method will be used instead, which
+    /// automatically uses the correct span from the current position of the
+    /// parse stream.
+    ///
+    /// Use `Error::new` when the error needs to be triggered on some span other
+    /// than where the parse stream is currently positioned.
+    ///
+    /// [`ParseStream::error`]: crate::parse::ParseBuffer::error
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{Error, Ident, LitStr, Result, Token};
+    /// use syn::parse::ParseStream;
+    ///
+    /// // Parses input that looks like `name = "string"` where the key must be
+    /// // the identifier `name` and the value may be any string literal.
+    /// // Returns the string literal.
+    /// fn parse_name(input: ParseStream) -> Result<LitStr> {
+    ///     let name_token: Ident = input.parse()?;
+    ///     if name_token != "name" {
+    ///         // Trigger an error not on the current position of the stream,
+    ///         // but on the position of the unexpected identifier.
+    ///         return Err(Error::new(name_token.span(), "expected `name`"));
+    ///     }
+    ///     input.parse::<Token![=]>()?;
+    ///     let s: LitStr = input.parse()?;
+    ///     Ok(s)
+    /// }
+    /// ```
+    pub fn new<T: Display>(span: Span, message: T) -> Self {
+        return new(span, message.to_string());
+
+        fn new(span: Span, message: String) -> Error {
+            Error {
+                messages: vec![ErrorMessage {
+                    span: ThreadBound::new(SpanRange {
+                        start: span,
+                        end: span,
+                    }),
+                    message,
+                }],
+            }
+        }
+    }
+
+    /// Creates an error with the specified message spanning the given syntax
+    /// tree node.
+    ///
+    /// Unlike the `Error::new` constructor, this constructor takes an argument
+    /// `tokens` which is a syntax tree node. This allows the resulting `Error`
+    /// to attempt to span all tokens inside of `tokens`. While you would
+    /// typically be able to use the `Spanned` trait with the above `Error::new`
+    /// constructor, implementation limitations today mean that
+    /// `Error::new_spanned` may provide a higher-quality error message on
+    /// stable Rust.
+    ///
+    /// When in doubt it's recommended to stick to `Error::new` (or
+    /// `ParseStream::error`)!
+    #[cfg(feature = "printing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    pub fn new_spanned<T: ToTokens, U: Display>(tokens: T, message: U) -> Self {
+        return new_spanned(tokens.into_token_stream(), message.to_string());
+
+        fn new_spanned(tokens: TokenStream, message: String) -> Error {
+            let mut iter = tokens.into_iter();
+            let start = iter.next().map_or_else(Span::call_site, |t| t.span());
+            let end = iter.last().map_or(start, |t| t.span());
+            Error {
+                messages: vec![ErrorMessage {
+                    span: ThreadBound::new(SpanRange { start, end }),
+                    message,
+                }],
+            }
+        }
+    }
+
+    /// The source location of the error.
+    ///
+    /// Spans are not thread-safe so this function returns `Span::call_site()`
+    /// if called from a different thread than the one on which the `Error` was
+    /// originally created.
+    pub fn span(&self) -> Span {
+        let SpanRange { start, end } = match self.messages[0].span.get() {
+            Some(span) => *span,
+            None => return Span::call_site(),
+        };
+        start.join(end).unwrap_or(start)
+    }
+
+    /// Render the error as an invocation of [`compile_error!`].
+    ///
+    /// The [`parse_macro_input!`] macro provides a convenient way to invoke
+    /// this method correctly in a procedural macro.
+    ///
+    /// [`compile_error!`]: std::compile_error!
+    /// [`parse_macro_input!`]: crate::parse_macro_input!
+    pub fn to_compile_error(&self) -> TokenStream {
+        self.messages
+            .iter()
+            .map(ErrorMessage::to_compile_error)
+            .collect()
+    }
+
+    /// Render the error as an invocation of [`compile_error!`].
+    ///
+    /// [`compile_error!`]: std::compile_error!
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # extern crate proc_macro;
+    /// #
+    /// use proc_macro::TokenStream;
+    /// use syn::{parse_macro_input, DeriveInput, Error};
+    ///
+    /// # const _: &str = stringify! {
+    /// #[proc_macro_derive(MyTrait)]
+    /// # };
+    /// pub fn derive_my_trait(input: TokenStream) -> TokenStream {
+    ///     let input = parse_macro_input!(input as DeriveInput);
+    ///     my_trait::expand(input)
+    ///         .unwrap_or_else(Error::into_compile_error)
+    ///         .into()
+    /// }
+    ///
+    /// mod my_trait {
+    ///     use proc_macro2::TokenStream;
+    ///     use syn::{DeriveInput, Result};
+    ///
+    ///     pub(crate) fn expand(input: DeriveInput) -> Result<TokenStream> {
+    ///         /* ... */
+    ///         # unimplemented!()
+    ///     }
+    /// }
+    /// ```
+    pub fn into_compile_error(self) -> TokenStream {
+        self.to_compile_error()
+    }
+
+    /// Add another error message to self such that when `to_compile_error()` is
+    /// called, both errors will be emitted together.
+    pub fn combine(&mut self, another: Error) {
+        self.messages.extend(another.messages);
+    }
+}
+
+impl ErrorMessage {
+    fn to_compile_error(&self) -> TokenStream {
+        let (start, end) = match self.span.get() {
+            Some(range) => (range.start, range.end),
+            None => (Span::call_site(), Span::call_site()),
+        };
+
+        // ::core::compile_error!($message)
+        TokenStream::from_iter(vec![
+            TokenTree::Punct({
+                let mut punct = Punct::new(':', Spacing::Joint);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Punct({
+                let mut punct = Punct::new(':', Spacing::Alone);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Ident(Ident::new("core", start)),
+            TokenTree::Punct({
+                let mut punct = Punct::new(':', Spacing::Joint);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Punct({
+                let mut punct = Punct::new(':', Spacing::Alone);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Ident(Ident::new("compile_error", start)),
+            TokenTree::Punct({
+                let mut punct = Punct::new('!', Spacing::Alone);
+                punct.set_span(start);
+                punct
+            }),
+            TokenTree::Group({
+                let mut group = Group::new(Delimiter::Brace, {
+                    TokenStream::from_iter(vec![TokenTree::Literal({
+                        let mut string = Literal::string(&self.message);
+                        string.set_span(end);
+                        string
+                    })])
+                });
+                group.set_span(end);
+                group
+            }),
+        ])
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) fn new_at<T: Display>(scope: Span, cursor: Cursor, message: T) -> Error {
+    if cursor.eof() {
+        Error::new(scope, format!("unexpected end of input, {}", message))
+    } else {
+        let span = crate::buffer::open_span_of_group(cursor);
+        Error::new(span, message)
+    }
+}
+
+#[cfg(all(feature = "parsing", any(feature = "full", feature = "derive")))]
+pub(crate) fn new2<T: Display>(start: Span, end: Span, message: T) -> Error {
+    return new2(start, end, message.to_string());
+
+    fn new2(start: Span, end: Span, message: String) -> Error {
+        Error {
+            messages: vec![ErrorMessage {
+                span: ThreadBound::new(SpanRange { start, end }),
+                message,
+            }],
+        }
+    }
+}
+
+impl Debug for Error {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        if self.messages.len() == 1 {
+            formatter
+                .debug_tuple("Error")
+                .field(&self.messages[0])
+                .finish()
+        } else {
+            formatter
+                .debug_tuple("Error")
+                .field(&self.messages)
+                .finish()
+        }
+    }
+}
+
+impl Debug for ErrorMessage {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.message, formatter)
+    }
+}
+
+impl Display for Error {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str(&self.messages[0].message)
+    }
+}
+
+impl Clone for Error {
+    fn clone(&self) -> Self {
+        Error {
+            messages: self.messages.clone(),
+        }
+    }
+}
+
+impl Clone for ErrorMessage {
+    fn clone(&self) -> Self {
+        ErrorMessage {
+            span: self.span,
+            message: self.message.clone(),
+        }
+    }
+}
+
+impl Clone for SpanRange {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl Copy for SpanRange {}
+
+impl std::error::Error for Error {}
+
+impl From<LexError> for Error {
+    fn from(err: LexError) -> Self {
+        Error::new(err.span(), err)
+    }
+}
+
+impl IntoIterator for Error {
+    type Item = Error;
+    type IntoIter = IntoIter;
+
+    fn into_iter(self) -> Self::IntoIter {
+        IntoIter {
+            messages: self.messages.into_iter(),
+        }
+    }
+}
+
+pub struct IntoIter {
+    messages: vec::IntoIter<ErrorMessage>,
+}
+
+impl Iterator for IntoIter {
+    type Item = Error;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        Some(Error {
+            messages: vec![self.messages.next()?],
+        })
+    }
+}
+
+impl<'a> IntoIterator for &'a Error {
+    type Item = Error;
+    type IntoIter = Iter<'a>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        Iter {
+            messages: self.messages.iter(),
+        }
+    }
+}
+
+pub struct Iter<'a> {
+    messages: slice::Iter<'a, ErrorMessage>,
+}
+
+impl<'a> Iterator for Iter<'a> {
+    type Item = Error;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        Some(Error {
+            messages: vec![self.messages.next()?.clone()],
+        })
+    }
+}
+
+impl Extend<Error> for Error {
+    fn extend<T: IntoIterator<Item = Error>>(&mut self, iter: T) {
+        for err in iter {
+            self.combine(err);
+        }
+    }
+}
diff --git a/rust/syn/export.rs b/rust/syn/export.rs
new file mode 100644
index 0000000000000000000000000000000000000000..05dad324ba5106dead137c5479abfab539493ba0
--- /dev/null
+++ b/rust/syn/export.rs
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[doc(hidden)]
+pub use std::clone::Clone;
+#[doc(hidden)]
+pub use std::cmp::{Eq, PartialEq};
+#[doc(hidden)]
+pub use std::concat;
+#[doc(hidden)]
+pub use std::default::Default;
+#[doc(hidden)]
+pub use std::fmt::Debug;
+#[doc(hidden)]
+pub use std::hash::{Hash, Hasher};
+#[doc(hidden)]
+pub use std::marker::Copy;
+#[doc(hidden)]
+pub use std::option::Option::{None, Some};
+#[doc(hidden)]
+pub use std::result::Result::{Err, Ok};
+#[doc(hidden)]
+pub use std::stringify;
+
+#[doc(hidden)]
+pub type Formatter<'a> = std::fmt::Formatter<'a>;
+#[doc(hidden)]
+pub type FmtResult = std::fmt::Result;
+
+#[doc(hidden)]
+pub type bool = std::primitive::bool;
+#[doc(hidden)]
+pub type str = std::primitive::str;
+
+#[cfg(feature = "printing")]
+#[doc(hidden)]
+pub use quote;
+
+#[doc(hidden)]
+pub type Span = proc_macro2::Span;
+#[doc(hidden)]
+pub type TokenStream2 = proc_macro2::TokenStream;
+
+#[cfg(feature = "parsing")]
+#[doc(hidden)]
+pub use crate::group::{parse_braces, parse_brackets, parse_parens};
+
+#[doc(hidden)]
+pub use crate::span::IntoSpans;
+
+#[cfg(all(feature = "parsing", feature = "printing"))]
+#[doc(hidden)]
+pub use crate::parse_quote::parse as parse_quote;
+
+#[cfg(feature = "parsing")]
+#[doc(hidden)]
+pub use crate::token::parsing::{peek_punct, punct as parse_punct};
+
+#[cfg(feature = "printing")]
+#[doc(hidden)]
+pub use crate::token::printing::punct as print_punct;
+
+#[cfg(feature = "parsing")]
+#[doc(hidden)]
+pub use crate::token::private::CustomToken;
+
+#[cfg(feature = "proc-macro")]
+#[doc(hidden)]
+pub type TokenStream = proc_macro::TokenStream;
+
+#[cfg(feature = "printing")]
+#[doc(hidden)]
+pub use quote::{ToTokens, TokenStreamExt};
+
+#[doc(hidden)]
+pub struct private(pub(crate) ());
diff --git a/rust/syn/expr.rs b/rust/syn/expr.rs
new file mode 100644
index 0000000000000000000000000000000000000000..77f32de27a5190eae18155328a62bbe2f06a7dbd
--- /dev/null
+++ b/rust/syn/expr.rs
@@ -0,0 +1,3631 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+#[cfg(feature = "full")]
+use crate::generics::BoundLifetimes;
+use crate::ident::Ident;
+#[cfg(feature = "full")]
+use crate::lifetime::Lifetime;
+use crate::lit::Lit;
+use crate::mac::Macro;
+use crate::op::{BinOp, UnOp};
+#[cfg(feature = "full")]
+use crate::pat::Pat;
+use crate::path::{AngleBracketedGenericArguments, Path, QSelf};
+use crate::punctuated::Punctuated;
+#[cfg(feature = "full")]
+use crate::stmt::Block;
+use crate::token;
+#[cfg(feature = "full")]
+use crate::ty::ReturnType;
+use crate::ty::Type;
+use proc_macro2::{Span, TokenStream};
+#[cfg(feature = "printing")]
+use quote::IdentFragment;
+#[cfg(feature = "printing")]
+use std::fmt::{self, Display};
+use std::hash::{Hash, Hasher};
+#[cfg(all(feature = "parsing", feature = "full"))]
+use std::mem;
+
+ast_enum_of_structs! {
+    /// A Rust expression.
+    ///
+    /// *This type is available only if Syn is built with the `"derive"` or `"full"`
+    /// feature, but most of the variants are not available unless "full" is enabled.*
+    ///
+    /// # Syntax tree enums
+    ///
+    /// This type is a syntax tree enum. In Syn this and other syntax tree enums
+    /// are designed to be traversed using the following rebinding idiom.
+    ///
+    /// ```
+    /// # use syn::Expr;
+    /// #
+    /// # fn example(expr: Expr) {
+    /// # const IGNORE: &str = stringify! {
+    /// let expr: Expr = /* ... */;
+    /// # };
+    /// match expr {
+    ///     Expr::MethodCall(expr) => {
+    ///         /* ... */
+    ///     }
+    ///     Expr::Cast(expr) => {
+    ///         /* ... */
+    ///     }
+    ///     Expr::If(expr) => {
+    ///         /* ... */
+    ///     }
+    ///
+    ///     /* ... */
+    ///     # _ => {}
+    /// # }
+    /// # }
+    /// ```
+    ///
+    /// We begin with a variable `expr` of type `Expr` that has no fields
+    /// (because it is an enum), and by matching on it and rebinding a variable
+    /// with the same name `expr` we effectively imbue our variable with all of
+    /// the data fields provided by the variant that it turned out to be. So for
+    /// example above if we ended up in the `MethodCall` case then we get to use
+    /// `expr.receiver`, `expr.args` etc; if we ended up in the `If` case we get
+    /// to use `expr.cond`, `expr.then_branch`, `expr.else_branch`.
+    ///
+    /// This approach avoids repeating the variant names twice on every line.
+    ///
+    /// ```
+    /// # use syn::{Expr, ExprMethodCall};
+    /// #
+    /// # fn example(expr: Expr) {
+    /// // Repetitive; recommend not doing this.
+    /// match expr {
+    ///     Expr::MethodCall(ExprMethodCall { method, args, .. }) => {
+    /// # }
+    /// # _ => {}
+    /// # }
+    /// # }
+    /// ```
+    ///
+    /// In general, the name to which a syntax tree enum variant is bound should
+    /// be a suitable name for the complete syntax tree enum type.
+    ///
+    /// ```
+    /// # use syn::{Expr, ExprField};
+    /// #
+    /// # fn example(discriminant: ExprField) {
+    /// // Binding is called `base` which is the name I would use if I were
+    /// // assigning `*discriminant.base` without an `if let`.
+    /// if let Expr::Tuple(base) = *discriminant.base {
+    /// # }
+    /// # }
+    /// ```
+    ///
+    /// A sign that you may not be choosing the right variable names is if you
+    /// see names getting repeated in your code, like accessing
+    /// `receiver.receiver` or `pat.pat` or `cond.cond`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum Expr {
+        /// A slice literal expression: `[a, b, c, d]`.
+        Array(ExprArray),
+
+        /// An assignment expression: `a = compute()`.
+        Assign(ExprAssign),
+
+        /// An async block: `async { ... }`.
+        Async(ExprAsync),
+
+        /// An await expression: `fut.await`.
+        Await(ExprAwait),
+
+        /// A binary operation: `a + b`, `a += b`.
+        Binary(ExprBinary),
+
+        /// A blocked scope: `{ ... }`.
+        Block(ExprBlock),
+
+        /// A `break`, with an optional label to break and an optional
+        /// expression.
+        Break(ExprBreak),
+
+        /// A function call expression: `invoke(a, b)`.
+        Call(ExprCall),
+
+        /// A cast expression: `foo as f64`.
+        Cast(ExprCast),
+
+        /// A closure expression: `|a, b| a + b`.
+        Closure(ExprClosure),
+
+        /// A const block: `const { ... }`.
+        Const(ExprConst),
+
+        /// A `continue`, with an optional label.
+        Continue(ExprContinue),
+
+        /// Access of a named struct field (`obj.k`) or unnamed tuple struct
+        /// field (`obj.0`).
+        Field(ExprField),
+
+        /// A for loop: `for pat in expr { ... }`.
+        ForLoop(ExprForLoop),
+
+        /// An expression contained within invisible delimiters.
+        ///
+        /// This variant is important for faithfully representing the precedence
+        /// of expressions and is related to `None`-delimited spans in a
+        /// `TokenStream`.
+        Group(ExprGroup),
+
+        /// An `if` expression with an optional `else` block: `if expr { ... }
+        /// else { ... }`.
+        ///
+        /// The `else` branch expression may only be an `If` or `Block`
+        /// expression, not any of the other types of expression.
+        If(ExprIf),
+
+        /// A square bracketed indexing expression: `vector[2]`.
+        Index(ExprIndex),
+
+        /// The inferred value of a const generic argument, denoted `_`.
+        Infer(ExprInfer),
+
+        /// A `let` guard: `let Some(x) = opt`.
+        Let(ExprLet),
+
+        /// A literal in place of an expression: `1`, `"foo"`.
+        Lit(ExprLit),
+
+        /// Conditionless loop: `loop { ... }`.
+        Loop(ExprLoop),
+
+        /// A macro invocation expression: `format!("{}", q)`.
+        Macro(ExprMacro),
+
+        /// A `match` expression: `match n { Some(n) => {}, None => {} }`.
+        Match(ExprMatch),
+
+        /// A method call expression: `x.foo::<T>(a, b)`.
+        MethodCall(ExprMethodCall),
+
+        /// A parenthesized expression: `(a + b)`.
+        Paren(ExprParen),
+
+        /// A path like `std::mem::replace` possibly containing generic
+        /// parameters and a qualified self-type.
+        ///
+        /// A plain identifier like `x` is a path of length 1.
+        Path(ExprPath),
+
+        /// A range expression: `1..2`, `1..`, `..2`, `1..=2`, `..=2`.
+        Range(ExprRange),
+
+        /// A referencing operation: `&a` or `&mut a`.
+        Reference(ExprReference),
+
+        /// An array literal constructed from one repeated element: `[0u8; N]`.
+        Repeat(ExprRepeat),
+
+        /// A `return`, with an optional value to be returned.
+        Return(ExprReturn),
+
+        /// A struct literal expression: `Point { x: 1, y: 1 }`.
+        ///
+        /// The `rest` provides the value of the remaining fields as in `S { a:
+        /// 1, b: 1, ..rest }`.
+        Struct(ExprStruct),
+
+        /// A try-expression: `expr?`.
+        Try(ExprTry),
+
+        /// A try block: `try { ... }`.
+        TryBlock(ExprTryBlock),
+
+        /// A tuple expression: `(a, b, c, d)`.
+        Tuple(ExprTuple),
+
+        /// A unary operation: `!x`, `*x`.
+        Unary(ExprUnary),
+
+        /// An unsafe block: `unsafe { ... }`.
+        Unsafe(ExprUnsafe),
+
+        /// Tokens in expression position not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        /// A while loop: `while expr { ... }`.
+        While(ExprWhile),
+
+        /// A yield expression: `yield expr`.
+        Yield(ExprYield),
+
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match expr {
+        //         #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //
+        //         Expr::Array(expr) => {...}
+        //         Expr::Assign(expr) => {...}
+        //         ...
+        //         Expr::Yield(expr) => {...}
+        //
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+    }
+}
+
+ast_struct! {
+    /// A slice literal expression: `[a, b, c, d]`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprArray #full {
+        pub attrs: Vec<Attribute>,
+        pub bracket_token: token::Bracket,
+        pub elems: Punctuated<Expr, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// An assignment expression: `a = compute()`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprAssign #full {
+        pub attrs: Vec<Attribute>,
+        pub left: Box<Expr>,
+        pub eq_token: Token![=],
+        pub right: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// An async block: `async { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprAsync #full {
+        pub attrs: Vec<Attribute>,
+        pub async_token: Token![async],
+        pub capture: Option<Token![move]>,
+        pub block: Block,
+    }
+}
+
+ast_struct! {
+    /// An await expression: `fut.await`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprAwait #full {
+        pub attrs: Vec<Attribute>,
+        pub base: Box<Expr>,
+        pub dot_token: Token![.],
+        pub await_token: Token![await],
+    }
+}
+
+ast_struct! {
+    /// A binary operation: `a + b`, `a += b`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprBinary {
+        pub attrs: Vec<Attribute>,
+        pub left: Box<Expr>,
+        pub op: BinOp,
+        pub right: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// A blocked scope: `{ ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprBlock #full {
+        pub attrs: Vec<Attribute>,
+        pub label: Option<Label>,
+        pub block: Block,
+    }
+}
+
+ast_struct! {
+    /// A `break`, with an optional label to break and an optional
+    /// expression.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprBreak #full {
+        pub attrs: Vec<Attribute>,
+        pub break_token: Token![break],
+        pub label: Option<Lifetime>,
+        pub expr: Option<Box<Expr>>,
+    }
+}
+
+ast_struct! {
+    /// A function call expression: `invoke(a, b)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprCall {
+        pub attrs: Vec<Attribute>,
+        pub func: Box<Expr>,
+        pub paren_token: token::Paren,
+        pub args: Punctuated<Expr, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A cast expression: `foo as f64`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprCast {
+        pub attrs: Vec<Attribute>,
+        pub expr: Box<Expr>,
+        pub as_token: Token![as],
+        pub ty: Box<Type>,
+    }
+}
+
+ast_struct! {
+    /// A closure expression: `|a, b| a + b`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprClosure #full {
+        pub attrs: Vec<Attribute>,
+        pub lifetimes: Option<BoundLifetimes>,
+        pub constness: Option<Token![const]>,
+        pub movability: Option<Token![static]>,
+        pub asyncness: Option<Token![async]>,
+        pub capture: Option<Token![move]>,
+        pub or1_token: Token![|],
+        pub inputs: Punctuated<Pat, Token![,]>,
+        pub or2_token: Token![|],
+        pub output: ReturnType,
+        pub body: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// A const block: `const { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprConst #full {
+        pub attrs: Vec<Attribute>,
+        pub const_token: Token![const],
+        pub block: Block,
+    }
+}
+
+ast_struct! {
+    /// A `continue`, with an optional label.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprContinue #full {
+        pub attrs: Vec<Attribute>,
+        pub continue_token: Token![continue],
+        pub label: Option<Lifetime>,
+    }
+}
+
+ast_struct! {
+    /// Access of a named struct field (`obj.k`) or unnamed tuple struct
+    /// field (`obj.0`).
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprField {
+        pub attrs: Vec<Attribute>,
+        pub base: Box<Expr>,
+        pub dot_token: Token![.],
+        pub member: Member,
+    }
+}
+
+ast_struct! {
+    /// A for loop: `for pat in expr { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprForLoop #full {
+        pub attrs: Vec<Attribute>,
+        pub label: Option<Label>,
+        pub for_token: Token![for],
+        pub pat: Box<Pat>,
+        pub in_token: Token![in],
+        pub expr: Box<Expr>,
+        pub body: Block,
+    }
+}
+
+ast_struct! {
+    /// An expression contained within invisible delimiters.
+    ///
+    /// This variant is important for faithfully representing the precedence
+    /// of expressions and is related to `None`-delimited spans in a
+    /// `TokenStream`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprGroup {
+        pub attrs: Vec<Attribute>,
+        pub group_token: token::Group,
+        pub expr: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// An `if` expression with an optional `else` block: `if expr { ... }
+    /// else { ... }`.
+    ///
+    /// The `else` branch expression may only be an `If` or `Block`
+    /// expression, not any of the other types of expression.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprIf #full {
+        pub attrs: Vec<Attribute>,
+        pub if_token: Token![if],
+        pub cond: Box<Expr>,
+        pub then_branch: Block,
+        pub else_branch: Option<(Token![else], Box<Expr>)>,
+    }
+}
+
+ast_struct! {
+    /// A square bracketed indexing expression: `vector[2]`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprIndex {
+        pub attrs: Vec<Attribute>,
+        pub expr: Box<Expr>,
+        pub bracket_token: token::Bracket,
+        pub index: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// The inferred value of a const generic argument, denoted `_`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprInfer #full {
+        pub attrs: Vec<Attribute>,
+        pub underscore_token: Token![_],
+    }
+}
+
+ast_struct! {
+    /// A `let` guard: `let Some(x) = opt`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprLet #full {
+        pub attrs: Vec<Attribute>,
+        pub let_token: Token![let],
+        pub pat: Box<Pat>,
+        pub eq_token: Token![=],
+        pub expr: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// A literal in place of an expression: `1`, `"foo"`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprLit {
+        pub attrs: Vec<Attribute>,
+        pub lit: Lit,
+    }
+}
+
+ast_struct! {
+    /// Conditionless loop: `loop { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprLoop #full {
+        pub attrs: Vec<Attribute>,
+        pub label: Option<Label>,
+        pub loop_token: Token![loop],
+        pub body: Block,
+    }
+}
+
+ast_struct! {
+    /// A macro invocation expression: `format!("{}", q)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprMacro {
+        pub attrs: Vec<Attribute>,
+        pub mac: Macro,
+    }
+}
+
+ast_struct! {
+    /// A `match` expression: `match n { Some(n) => {}, None => {} }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprMatch #full {
+        pub attrs: Vec<Attribute>,
+        pub match_token: Token![match],
+        pub expr: Box<Expr>,
+        pub brace_token: token::Brace,
+        pub arms: Vec<Arm>,
+    }
+}
+
+ast_struct! {
+    /// A method call expression: `x.foo::<T>(a, b)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprMethodCall {
+        pub attrs: Vec<Attribute>,
+        pub receiver: Box<Expr>,
+        pub dot_token: Token![.],
+        pub method: Ident,
+        pub turbofish: Option<AngleBracketedGenericArguments>,
+        pub paren_token: token::Paren,
+        pub args: Punctuated<Expr, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A parenthesized expression: `(a + b)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprParen {
+        pub attrs: Vec<Attribute>,
+        pub paren_token: token::Paren,
+        pub expr: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// A path like `std::mem::replace` possibly containing generic
+    /// parameters and a qualified self-type.
+    ///
+    /// A plain identifier like `x` is a path of length 1.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprPath {
+        pub attrs: Vec<Attribute>,
+        pub qself: Option<QSelf>,
+        pub path: Path,
+    }
+}
+
+ast_struct! {
+    /// A range expression: `1..2`, `1..`, `..2`, `1..=2`, `..=2`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprRange #full {
+        pub attrs: Vec<Attribute>,
+        pub start: Option<Box<Expr>>,
+        pub limits: RangeLimits,
+        pub end: Option<Box<Expr>>,
+    }
+}
+
+ast_struct! {
+    /// A referencing operation: `&a` or `&mut a`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprReference {
+        pub attrs: Vec<Attribute>,
+        pub and_token: Token![&],
+        pub mutability: Option<Token![mut]>,
+        pub expr: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// An array literal constructed from one repeated element: `[0u8; N]`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprRepeat #full {
+        pub attrs: Vec<Attribute>,
+        pub bracket_token: token::Bracket,
+        pub expr: Box<Expr>,
+        pub semi_token: Token![;],
+        pub len: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// A `return`, with an optional value to be returned.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprReturn #full {
+        pub attrs: Vec<Attribute>,
+        pub return_token: Token![return],
+        pub expr: Option<Box<Expr>>,
+    }
+}
+
+ast_struct! {
+    /// A struct literal expression: `Point { x: 1, y: 1 }`.
+    ///
+    /// The `rest` provides the value of the remaining fields as in `S { a:
+    /// 1, b: 1, ..rest }`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprStruct {
+        pub attrs: Vec<Attribute>,
+        pub qself: Option<QSelf>,
+        pub path: Path,
+        pub brace_token: token::Brace,
+        pub fields: Punctuated<FieldValue, Token![,]>,
+        pub dot2_token: Option<Token![..]>,
+        pub rest: Option<Box<Expr>>,
+    }
+}
+
+ast_struct! {
+    /// A try-expression: `expr?`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprTry #full {
+        pub attrs: Vec<Attribute>,
+        pub expr: Box<Expr>,
+        pub question_token: Token![?],
+    }
+}
+
+ast_struct! {
+    /// A try block: `try { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprTryBlock #full {
+        pub attrs: Vec<Attribute>,
+        pub try_token: Token![try],
+        pub block: Block,
+    }
+}
+
+ast_struct! {
+    /// A tuple expression: `(a, b, c, d)`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprTuple #full {
+        pub attrs: Vec<Attribute>,
+        pub paren_token: token::Paren,
+        pub elems: Punctuated<Expr, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A unary operation: `!x`, `*x`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ExprUnary {
+        pub attrs: Vec<Attribute>,
+        pub op: UnOp,
+        pub expr: Box<Expr>,
+    }
+}
+
+ast_struct! {
+    /// An unsafe block: `unsafe { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprUnsafe #full {
+        pub attrs: Vec<Attribute>,
+        pub unsafe_token: Token![unsafe],
+        pub block: Block,
+    }
+}
+
+ast_struct! {
+    /// A while loop: `while expr { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprWhile #full {
+        pub attrs: Vec<Attribute>,
+        pub label: Option<Label>,
+        pub while_token: Token![while],
+        pub cond: Box<Expr>,
+        pub body: Block,
+    }
+}
+
+ast_struct! {
+    /// A yield expression: `yield expr`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ExprYield #full {
+        pub attrs: Vec<Attribute>,
+        pub yield_token: Token![yield],
+        pub expr: Option<Box<Expr>>,
+    }
+}
+
+impl Expr {
+    #[cfg(feature = "parsing")]
+    const DUMMY: Self = Expr::Path(ExprPath {
+        attrs: Vec::new(),
+        qself: None,
+        path: Path {
+            leading_colon: None,
+            segments: Punctuated::new(),
+        },
+    });
+
+    #[cfg(all(feature = "parsing", feature = "full"))]
+    pub(crate) fn replace_attrs(&mut self, new: Vec<Attribute>) -> Vec<Attribute> {
+        match self {
+            Expr::Array(ExprArray { attrs, .. })
+            | Expr::Assign(ExprAssign { attrs, .. })
+            | Expr::Async(ExprAsync { attrs, .. })
+            | Expr::Await(ExprAwait { attrs, .. })
+            | Expr::Binary(ExprBinary { attrs, .. })
+            | Expr::Block(ExprBlock { attrs, .. })
+            | Expr::Break(ExprBreak { attrs, .. })
+            | Expr::Call(ExprCall { attrs, .. })
+            | Expr::Cast(ExprCast { attrs, .. })
+            | Expr::Closure(ExprClosure { attrs, .. })
+            | Expr::Const(ExprConst { attrs, .. })
+            | Expr::Continue(ExprContinue { attrs, .. })
+            | Expr::Field(ExprField { attrs, .. })
+            | Expr::ForLoop(ExprForLoop { attrs, .. })
+            | Expr::Group(ExprGroup { attrs, .. })
+            | Expr::If(ExprIf { attrs, .. })
+            | Expr::Index(ExprIndex { attrs, .. })
+            | Expr::Infer(ExprInfer { attrs, .. })
+            | Expr::Let(ExprLet { attrs, .. })
+            | Expr::Lit(ExprLit { attrs, .. })
+            | Expr::Loop(ExprLoop { attrs, .. })
+            | Expr::Macro(ExprMacro { attrs, .. })
+            | Expr::Match(ExprMatch { attrs, .. })
+            | Expr::MethodCall(ExprMethodCall { attrs, .. })
+            | Expr::Paren(ExprParen { attrs, .. })
+            | Expr::Path(ExprPath { attrs, .. })
+            | Expr::Range(ExprRange { attrs, .. })
+            | Expr::Reference(ExprReference { attrs, .. })
+            | Expr::Repeat(ExprRepeat { attrs, .. })
+            | Expr::Return(ExprReturn { attrs, .. })
+            | Expr::Struct(ExprStruct { attrs, .. })
+            | Expr::Try(ExprTry { attrs, .. })
+            | Expr::TryBlock(ExprTryBlock { attrs, .. })
+            | Expr::Tuple(ExprTuple { attrs, .. })
+            | Expr::Unary(ExprUnary { attrs, .. })
+            | Expr::Unsafe(ExprUnsafe { attrs, .. })
+            | Expr::While(ExprWhile { attrs, .. })
+            | Expr::Yield(ExprYield { attrs, .. }) => mem::replace(attrs, new),
+            Expr::Verbatim(_) => Vec::new(),
+        }
+    }
+}
+
+ast_enum! {
+    /// A struct or tuple struct field accessed in a struct literal or field
+    /// expression.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum Member {
+        /// A named field like `self.x`.
+        Named(Ident),
+        /// An unnamed field like `self.0`.
+        Unnamed(Index),
+    }
+}
+
+impl From<Ident> for Member {
+    fn from(ident: Ident) -> Member {
+        Member::Named(ident)
+    }
+}
+
+impl From<Index> for Member {
+    fn from(index: Index) -> Member {
+        Member::Unnamed(index)
+    }
+}
+
+impl From<usize> for Member {
+    fn from(index: usize) -> Member {
+        Member::Unnamed(Index::from(index))
+    }
+}
+
+impl Eq for Member {}
+
+impl PartialEq for Member {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (Member::Named(this), Member::Named(other)) => this == other,
+            (Member::Unnamed(this), Member::Unnamed(other)) => this == other,
+            _ => false,
+        }
+    }
+}
+
+impl Hash for Member {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        match self {
+            Member::Named(m) => m.hash(state),
+            Member::Unnamed(m) => m.hash(state),
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+impl IdentFragment for Member {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self {
+            Member::Named(m) => Display::fmt(m, formatter),
+            Member::Unnamed(m) => Display::fmt(&m.index, formatter),
+        }
+    }
+
+    fn span(&self) -> Option<Span> {
+        match self {
+            Member::Named(m) => Some(m.span()),
+            Member::Unnamed(m) => Some(m.span),
+        }
+    }
+}
+
+ast_struct! {
+    /// The index of an unnamed tuple struct field.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct Index {
+        pub index: u32,
+        pub span: Span,
+    }
+}
+
+impl From<usize> for Index {
+    fn from(index: usize) -> Index {
+        assert!(index < u32::max_value() as usize);
+        Index {
+            index: index as u32,
+            span: Span::call_site(),
+        }
+    }
+}
+
+impl Eq for Index {}
+
+impl PartialEq for Index {
+    fn eq(&self, other: &Self) -> bool {
+        self.index == other.index
+    }
+}
+
+impl Hash for Index {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        self.index.hash(state);
+    }
+}
+
+#[cfg(feature = "printing")]
+impl IdentFragment for Index {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.index, formatter)
+    }
+
+    fn span(&self) -> Option<Span> {
+        Some(self.span)
+    }
+}
+
+ast_struct! {
+    /// A field-value pair in a struct literal.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct FieldValue {
+        pub attrs: Vec<Attribute>,
+        pub member: Member,
+
+        /// The colon in `Struct { x: x }`. If written in shorthand like
+        /// `Struct { x }`, there is no colon.
+        pub colon_token: Option<Token![:]>,
+
+        pub expr: Expr,
+    }
+}
+
+#[cfg(feature = "full")]
+ast_struct! {
+    /// A lifetime labeling a `for`, `while`, or `loop`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct Label {
+        pub name: Lifetime,
+        pub colon_token: Token![:],
+    }
+}
+
+#[cfg(feature = "full")]
+ast_struct! {
+    /// One arm of a `match` expression: `0..=10 => { return true; }`.
+    ///
+    /// As in:
+    ///
+    /// ```
+    /// # fn f() -> bool {
+    /// #     let n = 0;
+    /// match n {
+    ///     0..=10 => {
+    ///         return true;
+    ///     }
+    ///     // ...
+    ///     # _ => {}
+    /// }
+    /// #   false
+    /// # }
+    /// ```
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct Arm {
+        pub attrs: Vec<Attribute>,
+        pub pat: Pat,
+        pub guard: Option<(Token![if], Box<Expr>)>,
+        pub fat_arrow_token: Token![=>],
+        pub body: Box<Expr>,
+        pub comma: Option<Token![,]>,
+    }
+}
+
+#[cfg(feature = "full")]
+ast_enum! {
+    /// Limit types of a range, inclusive or exclusive.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub enum RangeLimits {
+        /// Inclusive at the beginning, exclusive at the end.
+        HalfOpen(Token![..]),
+        /// Inclusive at the beginning and end.
+        Closed(Token![..=]),
+    }
+}
+
+#[cfg(any(feature = "parsing", feature = "printing"))]
+#[cfg(feature = "full")]
+pub(crate) fn requires_terminator(expr: &Expr) -> bool {
+    // see https://github.com/rust-lang/rust/blob/9a19e7604/compiler/rustc_ast/src/util/classify.rs#L7-L26
+    match expr {
+        Expr::If(_)
+        | Expr::Match(_)
+        | Expr::Block(_) | Expr::Unsafe(_) // both under ExprKind::Block in rustc
+        | Expr::While(_)
+        | Expr::Loop(_)
+        | Expr::ForLoop(_)
+        | Expr::TryBlock(_)
+        | Expr::Const(_) => false,
+        Expr::Array(_)
+        | Expr::Assign(_)
+        | Expr::Async(_)
+        | Expr::Await(_)
+        | Expr::Binary(_)
+        | Expr::Break(_)
+        | Expr::Call(_)
+        | Expr::Cast(_)
+        | Expr::Closure(_)
+        | Expr::Continue(_)
+        | Expr::Field(_)
+        | Expr::Group(_)
+        | Expr::Index(_)
+        | Expr::Infer(_)
+        | Expr::Let(_)
+        | Expr::Lit(_)
+        | Expr::Macro(_)
+        | Expr::MethodCall(_)
+        | Expr::Paren(_)
+        | Expr::Path(_)
+        | Expr::Range(_)
+        | Expr::Reference(_)
+        | Expr::Repeat(_)
+        | Expr::Return(_)
+        | Expr::Struct(_)
+        | Expr::Try(_)
+        | Expr::Tuple(_)
+        | Expr::Unary(_)
+        | Expr::Yield(_)
+        | Expr::Verbatim(_) => true
+    }
+}
+
+#[cfg(feature = "parsing")]
+mod precedence {
+    use super::BinOp;
+
+    pub(crate) enum Precedence {
+        Any,
+        Assign,
+        Range,
+        Or,
+        And,
+        Compare,
+        BitOr,
+        BitXor,
+        BitAnd,
+        Shift,
+        Arithmetic,
+        Term,
+        Cast,
+    }
+
+    impl Precedence {
+        pub(crate) fn of(op: &BinOp) -> Self {
+            match op {
+                BinOp::Add(_) | BinOp::Sub(_) => Precedence::Arithmetic,
+                BinOp::Mul(_) | BinOp::Div(_) | BinOp::Rem(_) => Precedence::Term,
+                BinOp::And(_) => Precedence::And,
+                BinOp::Or(_) => Precedence::Or,
+                BinOp::BitXor(_) => Precedence::BitXor,
+                BinOp::BitAnd(_) => Precedence::BitAnd,
+                BinOp::BitOr(_) => Precedence::BitOr,
+                BinOp::Shl(_) | BinOp::Shr(_) => Precedence::Shift,
+                BinOp::Eq(_)
+                | BinOp::Lt(_)
+                | BinOp::Le(_)
+                | BinOp::Ne(_)
+                | BinOp::Ge(_)
+                | BinOp::Gt(_) => Precedence::Compare,
+                BinOp::AddAssign(_)
+                | BinOp::SubAssign(_)
+                | BinOp::MulAssign(_)
+                | BinOp::DivAssign(_)
+                | BinOp::RemAssign(_)
+                | BinOp::BitXorAssign(_)
+                | BinOp::BitAndAssign(_)
+                | BinOp::BitOrAssign(_)
+                | BinOp::ShlAssign(_)
+                | BinOp::ShrAssign(_) => Precedence::Assign,
+            }
+        }
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    #[cfg(feature = "full")]
+    use crate::attr;
+    use crate::attr::Attribute;
+    use crate::error::{Error, Result};
+    use crate::expr::precedence::Precedence;
+    #[cfg(feature = "full")]
+    use crate::expr::{
+        requires_terminator, Arm, ExprArray, ExprAssign, ExprAsync, ExprAwait, ExprBlock,
+        ExprBreak, ExprClosure, ExprConst, ExprContinue, ExprForLoop, ExprIf, ExprInfer, ExprLet,
+        ExprLoop, ExprMatch, ExprRange, ExprRepeat, ExprReturn, ExprTry, ExprTryBlock, ExprTuple,
+        ExprUnsafe, ExprWhile, ExprYield, Label, RangeLimits,
+    };
+    use crate::expr::{
+        Expr, ExprBinary, ExprCall, ExprCast, ExprField, ExprGroup, ExprIndex, ExprLit, ExprMacro,
+        ExprMethodCall, ExprParen, ExprPath, ExprReference, ExprStruct, ExprUnary, FieldValue,
+        Index, Member,
+    };
+    #[cfg(feature = "full")]
+    use crate::ext::IdentExt as _;
+    #[cfg(feature = "full")]
+    use crate::generics::BoundLifetimes;
+    use crate::ident::Ident;
+    #[cfg(feature = "full")]
+    use crate::lifetime::Lifetime;
+    use crate::lit::{Lit, LitFloat, LitInt};
+    use crate::mac::{self, Macro};
+    use crate::op::BinOp;
+    use crate::parse::discouraged::Speculative as _;
+    #[cfg(feature = "full")]
+    use crate::parse::ParseBuffer;
+    use crate::parse::{Parse, ParseStream};
+    #[cfg(feature = "full")]
+    use crate::pat::{Pat, PatType};
+    use crate::path::{self, AngleBracketedGenericArguments, Path, QSelf};
+    use crate::punctuated::Punctuated;
+    #[cfg(feature = "full")]
+    use crate::stmt::Block;
+    use crate::token;
+    use crate::ty;
+    #[cfg(feature = "full")]
+    use crate::ty::{ReturnType, Type};
+    use crate::verbatim;
+    #[cfg(feature = "full")]
+    use proc_macro2::TokenStream;
+    use std::cmp::Ordering;
+    use std::mem;
+
+    mod kw {
+        crate::custom_keyword!(builtin);
+        crate::custom_keyword!(raw);
+    }
+
+    // When we're parsing expressions which occur before blocks, like in an if
+    // statement's condition, we cannot parse a struct literal.
+    //
+    // Struct literals are ambiguous in certain positions
+    // https://github.com/rust-lang/rfcs/pull/92
+    #[cfg(feature = "full")]
+    pub(crate) struct AllowStruct(bool);
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Expr {
+        fn parse(input: ParseStream) -> Result<Self> {
+            ambiguous_expr(
+                input,
+                #[cfg(feature = "full")]
+                AllowStruct(true),
+            )
+        }
+    }
+
+    impl Expr {
+        /// An alternative to the primary `Expr::parse` parser (from the
+        /// [`Parse`] trait) for ambiguous syntactic positions in which a
+        /// trailing brace should not be taken as part of the expression.
+        ///
+        /// Rust grammar has an ambiguity where braces sometimes turn a path
+        /// expression into a struct initialization and sometimes do not. In the
+        /// following code, the expression `S {}` is one expression. Presumably
+        /// there is an empty struct `struct S {}` defined somewhere which it is
+        /// instantiating.
+        ///
+        /// ```
+        /// # struct S;
+        /// # impl std::ops::Deref for S {
+        /// #     type Target = bool;
+        /// #     fn deref(&self) -> &Self::Target {
+        /// #         &true
+        /// #     }
+        /// # }
+        /// let _ = *S {};
+        ///
+        /// // parsed by rustc as: `*(S {})`
+        /// ```
+        ///
+        /// We would want to parse the above using `Expr::parse` after the `=`
+        /// token.
+        ///
+        /// But in the following, `S {}` is *not* a struct init expression.
+        ///
+        /// ```
+        /// # const S: &bool = &true;
+        /// if *S {} {}
+        ///
+        /// // parsed by rustc as:
+        /// //
+        /// //    if (*S) {
+        /// //        /* empty block */
+        /// //    }
+        /// //    {
+        /// //        /* another empty block */
+        /// //    }
+        /// ```
+        ///
+        /// For that reason we would want to parse if-conditions using
+        /// `Expr::parse_without_eager_brace` after the `if` token. Same for
+        /// similar syntactic positions such as the condition expr after a
+        /// `while` token or the expr at the top of a `match`.
+        ///
+        /// The Rust grammar's choices around which way this ambiguity is
+        /// resolved at various syntactic positions is fairly arbitrary. Really
+        /// either parse behavior could work in most positions, and language
+        /// designers just decide each case based on which is more likely to be
+        /// what the programmer had in mind most of the time.
+        ///
+        /// ```
+        /// # struct S;
+        /// # fn doc() -> S {
+        /// if return S {} {}
+        /// # unreachable!()
+        /// # }
+        ///
+        /// // parsed by rustc as:
+        /// //
+        /// //    if (return (S {})) {
+        /// //    }
+        /// //
+        /// // but could equally well have been this other arbitrary choice:
+        /// //
+        /// //    if (return S) {
+        /// //    }
+        /// //    {}
+        /// ```
+        ///
+        /// Note the grammar ambiguity on trailing braces is distinct from
+        /// precedence and is not captured by assigning a precedence level to
+        /// the braced struct init expr in relation to other operators. This can
+        /// be illustrated by `return 0..S {}` vs `match 0..S {}`. The former
+        /// parses as `return (0..(S {}))` implying tighter precedence for
+        /// struct init than `..`, while the latter parses as `match (0..S) {}`
+        /// implying tighter precedence for `..` than struct init, a
+        /// contradiction.
+        #[cfg(feature = "full")]
+        #[cfg_attr(doc_cfg, doc(cfg(all(feature = "full", feature = "parsing"))))]
+        pub fn parse_without_eager_brace(input: ParseStream) -> Result<Expr> {
+            ambiguous_expr(input, AllowStruct(false))
+        }
+
+        /// An alternative to the primary `Expr::parse` parser (from the
+        /// [`Parse`] trait) for syntactic positions in which expression
+        /// boundaries are placed more eagerly than done by the typical
+        /// expression grammar. This includes expressions at the head of a
+        /// statement or in the right-hand side of a `match` arm.
+        ///
+        /// Compare the following cases:
+        ///
+        /// 1.
+        ///   ```
+        ///   # let result = ();
+        ///   # let guard = false;
+        ///   # let cond = true;
+        ///   # let f = true;
+        ///   # let g = f;
+        ///   #
+        ///   let _ = match result {
+        ///       () if guard => if cond { f } else { g }
+        ///       () => false,
+        ///   };
+        ///   ```
+        ///
+        /// 2.
+        ///   ```
+        ///   # let cond = true;
+        ///   # let f = ();
+        ///   # let g = f;
+        ///   #
+        ///   let _ = || {
+        ///       if cond { f } else { g }
+        ///       ()
+        ///   };
+        ///   ```
+        ///
+        /// 3.
+        ///   ```
+        ///   # let cond = true;
+        ///   # let f = || ();
+        ///   # let g = f;
+        ///   #
+        ///   let _ = [if cond { f } else { g } ()];
+        ///   ```
+        ///
+        /// The same sequence of tokens `if cond { f } else { g } ()` appears in
+        /// expression position 3 times. The first two syntactic positions use
+        /// eager placement of expression boundaries, and parse as `Expr::If`,
+        /// with the adjacent `()` becoming `Pat::Tuple` or `Expr::Tuple`. In
+        /// contrast, the third case uses standard expression boundaries and
+        /// parses as `Expr::Call`.
+        ///
+        /// As with [`parse_without_eager_brace`], this ambiguity in the Rust
+        /// grammar is independent of precedence.
+        ///
+        /// [`parse_without_eager_brace`]: Self::parse_without_eager_brace
+        #[cfg(feature = "full")]
+        #[cfg_attr(doc_cfg, doc(cfg(all(feature = "full", feature = "parsing"))))]
+        pub fn parse_with_earlier_boundary_rule(input: ParseStream) -> Result<Expr> {
+            let mut attrs = input.call(expr_attrs)?;
+            let mut expr = if input.peek(token::Group) {
+                let allow_struct = AllowStruct(true);
+                let atom = expr_group(input, allow_struct)?;
+                if continue_parsing_early(&atom) {
+                    trailer_helper(input, atom)?
+                } else {
+                    atom
+                }
+            } else if input.peek(Token![if]) {
+                Expr::If(input.parse()?)
+            } else if input.peek(Token![while]) {
+                Expr::While(input.parse()?)
+            } else if input.peek(Token![for])
+                && !(input.peek2(Token![<]) && (input.peek3(Lifetime) || input.peek3(Token![>])))
+            {
+                Expr::ForLoop(input.parse()?)
+            } else if input.peek(Token![loop]) {
+                Expr::Loop(input.parse()?)
+            } else if input.peek(Token![match]) {
+                Expr::Match(input.parse()?)
+            } else if input.peek(Token![try]) && input.peek2(token::Brace) {
+                Expr::TryBlock(input.parse()?)
+            } else if input.peek(Token![unsafe]) {
+                Expr::Unsafe(input.parse()?)
+            } else if input.peek(Token![const]) && input.peek2(token::Brace) {
+                Expr::Const(input.parse()?)
+            } else if input.peek(token::Brace) {
+                Expr::Block(input.parse()?)
+            } else if input.peek(Lifetime) {
+                atom_labeled(input)?
+            } else {
+                let allow_struct = AllowStruct(true);
+                unary_expr(input, allow_struct)?
+            };
+
+            if continue_parsing_early(&expr) {
+                attrs.extend(expr.replace_attrs(Vec::new()));
+                expr.replace_attrs(attrs);
+
+                let allow_struct = AllowStruct(true);
+                return parse_expr(input, expr, allow_struct, Precedence::Any);
+            }
+
+            if input.peek(Token![.]) && !input.peek(Token![..]) || input.peek(Token![?]) {
+                expr = trailer_helper(input, expr)?;
+
+                attrs.extend(expr.replace_attrs(Vec::new()));
+                expr.replace_attrs(attrs);
+
+                let allow_struct = AllowStruct(true);
+                return parse_expr(input, expr, allow_struct, Precedence::Any);
+            }
+
+            attrs.extend(expr.replace_attrs(Vec::new()));
+            expr.replace_attrs(attrs);
+            Ok(expr)
+        }
+    }
+
+    #[cfg(feature = "full")]
+    impl Copy for AllowStruct {}
+
+    #[cfg(feature = "full")]
+    impl Clone for AllowStruct {
+        fn clone(&self) -> Self {
+            *self
+        }
+    }
+
+    impl Copy for Precedence {}
+
+    impl Clone for Precedence {
+        fn clone(&self) -> Self {
+            *self
+        }
+    }
+
+    impl PartialEq for Precedence {
+        fn eq(&self, other: &Self) -> bool {
+            *self as u8 == *other as u8
+        }
+    }
+
+    impl PartialOrd for Precedence {
+        fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+            let this = *self as u8;
+            let other = *other as u8;
+            Some(this.cmp(&other))
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn can_begin_expr(input: ParseStream) -> bool {
+        input.peek(Ident::peek_any) // value name or keyword
+            || input.peek(token::Paren) // tuple
+            || input.peek(token::Bracket) // array
+            || input.peek(token::Brace) // block
+            || input.peek(Lit) // literal
+            || input.peek(Token![!]) && !input.peek(Token![!=]) // operator not
+            || input.peek(Token![-]) && !input.peek(Token![-=]) && !input.peek(Token![->]) // unary minus
+            || input.peek(Token![*]) && !input.peek(Token![*=]) // dereference
+            || input.peek(Token![|]) && !input.peek(Token![|=]) // closure
+            || input.peek(Token![&]) && !input.peek(Token![&=]) // reference
+            || input.peek(Token![..]) // range notation
+            || input.peek(Token![<]) && !input.peek(Token![<=]) && !input.peek(Token![<<=]) // associated path
+            || input.peek(Token![::]) // global path
+            || input.peek(Lifetime) // labeled loop
+            || input.peek(Token![#]) // expression attributes
+    }
+
+    #[cfg(feature = "full")]
+    fn parse_expr(
+        input: ParseStream,
+        mut lhs: Expr,
+        allow_struct: AllowStruct,
+        base: Precedence,
+    ) -> Result<Expr> {
+        loop {
+            let ahead = input.fork();
+            if let Some(op) = match ahead.parse::<BinOp>() {
+                Ok(op) if Precedence::of(&op) >= base => Some(op),
+                _ => None,
+            } {
+                input.advance_to(&ahead);
+                let precedence = Precedence::of(&op);
+                let mut rhs = unary_expr(input, allow_struct)?;
+                loop {
+                    let next = peek_precedence(input);
+                    if next > precedence || next == precedence && precedence == Precedence::Assign {
+                        rhs = parse_expr(input, rhs, allow_struct, next)?;
+                    } else {
+                        break;
+                    }
+                }
+                lhs = Expr::Binary(ExprBinary {
+                    attrs: Vec::new(),
+                    left: Box::new(lhs),
+                    op,
+                    right: Box::new(rhs),
+                });
+            } else if Precedence::Assign >= base
+                && input.peek(Token![=])
+                && !input.peek(Token![==])
+                && !input.peek(Token![=>])
+            {
+                let eq_token: Token![=] = input.parse()?;
+                let mut rhs = unary_expr(input, allow_struct)?;
+                loop {
+                    let next = peek_precedence(input);
+                    if next >= Precedence::Assign {
+                        rhs = parse_expr(input, rhs, allow_struct, next)?;
+                    } else {
+                        break;
+                    }
+                }
+                lhs = Expr::Assign(ExprAssign {
+                    attrs: Vec::new(),
+                    left: Box::new(lhs),
+                    eq_token,
+                    right: Box::new(rhs),
+                });
+            } else if Precedence::Range >= base && input.peek(Token![..]) {
+                let limits: RangeLimits = input.parse()?;
+                let rhs = if matches!(limits, RangeLimits::HalfOpen(_))
+                    && (input.is_empty()
+                        || input.peek(Token![,])
+                        || input.peek(Token![;])
+                        || input.peek(Token![.]) && !input.peek(Token![..])
+                        || !allow_struct.0 && input.peek(token::Brace))
+                {
+                    None
+                } else {
+                    let mut rhs = unary_expr(input, allow_struct)?;
+                    loop {
+                        let next = peek_precedence(input);
+                        if next > Precedence::Range {
+                            rhs = parse_expr(input, rhs, allow_struct, next)?;
+                        } else {
+                            break;
+                        }
+                    }
+                    Some(rhs)
+                };
+                lhs = Expr::Range(ExprRange {
+                    attrs: Vec::new(),
+                    start: Some(Box::new(lhs)),
+                    limits,
+                    end: rhs.map(Box::new),
+                });
+            } else if Precedence::Cast >= base && input.peek(Token![as]) {
+                let as_token: Token![as] = input.parse()?;
+                let allow_plus = false;
+                let allow_group_generic = false;
+                let ty = ty::parsing::ambig_ty(input, allow_plus, allow_group_generic)?;
+                check_cast(input)?;
+                lhs = Expr::Cast(ExprCast {
+                    attrs: Vec::new(),
+                    expr: Box::new(lhs),
+                    as_token,
+                    ty: Box::new(ty),
+                });
+            } else {
+                break;
+            }
+        }
+        Ok(lhs)
+    }
+
+    #[cfg(not(feature = "full"))]
+    fn parse_expr(input: ParseStream, mut lhs: Expr, base: Precedence) -> Result<Expr> {
+        loop {
+            let ahead = input.fork();
+            if let Some(op) = match ahead.parse::<BinOp>() {
+                Ok(op) if Precedence::of(&op) >= base => Some(op),
+                _ => None,
+            } {
+                input.advance_to(&ahead);
+                let precedence = Precedence::of(&op);
+                let mut rhs = unary_expr(input)?;
+                loop {
+                    let next = peek_precedence(input);
+                    if next > precedence || next == precedence && precedence == Precedence::Assign {
+                        rhs = parse_expr(input, rhs, next)?;
+                    } else {
+                        break;
+                    }
+                }
+                lhs = Expr::Binary(ExprBinary {
+                    attrs: Vec::new(),
+                    left: Box::new(lhs),
+                    op,
+                    right: Box::new(rhs),
+                });
+            } else if Precedence::Cast >= base && input.peek(Token![as]) {
+                let as_token: Token![as] = input.parse()?;
+                let allow_plus = false;
+                let allow_group_generic = false;
+                let ty = ty::parsing::ambig_ty(input, allow_plus, allow_group_generic)?;
+                check_cast(input)?;
+                lhs = Expr::Cast(ExprCast {
+                    attrs: Vec::new(),
+                    expr: Box::new(lhs),
+                    as_token,
+                    ty: Box::new(ty),
+                });
+            } else {
+                break;
+            }
+        }
+        Ok(lhs)
+    }
+
+    fn peek_precedence(input: ParseStream) -> Precedence {
+        if let Ok(op) = input.fork().parse() {
+            Precedence::of(&op)
+        } else if input.peek(Token![=]) && !input.peek(Token![=>]) {
+            Precedence::Assign
+        } else if input.peek(Token![..]) {
+            Precedence::Range
+        } else if input.peek(Token![as]) {
+            Precedence::Cast
+        } else {
+            Precedence::Any
+        }
+    }
+
+    // Parse an arbitrary expression.
+    fn ambiguous_expr(
+        input: ParseStream,
+        #[cfg(feature = "full")] allow_struct: AllowStruct,
+    ) -> Result<Expr> {
+        let lhs = unary_expr(
+            input,
+            #[cfg(feature = "full")]
+            allow_struct,
+        )?;
+        parse_expr(
+            input,
+            lhs,
+            #[cfg(feature = "full")]
+            allow_struct,
+            Precedence::Any,
+        )
+    }
+
+    #[cfg(feature = "full")]
+    fn expr_attrs(input: ParseStream) -> Result<Vec<Attribute>> {
+        let mut attrs = Vec::new();
+        while !input.peek(token::Group) && input.peek(Token![#]) {
+            attrs.push(input.call(attr::parsing::single_parse_outer)?);
+        }
+        Ok(attrs)
+    }
+
+    // <UnOp> <trailer>
+    // & <trailer>
+    // &mut <trailer>
+    // box <trailer>
+    #[cfg(feature = "full")]
+    fn unary_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> {
+        let begin = input.fork();
+        let attrs = input.call(expr_attrs)?;
+        if input.peek(token::Group) {
+            return trailer_expr(begin, attrs, input, allow_struct);
+        }
+
+        if input.peek(Token![&]) {
+            let and_token: Token![&] = input.parse()?;
+            let raw: Option<kw::raw> = if input.peek(kw::raw)
+                && (input.peek2(Token![mut]) || input.peek2(Token![const]))
+            {
+                Some(input.parse()?)
+            } else {
+                None
+            };
+            let mutability: Option<Token![mut]> = input.parse()?;
+            if raw.is_some() && mutability.is_none() {
+                input.parse::<Token![const]>()?;
+            }
+            let expr = Box::new(unary_expr(input, allow_struct)?);
+            if raw.is_some() {
+                Ok(Expr::Verbatim(verbatim::between(&begin, input)))
+            } else {
+                Ok(Expr::Reference(ExprReference {
+                    attrs,
+                    and_token,
+                    mutability,
+                    expr,
+                }))
+            }
+        } else if input.peek(Token![*]) || input.peek(Token![!]) || input.peek(Token![-]) {
+            expr_unary(input, attrs, allow_struct).map(Expr::Unary)
+        } else {
+            trailer_expr(begin, attrs, input, allow_struct)
+        }
+    }
+
+    #[cfg(not(feature = "full"))]
+    fn unary_expr(input: ParseStream) -> Result<Expr> {
+        if input.peek(Token![&]) {
+            Ok(Expr::Reference(ExprReference {
+                attrs: Vec::new(),
+                and_token: input.parse()?,
+                mutability: input.parse()?,
+                expr: Box::new(unary_expr(input)?),
+            }))
+        } else if input.peek(Token![*]) || input.peek(Token![!]) || input.peek(Token![-]) {
+            Ok(Expr::Unary(ExprUnary {
+                attrs: Vec::new(),
+                op: input.parse()?,
+                expr: Box::new(unary_expr(input)?),
+            }))
+        } else {
+            trailer_expr(input)
+        }
+    }
+
+    // <atom> (..<args>) ...
+    // <atom> . <ident> (..<args>) ...
+    // <atom> . <ident> ...
+    // <atom> . <lit> ...
+    // <atom> [ <expr> ] ...
+    // <atom> ? ...
+    #[cfg(feature = "full")]
+    fn trailer_expr(
+        begin: ParseBuffer,
+        mut attrs: Vec<Attribute>,
+        input: ParseStream,
+        allow_struct: AllowStruct,
+    ) -> Result<Expr> {
+        let atom = atom_expr(input, allow_struct)?;
+        let mut e = trailer_helper(input, atom)?;
+
+        if let Expr::Verbatim(tokens) = &mut e {
+            *tokens = verbatim::between(&begin, input);
+        } else {
+            let inner_attrs = e.replace_attrs(Vec::new());
+            attrs.extend(inner_attrs);
+            e.replace_attrs(attrs);
+        }
+
+        Ok(e)
+    }
+
+    #[cfg(feature = "full")]
+    fn trailer_helper(input: ParseStream, mut e: Expr) -> Result<Expr> {
+        loop {
+            if input.peek(token::Paren) {
+                let content;
+                e = Expr::Call(ExprCall {
+                    attrs: Vec::new(),
+                    func: Box::new(e),
+                    paren_token: parenthesized!(content in input),
+                    args: content.parse_terminated(Expr::parse, Token![,])?,
+                });
+            } else if input.peek(Token![.])
+                && !input.peek(Token![..])
+                && match e {
+                    Expr::Range(_) => false,
+                    _ => true,
+                }
+            {
+                let mut dot_token: Token![.] = input.parse()?;
+
+                let float_token: Option<LitFloat> = input.parse()?;
+                if let Some(float_token) = float_token {
+                    if multi_index(&mut e, &mut dot_token, float_token)? {
+                        continue;
+                    }
+                }
+
+                let await_token: Option<Token![await]> = input.parse()?;
+                if let Some(await_token) = await_token {
+                    e = Expr::Await(ExprAwait {
+                        attrs: Vec::new(),
+                        base: Box::new(e),
+                        dot_token,
+                        await_token,
+                    });
+                    continue;
+                }
+
+                let member: Member = input.parse()?;
+                let turbofish = if member.is_named() && input.peek(Token![::]) {
+                    Some(AngleBracketedGenericArguments::parse_turbofish(input)?)
+                } else {
+                    None
+                };
+
+                if turbofish.is_some() || input.peek(token::Paren) {
+                    if let Member::Named(method) = member {
+                        let content;
+                        e = Expr::MethodCall(ExprMethodCall {
+                            attrs: Vec::new(),
+                            receiver: Box::new(e),
+                            dot_token,
+                            method,
+                            turbofish,
+                            paren_token: parenthesized!(content in input),
+                            args: content.parse_terminated(Expr::parse, Token![,])?,
+                        });
+                        continue;
+                    }
+                }
+
+                e = Expr::Field(ExprField {
+                    attrs: Vec::new(),
+                    base: Box::new(e),
+                    dot_token,
+                    member,
+                });
+            } else if input.peek(token::Bracket) {
+                let content;
+                e = Expr::Index(ExprIndex {
+                    attrs: Vec::new(),
+                    expr: Box::new(e),
+                    bracket_token: bracketed!(content in input),
+                    index: content.parse()?,
+                });
+            } else if input.peek(Token![?]) {
+                e = Expr::Try(ExprTry {
+                    attrs: Vec::new(),
+                    expr: Box::new(e),
+                    question_token: input.parse()?,
+                });
+            } else {
+                break;
+            }
+        }
+        Ok(e)
+    }
+
+    #[cfg(not(feature = "full"))]
+    fn trailer_expr(input: ParseStream) -> Result<Expr> {
+        let mut e = atom_expr(input)?;
+
+        loop {
+            if input.peek(token::Paren) {
+                let content;
+                e = Expr::Call(ExprCall {
+                    attrs: Vec::new(),
+                    func: Box::new(e),
+                    paren_token: parenthesized!(content in input),
+                    args: content.parse_terminated(Expr::parse, Token![,])?,
+                });
+            } else if input.peek(Token![.])
+                && !input.peek(Token![..])
+                && !input.peek2(Token![await])
+            {
+                let mut dot_token: Token![.] = input.parse()?;
+
+                let float_token: Option<LitFloat> = input.parse()?;
+                if let Some(float_token) = float_token {
+                    if multi_index(&mut e, &mut dot_token, float_token)? {
+                        continue;
+                    }
+                }
+
+                let member: Member = input.parse()?;
+                let turbofish = if member.is_named() && input.peek(Token![::]) {
+                    let colon2_token: Token![::] = input.parse()?;
+                    let turbofish =
+                        AngleBracketedGenericArguments::do_parse(Some(colon2_token), input)?;
+                    Some(turbofish)
+                } else {
+                    None
+                };
+
+                if turbofish.is_some() || input.peek(token::Paren) {
+                    if let Member::Named(method) = member {
+                        let content;
+                        e = Expr::MethodCall(ExprMethodCall {
+                            attrs: Vec::new(),
+                            receiver: Box::new(e),
+                            dot_token,
+                            method,
+                            turbofish,
+                            paren_token: parenthesized!(content in input),
+                            args: content.parse_terminated(Expr::parse, Token![,])?,
+                        });
+                        continue;
+                    }
+                }
+
+                e = Expr::Field(ExprField {
+                    attrs: Vec::new(),
+                    base: Box::new(e),
+                    dot_token,
+                    member,
+                });
+            } else if input.peek(token::Bracket) {
+                let content;
+                e = Expr::Index(ExprIndex {
+                    attrs: Vec::new(),
+                    expr: Box::new(e),
+                    bracket_token: bracketed!(content in input),
+                    index: content.parse()?,
+                });
+            } else {
+                break;
+            }
+        }
+
+        Ok(e)
+    }
+
+    // Parse all atomic expressions which don't have to worry about precedence
+    // interactions, as they are fully contained.
+    #[cfg(feature = "full")]
+    fn atom_expr(input: ParseStream, allow_struct: AllowStruct) -> Result<Expr> {
+        if input.peek(token::Group) {
+            expr_group(input, allow_struct)
+        } else if input.peek(Lit) {
+            input.parse().map(Expr::Lit)
+        } else if input.peek(Token![async])
+            && (input.peek2(token::Brace) || input.peek2(Token![move]) && input.peek3(token::Brace))
+        {
+            input.parse().map(Expr::Async)
+        } else if input.peek(Token![try]) && input.peek2(token::Brace) {
+            input.parse().map(Expr::TryBlock)
+        } else if input.peek(Token![|])
+            || input.peek(Token![move])
+            || input.peek(Token![for])
+                && input.peek2(Token![<])
+                && (input.peek3(Lifetime) || input.peek3(Token![>]))
+            || input.peek(Token![const]) && !input.peek2(token::Brace)
+            || input.peek(Token![static])
+            || input.peek(Token![async]) && (input.peek2(Token![|]) || input.peek2(Token![move]))
+        {
+            expr_closure(input, allow_struct).map(Expr::Closure)
+        } else if input.peek(kw::builtin) && input.peek2(Token![#]) {
+            expr_builtin(input)
+        } else if input.peek(Ident)
+            || input.peek(Token![::])
+            || input.peek(Token![<])
+            || input.peek(Token![self])
+            || input.peek(Token![Self])
+            || input.peek(Token![super])
+            || input.peek(Token![crate])
+            || input.peek(Token![try]) && (input.peek2(Token![!]) || input.peek2(Token![::]))
+        {
+            path_or_macro_or_struct(input, allow_struct)
+        } else if input.peek(token::Paren) {
+            paren_or_tuple(input)
+        } else if input.peek(Token![break]) {
+            expr_break(input, allow_struct).map(Expr::Break)
+        } else if input.peek(Token![continue]) {
+            input.parse().map(Expr::Continue)
+        } else if input.peek(Token![return]) {
+            expr_return(input, allow_struct).map(Expr::Return)
+        } else if input.peek(token::Bracket) {
+            array_or_repeat(input)
+        } else if input.peek(Token![let]) {
+            input.parse().map(Expr::Let)
+        } else if input.peek(Token![if]) {
+            input.parse().map(Expr::If)
+        } else if input.peek(Token![while]) {
+            input.parse().map(Expr::While)
+        } else if input.peek(Token![for]) {
+            input.parse().map(Expr::ForLoop)
+        } else if input.peek(Token![loop]) {
+            input.parse().map(Expr::Loop)
+        } else if input.peek(Token![match]) {
+            input.parse().map(Expr::Match)
+        } else if input.peek(Token![yield]) {
+            input.parse().map(Expr::Yield)
+        } else if input.peek(Token![unsafe]) {
+            input.parse().map(Expr::Unsafe)
+        } else if input.peek(Token![const]) {
+            input.parse().map(Expr::Const)
+        } else if input.peek(token::Brace) {
+            input.parse().map(Expr::Block)
+        } else if input.peek(Token![..]) {
+            expr_range(input, allow_struct).map(Expr::Range)
+        } else if input.peek(Token![_]) {
+            input.parse().map(Expr::Infer)
+        } else if input.peek(Lifetime) {
+            atom_labeled(input)
+        } else {
+            Err(input.error("expected an expression"))
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn atom_labeled(input: ParseStream) -> Result<Expr> {
+        let the_label: Label = input.parse()?;
+        let mut expr = if input.peek(Token![while]) {
+            Expr::While(input.parse()?)
+        } else if input.peek(Token![for]) {
+            Expr::ForLoop(input.parse()?)
+        } else if input.peek(Token![loop]) {
+            Expr::Loop(input.parse()?)
+        } else if input.peek(token::Brace) {
+            Expr::Block(input.parse()?)
+        } else {
+            return Err(input.error("expected loop or block expression"));
+        };
+        match &mut expr {
+            Expr::While(ExprWhile { label, .. })
+            | Expr::ForLoop(ExprForLoop { label, .. })
+            | Expr::Loop(ExprLoop { label, .. })
+            | Expr::Block(ExprBlock { label, .. }) => *label = Some(the_label),
+            _ => unreachable!(),
+        }
+        Ok(expr)
+    }
+
+    #[cfg(not(feature = "full"))]
+    fn atom_expr(input: ParseStream) -> Result<Expr> {
+        if input.peek(token::Group) {
+            expr_group(input)
+        } else if input.peek(Lit) {
+            input.parse().map(Expr::Lit)
+        } else if input.peek(token::Paren) {
+            input.call(expr_paren).map(Expr::Paren)
+        } else if input.peek(Ident)
+            || input.peek(Token![::])
+            || input.peek(Token![<])
+            || input.peek(Token![self])
+            || input.peek(Token![Self])
+            || input.peek(Token![super])
+            || input.peek(Token![crate])
+        {
+            path_or_macro_or_struct(input)
+        } else if input.is_empty() {
+            Err(input.error("expected an expression"))
+        } else {
+            if input.peek(token::Brace) {
+                let scan = input.fork();
+                let content;
+                braced!(content in scan);
+                if content.parse::<Expr>().is_ok() && content.is_empty() {
+                    let expr_block = verbatim::between(input, &scan);
+                    input.advance_to(&scan);
+                    return Ok(Expr::Verbatim(expr_block));
+                }
+            }
+            Err(input.error("unsupported expression; enable syn's features=[\"full\"]"))
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn expr_builtin(input: ParseStream) -> Result<Expr> {
+        let begin = input.fork();
+
+        input.parse::<kw::builtin>()?;
+        input.parse::<Token![#]>()?;
+        input.parse::<Ident>()?;
+
+        let args;
+        parenthesized!(args in input);
+        args.parse::<TokenStream>()?;
+
+        Ok(Expr::Verbatim(verbatim::between(&begin, input)))
+    }
+
+    fn path_or_macro_or_struct(
+        input: ParseStream,
+        #[cfg(feature = "full")] allow_struct: AllowStruct,
+    ) -> Result<Expr> {
+        let (qself, path) = path::parsing::qpath(input, true)?;
+        rest_of_path_or_macro_or_struct(
+            qself,
+            path,
+            input,
+            #[cfg(feature = "full")]
+            allow_struct,
+        )
+    }
+
+    fn rest_of_path_or_macro_or_struct(
+        qself: Option<QSelf>,
+        path: Path,
+        input: ParseStream,
+        #[cfg(feature = "full")] allow_struct: AllowStruct,
+    ) -> Result<Expr> {
+        if qself.is_none()
+            && input.peek(Token![!])
+            && !input.peek(Token![!=])
+            && path.is_mod_style()
+        {
+            let bang_token: Token![!] = input.parse()?;
+            let (delimiter, tokens) = mac::parse_delimiter(input)?;
+            return Ok(Expr::Macro(ExprMacro {
+                attrs: Vec::new(),
+                mac: Macro {
+                    path,
+                    bang_token,
+                    delimiter,
+                    tokens,
+                },
+            }));
+        }
+
+        #[cfg(not(feature = "full"))]
+        let allow_struct = (true,);
+        if allow_struct.0 && input.peek(token::Brace) {
+            return expr_struct_helper(input, qself, path).map(Expr::Struct);
+        }
+
+        Ok(Expr::Path(ExprPath {
+            attrs: Vec::new(),
+            qself,
+            path,
+        }))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ExprMacro {
+                attrs: Vec::new(),
+                mac: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn paren_or_tuple(input: ParseStream) -> Result<Expr> {
+        let content;
+        let paren_token = parenthesized!(content in input);
+        if content.is_empty() {
+            return Ok(Expr::Tuple(ExprTuple {
+                attrs: Vec::new(),
+                paren_token,
+                elems: Punctuated::new(),
+            }));
+        }
+
+        let first: Expr = content.parse()?;
+        if content.is_empty() {
+            return Ok(Expr::Paren(ExprParen {
+                attrs: Vec::new(),
+                paren_token,
+                expr: Box::new(first),
+            }));
+        }
+
+        let mut elems = Punctuated::new();
+        elems.push_value(first);
+        while !content.is_empty() {
+            let punct = content.parse()?;
+            elems.push_punct(punct);
+            if content.is_empty() {
+                break;
+            }
+            let value = content.parse()?;
+            elems.push_value(value);
+        }
+        Ok(Expr::Tuple(ExprTuple {
+            attrs: Vec::new(),
+            paren_token,
+            elems,
+        }))
+    }
+
+    #[cfg(feature = "full")]
+    fn array_or_repeat(input: ParseStream) -> Result<Expr> {
+        let content;
+        let bracket_token = bracketed!(content in input);
+        if content.is_empty() {
+            return Ok(Expr::Array(ExprArray {
+                attrs: Vec::new(),
+                bracket_token,
+                elems: Punctuated::new(),
+            }));
+        }
+
+        let first: Expr = content.parse()?;
+        if content.is_empty() || content.peek(Token![,]) {
+            let mut elems = Punctuated::new();
+            elems.push_value(first);
+            while !content.is_empty() {
+                let punct = content.parse()?;
+                elems.push_punct(punct);
+                if content.is_empty() {
+                    break;
+                }
+                let value = content.parse()?;
+                elems.push_value(value);
+            }
+            Ok(Expr::Array(ExprArray {
+                attrs: Vec::new(),
+                bracket_token,
+                elems,
+            }))
+        } else if content.peek(Token![;]) {
+            let semi_token: Token![;] = content.parse()?;
+            let len: Expr = content.parse()?;
+            Ok(Expr::Repeat(ExprRepeat {
+                attrs: Vec::new(),
+                bracket_token,
+                expr: Box::new(first),
+                semi_token,
+                len: Box::new(len),
+            }))
+        } else {
+            Err(content.error("expected `,` or `;`"))
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprArray {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let content;
+            let bracket_token = bracketed!(content in input);
+            let mut elems = Punctuated::new();
+
+            while !content.is_empty() {
+                let first: Expr = content.parse()?;
+                elems.push_value(first);
+                if content.is_empty() {
+                    break;
+                }
+                let punct = content.parse()?;
+                elems.push_punct(punct);
+            }
+
+            Ok(ExprArray {
+                attrs: Vec::new(),
+                bracket_token,
+                elems,
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprRepeat {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let content;
+            Ok(ExprRepeat {
+                bracket_token: bracketed!(content in input),
+                attrs: Vec::new(),
+                expr: content.parse()?,
+                semi_token: content.parse()?,
+                len: content.parse()?,
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn continue_parsing_early(mut expr: &Expr) -> bool {
+        while let Expr::Group(group) = expr {
+            expr = &group.expr;
+        }
+        match expr {
+            Expr::If(_)
+            | Expr::While(_)
+            | Expr::ForLoop(_)
+            | Expr::Loop(_)
+            | Expr::Match(_)
+            | Expr::TryBlock(_)
+            | Expr::Unsafe(_)
+            | Expr::Const(_)
+            | Expr::Block(_) => false,
+            _ => true,
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprLit {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ExprLit {
+                attrs: Vec::new(),
+                lit: input.parse()?,
+            })
+        }
+    }
+
+    fn expr_group(
+        input: ParseStream,
+        #[cfg(feature = "full")] allow_struct: AllowStruct,
+    ) -> Result<Expr> {
+        let group = crate::group::parse_group(input)?;
+        let mut inner: Expr = group.content.parse()?;
+
+        match inner {
+            Expr::Path(mut expr) if expr.attrs.is_empty() => {
+                let grouped_len = expr.path.segments.len();
+                Path::parse_rest(input, &mut expr.path, true)?;
+                match rest_of_path_or_macro_or_struct(
+                    expr.qself,
+                    expr.path,
+                    input,
+                    #[cfg(feature = "full")]
+                    allow_struct,
+                )? {
+                    Expr::Path(expr) if expr.path.segments.len() == grouped_len => {
+                        inner = Expr::Path(expr);
+                    }
+                    extended => return Ok(extended),
+                }
+            }
+            _ => {}
+        }
+
+        Ok(Expr::Group(ExprGroup {
+            attrs: Vec::new(),
+            group_token: group.token,
+            expr: Box::new(inner),
+        }))
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprParen {
+        fn parse(input: ParseStream) -> Result<Self> {
+            expr_paren(input)
+        }
+    }
+
+    fn expr_paren(input: ParseStream) -> Result<ExprParen> {
+        let content;
+        Ok(ExprParen {
+            attrs: Vec::new(),
+            paren_token: parenthesized!(content in input),
+            expr: content.parse()?,
+        })
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprLet {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ExprLet {
+                attrs: Vec::new(),
+                let_token: input.parse()?,
+                pat: Box::new(Pat::parse_multi_with_leading_vert(input)?),
+                eq_token: input.parse()?,
+                expr: Box::new({
+                    let allow_struct = AllowStruct(false);
+                    let lhs = unary_expr(input, allow_struct)?;
+                    parse_expr(input, lhs, allow_struct, Precedence::Compare)?
+                }),
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprIf {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            Ok(ExprIf {
+                attrs,
+                if_token: input.parse()?,
+                cond: Box::new(input.call(Expr::parse_without_eager_brace)?),
+                then_branch: input.parse()?,
+                else_branch: {
+                    if input.peek(Token![else]) {
+                        Some(input.call(else_block)?)
+                    } else {
+                        None
+                    }
+                },
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn else_block(input: ParseStream) -> Result<(Token![else], Box<Expr>)> {
+        let else_token: Token![else] = input.parse()?;
+
+        let lookahead = input.lookahead1();
+        let else_branch = if lookahead.peek(Token![if]) {
+            input.parse().map(Expr::If)?
+        } else if lookahead.peek(token::Brace) {
+            Expr::Block(ExprBlock {
+                attrs: Vec::new(),
+                label: None,
+                block: input.parse()?,
+            })
+        } else {
+            return Err(lookahead.error());
+        };
+
+        Ok((else_token, Box::new(else_branch)))
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprInfer {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ExprInfer {
+                attrs: input.call(Attribute::parse_outer)?,
+                underscore_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprForLoop {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let label: Option<Label> = input.parse()?;
+            let for_token: Token![for] = input.parse()?;
+
+            let pat = Pat::parse_multi_with_leading_vert(input)?;
+
+            let in_token: Token![in] = input.parse()?;
+            let expr: Expr = input.call(Expr::parse_without_eager_brace)?;
+
+            let content;
+            let brace_token = braced!(content in input);
+            attr::parsing::parse_inner(&content, &mut attrs)?;
+            let stmts = content.call(Block::parse_within)?;
+
+            Ok(ExprForLoop {
+                attrs,
+                label,
+                for_token,
+                pat: Box::new(pat),
+                in_token,
+                expr: Box::new(expr),
+                body: Block { brace_token, stmts },
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprLoop {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let label: Option<Label> = input.parse()?;
+            let loop_token: Token![loop] = input.parse()?;
+
+            let content;
+            let brace_token = braced!(content in input);
+            attr::parsing::parse_inner(&content, &mut attrs)?;
+            let stmts = content.call(Block::parse_within)?;
+
+            Ok(ExprLoop {
+                attrs,
+                label,
+                loop_token,
+                body: Block { brace_token, stmts },
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprMatch {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let match_token: Token![match] = input.parse()?;
+            let expr = Expr::parse_without_eager_brace(input)?;
+
+            let content;
+            let brace_token = braced!(content in input);
+            attr::parsing::parse_inner(&content, &mut attrs)?;
+
+            let mut arms = Vec::new();
+            while !content.is_empty() {
+                arms.push(content.call(Arm::parse)?);
+            }
+
+            Ok(ExprMatch {
+                attrs,
+                match_token,
+                expr: Box::new(expr),
+                brace_token,
+                arms,
+            })
+        }
+    }
+
+    macro_rules! impl_by_parsing_expr {
+        (
+            $(
+                $expr_type:ty, $variant:ident, $msg:expr,
+            )*
+        ) => {
+            $(
+                #[cfg(all(feature = "full", feature = "printing"))]
+                #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+                impl Parse for $expr_type {
+                    fn parse(input: ParseStream) -> Result<Self> {
+                        let mut expr: Expr = input.parse()?;
+                        loop {
+                            match expr {
+                                Expr::$variant(inner) => return Ok(inner),
+                                Expr::Group(next) => expr = *next.expr,
+                                _ => return Err(Error::new_spanned(expr, $msg)),
+                            }
+                        }
+                    }
+                }
+            )*
+        };
+    }
+
+    impl_by_parsing_expr! {
+        ExprAssign, Assign, "expected assignment expression",
+        ExprAwait, Await, "expected await expression",
+        ExprBinary, Binary, "expected binary operation",
+        ExprCall, Call, "expected function call expression",
+        ExprCast, Cast, "expected cast expression",
+        ExprField, Field, "expected struct field access",
+        ExprIndex, Index, "expected indexing expression",
+        ExprMethodCall, MethodCall, "expected method call expression",
+        ExprRange, Range, "expected range expression",
+        ExprTry, Try, "expected try expression",
+        ExprTuple, Tuple, "expected tuple expression",
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprUnary {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = Vec::new();
+            let allow_struct = AllowStruct(true);
+            expr_unary(input, attrs, allow_struct)
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn expr_unary(
+        input: ParseStream,
+        attrs: Vec<Attribute>,
+        allow_struct: AllowStruct,
+    ) -> Result<ExprUnary> {
+        Ok(ExprUnary {
+            attrs,
+            op: input.parse()?,
+            expr: Box::new(unary_expr(input, allow_struct)?),
+        })
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprClosure {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_struct = AllowStruct(true);
+            expr_closure(input, allow_struct)
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprReference {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_struct = AllowStruct(true);
+            Ok(ExprReference {
+                attrs: Vec::new(),
+                and_token: input.parse()?,
+                mutability: input.parse()?,
+                expr: Box::new(unary_expr(input, allow_struct)?),
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprBreak {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_struct = AllowStruct(true);
+            expr_break(input, allow_struct)
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprReturn {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_struct = AllowStruct(true);
+            expr_return(input, allow_struct)
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprTryBlock {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ExprTryBlock {
+                attrs: Vec::new(),
+                try_token: input.parse()?,
+                block: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprYield {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ExprYield {
+                attrs: Vec::new(),
+                yield_token: input.parse()?,
+                expr: {
+                    if can_begin_expr(input) {
+                        Some(input.parse()?)
+                    } else {
+                        None
+                    }
+                },
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn expr_closure(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprClosure> {
+        let lifetimes: Option<BoundLifetimes> = input.parse()?;
+        let constness: Option<Token![const]> = input.parse()?;
+        let movability: Option<Token![static]> = input.parse()?;
+        let asyncness: Option<Token![async]> = input.parse()?;
+        let capture: Option<Token![move]> = input.parse()?;
+        let or1_token: Token![|] = input.parse()?;
+
+        let mut inputs = Punctuated::new();
+        loop {
+            if input.peek(Token![|]) {
+                break;
+            }
+            let value = closure_arg(input)?;
+            inputs.push_value(value);
+            if input.peek(Token![|]) {
+                break;
+            }
+            let punct: Token![,] = input.parse()?;
+            inputs.push_punct(punct);
+        }
+
+        let or2_token: Token![|] = input.parse()?;
+
+        let (output, body) = if input.peek(Token![->]) {
+            let arrow_token: Token![->] = input.parse()?;
+            let ty: Type = input.parse()?;
+            let body: Block = input.parse()?;
+            let output = ReturnType::Type(arrow_token, Box::new(ty));
+            let block = Expr::Block(ExprBlock {
+                attrs: Vec::new(),
+                label: None,
+                block: body,
+            });
+            (output, block)
+        } else {
+            let body = ambiguous_expr(input, allow_struct)?;
+            (ReturnType::Default, body)
+        };
+
+        Ok(ExprClosure {
+            attrs: Vec::new(),
+            lifetimes,
+            constness,
+            movability,
+            asyncness,
+            capture,
+            or1_token,
+            inputs,
+            or2_token,
+            output,
+            body: Box::new(body),
+        })
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprAsync {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ExprAsync {
+                attrs: Vec::new(),
+                async_token: input.parse()?,
+                capture: input.parse()?,
+                block: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn closure_arg(input: ParseStream) -> Result<Pat> {
+        let attrs = input.call(Attribute::parse_outer)?;
+        let mut pat = Pat::parse_single(input)?;
+
+        if input.peek(Token![:]) {
+            Ok(Pat::Type(PatType {
+                attrs,
+                pat: Box::new(pat),
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+            }))
+        } else {
+            match &mut pat {
+                Pat::Const(pat) => pat.attrs = attrs,
+                Pat::Ident(pat) => pat.attrs = attrs,
+                Pat::Lit(pat) => pat.attrs = attrs,
+                Pat::Macro(pat) => pat.attrs = attrs,
+                Pat::Or(pat) => pat.attrs = attrs,
+                Pat::Paren(pat) => pat.attrs = attrs,
+                Pat::Path(pat) => pat.attrs = attrs,
+                Pat::Range(pat) => pat.attrs = attrs,
+                Pat::Reference(pat) => pat.attrs = attrs,
+                Pat::Rest(pat) => pat.attrs = attrs,
+                Pat::Slice(pat) => pat.attrs = attrs,
+                Pat::Struct(pat) => pat.attrs = attrs,
+                Pat::Tuple(pat) => pat.attrs = attrs,
+                Pat::TupleStruct(pat) => pat.attrs = attrs,
+                Pat::Type(_) => unreachable!(),
+                Pat::Verbatim(_) => {}
+                Pat::Wild(pat) => pat.attrs = attrs,
+            }
+            Ok(pat)
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprWhile {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let label: Option<Label> = input.parse()?;
+            let while_token: Token![while] = input.parse()?;
+            let cond = Expr::parse_without_eager_brace(input)?;
+
+            let content;
+            let brace_token = braced!(content in input);
+            attr::parsing::parse_inner(&content, &mut attrs)?;
+            let stmts = content.call(Block::parse_within)?;
+
+            Ok(ExprWhile {
+                attrs,
+                label,
+                while_token,
+                cond: Box::new(cond),
+                body: Block { brace_token, stmts },
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprConst {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let const_token: Token![const] = input.parse()?;
+
+            let content;
+            let brace_token = braced!(content in input);
+            let inner_attrs = content.call(Attribute::parse_inner)?;
+            let stmts = content.call(Block::parse_within)?;
+
+            Ok(ExprConst {
+                attrs: inner_attrs,
+                const_token,
+                block: Block { brace_token, stmts },
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Label {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(Label {
+                name: input.parse()?,
+                colon_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Option<Label> {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Lifetime) {
+                input.parse().map(Some)
+            } else {
+                Ok(None)
+            }
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprContinue {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ExprContinue {
+                attrs: Vec::new(),
+                continue_token: input.parse()?,
+                label: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn expr_break(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprBreak> {
+        let break_token: Token![break] = input.parse()?;
+
+        let ahead = input.fork();
+        let label: Option<Lifetime> = ahead.parse()?;
+        if label.is_some() && ahead.peek(Token![:]) {
+            // Not allowed: `break 'label: loop {...}`
+            // Parentheses are required. `break ('label: loop {...})`
+            let _ = ambiguous_expr(input, allow_struct)?;
+            let start_span = label.unwrap().apostrophe;
+            let end_span = input.cursor().prev_span();
+            return Err(crate::error::new2(
+                start_span,
+                end_span,
+                "parentheses required",
+            ));
+        }
+
+        input.advance_to(&ahead);
+        let expr = if can_begin_expr(input) && (allow_struct.0 || !input.peek(token::Brace)) {
+            let expr = ambiguous_expr(input, allow_struct)?;
+            Some(Box::new(expr))
+        } else {
+            None
+        };
+
+        Ok(ExprBreak {
+            attrs: Vec::new(),
+            break_token,
+            label,
+            expr,
+        })
+    }
+
+    #[cfg(feature = "full")]
+    fn expr_return(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprReturn> {
+        Ok(ExprReturn {
+            attrs: Vec::new(),
+            return_token: input.parse()?,
+            expr: {
+                if can_begin_expr(input) {
+                    // NOTE: return is greedy and eats blocks after it even when in a
+                    // position where structs are not allowed, such as in if statement
+                    // conditions. For example:
+                    //
+                    // if return { println!("A") } {} // Prints "A"
+                    let expr = ambiguous_expr(input, allow_struct)?;
+                    Some(Box::new(expr))
+                } else {
+                    None
+                }
+            },
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for FieldValue {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let member: Member = input.parse()?;
+            let (colon_token, value) = if input.peek(Token![:]) || !member.is_named() {
+                let colon_token: Token![:] = input.parse()?;
+                let value: Expr = input.parse()?;
+                (Some(colon_token), value)
+            } else if let Member::Named(ident) = &member {
+                let value = Expr::Path(ExprPath {
+                    attrs: Vec::new(),
+                    qself: None,
+                    path: Path::from(ident.clone()),
+                });
+                (None, value)
+            } else {
+                unreachable!()
+            };
+
+            Ok(FieldValue {
+                attrs,
+                member,
+                colon_token,
+                expr: value,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprStruct {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let (qself, path) = path::parsing::qpath(input, true)?;
+            expr_struct_helper(input, qself, path)
+        }
+    }
+
+    fn expr_struct_helper(
+        input: ParseStream,
+        qself: Option<QSelf>,
+        path: Path,
+    ) -> Result<ExprStruct> {
+        let content;
+        let brace_token = braced!(content in input);
+
+        let mut fields = Punctuated::new();
+        while !content.is_empty() {
+            if content.peek(Token![..]) {
+                return Ok(ExprStruct {
+                    attrs: Vec::new(),
+                    qself,
+                    path,
+                    brace_token,
+                    fields,
+                    dot2_token: Some(content.parse()?),
+                    rest: if content.is_empty() {
+                        None
+                    } else {
+                        Some(Box::new(content.parse()?))
+                    },
+                });
+            }
+
+            fields.push(content.parse()?);
+            if content.is_empty() {
+                break;
+            }
+            let punct: Token![,] = content.parse()?;
+            fields.push_punct(punct);
+        }
+
+        Ok(ExprStruct {
+            attrs: Vec::new(),
+            qself,
+            path,
+            brace_token,
+            fields,
+            dot2_token: None,
+            rest: None,
+        })
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprUnsafe {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let unsafe_token: Token![unsafe] = input.parse()?;
+
+            let content;
+            let brace_token = braced!(content in input);
+            let inner_attrs = content.call(Attribute::parse_inner)?;
+            let stmts = content.call(Block::parse_within)?;
+
+            Ok(ExprUnsafe {
+                attrs: inner_attrs,
+                unsafe_token,
+                block: Block { brace_token, stmts },
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprBlock {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let label: Option<Label> = input.parse()?;
+
+            let content;
+            let brace_token = braced!(content in input);
+            attr::parsing::parse_inner(&content, &mut attrs)?;
+            let stmts = content.call(Block::parse_within)?;
+
+            Ok(ExprBlock {
+                attrs,
+                label,
+                block: Block { brace_token, stmts },
+            })
+        }
+    }
+
+    #[cfg(feature = "full")]
+    fn expr_range(input: ParseStream, allow_struct: AllowStruct) -> Result<ExprRange> {
+        let limits: RangeLimits = input.parse()?;
+        let end = if matches!(limits, RangeLimits::HalfOpen(_))
+            && (input.is_empty()
+                || input.peek(Token![,])
+                || input.peek(Token![;])
+                || input.peek(Token![.]) && !input.peek(Token![..])
+                || !allow_struct.0 && input.peek(token::Brace))
+        {
+            None
+        } else {
+            let to = ambiguous_expr(input, allow_struct)?;
+            Some(Box::new(to))
+        };
+        Ok(ExprRange {
+            attrs: Vec::new(),
+            start: None,
+            limits,
+            end,
+        })
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for RangeLimits {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let lookahead = input.lookahead1();
+            let dot_dot = lookahead.peek(Token![..]);
+            let dot_dot_eq = dot_dot && lookahead.peek(Token![..=]);
+            let dot_dot_dot = dot_dot && input.peek(Token![...]);
+            if dot_dot_eq {
+                input.parse().map(RangeLimits::Closed)
+            } else if dot_dot && !dot_dot_dot {
+                input.parse().map(RangeLimits::HalfOpen)
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+
+    #[cfg(feature = "full")]
+    impl RangeLimits {
+        pub(crate) fn parse_obsolete(input: ParseStream) -> Result<Self> {
+            let lookahead = input.lookahead1();
+            let dot_dot = lookahead.peek(Token![..]);
+            let dot_dot_eq = dot_dot && lookahead.peek(Token![..=]);
+            let dot_dot_dot = dot_dot && input.peek(Token![...]);
+            if dot_dot_eq {
+                input.parse().map(RangeLimits::Closed)
+            } else if dot_dot_dot {
+                let dot3: Token![...] = input.parse()?;
+                Ok(RangeLimits::Closed(Token![..=](dot3.spans)))
+            } else if dot_dot {
+                input.parse().map(RangeLimits::HalfOpen)
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ExprPath {
+        fn parse(input: ParseStream) -> Result<Self> {
+            #[cfg(not(feature = "full"))]
+            let attrs = Vec::new();
+            #[cfg(feature = "full")]
+            let attrs = input.call(Attribute::parse_outer)?;
+
+            let (qself, path) = path::parsing::qpath(input, true)?;
+
+            Ok(ExprPath { attrs, qself, path })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Member {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Ident) {
+                input.parse().map(Member::Named)
+            } else if input.peek(LitInt) {
+                input.parse().map(Member::Unnamed)
+            } else {
+                Err(input.error("expected identifier or integer"))
+            }
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Arm {
+        fn parse(input: ParseStream) -> Result<Arm> {
+            let requires_comma;
+            Ok(Arm {
+                attrs: input.call(Attribute::parse_outer)?,
+                pat: Pat::parse_multi_with_leading_vert(input)?,
+                guard: {
+                    if input.peek(Token![if]) {
+                        let if_token: Token![if] = input.parse()?;
+                        let guard: Expr = input.parse()?;
+                        Some((if_token, Box::new(guard)))
+                    } else {
+                        None
+                    }
+                },
+                fat_arrow_token: input.parse()?,
+                body: {
+                    let body = Expr::parse_with_earlier_boundary_rule(input)?;
+                    requires_comma = requires_terminator(&body);
+                    Box::new(body)
+                },
+                comma: {
+                    if requires_comma && !input.is_empty() {
+                        Some(input.parse()?)
+                    } else {
+                        input.parse()?
+                    }
+                },
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Index {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let lit: LitInt = input.parse()?;
+            if lit.suffix().is_empty() {
+                Ok(Index {
+                    index: lit
+                        .base10_digits()
+                        .parse()
+                        .map_err(|err| Error::new(lit.span(), err))?,
+                    span: lit.span(),
+                })
+            } else {
+                Err(Error::new(lit.span(), "expected unsuffixed integer"))
+            }
+        }
+    }
+
+    fn multi_index(e: &mut Expr, dot_token: &mut Token![.], float: LitFloat) -> Result<bool> {
+        let float_token = float.token();
+        let float_span = float_token.span();
+        let mut float_repr = float_token.to_string();
+        let trailing_dot = float_repr.ends_with('.');
+        if trailing_dot {
+            float_repr.truncate(float_repr.len() - 1);
+        }
+
+        let mut offset = 0;
+        for part in float_repr.split('.') {
+            let mut index: Index =
+                crate::parse_str(part).map_err(|err| Error::new(float_span, err))?;
+            let part_end = offset + part.len();
+            index.span = float_token.subspan(offset..part_end).unwrap_or(float_span);
+
+            let base = mem::replace(e, Expr::DUMMY);
+            *e = Expr::Field(ExprField {
+                attrs: Vec::new(),
+                base: Box::new(base),
+                dot_token: Token![.](dot_token.span),
+                member: Member::Unnamed(index),
+            });
+
+            let dot_span = float_token
+                .subspan(part_end..part_end + 1)
+                .unwrap_or(float_span);
+            *dot_token = Token![.](dot_span);
+            offset = part_end + 1;
+        }
+
+        Ok(!trailing_dot)
+    }
+
+    impl Member {
+        pub(crate) fn is_named(&self) -> bool {
+            match self {
+                Member::Named(_) => true,
+                Member::Unnamed(_) => false,
+            }
+        }
+    }
+
+    fn check_cast(input: ParseStream) -> Result<()> {
+        let kind = if input.peek(Token![.]) && !input.peek(Token![..]) {
+            if input.peek2(Token![await]) {
+                "`.await`"
+            } else if input.peek2(Ident) && (input.peek3(token::Paren) || input.peek3(Token![::])) {
+                "a method call"
+            } else {
+                "a field access"
+            }
+        } else if input.peek(Token![?]) {
+            "`?`"
+        } else if input.peek(token::Bracket) {
+            "indexing"
+        } else if input.peek(token::Paren) {
+            "a function call"
+        } else {
+            return Ok(());
+        };
+        let msg = format!("casts cannot be followed by {}", kind);
+        Err(input.error(msg))
+    }
+}
+
+#[cfg(feature = "printing")]
+pub(crate) mod printing {
+    use crate::attr::Attribute;
+    #[cfg(feature = "full")]
+    use crate::attr::FilterAttrs;
+    #[cfg(feature = "full")]
+    use crate::expr::{
+        requires_terminator, Arm, Expr, ExprArray, ExprAssign, ExprAsync, ExprAwait, ExprBlock,
+        ExprBreak, ExprClosure, ExprConst, ExprContinue, ExprForLoop, ExprIf, ExprInfer, ExprLet,
+        ExprLoop, ExprMatch, ExprRange, ExprRepeat, ExprReturn, ExprTry, ExprTryBlock, ExprTuple,
+        ExprUnsafe, ExprWhile, ExprYield, Label, RangeLimits,
+    };
+    use crate::expr::{
+        ExprBinary, ExprCall, ExprCast, ExprField, ExprGroup, ExprIndex, ExprLit, ExprMacro,
+        ExprMethodCall, ExprParen, ExprPath, ExprReference, ExprStruct, ExprUnary, FieldValue,
+        Index, Member,
+    };
+    use crate::path;
+    #[cfg(feature = "full")]
+    use crate::token;
+    use proc_macro2::{Literal, Span, TokenStream};
+    use quote::{ToTokens, TokenStreamExt};
+
+    // If the given expression is a bare `ExprStruct`, wraps it in parenthesis
+    // before appending it to `TokenStream`.
+    #[cfg(feature = "full")]
+    fn wrap_bare_struct(tokens: &mut TokenStream, e: &Expr) {
+        if let Expr::Struct(_) = *e {
+            token::Paren::default().surround(tokens, |tokens| {
+                e.to_tokens(tokens);
+            });
+        } else {
+            e.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    pub(crate) fn outer_attrs_to_tokens(attrs: &[Attribute], tokens: &mut TokenStream) {
+        tokens.append_all(attrs.outer());
+    }
+
+    #[cfg(feature = "full")]
+    fn inner_attrs_to_tokens(attrs: &[Attribute], tokens: &mut TokenStream) {
+        tokens.append_all(attrs.inner());
+    }
+
+    #[cfg(not(feature = "full"))]
+    pub(crate) fn outer_attrs_to_tokens(_attrs: &[Attribute], _tokens: &mut TokenStream) {}
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprArray {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.bracket_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprAssign {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.left.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.right.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprAsync {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.async_token.to_tokens(tokens);
+            self.capture.to_tokens(tokens);
+            self.block.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprAwait {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.base.to_tokens(tokens);
+            self.dot_token.to_tokens(tokens);
+            self.await_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprBinary {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.left.to_tokens(tokens);
+            self.op.to_tokens(tokens);
+            self.right.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprBlock {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.label.to_tokens(tokens);
+            self.block.brace_token.surround(tokens, |tokens| {
+                inner_attrs_to_tokens(&self.attrs, tokens);
+                tokens.append_all(&self.block.stmts);
+            });
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprBreak {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.break_token.to_tokens(tokens);
+            self.label.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprCall {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.func.to_tokens(tokens);
+            self.paren_token.surround(tokens, |tokens| {
+                self.args.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprCast {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.expr.to_tokens(tokens);
+            self.as_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprClosure {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.lifetimes.to_tokens(tokens);
+            self.constness.to_tokens(tokens);
+            self.movability.to_tokens(tokens);
+            self.asyncness.to_tokens(tokens);
+            self.capture.to_tokens(tokens);
+            self.or1_token.to_tokens(tokens);
+            self.inputs.to_tokens(tokens);
+            self.or2_token.to_tokens(tokens);
+            self.output.to_tokens(tokens);
+            self.body.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprConst {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.const_token.to_tokens(tokens);
+            self.block.brace_token.surround(tokens, |tokens| {
+                inner_attrs_to_tokens(&self.attrs, tokens);
+                tokens.append_all(&self.block.stmts);
+            });
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprContinue {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.continue_token.to_tokens(tokens);
+            self.label.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprField {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.base.to_tokens(tokens);
+            self.dot_token.to_tokens(tokens);
+            self.member.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprForLoop {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.label.to_tokens(tokens);
+            self.for_token.to_tokens(tokens);
+            self.pat.to_tokens(tokens);
+            self.in_token.to_tokens(tokens);
+            wrap_bare_struct(tokens, &self.expr);
+            self.body.brace_token.surround(tokens, |tokens| {
+                inner_attrs_to_tokens(&self.attrs, tokens);
+                tokens.append_all(&self.body.stmts);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprGroup {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.group_token.surround(tokens, |tokens| {
+                self.expr.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprIf {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.if_token.to_tokens(tokens);
+            wrap_bare_struct(tokens, &self.cond);
+            self.then_branch.to_tokens(tokens);
+            if let Some((else_token, else_)) = &self.else_branch {
+                else_token.to_tokens(tokens);
+                // If we are not one of the valid expressions to exist in an else
+                // clause, wrap ourselves in a block.
+                match **else_ {
+                    Expr::If(_) | Expr::Block(_) => else_.to_tokens(tokens),
+                    _ => token::Brace::default().surround(tokens, |tokens| else_.to_tokens(tokens)),
+                }
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprIndex {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.expr.to_tokens(tokens);
+            self.bracket_token.surround(tokens, |tokens| {
+                self.index.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprInfer {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.underscore_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprLet {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.let_token.to_tokens(tokens);
+            self.pat.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            wrap_bare_struct(tokens, &self.expr);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprLit {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.lit.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprLoop {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.label.to_tokens(tokens);
+            self.loop_token.to_tokens(tokens);
+            self.body.brace_token.surround(tokens, |tokens| {
+                inner_attrs_to_tokens(&self.attrs, tokens);
+                tokens.append_all(&self.body.stmts);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.mac.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprMatch {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.match_token.to_tokens(tokens);
+            wrap_bare_struct(tokens, &self.expr);
+            self.brace_token.surround(tokens, |tokens| {
+                inner_attrs_to_tokens(&self.attrs, tokens);
+                for (i, arm) in self.arms.iter().enumerate() {
+                    arm.to_tokens(tokens);
+                    // Ensure that we have a comma after a non-block arm, except
+                    // for the last one.
+                    let is_last = i == self.arms.len() - 1;
+                    if !is_last && requires_terminator(&arm.body) && arm.comma.is_none() {
+                        <Token![,]>::default().to_tokens(tokens);
+                    }
+                }
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprMethodCall {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.receiver.to_tokens(tokens);
+            self.dot_token.to_tokens(tokens);
+            self.method.to_tokens(tokens);
+            self.turbofish.to_tokens(tokens);
+            self.paren_token.surround(tokens, |tokens| {
+                self.args.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprParen {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.paren_token.surround(tokens, |tokens| {
+                self.expr.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprPath {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            path::printing::print_path(tokens, &self.qself, &self.path);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprRange {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.start.to_tokens(tokens);
+            self.limits.to_tokens(tokens);
+            self.end.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprReference {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.and_token.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprRepeat {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.bracket_token.surround(tokens, |tokens| {
+                self.expr.to_tokens(tokens);
+                self.semi_token.to_tokens(tokens);
+                self.len.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprReturn {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.return_token.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprStruct {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            path::printing::print_path(tokens, &self.qself, &self.path);
+            self.brace_token.surround(tokens, |tokens| {
+                self.fields.to_tokens(tokens);
+                if let Some(dot2_token) = &self.dot2_token {
+                    dot2_token.to_tokens(tokens);
+                } else if self.rest.is_some() {
+                    Token![..](Span::call_site()).to_tokens(tokens);
+                }
+                self.rest.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprTry {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.expr.to_tokens(tokens);
+            self.question_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprTryBlock {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.try_token.to_tokens(tokens);
+            self.block.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprTuple {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.paren_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+                // If we only have one argument, we need a trailing comma to
+                // distinguish ExprTuple from ExprParen.
+                if self.elems.len() == 1 && !self.elems.trailing_punct() {
+                    <Token![,]>::default().to_tokens(tokens);
+                }
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprUnary {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.op.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprUnsafe {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.unsafe_token.to_tokens(tokens);
+            self.block.brace_token.surround(tokens, |tokens| {
+                inner_attrs_to_tokens(&self.attrs, tokens);
+                tokens.append_all(&self.block.stmts);
+            });
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprWhile {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.label.to_tokens(tokens);
+            self.while_token.to_tokens(tokens);
+            wrap_bare_struct(tokens, &self.cond);
+            self.body.brace_token.surround(tokens, |tokens| {
+                inner_attrs_to_tokens(&self.attrs, tokens);
+                tokens.append_all(&self.body.stmts);
+            });
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ExprYield {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.yield_token.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Arm {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(&self.attrs);
+            self.pat.to_tokens(tokens);
+            if let Some((if_token, guard)) = &self.guard {
+                if_token.to_tokens(tokens);
+                guard.to_tokens(tokens);
+            }
+            self.fat_arrow_token.to_tokens(tokens);
+            self.body.to_tokens(tokens);
+            self.comma.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for FieldValue {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            outer_attrs_to_tokens(&self.attrs, tokens);
+            self.member.to_tokens(tokens);
+            if let Some(colon_token) = &self.colon_token {
+                colon_token.to_tokens(tokens);
+                self.expr.to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Index {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            let mut lit = Literal::i64_unsuffixed(i64::from(self.index));
+            lit.set_span(self.span);
+            tokens.append(lit);
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Label {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.name.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Member {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                Member::Named(ident) => ident.to_tokens(tokens),
+                Member::Unnamed(index) => index.to_tokens(tokens),
+            }
+        }
+    }
+
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for RangeLimits {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                RangeLimits::HalfOpen(t) => t.to_tokens(tokens),
+                RangeLimits::Closed(t) => t.to_tokens(tokens),
+            }
+        }
+    }
+}
diff --git a/rust/syn/ext.rs b/rust/syn/ext.rs
new file mode 100644
index 0000000000000000000000000000000000000000..a9be9af427874eb75b2e95e45c8c3000e4c5a793
--- /dev/null
+++ b/rust/syn/ext.rs
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! Extension traits to provide parsing methods on foreign types.
+
+use crate::buffer::Cursor;
+use crate::error::Result;
+use crate::parse::ParseStream;
+use crate::parse::Peek;
+use crate::sealed::lookahead;
+use crate::token::CustomToken;
+use proc_macro2::Ident;
+
+/// Additional methods for `Ident` not provided by proc-macro2 or libproc_macro.
+///
+/// This trait is sealed and cannot be implemented for types outside of Syn. It
+/// is implemented only for `proc_macro2::Ident`.
+pub trait IdentExt: Sized + private::Sealed {
+    /// Parses any identifier including keywords.
+    ///
+    /// This is useful when parsing macro input which allows Rust keywords as
+    /// identifiers.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{Error, Ident, Result, Token};
+    /// use syn::ext::IdentExt;
+    /// use syn::parse::ParseStream;
+    ///
+    /// mod kw {
+    ///     syn::custom_keyword!(name);
+    /// }
+    ///
+    /// // Parses input that looks like `name = NAME` where `NAME` can be
+    /// // any identifier.
+    /// //
+    /// // Examples:
+    /// //
+    /// //     name = anything
+    /// //     name = impl
+    /// fn parse_dsl(input: ParseStream) -> Result<Ident> {
+    ///     input.parse::<kw::name>()?;
+    ///     input.parse::<Token![=]>()?;
+    ///     let name = input.call(Ident::parse_any)?;
+    ///     Ok(name)
+    /// }
+    /// ```
+    fn parse_any(input: ParseStream) -> Result<Self>;
+
+    /// Peeks any identifier including keywords. Usage:
+    /// `input.peek(Ident::peek_any)`
+    ///
+    /// This is different from `input.peek(Ident)` which only returns true in
+    /// the case of an ident which is not a Rust keyword.
+    #[allow(non_upper_case_globals)]
+    const peek_any: private::PeekFn = private::PeekFn;
+
+    /// Strips the raw marker `r#`, if any, from the beginning of an ident.
+    ///
+    ///   - unraw(`x`) = `x`
+    ///   - unraw(`move`) = `move`
+    ///   - unraw(`r#move`) = `move`
+    ///
+    /// # Example
+    ///
+    /// In the case of interop with other languages like Python that have a
+    /// different set of keywords than Rust, we might come across macro input
+    /// that involves raw identifiers to refer to ordinary variables in the
+    /// other language with a name that happens to be a Rust keyword.
+    ///
+    /// The function below appends an identifier from the caller's input onto a
+    /// fixed prefix. Without using `unraw()`, this would tend to produce
+    /// invalid identifiers like `__pyo3_get_r#move`.
+    ///
+    /// ```
+    /// use proc_macro2::Span;
+    /// use syn::Ident;
+    /// use syn::ext::IdentExt;
+    ///
+    /// fn ident_for_getter(variable: &Ident) -> Ident {
+    ///     let getter = format!("__pyo3_get_{}", variable.unraw());
+    ///     Ident::new(&getter, Span::call_site())
+    /// }
+    /// ```
+    fn unraw(&self) -> Ident;
+}
+
+impl IdentExt for Ident {
+    fn parse_any(input: ParseStream) -> Result<Self> {
+        input.step(|cursor| match cursor.ident() {
+            Some((ident, rest)) => Ok((ident, rest)),
+            None => Err(cursor.error("expected ident")),
+        })
+    }
+
+    fn unraw(&self) -> Ident {
+        let string = self.to_string();
+        if let Some(string) = string.strip_prefix("r#") {
+            Ident::new(string, self.span())
+        } else {
+            self.clone()
+        }
+    }
+}
+
+impl Peek for private::PeekFn {
+    type Token = private::IdentAny;
+}
+
+impl CustomToken for private::IdentAny {
+    fn peek(cursor: Cursor) -> bool {
+        cursor.ident().is_some()
+    }
+
+    fn display() -> &'static str {
+        "identifier"
+    }
+}
+
+impl lookahead::Sealed for private::PeekFn {}
+
+mod private {
+    use proc_macro2::Ident;
+
+    pub trait Sealed {}
+
+    impl Sealed for Ident {}
+
+    pub struct PeekFn;
+    pub struct IdentAny;
+
+    impl Copy for PeekFn {}
+    impl Clone for PeekFn {
+        fn clone(&self) -> Self {
+            *self
+        }
+    }
+}
diff --git a/rust/syn/file.rs b/rust/syn/file.rs
new file mode 100644
index 0000000000000000000000000000000000000000..2bd452d68151527c1266fafee3798762fed8f710
--- /dev/null
+++ b/rust/syn/file.rs
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+use crate::item::Item;
+
+ast_struct! {
+    /// A complete file of Rust source code.
+    ///
+    /// Typically `File` objects are created with [`parse_file`].
+    ///
+    /// [`parse_file`]: crate::parse_file
+    ///
+    /// # Example
+    ///
+    /// Parse a Rust source file into a `syn::File` and print out a debug
+    /// representation of the syntax tree.
+    ///
+    /// ```
+    /// use std::env;
+    /// use std::fs::File;
+    /// use std::io::Read;
+    /// use std::process;
+    ///
+    /// fn main() {
+    /// # }
+    /// #
+    /// # fn fake_main() {
+    ///     let mut args = env::args();
+    ///     let _ = args.next(); // executable name
+    ///
+    ///     let filename = match (args.next(), args.next()) {
+    ///         (Some(filename), None) => filename,
+    ///         _ => {
+    ///             eprintln!("Usage: dump-syntax path/to/filename.rs");
+    ///             process::exit(1);
+    ///         }
+    ///     };
+    ///
+    ///     let mut file = File::open(&filename).expect("Unable to open file");
+    ///
+    ///     let mut src = String::new();
+    ///     file.read_to_string(&mut src).expect("Unable to read file");
+    ///
+    ///     let syntax = syn::parse_file(&src).expect("Unable to parse file");
+    ///
+    ///     // Debug impl is available if Syn is built with "extra-traits" feature.
+    ///     println!("{:#?}", syntax);
+    /// }
+    /// ```
+    ///
+    /// Running with its own source code as input, this program prints output
+    /// that begins with:
+    ///
+    /// ```text
+    /// File {
+    ///     shebang: None,
+    ///     attrs: [],
+    ///     items: [
+    ///         Use(
+    ///             ItemUse {
+    ///                 attrs: [],
+    ///                 vis: Inherited,
+    ///                 use_token: Use,
+    ///                 leading_colon: None,
+    ///                 tree: Path(
+    ///                     UsePath {
+    ///                         ident: Ident(
+    ///                             std,
+    ///                         ),
+    ///                         colon2_token: Colon2,
+    ///                         tree: Name(
+    ///                             UseName {
+    ///                                 ident: Ident(
+    ///                                     env,
+    ///                                 ),
+    ///                             },
+    ///                         ),
+    ///                     },
+    ///                 ),
+    ///                 semi_token: Semi,
+    ///             },
+    ///         ),
+    /// ...
+    /// ```
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct File {
+        pub shebang: Option<String>,
+        pub attrs: Vec<Attribute>,
+        pub items: Vec<Item>,
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::Attribute;
+    use crate::error::Result;
+    use crate::file::File;
+    use crate::parse::{Parse, ParseStream};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for File {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(File {
+                shebang: None,
+                attrs: input.call(Attribute::parse_inner)?,
+                items: {
+                    let mut items = Vec::new();
+                    while !input.is_empty() {
+                        items.push(input.parse()?);
+                    }
+                    items
+                },
+            })
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::attr::FilterAttrs;
+    use crate::file::File;
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for File {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.inner());
+            tokens.append_all(&self.items);
+        }
+    }
+}
diff --git a/rust/syn/gen/clone.rs b/rust/syn/gen/clone.rs
new file mode 100644
index 0000000000000000000000000000000000000000..1226668f3ae0fe2143111aca935ec82b49ebb568
--- /dev/null
+++ b/rust/syn/gen/clone.rs
@@ -0,0 +1,2210 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#![allow(clippy::clone_on_copy, clippy::expl_impl_clone_on_copy)]
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Abi {
+    fn clone(&self) -> Self {
+        crate::Abi {
+            extern_token: self.extern_token.clone(),
+            name: self.name.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::AngleBracketedGenericArguments {
+    fn clone(&self) -> Self {
+        crate::AngleBracketedGenericArguments {
+            colon2_token: self.colon2_token.clone(),
+            lt_token: self.lt_token.clone(),
+            args: self.args.clone(),
+            gt_token: self.gt_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Arm {
+    fn clone(&self) -> Self {
+        crate::Arm {
+            attrs: self.attrs.clone(),
+            pat: self.pat.clone(),
+            guard: self.guard.clone(),
+            fat_arrow_token: self.fat_arrow_token.clone(),
+            body: self.body.clone(),
+            comma: self.comma.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::AssocConst {
+    fn clone(&self) -> Self {
+        crate::AssocConst {
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            eq_token: self.eq_token.clone(),
+            value: self.value.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::AssocType {
+    fn clone(&self) -> Self {
+        crate::AssocType {
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            eq_token: self.eq_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Copy for crate::AttrStyle {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::AttrStyle {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Attribute {
+    fn clone(&self) -> Self {
+        crate::Attribute {
+            pound_token: self.pound_token.clone(),
+            style: self.style.clone(),
+            bracket_token: self.bracket_token.clone(),
+            meta: self.meta.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::BareFnArg {
+    fn clone(&self) -> Self {
+        crate::BareFnArg {
+            attrs: self.attrs.clone(),
+            name: self.name.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::BareVariadic {
+    fn clone(&self) -> Self {
+        crate::BareVariadic {
+            attrs: self.attrs.clone(),
+            name: self.name.clone(),
+            dots: self.dots.clone(),
+            comma: self.comma.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Copy for crate::BinOp {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::BinOp {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Block {
+    fn clone(&self) -> Self {
+        crate::Block {
+            brace_token: self.brace_token.clone(),
+            stmts: self.stmts.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::BoundLifetimes {
+    fn clone(&self) -> Self {
+        crate::BoundLifetimes {
+            for_token: self.for_token.clone(),
+            lt_token: self.lt_token.clone(),
+            lifetimes: self.lifetimes.clone(),
+            gt_token: self.gt_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ConstParam {
+    fn clone(&self) -> Self {
+        crate::ConstParam {
+            attrs: self.attrs.clone(),
+            const_token: self.const_token.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            eq_token: self.eq_token.clone(),
+            default: self.default.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Constraint {
+    fn clone(&self) -> Self {
+        crate::Constraint {
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Data {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Data::Struct(v0) => crate::Data::Struct(v0.clone()),
+            crate::Data::Enum(v0) => crate::Data::Enum(v0.clone()),
+            crate::Data::Union(v0) => crate::Data::Union(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::DataEnum {
+    fn clone(&self) -> Self {
+        crate::DataEnum {
+            enum_token: self.enum_token.clone(),
+            brace_token: self.brace_token.clone(),
+            variants: self.variants.clone(),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::DataStruct {
+    fn clone(&self) -> Self {
+        crate::DataStruct {
+            struct_token: self.struct_token.clone(),
+            fields: self.fields.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::DataUnion {
+    fn clone(&self) -> Self {
+        crate::DataUnion {
+            union_token: self.union_token.clone(),
+            fields: self.fields.clone(),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::DeriveInput {
+    fn clone(&self) -> Self {
+        crate::DeriveInput {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            data: self.data.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Expr {
+    fn clone(&self) -> Self {
+        match self {
+            #[cfg(feature = "full")]
+            crate::Expr::Array(v0) => crate::Expr::Array(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Assign(v0) => crate::Expr::Assign(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Async(v0) => crate::Expr::Async(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Await(v0) => crate::Expr::Await(v0.clone()),
+            crate::Expr::Binary(v0) => crate::Expr::Binary(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Block(v0) => crate::Expr::Block(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Break(v0) => crate::Expr::Break(v0.clone()),
+            crate::Expr::Call(v0) => crate::Expr::Call(v0.clone()),
+            crate::Expr::Cast(v0) => crate::Expr::Cast(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Closure(v0) => crate::Expr::Closure(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Const(v0) => crate::Expr::Const(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Continue(v0) => crate::Expr::Continue(v0.clone()),
+            crate::Expr::Field(v0) => crate::Expr::Field(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::ForLoop(v0) => crate::Expr::ForLoop(v0.clone()),
+            crate::Expr::Group(v0) => crate::Expr::Group(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::If(v0) => crate::Expr::If(v0.clone()),
+            crate::Expr::Index(v0) => crate::Expr::Index(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Infer(v0) => crate::Expr::Infer(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Let(v0) => crate::Expr::Let(v0.clone()),
+            crate::Expr::Lit(v0) => crate::Expr::Lit(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Loop(v0) => crate::Expr::Loop(v0.clone()),
+            crate::Expr::Macro(v0) => crate::Expr::Macro(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Match(v0) => crate::Expr::Match(v0.clone()),
+            crate::Expr::MethodCall(v0) => crate::Expr::MethodCall(v0.clone()),
+            crate::Expr::Paren(v0) => crate::Expr::Paren(v0.clone()),
+            crate::Expr::Path(v0) => crate::Expr::Path(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Range(v0) => crate::Expr::Range(v0.clone()),
+            crate::Expr::Reference(v0) => crate::Expr::Reference(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Repeat(v0) => crate::Expr::Repeat(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Return(v0) => crate::Expr::Return(v0.clone()),
+            crate::Expr::Struct(v0) => crate::Expr::Struct(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Try(v0) => crate::Expr::Try(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::TryBlock(v0) => crate::Expr::TryBlock(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Tuple(v0) => crate::Expr::Tuple(v0.clone()),
+            crate::Expr::Unary(v0) => crate::Expr::Unary(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Unsafe(v0) => crate::Expr::Unsafe(v0.clone()),
+            crate::Expr::Verbatim(v0) => crate::Expr::Verbatim(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::While(v0) => crate::Expr::While(v0.clone()),
+            #[cfg(feature = "full")]
+            crate::Expr::Yield(v0) => crate::Expr::Yield(v0.clone()),
+            #[cfg(not(feature = "full"))]
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprArray {
+    fn clone(&self) -> Self {
+        crate::ExprArray {
+            attrs: self.attrs.clone(),
+            bracket_token: self.bracket_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprAssign {
+    fn clone(&self) -> Self {
+        crate::ExprAssign {
+            attrs: self.attrs.clone(),
+            left: self.left.clone(),
+            eq_token: self.eq_token.clone(),
+            right: self.right.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprAsync {
+    fn clone(&self) -> Self {
+        crate::ExprAsync {
+            attrs: self.attrs.clone(),
+            async_token: self.async_token.clone(),
+            capture: self.capture.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprAwait {
+    fn clone(&self) -> Self {
+        crate::ExprAwait {
+            attrs: self.attrs.clone(),
+            base: self.base.clone(),
+            dot_token: self.dot_token.clone(),
+            await_token: self.await_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprBinary {
+    fn clone(&self) -> Self {
+        crate::ExprBinary {
+            attrs: self.attrs.clone(),
+            left: self.left.clone(),
+            op: self.op.clone(),
+            right: self.right.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprBlock {
+    fn clone(&self) -> Self {
+        crate::ExprBlock {
+            attrs: self.attrs.clone(),
+            label: self.label.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprBreak {
+    fn clone(&self) -> Self {
+        crate::ExprBreak {
+            attrs: self.attrs.clone(),
+            break_token: self.break_token.clone(),
+            label: self.label.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprCall {
+    fn clone(&self) -> Self {
+        crate::ExprCall {
+            attrs: self.attrs.clone(),
+            func: self.func.clone(),
+            paren_token: self.paren_token.clone(),
+            args: self.args.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprCast {
+    fn clone(&self) -> Self {
+        crate::ExprCast {
+            attrs: self.attrs.clone(),
+            expr: self.expr.clone(),
+            as_token: self.as_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprClosure {
+    fn clone(&self) -> Self {
+        crate::ExprClosure {
+            attrs: self.attrs.clone(),
+            lifetimes: self.lifetimes.clone(),
+            constness: self.constness.clone(),
+            movability: self.movability.clone(),
+            asyncness: self.asyncness.clone(),
+            capture: self.capture.clone(),
+            or1_token: self.or1_token.clone(),
+            inputs: self.inputs.clone(),
+            or2_token: self.or2_token.clone(),
+            output: self.output.clone(),
+            body: self.body.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprConst {
+    fn clone(&self) -> Self {
+        crate::ExprConst {
+            attrs: self.attrs.clone(),
+            const_token: self.const_token.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprContinue {
+    fn clone(&self) -> Self {
+        crate::ExprContinue {
+            attrs: self.attrs.clone(),
+            continue_token: self.continue_token.clone(),
+            label: self.label.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprField {
+    fn clone(&self) -> Self {
+        crate::ExprField {
+            attrs: self.attrs.clone(),
+            base: self.base.clone(),
+            dot_token: self.dot_token.clone(),
+            member: self.member.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprForLoop {
+    fn clone(&self) -> Self {
+        crate::ExprForLoop {
+            attrs: self.attrs.clone(),
+            label: self.label.clone(),
+            for_token: self.for_token.clone(),
+            pat: self.pat.clone(),
+            in_token: self.in_token.clone(),
+            expr: self.expr.clone(),
+            body: self.body.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprGroup {
+    fn clone(&self) -> Self {
+        crate::ExprGroup {
+            attrs: self.attrs.clone(),
+            group_token: self.group_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprIf {
+    fn clone(&self) -> Self {
+        crate::ExprIf {
+            attrs: self.attrs.clone(),
+            if_token: self.if_token.clone(),
+            cond: self.cond.clone(),
+            then_branch: self.then_branch.clone(),
+            else_branch: self.else_branch.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprIndex {
+    fn clone(&self) -> Self {
+        crate::ExprIndex {
+            attrs: self.attrs.clone(),
+            expr: self.expr.clone(),
+            bracket_token: self.bracket_token.clone(),
+            index: self.index.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprInfer {
+    fn clone(&self) -> Self {
+        crate::ExprInfer {
+            attrs: self.attrs.clone(),
+            underscore_token: self.underscore_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprLet {
+    fn clone(&self) -> Self {
+        crate::ExprLet {
+            attrs: self.attrs.clone(),
+            let_token: self.let_token.clone(),
+            pat: self.pat.clone(),
+            eq_token: self.eq_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprLit {
+    fn clone(&self) -> Self {
+        crate::ExprLit {
+            attrs: self.attrs.clone(),
+            lit: self.lit.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprLoop {
+    fn clone(&self) -> Self {
+        crate::ExprLoop {
+            attrs: self.attrs.clone(),
+            label: self.label.clone(),
+            loop_token: self.loop_token.clone(),
+            body: self.body.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprMacro {
+    fn clone(&self) -> Self {
+        crate::ExprMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprMatch {
+    fn clone(&self) -> Self {
+        crate::ExprMatch {
+            attrs: self.attrs.clone(),
+            match_token: self.match_token.clone(),
+            expr: self.expr.clone(),
+            brace_token: self.brace_token.clone(),
+            arms: self.arms.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprMethodCall {
+    fn clone(&self) -> Self {
+        crate::ExprMethodCall {
+            attrs: self.attrs.clone(),
+            receiver: self.receiver.clone(),
+            dot_token: self.dot_token.clone(),
+            method: self.method.clone(),
+            turbofish: self.turbofish.clone(),
+            paren_token: self.paren_token.clone(),
+            args: self.args.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprParen {
+    fn clone(&self) -> Self {
+        crate::ExprParen {
+            attrs: self.attrs.clone(),
+            paren_token: self.paren_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprPath {
+    fn clone(&self) -> Self {
+        crate::ExprPath {
+            attrs: self.attrs.clone(),
+            qself: self.qself.clone(),
+            path: self.path.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprRange {
+    fn clone(&self) -> Self {
+        crate::ExprRange {
+            attrs: self.attrs.clone(),
+            start: self.start.clone(),
+            limits: self.limits.clone(),
+            end: self.end.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprReference {
+    fn clone(&self) -> Self {
+        crate::ExprReference {
+            attrs: self.attrs.clone(),
+            and_token: self.and_token.clone(),
+            mutability: self.mutability.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprRepeat {
+    fn clone(&self) -> Self {
+        crate::ExprRepeat {
+            attrs: self.attrs.clone(),
+            bracket_token: self.bracket_token.clone(),
+            expr: self.expr.clone(),
+            semi_token: self.semi_token.clone(),
+            len: self.len.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprReturn {
+    fn clone(&self) -> Self {
+        crate::ExprReturn {
+            attrs: self.attrs.clone(),
+            return_token: self.return_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprStruct {
+    fn clone(&self) -> Self {
+        crate::ExprStruct {
+            attrs: self.attrs.clone(),
+            qself: self.qself.clone(),
+            path: self.path.clone(),
+            brace_token: self.brace_token.clone(),
+            fields: self.fields.clone(),
+            dot2_token: self.dot2_token.clone(),
+            rest: self.rest.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprTry {
+    fn clone(&self) -> Self {
+        crate::ExprTry {
+            attrs: self.attrs.clone(),
+            expr: self.expr.clone(),
+            question_token: self.question_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprTryBlock {
+    fn clone(&self) -> Self {
+        crate::ExprTryBlock {
+            attrs: self.attrs.clone(),
+            try_token: self.try_token.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprTuple {
+    fn clone(&self) -> Self {
+        crate::ExprTuple {
+            attrs: self.attrs.clone(),
+            paren_token: self.paren_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprUnary {
+    fn clone(&self) -> Self {
+        crate::ExprUnary {
+            attrs: self.attrs.clone(),
+            op: self.op.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprUnsafe {
+    fn clone(&self) -> Self {
+        crate::ExprUnsafe {
+            attrs: self.attrs.clone(),
+            unsafe_token: self.unsafe_token.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprWhile {
+    fn clone(&self) -> Self {
+        crate::ExprWhile {
+            attrs: self.attrs.clone(),
+            label: self.label.clone(),
+            while_token: self.while_token.clone(),
+            cond: self.cond.clone(),
+            body: self.body.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ExprYield {
+    fn clone(&self) -> Self {
+        crate::ExprYield {
+            attrs: self.attrs.clone(),
+            yield_token: self.yield_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Field {
+    fn clone(&self) -> Self {
+        crate::Field {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            mutability: self.mutability.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::FieldMutability {
+    fn clone(&self) -> Self {
+        match self {
+            crate::FieldMutability::None => crate::FieldMutability::None,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::FieldPat {
+    fn clone(&self) -> Self {
+        crate::FieldPat {
+            attrs: self.attrs.clone(),
+            member: self.member.clone(),
+            colon_token: self.colon_token.clone(),
+            pat: self.pat.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::FieldValue {
+    fn clone(&self) -> Self {
+        crate::FieldValue {
+            attrs: self.attrs.clone(),
+            member: self.member.clone(),
+            colon_token: self.colon_token.clone(),
+            expr: self.expr.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Fields {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Fields::Named(v0) => crate::Fields::Named(v0.clone()),
+            crate::Fields::Unnamed(v0) => crate::Fields::Unnamed(v0.clone()),
+            crate::Fields::Unit => crate::Fields::Unit,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::FieldsNamed {
+    fn clone(&self) -> Self {
+        crate::FieldsNamed {
+            brace_token: self.brace_token.clone(),
+            named: self.named.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::FieldsUnnamed {
+    fn clone(&self) -> Self {
+        crate::FieldsUnnamed {
+            paren_token: self.paren_token.clone(),
+            unnamed: self.unnamed.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::File {
+    fn clone(&self) -> Self {
+        crate::File {
+            shebang: self.shebang.clone(),
+            attrs: self.attrs.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::FnArg {
+    fn clone(&self) -> Self {
+        match self {
+            crate::FnArg::Receiver(v0) => crate::FnArg::Receiver(v0.clone()),
+            crate::FnArg::Typed(v0) => crate::FnArg::Typed(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ForeignItem {
+    fn clone(&self) -> Self {
+        match self {
+            crate::ForeignItem::Fn(v0) => crate::ForeignItem::Fn(v0.clone()),
+            crate::ForeignItem::Static(v0) => crate::ForeignItem::Static(v0.clone()),
+            crate::ForeignItem::Type(v0) => crate::ForeignItem::Type(v0.clone()),
+            crate::ForeignItem::Macro(v0) => crate::ForeignItem::Macro(v0.clone()),
+            crate::ForeignItem::Verbatim(v0) => crate::ForeignItem::Verbatim(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ForeignItemFn {
+    fn clone(&self) -> Self {
+        crate::ForeignItemFn {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            sig: self.sig.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ForeignItemMacro {
+    fn clone(&self) -> Self {
+        crate::ForeignItemMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ForeignItemStatic {
+    fn clone(&self) -> Self {
+        crate::ForeignItemStatic {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            static_token: self.static_token.clone(),
+            mutability: self.mutability.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ForeignItemType {
+    fn clone(&self) -> Self {
+        crate::ForeignItemType {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            type_token: self.type_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::GenericArgument {
+    fn clone(&self) -> Self {
+        match self {
+            crate::GenericArgument::Lifetime(v0) => {
+                crate::GenericArgument::Lifetime(v0.clone())
+            }
+            crate::GenericArgument::Type(v0) => crate::GenericArgument::Type(v0.clone()),
+            crate::GenericArgument::Const(v0) => {
+                crate::GenericArgument::Const(v0.clone())
+            }
+            crate::GenericArgument::AssocType(v0) => {
+                crate::GenericArgument::AssocType(v0.clone())
+            }
+            crate::GenericArgument::AssocConst(v0) => {
+                crate::GenericArgument::AssocConst(v0.clone())
+            }
+            crate::GenericArgument::Constraint(v0) => {
+                crate::GenericArgument::Constraint(v0.clone())
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::GenericParam {
+    fn clone(&self) -> Self {
+        match self {
+            crate::GenericParam::Lifetime(v0) => {
+                crate::GenericParam::Lifetime(v0.clone())
+            }
+            crate::GenericParam::Type(v0) => crate::GenericParam::Type(v0.clone()),
+            crate::GenericParam::Const(v0) => crate::GenericParam::Const(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Generics {
+    fn clone(&self) -> Self {
+        crate::Generics {
+            lt_token: self.lt_token.clone(),
+            params: self.params.clone(),
+            gt_token: self.gt_token.clone(),
+            where_clause: self.where_clause.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ImplItem {
+    fn clone(&self) -> Self {
+        match self {
+            crate::ImplItem::Const(v0) => crate::ImplItem::Const(v0.clone()),
+            crate::ImplItem::Fn(v0) => crate::ImplItem::Fn(v0.clone()),
+            crate::ImplItem::Type(v0) => crate::ImplItem::Type(v0.clone()),
+            crate::ImplItem::Macro(v0) => crate::ImplItem::Macro(v0.clone()),
+            crate::ImplItem::Verbatim(v0) => crate::ImplItem::Verbatim(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ImplItemConst {
+    fn clone(&self) -> Self {
+        crate::ImplItemConst {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            defaultness: self.defaultness.clone(),
+            const_token: self.const_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            eq_token: self.eq_token.clone(),
+            expr: self.expr.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ImplItemFn {
+    fn clone(&self) -> Self {
+        crate::ImplItemFn {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            defaultness: self.defaultness.clone(),
+            sig: self.sig.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ImplItemMacro {
+    fn clone(&self) -> Self {
+        crate::ImplItemMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ImplItemType {
+    fn clone(&self) -> Self {
+        crate::ImplItemType {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            defaultness: self.defaultness.clone(),
+            type_token: self.type_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            eq_token: self.eq_token.clone(),
+            ty: self.ty.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ImplRestriction {
+    fn clone(&self) -> Self {
+        match *self {}
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Index {
+    fn clone(&self) -> Self {
+        crate::Index {
+            index: self.index.clone(),
+            span: self.span.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Item {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Item::Const(v0) => crate::Item::Const(v0.clone()),
+            crate::Item::Enum(v0) => crate::Item::Enum(v0.clone()),
+            crate::Item::ExternCrate(v0) => crate::Item::ExternCrate(v0.clone()),
+            crate::Item::Fn(v0) => crate::Item::Fn(v0.clone()),
+            crate::Item::ForeignMod(v0) => crate::Item::ForeignMod(v0.clone()),
+            crate::Item::Impl(v0) => crate::Item::Impl(v0.clone()),
+            crate::Item::Macro(v0) => crate::Item::Macro(v0.clone()),
+            crate::Item::Mod(v0) => crate::Item::Mod(v0.clone()),
+            crate::Item::Static(v0) => crate::Item::Static(v0.clone()),
+            crate::Item::Struct(v0) => crate::Item::Struct(v0.clone()),
+            crate::Item::Trait(v0) => crate::Item::Trait(v0.clone()),
+            crate::Item::TraitAlias(v0) => crate::Item::TraitAlias(v0.clone()),
+            crate::Item::Type(v0) => crate::Item::Type(v0.clone()),
+            crate::Item::Union(v0) => crate::Item::Union(v0.clone()),
+            crate::Item::Use(v0) => crate::Item::Use(v0.clone()),
+            crate::Item::Verbatim(v0) => crate::Item::Verbatim(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemConst {
+    fn clone(&self) -> Self {
+        crate::ItemConst {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            const_token: self.const_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            eq_token: self.eq_token.clone(),
+            expr: self.expr.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemEnum {
+    fn clone(&self) -> Self {
+        crate::ItemEnum {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            enum_token: self.enum_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            brace_token: self.brace_token.clone(),
+            variants: self.variants.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemExternCrate {
+    fn clone(&self) -> Self {
+        crate::ItemExternCrate {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            extern_token: self.extern_token.clone(),
+            crate_token: self.crate_token.clone(),
+            ident: self.ident.clone(),
+            rename: self.rename.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemFn {
+    fn clone(&self) -> Self {
+        crate::ItemFn {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            sig: self.sig.clone(),
+            block: self.block.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemForeignMod {
+    fn clone(&self) -> Self {
+        crate::ItemForeignMod {
+            attrs: self.attrs.clone(),
+            unsafety: self.unsafety.clone(),
+            abi: self.abi.clone(),
+            brace_token: self.brace_token.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemImpl {
+    fn clone(&self) -> Self {
+        crate::ItemImpl {
+            attrs: self.attrs.clone(),
+            defaultness: self.defaultness.clone(),
+            unsafety: self.unsafety.clone(),
+            impl_token: self.impl_token.clone(),
+            generics: self.generics.clone(),
+            trait_: self.trait_.clone(),
+            self_ty: self.self_ty.clone(),
+            brace_token: self.brace_token.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemMacro {
+    fn clone(&self) -> Self {
+        crate::ItemMacro {
+            attrs: self.attrs.clone(),
+            ident: self.ident.clone(),
+            mac: self.mac.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemMod {
+    fn clone(&self) -> Self {
+        crate::ItemMod {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            unsafety: self.unsafety.clone(),
+            mod_token: self.mod_token.clone(),
+            ident: self.ident.clone(),
+            content: self.content.clone(),
+            semi: self.semi.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemStatic {
+    fn clone(&self) -> Self {
+        crate::ItemStatic {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            static_token: self.static_token.clone(),
+            mutability: self.mutability.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            eq_token: self.eq_token.clone(),
+            expr: self.expr.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemStruct {
+    fn clone(&self) -> Self {
+        crate::ItemStruct {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            struct_token: self.struct_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            fields: self.fields.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemTrait {
+    fn clone(&self) -> Self {
+        crate::ItemTrait {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            unsafety: self.unsafety.clone(),
+            auto_token: self.auto_token.clone(),
+            restriction: self.restriction.clone(),
+            trait_token: self.trait_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            colon_token: self.colon_token.clone(),
+            supertraits: self.supertraits.clone(),
+            brace_token: self.brace_token.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemTraitAlias {
+    fn clone(&self) -> Self {
+        crate::ItemTraitAlias {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            trait_token: self.trait_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            eq_token: self.eq_token.clone(),
+            bounds: self.bounds.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemType {
+    fn clone(&self) -> Self {
+        crate::ItemType {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            type_token: self.type_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            eq_token: self.eq_token.clone(),
+            ty: self.ty.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemUnion {
+    fn clone(&self) -> Self {
+        crate::ItemUnion {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            union_token: self.union_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            fields: self.fields.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ItemUse {
+    fn clone(&self) -> Self {
+        crate::ItemUse {
+            attrs: self.attrs.clone(),
+            vis: self.vis.clone(),
+            use_token: self.use_token.clone(),
+            leading_colon: self.leading_colon.clone(),
+            tree: self.tree.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Label {
+    fn clone(&self) -> Self {
+        crate::Label {
+            name: self.name.clone(),
+            colon_token: self.colon_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::LifetimeParam {
+    fn clone(&self) -> Self {
+        crate::LifetimeParam {
+            attrs: self.attrs.clone(),
+            lifetime: self.lifetime.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Lit {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Lit::Str(v0) => crate::Lit::Str(v0.clone()),
+            crate::Lit::ByteStr(v0) => crate::Lit::ByteStr(v0.clone()),
+            crate::Lit::Byte(v0) => crate::Lit::Byte(v0.clone()),
+            crate::Lit::Char(v0) => crate::Lit::Char(v0.clone()),
+            crate::Lit::Int(v0) => crate::Lit::Int(v0.clone()),
+            crate::Lit::Float(v0) => crate::Lit::Float(v0.clone()),
+            crate::Lit::Bool(v0) => crate::Lit::Bool(v0.clone()),
+            crate::Lit::Verbatim(v0) => crate::Lit::Verbatim(v0.clone()),
+        }
+    }
+}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::LitBool {
+    fn clone(&self) -> Self {
+        crate::LitBool {
+            value: self.value.clone(),
+            span: self.span.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Local {
+    fn clone(&self) -> Self {
+        crate::Local {
+            attrs: self.attrs.clone(),
+            let_token: self.let_token.clone(),
+            pat: self.pat.clone(),
+            init: self.init.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::LocalInit {
+    fn clone(&self) -> Self {
+        crate::LocalInit {
+            eq_token: self.eq_token.clone(),
+            expr: self.expr.clone(),
+            diverge: self.diverge.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Macro {
+    fn clone(&self) -> Self {
+        crate::Macro {
+            path: self.path.clone(),
+            bang_token: self.bang_token.clone(),
+            delimiter: self.delimiter.clone(),
+            tokens: self.tokens.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::MacroDelimiter {
+    fn clone(&self) -> Self {
+        match self {
+            crate::MacroDelimiter::Paren(v0) => crate::MacroDelimiter::Paren(v0.clone()),
+            crate::MacroDelimiter::Brace(v0) => crate::MacroDelimiter::Brace(v0.clone()),
+            crate::MacroDelimiter::Bracket(v0) => {
+                crate::MacroDelimiter::Bracket(v0.clone())
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Member {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Member::Named(v0) => crate::Member::Named(v0.clone()),
+            crate::Member::Unnamed(v0) => crate::Member::Unnamed(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Meta {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Meta::Path(v0) => crate::Meta::Path(v0.clone()),
+            crate::Meta::List(v0) => crate::Meta::List(v0.clone()),
+            crate::Meta::NameValue(v0) => crate::Meta::NameValue(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::MetaList {
+    fn clone(&self) -> Self {
+        crate::MetaList {
+            path: self.path.clone(),
+            delimiter: self.delimiter.clone(),
+            tokens: self.tokens.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::MetaNameValue {
+    fn clone(&self) -> Self {
+        crate::MetaNameValue {
+            path: self.path.clone(),
+            eq_token: self.eq_token.clone(),
+            value: self.value.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ParenthesizedGenericArguments {
+    fn clone(&self) -> Self {
+        crate::ParenthesizedGenericArguments {
+            paren_token: self.paren_token.clone(),
+            inputs: self.inputs.clone(),
+            output: self.output.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Pat {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Pat::Const(v0) => crate::Pat::Const(v0.clone()),
+            crate::Pat::Ident(v0) => crate::Pat::Ident(v0.clone()),
+            crate::Pat::Lit(v0) => crate::Pat::Lit(v0.clone()),
+            crate::Pat::Macro(v0) => crate::Pat::Macro(v0.clone()),
+            crate::Pat::Or(v0) => crate::Pat::Or(v0.clone()),
+            crate::Pat::Paren(v0) => crate::Pat::Paren(v0.clone()),
+            crate::Pat::Path(v0) => crate::Pat::Path(v0.clone()),
+            crate::Pat::Range(v0) => crate::Pat::Range(v0.clone()),
+            crate::Pat::Reference(v0) => crate::Pat::Reference(v0.clone()),
+            crate::Pat::Rest(v0) => crate::Pat::Rest(v0.clone()),
+            crate::Pat::Slice(v0) => crate::Pat::Slice(v0.clone()),
+            crate::Pat::Struct(v0) => crate::Pat::Struct(v0.clone()),
+            crate::Pat::Tuple(v0) => crate::Pat::Tuple(v0.clone()),
+            crate::Pat::TupleStruct(v0) => crate::Pat::TupleStruct(v0.clone()),
+            crate::Pat::Type(v0) => crate::Pat::Type(v0.clone()),
+            crate::Pat::Verbatim(v0) => crate::Pat::Verbatim(v0.clone()),
+            crate::Pat::Wild(v0) => crate::Pat::Wild(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatIdent {
+    fn clone(&self) -> Self {
+        crate::PatIdent {
+            attrs: self.attrs.clone(),
+            by_ref: self.by_ref.clone(),
+            mutability: self.mutability.clone(),
+            ident: self.ident.clone(),
+            subpat: self.subpat.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatOr {
+    fn clone(&self) -> Self {
+        crate::PatOr {
+            attrs: self.attrs.clone(),
+            leading_vert: self.leading_vert.clone(),
+            cases: self.cases.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatParen {
+    fn clone(&self) -> Self {
+        crate::PatParen {
+            attrs: self.attrs.clone(),
+            paren_token: self.paren_token.clone(),
+            pat: self.pat.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatReference {
+    fn clone(&self) -> Self {
+        crate::PatReference {
+            attrs: self.attrs.clone(),
+            and_token: self.and_token.clone(),
+            mutability: self.mutability.clone(),
+            pat: self.pat.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatRest {
+    fn clone(&self) -> Self {
+        crate::PatRest {
+            attrs: self.attrs.clone(),
+            dot2_token: self.dot2_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatSlice {
+    fn clone(&self) -> Self {
+        crate::PatSlice {
+            attrs: self.attrs.clone(),
+            bracket_token: self.bracket_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatStruct {
+    fn clone(&self) -> Self {
+        crate::PatStruct {
+            attrs: self.attrs.clone(),
+            qself: self.qself.clone(),
+            path: self.path.clone(),
+            brace_token: self.brace_token.clone(),
+            fields: self.fields.clone(),
+            rest: self.rest.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatTuple {
+    fn clone(&self) -> Self {
+        crate::PatTuple {
+            attrs: self.attrs.clone(),
+            paren_token: self.paren_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatTupleStruct {
+    fn clone(&self) -> Self {
+        crate::PatTupleStruct {
+            attrs: self.attrs.clone(),
+            qself: self.qself.clone(),
+            path: self.path.clone(),
+            paren_token: self.paren_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatType {
+    fn clone(&self) -> Self {
+        crate::PatType {
+            attrs: self.attrs.clone(),
+            pat: self.pat.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PatWild {
+    fn clone(&self) -> Self {
+        crate::PatWild {
+            attrs: self.attrs.clone(),
+            underscore_token: self.underscore_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Path {
+    fn clone(&self) -> Self {
+        crate::Path {
+            leading_colon: self.leading_colon.clone(),
+            segments: self.segments.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PathArguments {
+    fn clone(&self) -> Self {
+        match self {
+            crate::PathArguments::None => crate::PathArguments::None,
+            crate::PathArguments::AngleBracketed(v0) => {
+                crate::PathArguments::AngleBracketed(v0.clone())
+            }
+            crate::PathArguments::Parenthesized(v0) => {
+                crate::PathArguments::Parenthesized(v0.clone())
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PathSegment {
+    fn clone(&self) -> Self {
+        crate::PathSegment {
+            ident: self.ident.clone(),
+            arguments: self.arguments.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PredicateLifetime {
+    fn clone(&self) -> Self {
+        crate::PredicateLifetime {
+            lifetime: self.lifetime.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::PredicateType {
+    fn clone(&self) -> Self {
+        crate::PredicateType {
+            lifetimes: self.lifetimes.clone(),
+            bounded_ty: self.bounded_ty.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::QSelf {
+    fn clone(&self) -> Self {
+        crate::QSelf {
+            lt_token: self.lt_token.clone(),
+            ty: self.ty.clone(),
+            position: self.position.clone(),
+            as_token: self.as_token.clone(),
+            gt_token: self.gt_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Copy for crate::RangeLimits {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::RangeLimits {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Receiver {
+    fn clone(&self) -> Self {
+        crate::Receiver {
+            attrs: self.attrs.clone(),
+            reference: self.reference.clone(),
+            mutability: self.mutability.clone(),
+            self_token: self.self_token.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::ReturnType {
+    fn clone(&self) -> Self {
+        match self {
+            crate::ReturnType::Default => crate::ReturnType::Default,
+            crate::ReturnType::Type(v0, v1) => {
+                crate::ReturnType::Type(v0.clone(), v1.clone())
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Signature {
+    fn clone(&self) -> Self {
+        crate::Signature {
+            constness: self.constness.clone(),
+            asyncness: self.asyncness.clone(),
+            unsafety: self.unsafety.clone(),
+            abi: self.abi.clone(),
+            fn_token: self.fn_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            paren_token: self.paren_token.clone(),
+            inputs: self.inputs.clone(),
+            variadic: self.variadic.clone(),
+            output: self.output.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::StaticMutability {
+    fn clone(&self) -> Self {
+        match self {
+            crate::StaticMutability::Mut(v0) => crate::StaticMutability::Mut(v0.clone()),
+            crate::StaticMutability::None => crate::StaticMutability::None,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Stmt {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Stmt::Local(v0) => crate::Stmt::Local(v0.clone()),
+            crate::Stmt::Item(v0) => crate::Stmt::Item(v0.clone()),
+            crate::Stmt::Expr(v0, v1) => crate::Stmt::Expr(v0.clone(), v1.clone()),
+            crate::Stmt::Macro(v0) => crate::Stmt::Macro(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::StmtMacro {
+    fn clone(&self) -> Self {
+        crate::StmtMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TraitBound {
+    fn clone(&self) -> Self {
+        crate::TraitBound {
+            paren_token: self.paren_token.clone(),
+            modifier: self.modifier.clone(),
+            lifetimes: self.lifetimes.clone(),
+            path: self.path.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Copy for crate::TraitBoundModifier {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TraitBoundModifier {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TraitItem {
+    fn clone(&self) -> Self {
+        match self {
+            crate::TraitItem::Const(v0) => crate::TraitItem::Const(v0.clone()),
+            crate::TraitItem::Fn(v0) => crate::TraitItem::Fn(v0.clone()),
+            crate::TraitItem::Type(v0) => crate::TraitItem::Type(v0.clone()),
+            crate::TraitItem::Macro(v0) => crate::TraitItem::Macro(v0.clone()),
+            crate::TraitItem::Verbatim(v0) => crate::TraitItem::Verbatim(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TraitItemConst {
+    fn clone(&self) -> Self {
+        crate::TraitItemConst {
+            attrs: self.attrs.clone(),
+            const_token: self.const_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            colon_token: self.colon_token.clone(),
+            ty: self.ty.clone(),
+            default: self.default.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TraitItemFn {
+    fn clone(&self) -> Self {
+        crate::TraitItemFn {
+            attrs: self.attrs.clone(),
+            sig: self.sig.clone(),
+            default: self.default.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TraitItemMacro {
+    fn clone(&self) -> Self {
+        crate::TraitItemMacro {
+            attrs: self.attrs.clone(),
+            mac: self.mac.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TraitItemType {
+    fn clone(&self) -> Self {
+        crate::TraitItemType {
+            attrs: self.attrs.clone(),
+            type_token: self.type_token.clone(),
+            ident: self.ident.clone(),
+            generics: self.generics.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+            default: self.default.clone(),
+            semi_token: self.semi_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Type {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Type::Array(v0) => crate::Type::Array(v0.clone()),
+            crate::Type::BareFn(v0) => crate::Type::BareFn(v0.clone()),
+            crate::Type::Group(v0) => crate::Type::Group(v0.clone()),
+            crate::Type::ImplTrait(v0) => crate::Type::ImplTrait(v0.clone()),
+            crate::Type::Infer(v0) => crate::Type::Infer(v0.clone()),
+            crate::Type::Macro(v0) => crate::Type::Macro(v0.clone()),
+            crate::Type::Never(v0) => crate::Type::Never(v0.clone()),
+            crate::Type::Paren(v0) => crate::Type::Paren(v0.clone()),
+            crate::Type::Path(v0) => crate::Type::Path(v0.clone()),
+            crate::Type::Ptr(v0) => crate::Type::Ptr(v0.clone()),
+            crate::Type::Reference(v0) => crate::Type::Reference(v0.clone()),
+            crate::Type::Slice(v0) => crate::Type::Slice(v0.clone()),
+            crate::Type::TraitObject(v0) => crate::Type::TraitObject(v0.clone()),
+            crate::Type::Tuple(v0) => crate::Type::Tuple(v0.clone()),
+            crate::Type::Verbatim(v0) => crate::Type::Verbatim(v0.clone()),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeArray {
+    fn clone(&self) -> Self {
+        crate::TypeArray {
+            bracket_token: self.bracket_token.clone(),
+            elem: self.elem.clone(),
+            semi_token: self.semi_token.clone(),
+            len: self.len.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeBareFn {
+    fn clone(&self) -> Self {
+        crate::TypeBareFn {
+            lifetimes: self.lifetimes.clone(),
+            unsafety: self.unsafety.clone(),
+            abi: self.abi.clone(),
+            fn_token: self.fn_token.clone(),
+            paren_token: self.paren_token.clone(),
+            inputs: self.inputs.clone(),
+            variadic: self.variadic.clone(),
+            output: self.output.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeGroup {
+    fn clone(&self) -> Self {
+        crate::TypeGroup {
+            group_token: self.group_token.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeImplTrait {
+    fn clone(&self) -> Self {
+        crate::TypeImplTrait {
+            impl_token: self.impl_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeInfer {
+    fn clone(&self) -> Self {
+        crate::TypeInfer {
+            underscore_token: self.underscore_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeMacro {
+    fn clone(&self) -> Self {
+        crate::TypeMacro {
+            mac: self.mac.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeNever {
+    fn clone(&self) -> Self {
+        crate::TypeNever {
+            bang_token: self.bang_token.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeParam {
+    fn clone(&self) -> Self {
+        crate::TypeParam {
+            attrs: self.attrs.clone(),
+            ident: self.ident.clone(),
+            colon_token: self.colon_token.clone(),
+            bounds: self.bounds.clone(),
+            eq_token: self.eq_token.clone(),
+            default: self.default.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeParamBound {
+    fn clone(&self) -> Self {
+        match self {
+            crate::TypeParamBound::Trait(v0) => crate::TypeParamBound::Trait(v0.clone()),
+            crate::TypeParamBound::Lifetime(v0) => {
+                crate::TypeParamBound::Lifetime(v0.clone())
+            }
+            crate::TypeParamBound::Verbatim(v0) => {
+                crate::TypeParamBound::Verbatim(v0.clone())
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeParen {
+    fn clone(&self) -> Self {
+        crate::TypeParen {
+            paren_token: self.paren_token.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypePath {
+    fn clone(&self) -> Self {
+        crate::TypePath {
+            qself: self.qself.clone(),
+            path: self.path.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypePtr {
+    fn clone(&self) -> Self {
+        crate::TypePtr {
+            star_token: self.star_token.clone(),
+            const_token: self.const_token.clone(),
+            mutability: self.mutability.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeReference {
+    fn clone(&self) -> Self {
+        crate::TypeReference {
+            and_token: self.and_token.clone(),
+            lifetime: self.lifetime.clone(),
+            mutability: self.mutability.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeSlice {
+    fn clone(&self) -> Self {
+        crate::TypeSlice {
+            bracket_token: self.bracket_token.clone(),
+            elem: self.elem.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeTraitObject {
+    fn clone(&self) -> Self {
+        crate::TypeTraitObject {
+            dyn_token: self.dyn_token.clone(),
+            bounds: self.bounds.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::TypeTuple {
+    fn clone(&self) -> Self {
+        crate::TypeTuple {
+            paren_token: self.paren_token.clone(),
+            elems: self.elems.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Copy for crate::UnOp {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::UnOp {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::UseGlob {
+    fn clone(&self) -> Self {
+        crate::UseGlob {
+            star_token: self.star_token.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::UseGroup {
+    fn clone(&self) -> Self {
+        crate::UseGroup {
+            brace_token: self.brace_token.clone(),
+            items: self.items.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::UseName {
+    fn clone(&self) -> Self {
+        crate::UseName {
+            ident: self.ident.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::UsePath {
+    fn clone(&self) -> Self {
+        crate::UsePath {
+            ident: self.ident.clone(),
+            colon2_token: self.colon2_token.clone(),
+            tree: self.tree.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::UseRename {
+    fn clone(&self) -> Self {
+        crate::UseRename {
+            ident: self.ident.clone(),
+            as_token: self.as_token.clone(),
+            rename: self.rename.clone(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::UseTree {
+    fn clone(&self) -> Self {
+        match self {
+            crate::UseTree::Path(v0) => crate::UseTree::Path(v0.clone()),
+            crate::UseTree::Name(v0) => crate::UseTree::Name(v0.clone()),
+            crate::UseTree::Rename(v0) => crate::UseTree::Rename(v0.clone()),
+            crate::UseTree::Glob(v0) => crate::UseTree::Glob(v0.clone()),
+            crate::UseTree::Group(v0) => crate::UseTree::Group(v0.clone()),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Variadic {
+    fn clone(&self) -> Self {
+        crate::Variadic {
+            attrs: self.attrs.clone(),
+            pat: self.pat.clone(),
+            dots: self.dots.clone(),
+            comma: self.comma.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Variant {
+    fn clone(&self) -> Self {
+        crate::Variant {
+            attrs: self.attrs.clone(),
+            ident: self.ident.clone(),
+            fields: self.fields.clone(),
+            discriminant: self.discriminant.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::VisRestricted {
+    fn clone(&self) -> Self {
+        crate::VisRestricted {
+            pub_token: self.pub_token.clone(),
+            paren_token: self.paren_token.clone(),
+            in_token: self.in_token.clone(),
+            path: self.path.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::Visibility {
+    fn clone(&self) -> Self {
+        match self {
+            crate::Visibility::Public(v0) => crate::Visibility::Public(v0.clone()),
+            crate::Visibility::Restricted(v0) => {
+                crate::Visibility::Restricted(v0.clone())
+            }
+            crate::Visibility::Inherited => crate::Visibility::Inherited,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::WhereClause {
+    fn clone(&self) -> Self {
+        crate::WhereClause {
+            where_token: self.where_token.clone(),
+            predicates: self.predicates.clone(),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for crate::WherePredicate {
+    fn clone(&self) -> Self {
+        match self {
+            crate::WherePredicate::Lifetime(v0) => {
+                crate::WherePredicate::Lifetime(v0.clone())
+            }
+            crate::WherePredicate::Type(v0) => crate::WherePredicate::Type(v0.clone()),
+        }
+    }
+}
diff --git a/rust/syn/gen/debug.rs b/rust/syn/gen/debug.rs
new file mode 100644
index 0000000000000000000000000000000000000000..aae24df1fa3a7d9b6372f316f75ed85d8a7fc806
--- /dev/null
+++ b/rust/syn/gen/debug.rs
@@ -0,0 +1,3161 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#![allow(unknown_lints, non_local_definitions)]
+use std::fmt::{self, Debug};
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Abi {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Abi");
+        formatter.field("extern_token", &self.extern_token);
+        formatter.field("name", &self.name);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::AngleBracketedGenericArguments {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "AngleBracketedGenericArguments")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::AngleBracketedGenericArguments {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("colon2_token", &self.colon2_token);
+        formatter.field("lt_token", &self.lt_token);
+        formatter.field("args", &self.args);
+        formatter.field("gt_token", &self.gt_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Arm {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Arm");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("pat", &self.pat);
+        formatter.field("guard", &self.guard);
+        formatter.field("fat_arrow_token", &self.fat_arrow_token);
+        formatter.field("body", &self.body);
+        formatter.field("comma", &self.comma);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::AssocConst {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("AssocConst");
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("value", &self.value);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::AssocType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("AssocType");
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::AttrStyle {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("AttrStyle::")?;
+        match self {
+            crate::AttrStyle::Outer => formatter.write_str("Outer"),
+            crate::AttrStyle::Inner(v0) => {
+                let mut formatter = formatter.debug_tuple("Inner");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Attribute {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Attribute");
+        formatter.field("pound_token", &self.pound_token);
+        formatter.field("style", &self.style);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("meta", &self.meta);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::BareFnArg {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("BareFnArg");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("name", &self.name);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::BareVariadic {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("BareVariadic");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("name", &self.name);
+        formatter.field("dots", &self.dots);
+        formatter.field("comma", &self.comma);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::BinOp {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("BinOp::")?;
+        match self {
+            crate::BinOp::Add(v0) => {
+                let mut formatter = formatter.debug_tuple("Add");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Sub(v0) => {
+                let mut formatter = formatter.debug_tuple("Sub");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Mul(v0) => {
+                let mut formatter = formatter.debug_tuple("Mul");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Div(v0) => {
+                let mut formatter = formatter.debug_tuple("Div");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Rem(v0) => {
+                let mut formatter = formatter.debug_tuple("Rem");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::And(v0) => {
+                let mut formatter = formatter.debug_tuple("And");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Or(v0) => {
+                let mut formatter = formatter.debug_tuple("Or");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::BitXor(v0) => {
+                let mut formatter = formatter.debug_tuple("BitXor");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::BitAnd(v0) => {
+                let mut formatter = formatter.debug_tuple("BitAnd");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::BitOr(v0) => {
+                let mut formatter = formatter.debug_tuple("BitOr");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Shl(v0) => {
+                let mut formatter = formatter.debug_tuple("Shl");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Shr(v0) => {
+                let mut formatter = formatter.debug_tuple("Shr");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Eq(v0) => {
+                let mut formatter = formatter.debug_tuple("Eq");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Lt(v0) => {
+                let mut formatter = formatter.debug_tuple("Lt");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Le(v0) => {
+                let mut formatter = formatter.debug_tuple("Le");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Ne(v0) => {
+                let mut formatter = formatter.debug_tuple("Ne");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Ge(v0) => {
+                let mut formatter = formatter.debug_tuple("Ge");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::Gt(v0) => {
+                let mut formatter = formatter.debug_tuple("Gt");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::AddAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("AddAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::SubAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("SubAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::MulAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("MulAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::DivAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("DivAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::RemAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("RemAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::BitXorAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("BitXorAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::BitAndAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("BitAndAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::BitOrAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("BitOrAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::ShlAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("ShlAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::BinOp::ShrAssign(v0) => {
+                let mut formatter = formatter.debug_tuple("ShrAssign");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Block {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Block");
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("stmts", &self.stmts);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::BoundLifetimes {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("BoundLifetimes");
+        formatter.field("for_token", &self.for_token);
+        formatter.field("lt_token", &self.lt_token);
+        formatter.field("lifetimes", &self.lifetimes);
+        formatter.field("gt_token", &self.gt_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ConstParam {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("ConstParam");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("default", &self.default);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Constraint {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Constraint");
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Data {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Data::")?;
+        match self {
+            crate::Data::Struct(v0) => v0.debug(formatter, "Struct"),
+            crate::Data::Enum(v0) => v0.debug(formatter, "Enum"),
+            crate::Data::Union(v0) => v0.debug(formatter, "Union"),
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::DataEnum {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "DataEnum")
+    }
+}
+#[cfg(feature = "derive")]
+impl crate::DataEnum {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("enum_token", &self.enum_token);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("variants", &self.variants);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::DataStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "DataStruct")
+    }
+}
+#[cfg(feature = "derive")]
+impl crate::DataStruct {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("struct_token", &self.struct_token);
+        formatter.field("fields", &self.fields);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::DataUnion {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "DataUnion")
+    }
+}
+#[cfg(feature = "derive")]
+impl crate::DataUnion {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("union_token", &self.union_token);
+        formatter.field("fields", &self.fields);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::DeriveInput {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("DeriveInput");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("data", &self.data);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Expr {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Expr::")?;
+        match self {
+            #[cfg(feature = "full")]
+            crate::Expr::Array(v0) => v0.debug(formatter, "Array"),
+            #[cfg(feature = "full")]
+            crate::Expr::Assign(v0) => v0.debug(formatter, "Assign"),
+            #[cfg(feature = "full")]
+            crate::Expr::Async(v0) => v0.debug(formatter, "Async"),
+            #[cfg(feature = "full")]
+            crate::Expr::Await(v0) => v0.debug(formatter, "Await"),
+            crate::Expr::Binary(v0) => v0.debug(formatter, "Binary"),
+            #[cfg(feature = "full")]
+            crate::Expr::Block(v0) => v0.debug(formatter, "Block"),
+            #[cfg(feature = "full")]
+            crate::Expr::Break(v0) => v0.debug(formatter, "Break"),
+            crate::Expr::Call(v0) => v0.debug(formatter, "Call"),
+            crate::Expr::Cast(v0) => v0.debug(formatter, "Cast"),
+            #[cfg(feature = "full")]
+            crate::Expr::Closure(v0) => v0.debug(formatter, "Closure"),
+            #[cfg(feature = "full")]
+            crate::Expr::Const(v0) => v0.debug(formatter, "Const"),
+            #[cfg(feature = "full")]
+            crate::Expr::Continue(v0) => v0.debug(formatter, "Continue"),
+            crate::Expr::Field(v0) => v0.debug(formatter, "Field"),
+            #[cfg(feature = "full")]
+            crate::Expr::ForLoop(v0) => v0.debug(formatter, "ForLoop"),
+            crate::Expr::Group(v0) => v0.debug(formatter, "Group"),
+            #[cfg(feature = "full")]
+            crate::Expr::If(v0) => v0.debug(formatter, "If"),
+            crate::Expr::Index(v0) => v0.debug(formatter, "Index"),
+            #[cfg(feature = "full")]
+            crate::Expr::Infer(v0) => v0.debug(formatter, "Infer"),
+            #[cfg(feature = "full")]
+            crate::Expr::Let(v0) => v0.debug(formatter, "Let"),
+            crate::Expr::Lit(v0) => v0.debug(formatter, "Lit"),
+            #[cfg(feature = "full")]
+            crate::Expr::Loop(v0) => v0.debug(formatter, "Loop"),
+            crate::Expr::Macro(v0) => v0.debug(formatter, "Macro"),
+            #[cfg(feature = "full")]
+            crate::Expr::Match(v0) => v0.debug(formatter, "Match"),
+            crate::Expr::MethodCall(v0) => v0.debug(formatter, "MethodCall"),
+            crate::Expr::Paren(v0) => v0.debug(formatter, "Paren"),
+            crate::Expr::Path(v0) => v0.debug(formatter, "Path"),
+            #[cfg(feature = "full")]
+            crate::Expr::Range(v0) => v0.debug(formatter, "Range"),
+            crate::Expr::Reference(v0) => v0.debug(formatter, "Reference"),
+            #[cfg(feature = "full")]
+            crate::Expr::Repeat(v0) => v0.debug(formatter, "Repeat"),
+            #[cfg(feature = "full")]
+            crate::Expr::Return(v0) => v0.debug(formatter, "Return"),
+            crate::Expr::Struct(v0) => v0.debug(formatter, "Struct"),
+            #[cfg(feature = "full")]
+            crate::Expr::Try(v0) => v0.debug(formatter, "Try"),
+            #[cfg(feature = "full")]
+            crate::Expr::TryBlock(v0) => v0.debug(formatter, "TryBlock"),
+            #[cfg(feature = "full")]
+            crate::Expr::Tuple(v0) => v0.debug(formatter, "Tuple"),
+            crate::Expr::Unary(v0) => v0.debug(formatter, "Unary"),
+            #[cfg(feature = "full")]
+            crate::Expr::Unsafe(v0) => v0.debug(formatter, "Unsafe"),
+            crate::Expr::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::While(v0) => v0.debug(formatter, "While"),
+            #[cfg(feature = "full")]
+            crate::Expr::Yield(v0) => v0.debug(formatter, "Yield"),
+            #[cfg(not(feature = "full"))]
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprArray {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprArray")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprArray {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprAssign {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprAssign")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprAssign {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("left", &self.left);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("right", &self.right);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprAsync {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprAsync")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprAsync {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("async_token", &self.async_token);
+        formatter.field("capture", &self.capture);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprAwait {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprAwait")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprAwait {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("base", &self.base);
+        formatter.field("dot_token", &self.dot_token);
+        formatter.field("await_token", &self.await_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprBinary {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprBinary")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprBinary {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("left", &self.left);
+        formatter.field("op", &self.op);
+        formatter.field("right", &self.right);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprBlock {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprBlock")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprBlock {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("label", &self.label);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprBreak {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprBreak")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprBreak {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("break_token", &self.break_token);
+        formatter.field("label", &self.label);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprCall {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprCall")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprCall {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("func", &self.func);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("args", &self.args);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprCast {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprCast")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprCast {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("expr", &self.expr);
+        formatter.field("as_token", &self.as_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprClosure {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprClosure")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprClosure {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("lifetimes", &self.lifetimes);
+        formatter.field("constness", &self.constness);
+        formatter.field("movability", &self.movability);
+        formatter.field("asyncness", &self.asyncness);
+        formatter.field("capture", &self.capture);
+        formatter.field("or1_token", &self.or1_token);
+        formatter.field("inputs", &self.inputs);
+        formatter.field("or2_token", &self.or2_token);
+        formatter.field("output", &self.output);
+        formatter.field("body", &self.body);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprConst {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprConst")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprConst {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprContinue {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprContinue")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprContinue {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("continue_token", &self.continue_token);
+        formatter.field("label", &self.label);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprField {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprField")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprField {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("base", &self.base);
+        formatter.field("dot_token", &self.dot_token);
+        formatter.field("member", &self.member);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprForLoop {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprForLoop")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprForLoop {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("label", &self.label);
+        formatter.field("for_token", &self.for_token);
+        formatter.field("pat", &self.pat);
+        formatter.field("in_token", &self.in_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("body", &self.body);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprGroup {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprGroup")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprGroup {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("group_token", &self.group_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprIf {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprIf")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprIf {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("if_token", &self.if_token);
+        formatter.field("cond", &self.cond);
+        formatter.field("then_branch", &self.then_branch);
+        formatter.field("else_branch", &self.else_branch);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprIndex {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprIndex")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprIndex {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("expr", &self.expr);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("index", &self.index);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprInfer {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprInfer")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprInfer {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("underscore_token", &self.underscore_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprLet {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprLet")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprLet {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("let_token", &self.let_token);
+        formatter.field("pat", &self.pat);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprLit {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprLit")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprLit {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("lit", &self.lit);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprLoop {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprLoop")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprLoop {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("label", &self.label);
+        formatter.field("loop_token", &self.loop_token);
+        formatter.field("body", &self.body);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprMacro")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprMacro {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprMatch {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprMatch")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprMatch {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("match_token", &self.match_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("arms", &self.arms);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprMethodCall {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprMethodCall")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprMethodCall {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("receiver", &self.receiver);
+        formatter.field("dot_token", &self.dot_token);
+        formatter.field("method", &self.method);
+        formatter.field("turbofish", &self.turbofish);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("args", &self.args);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprParen {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprParen")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprParen {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprPath {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprPath")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprPath {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("qself", &self.qself);
+        formatter.field("path", &self.path);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprRange {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprRange")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprRange {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("start", &self.start);
+        formatter.field("limits", &self.limits);
+        formatter.field("end", &self.end);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprReference {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprReference")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprReference {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("and_token", &self.and_token);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprRepeat {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprRepeat")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprRepeat {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.field("len", &self.len);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprReturn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprReturn")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprReturn {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("return_token", &self.return_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprStruct")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprStruct {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("qself", &self.qself);
+        formatter.field("path", &self.path);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("fields", &self.fields);
+        formatter.field("dot2_token", &self.dot2_token);
+        formatter.field("rest", &self.rest);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprTry {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprTry")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprTry {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("expr", &self.expr);
+        formatter.field("question_token", &self.question_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprTryBlock {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprTryBlock")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprTryBlock {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("try_token", &self.try_token);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprTuple {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprTuple")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprTuple {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprUnary {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprUnary")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ExprUnary {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("op", &self.op);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprUnsafe {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprUnsafe")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprUnsafe {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("unsafe_token", &self.unsafe_token);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprWhile {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprWhile")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprWhile {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("label", &self.label);
+        formatter.field("while_token", &self.while_token);
+        formatter.field("cond", &self.cond);
+        formatter.field("body", &self.body);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ExprYield {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ExprYield")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ExprYield {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("yield_token", &self.yield_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Field {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Field");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::FieldMutability {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("FieldMutability::")?;
+        match self {
+            crate::FieldMutability::None => formatter.write_str("None"),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::FieldPat {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("FieldPat");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("member", &self.member);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("pat", &self.pat);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::FieldValue {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("FieldValue");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("member", &self.member);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("expr", &self.expr);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Fields {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Fields::")?;
+        match self {
+            crate::Fields::Named(v0) => v0.debug(formatter, "Named"),
+            crate::Fields::Unnamed(v0) => v0.debug(formatter, "Unnamed"),
+            crate::Fields::Unit => formatter.write_str("Unit"),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::FieldsNamed {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "FieldsNamed")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::FieldsNamed {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("named", &self.named);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::FieldsUnnamed {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "FieldsUnnamed")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::FieldsUnnamed {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("unnamed", &self.unnamed);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::File {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("File");
+        formatter.field("shebang", &self.shebang);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::FnArg {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("FnArg::")?;
+        match self {
+            crate::FnArg::Receiver(v0) => {
+                let mut formatter = formatter.debug_tuple("Receiver");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::FnArg::Typed(v0) => {
+                let mut formatter = formatter.debug_tuple("Typed");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ForeignItem {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("ForeignItem::")?;
+        match self {
+            crate::ForeignItem::Fn(v0) => v0.debug(formatter, "Fn"),
+            crate::ForeignItem::Static(v0) => v0.debug(formatter, "Static"),
+            crate::ForeignItem::Type(v0) => v0.debug(formatter, "Type"),
+            crate::ForeignItem::Macro(v0) => v0.debug(formatter, "Macro"),
+            crate::ForeignItem::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ForeignItemFn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ForeignItemFn")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ForeignItemFn {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("sig", &self.sig);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ForeignItemMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ForeignItemMacro")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ForeignItemMacro {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ForeignItemStatic {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ForeignItemStatic")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ForeignItemStatic {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("static_token", &self.static_token);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ForeignItemType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ForeignItemType")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ForeignItemType {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("type_token", &self.type_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::GenericArgument {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("GenericArgument::")?;
+        match self {
+            crate::GenericArgument::Lifetime(v0) => {
+                let mut formatter = formatter.debug_tuple("Lifetime");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::GenericArgument::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::GenericArgument::Const(v0) => {
+                let mut formatter = formatter.debug_tuple("Const");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::GenericArgument::AssocType(v0) => {
+                let mut formatter = formatter.debug_tuple("AssocType");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::GenericArgument::AssocConst(v0) => {
+                let mut formatter = formatter.debug_tuple("AssocConst");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::GenericArgument::Constraint(v0) => {
+                let mut formatter = formatter.debug_tuple("Constraint");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::GenericParam {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("GenericParam::")?;
+        match self {
+            crate::GenericParam::Lifetime(v0) => {
+                let mut formatter = formatter.debug_tuple("Lifetime");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::GenericParam::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::GenericParam::Const(v0) => {
+                let mut formatter = formatter.debug_tuple("Const");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Generics {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Generics");
+        formatter.field("lt_token", &self.lt_token);
+        formatter.field("params", &self.params);
+        formatter.field("gt_token", &self.gt_token);
+        formatter.field("where_clause", &self.where_clause);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ImplItem {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("ImplItem::")?;
+        match self {
+            crate::ImplItem::Const(v0) => v0.debug(formatter, "Const"),
+            crate::ImplItem::Fn(v0) => v0.debug(formatter, "Fn"),
+            crate::ImplItem::Type(v0) => v0.debug(formatter, "Type"),
+            crate::ImplItem::Macro(v0) => v0.debug(formatter, "Macro"),
+            crate::ImplItem::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ImplItemConst {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ImplItemConst")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ImplItemConst {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("defaultness", &self.defaultness);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ImplItemFn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ImplItemFn")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ImplItemFn {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("defaultness", &self.defaultness);
+        formatter.field("sig", &self.sig);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ImplItemMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ImplItemMacro")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ImplItemMacro {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ImplItemType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ImplItemType")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ImplItemType {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("defaultness", &self.defaultness);
+        formatter.field("type_token", &self.type_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ImplRestriction {
+    fn fmt(&self, _formatter: &mut fmt::Formatter) -> fmt::Result {
+        match *self {}
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Index {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Index");
+        formatter.field("index", &self.index);
+        formatter.field("span", &self.span);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Item {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Item::")?;
+        match self {
+            crate::Item::Const(v0) => v0.debug(formatter, "Const"),
+            crate::Item::Enum(v0) => v0.debug(formatter, "Enum"),
+            crate::Item::ExternCrate(v0) => v0.debug(formatter, "ExternCrate"),
+            crate::Item::Fn(v0) => v0.debug(formatter, "Fn"),
+            crate::Item::ForeignMod(v0) => v0.debug(formatter, "ForeignMod"),
+            crate::Item::Impl(v0) => v0.debug(formatter, "Impl"),
+            crate::Item::Macro(v0) => v0.debug(formatter, "Macro"),
+            crate::Item::Mod(v0) => v0.debug(formatter, "Mod"),
+            crate::Item::Static(v0) => v0.debug(formatter, "Static"),
+            crate::Item::Struct(v0) => v0.debug(formatter, "Struct"),
+            crate::Item::Trait(v0) => v0.debug(formatter, "Trait"),
+            crate::Item::TraitAlias(v0) => v0.debug(formatter, "TraitAlias"),
+            crate::Item::Type(v0) => v0.debug(formatter, "Type"),
+            crate::Item::Union(v0) => v0.debug(formatter, "Union"),
+            crate::Item::Use(v0) => v0.debug(formatter, "Use"),
+            crate::Item::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemConst {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemConst")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemConst {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemEnum {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemEnum")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemEnum {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("enum_token", &self.enum_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("variants", &self.variants);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemExternCrate {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemExternCrate")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemExternCrate {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("extern_token", &self.extern_token);
+        formatter.field("crate_token", &self.crate_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("rename", &self.rename);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemFn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemFn")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemFn {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("sig", &self.sig);
+        formatter.field("block", &self.block);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemForeignMod {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemForeignMod")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemForeignMod {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("abi", &self.abi);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemImpl {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemImpl")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemImpl {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("defaultness", &self.defaultness);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("impl_token", &self.impl_token);
+        formatter.field("generics", &self.generics);
+        formatter.field("trait_", &self.trait_);
+        formatter.field("self_ty", &self.self_ty);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemMacro")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemMacro {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("ident", &self.ident);
+        formatter.field("mac", &self.mac);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemMod {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemMod")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemMod {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("mod_token", &self.mod_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("content", &self.content);
+        formatter.field("semi", &self.semi);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemStatic {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemStatic")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemStatic {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("static_token", &self.static_token);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemStruct")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemStruct {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("struct_token", &self.struct_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("fields", &self.fields);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemTrait {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemTrait")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemTrait {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("auto_token", &self.auto_token);
+        formatter.field("restriction", &self.restriction);
+        formatter.field("trait_token", &self.trait_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("supertraits", &self.supertraits);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemTraitAlias {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemTraitAlias")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemTraitAlias {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("trait_token", &self.trait_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemType")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemType {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("type_token", &self.type_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemUnion {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemUnion")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemUnion {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("union_token", &self.union_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("fields", &self.fields);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ItemUse {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ItemUse")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::ItemUse {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("vis", &self.vis);
+        formatter.field("use_token", &self.use_token);
+        formatter.field("leading_colon", &self.leading_colon);
+        formatter.field("tree", &self.tree);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Label {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Label");
+        formatter.field("name", &self.name);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.finish()
+    }
+}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Lifetime {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "Lifetime")
+    }
+}
+impl crate::Lifetime {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("apostrophe", &self.apostrophe);
+        formatter.field("ident", &self.ident);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::LifetimeParam {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("LifetimeParam");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("lifetime", &self.lifetime);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Lit {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Lit::")?;
+        match self {
+            crate::Lit::Str(v0) => v0.debug(formatter, "Str"),
+            crate::Lit::ByteStr(v0) => v0.debug(formatter, "ByteStr"),
+            crate::Lit::Byte(v0) => v0.debug(formatter, "Byte"),
+            crate::Lit::Char(v0) => v0.debug(formatter, "Char"),
+            crate::Lit::Int(v0) => v0.debug(formatter, "Int"),
+            crate::Lit::Float(v0) => v0.debug(formatter, "Float"),
+            crate::Lit::Bool(v0) => v0.debug(formatter, "Bool"),
+            crate::Lit::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Local {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "Local")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::Local {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("let_token", &self.let_token);
+        formatter.field("pat", &self.pat);
+        formatter.field("init", &self.init);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::LocalInit {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("LocalInit");
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("expr", &self.expr);
+        formatter.field("diverge", &self.diverge);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Macro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Macro");
+        formatter.field("path", &self.path);
+        formatter.field("bang_token", &self.bang_token);
+        formatter.field("delimiter", &self.delimiter);
+        formatter.field("tokens", &self.tokens);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::MacroDelimiter {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("MacroDelimiter::")?;
+        match self {
+            crate::MacroDelimiter::Paren(v0) => {
+                let mut formatter = formatter.debug_tuple("Paren");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::MacroDelimiter::Brace(v0) => {
+                let mut formatter = formatter.debug_tuple("Brace");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::MacroDelimiter::Bracket(v0) => {
+                let mut formatter = formatter.debug_tuple("Bracket");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Member {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Member::")?;
+        match self {
+            crate::Member::Named(v0) => {
+                let mut formatter = formatter.debug_tuple("Named");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::Member::Unnamed(v0) => {
+                let mut formatter = formatter.debug_tuple("Unnamed");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Meta {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Meta::")?;
+        match self {
+            crate::Meta::Path(v0) => v0.debug(formatter, "Path"),
+            crate::Meta::List(v0) => v0.debug(formatter, "List"),
+            crate::Meta::NameValue(v0) => v0.debug(formatter, "NameValue"),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::MetaList {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "MetaList")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::MetaList {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("path", &self.path);
+        formatter.field("delimiter", &self.delimiter);
+        formatter.field("tokens", &self.tokens);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::MetaNameValue {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "MetaNameValue")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::MetaNameValue {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("path", &self.path);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("value", &self.value);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ParenthesizedGenericArguments {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "ParenthesizedGenericArguments")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::ParenthesizedGenericArguments {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("inputs", &self.inputs);
+        formatter.field("output", &self.output);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Pat {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Pat::")?;
+        match self {
+            crate::Pat::Const(v0) => v0.debug(formatter, "Const"),
+            crate::Pat::Ident(v0) => v0.debug(formatter, "Ident"),
+            crate::Pat::Lit(v0) => v0.debug(formatter, "Lit"),
+            crate::Pat::Macro(v0) => v0.debug(formatter, "Macro"),
+            crate::Pat::Or(v0) => v0.debug(formatter, "Or"),
+            crate::Pat::Paren(v0) => v0.debug(formatter, "Paren"),
+            crate::Pat::Path(v0) => v0.debug(formatter, "Path"),
+            crate::Pat::Range(v0) => v0.debug(formatter, "Range"),
+            crate::Pat::Reference(v0) => v0.debug(formatter, "Reference"),
+            crate::Pat::Rest(v0) => v0.debug(formatter, "Rest"),
+            crate::Pat::Slice(v0) => v0.debug(formatter, "Slice"),
+            crate::Pat::Struct(v0) => v0.debug(formatter, "Struct"),
+            crate::Pat::Tuple(v0) => v0.debug(formatter, "Tuple"),
+            crate::Pat::TupleStruct(v0) => v0.debug(formatter, "TupleStruct"),
+            crate::Pat::Type(v0) => v0.debug(formatter, "Type"),
+            crate::Pat::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::Pat::Wild(v0) => v0.debug(formatter, "Wild"),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatIdent {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatIdent")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatIdent {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("by_ref", &self.by_ref);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("ident", &self.ident);
+        formatter.field("subpat", &self.subpat);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatOr {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatOr")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatOr {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("leading_vert", &self.leading_vert);
+        formatter.field("cases", &self.cases);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatParen {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatParen")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatParen {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("pat", &self.pat);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatReference {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatReference")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatReference {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("and_token", &self.and_token);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("pat", &self.pat);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatRest {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatRest")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatRest {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("dot2_token", &self.dot2_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatSlice {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatSlice")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatSlice {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatStruct")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatStruct {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("qself", &self.qself);
+        formatter.field("path", &self.path);
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("fields", &self.fields);
+        formatter.field("rest", &self.rest);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatTuple {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatTuple")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatTuple {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatTupleStruct {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatTupleStruct")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatTupleStruct {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("qself", &self.qself);
+        formatter.field("path", &self.path);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatType")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatType {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("pat", &self.pat);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PatWild {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "PatWild")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::PatWild {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("underscore_token", &self.underscore_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Path {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "Path")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::Path {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("leading_colon", &self.leading_colon);
+        formatter.field("segments", &self.segments);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PathArguments {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("PathArguments::")?;
+        match self {
+            crate::PathArguments::None => formatter.write_str("None"),
+            crate::PathArguments::AngleBracketed(v0) => {
+                v0.debug(formatter, "AngleBracketed")
+            }
+            crate::PathArguments::Parenthesized(v0) => {
+                v0.debug(formatter, "Parenthesized")
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PathSegment {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PathSegment");
+        formatter.field("ident", &self.ident);
+        formatter.field("arguments", &self.arguments);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PredicateLifetime {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PredicateLifetime");
+        formatter.field("lifetime", &self.lifetime);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::PredicateType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("PredicateType");
+        formatter.field("lifetimes", &self.lifetimes);
+        formatter.field("bounded_ty", &self.bounded_ty);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::QSelf {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("QSelf");
+        formatter.field("lt_token", &self.lt_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("position", &self.position);
+        formatter.field("as_token", &self.as_token);
+        formatter.field("gt_token", &self.gt_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::RangeLimits {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("RangeLimits::")?;
+        match self {
+            crate::RangeLimits::HalfOpen(v0) => {
+                let mut formatter = formatter.debug_tuple("HalfOpen");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::RangeLimits::Closed(v0) => {
+                let mut formatter = formatter.debug_tuple("Closed");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Receiver {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Receiver");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("reference", &self.reference);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("self_token", &self.self_token);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::ReturnType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("ReturnType::")?;
+        match self {
+            crate::ReturnType::Default => formatter.write_str("Default"),
+            crate::ReturnType::Type(v0, v1) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.field(v1);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Signature {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Signature");
+        formatter.field("constness", &self.constness);
+        formatter.field("asyncness", &self.asyncness);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("abi", &self.abi);
+        formatter.field("fn_token", &self.fn_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("inputs", &self.inputs);
+        formatter.field("variadic", &self.variadic);
+        formatter.field("output", &self.output);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::StaticMutability {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("StaticMutability::")?;
+        match self {
+            crate::StaticMutability::Mut(v0) => {
+                let mut formatter = formatter.debug_tuple("Mut");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::StaticMutability::None => formatter.write_str("None"),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Stmt {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Stmt::")?;
+        match self {
+            crate::Stmt::Local(v0) => v0.debug(formatter, "Local"),
+            crate::Stmt::Item(v0) => {
+                let mut formatter = formatter.debug_tuple("Item");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::Stmt::Expr(v0, v1) => {
+                let mut formatter = formatter.debug_tuple("Expr");
+                formatter.field(v0);
+                formatter.field(v1);
+                formatter.finish()
+            }
+            crate::Stmt::Macro(v0) => v0.debug(formatter, "Macro"),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::StmtMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "StmtMacro")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::StmtMacro {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TraitBound {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TraitBound");
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("modifier", &self.modifier);
+        formatter.field("lifetimes", &self.lifetimes);
+        formatter.field("path", &self.path);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TraitBoundModifier {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("TraitBoundModifier::")?;
+        match self {
+            crate::TraitBoundModifier::None => formatter.write_str("None"),
+            crate::TraitBoundModifier::Maybe(v0) => {
+                let mut formatter = formatter.debug_tuple("Maybe");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TraitItem {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("TraitItem::")?;
+        match self {
+            crate::TraitItem::Const(v0) => v0.debug(formatter, "Const"),
+            crate::TraitItem::Fn(v0) => v0.debug(formatter, "Fn"),
+            crate::TraitItem::Type(v0) => v0.debug(formatter, "Type"),
+            crate::TraitItem::Macro(v0) => v0.debug(formatter, "Macro"),
+            crate::TraitItem::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TraitItemConst {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TraitItemConst")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::TraitItemConst {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("ty", &self.ty);
+        formatter.field("default", &self.default);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TraitItemFn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TraitItemFn")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::TraitItemFn {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("sig", &self.sig);
+        formatter.field("default", &self.default);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TraitItemMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TraitItemMacro")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::TraitItemMacro {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("mac", &self.mac);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TraitItemType {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TraitItemType")
+    }
+}
+#[cfg(feature = "full")]
+impl crate::TraitItemType {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("attrs", &self.attrs);
+        formatter.field("type_token", &self.type_token);
+        formatter.field("ident", &self.ident);
+        formatter.field("generics", &self.generics);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.field("default", &self.default);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Type {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Type::")?;
+        match self {
+            crate::Type::Array(v0) => v0.debug(formatter, "Array"),
+            crate::Type::BareFn(v0) => v0.debug(formatter, "BareFn"),
+            crate::Type::Group(v0) => v0.debug(formatter, "Group"),
+            crate::Type::ImplTrait(v0) => v0.debug(formatter, "ImplTrait"),
+            crate::Type::Infer(v0) => v0.debug(formatter, "Infer"),
+            crate::Type::Macro(v0) => v0.debug(formatter, "Macro"),
+            crate::Type::Never(v0) => v0.debug(formatter, "Never"),
+            crate::Type::Paren(v0) => v0.debug(formatter, "Paren"),
+            crate::Type::Path(v0) => v0.debug(formatter, "Path"),
+            crate::Type::Ptr(v0) => v0.debug(formatter, "Ptr"),
+            crate::Type::Reference(v0) => v0.debug(formatter, "Reference"),
+            crate::Type::Slice(v0) => v0.debug(formatter, "Slice"),
+            crate::Type::TraitObject(v0) => v0.debug(formatter, "TraitObject"),
+            crate::Type::Tuple(v0) => v0.debug(formatter, "Tuple"),
+            crate::Type::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeArray {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeArray")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeArray {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("elem", &self.elem);
+        formatter.field("semi_token", &self.semi_token);
+        formatter.field("len", &self.len);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeBareFn {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeBareFn")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeBareFn {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("lifetimes", &self.lifetimes);
+        formatter.field("unsafety", &self.unsafety);
+        formatter.field("abi", &self.abi);
+        formatter.field("fn_token", &self.fn_token);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("inputs", &self.inputs);
+        formatter.field("variadic", &self.variadic);
+        formatter.field("output", &self.output);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeGroup {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeGroup")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeGroup {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("group_token", &self.group_token);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeImplTrait {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeImplTrait")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeImplTrait {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("impl_token", &self.impl_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeInfer {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeInfer")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeInfer {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("underscore_token", &self.underscore_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeMacro {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeMacro")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeMacro {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("mac", &self.mac);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeNever {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeNever")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeNever {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("bang_token", &self.bang_token);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeParam {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("TypeParam");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("ident", &self.ident);
+        formatter.field("colon_token", &self.colon_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.field("eq_token", &self.eq_token);
+        formatter.field("default", &self.default);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeParamBound {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("TypeParamBound::")?;
+        match self {
+            crate::TypeParamBound::Trait(v0) => {
+                let mut formatter = formatter.debug_tuple("Trait");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::TypeParamBound::Lifetime(v0) => v0.debug(formatter, "Lifetime"),
+            crate::TypeParamBound::Verbatim(v0) => {
+                let mut formatter = formatter.debug_tuple("Verbatim");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeParen {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeParen")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeParen {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypePath {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypePath")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypePath {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("qself", &self.qself);
+        formatter.field("path", &self.path);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypePtr {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypePtr")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypePtr {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("star_token", &self.star_token);
+        formatter.field("const_token", &self.const_token);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeReference {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeReference")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeReference {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("and_token", &self.and_token);
+        formatter.field("lifetime", &self.lifetime);
+        formatter.field("mutability", &self.mutability);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeSlice {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeSlice")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeSlice {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("bracket_token", &self.bracket_token);
+        formatter.field("elem", &self.elem);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeTraitObject {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeTraitObject")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeTraitObject {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("dyn_token", &self.dyn_token);
+        formatter.field("bounds", &self.bounds);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::TypeTuple {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "TypeTuple")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::TypeTuple {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("elems", &self.elems);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::UnOp {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("UnOp::")?;
+        match self {
+            crate::UnOp::Deref(v0) => {
+                let mut formatter = formatter.debug_tuple("Deref");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::UnOp::Not(v0) => {
+                let mut formatter = formatter.debug_tuple("Not");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::UnOp::Neg(v0) => {
+                let mut formatter = formatter.debug_tuple("Neg");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::UseGlob {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UseGlob");
+        formatter.field("star_token", &self.star_token);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::UseGroup {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UseGroup");
+        formatter.field("brace_token", &self.brace_token);
+        formatter.field("items", &self.items);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::UseName {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UseName");
+        formatter.field("ident", &self.ident);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::UsePath {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UsePath");
+        formatter.field("ident", &self.ident);
+        formatter.field("colon2_token", &self.colon2_token);
+        formatter.field("tree", &self.tree);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::UseRename {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("UseRename");
+        formatter.field("ident", &self.ident);
+        formatter.field("as_token", &self.as_token);
+        formatter.field("rename", &self.rename);
+        formatter.finish()
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::UseTree {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("UseTree::")?;
+        match self {
+            crate::UseTree::Path(v0) => {
+                let mut formatter = formatter.debug_tuple("Path");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::UseTree::Name(v0) => {
+                let mut formatter = formatter.debug_tuple("Name");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::UseTree::Rename(v0) => {
+                let mut formatter = formatter.debug_tuple("Rename");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::UseTree::Glob(v0) => {
+                let mut formatter = formatter.debug_tuple("Glob");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::UseTree::Group(v0) => {
+                let mut formatter = formatter.debug_tuple("Group");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Variadic {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Variadic");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("pat", &self.pat);
+        formatter.field("dots", &self.dots);
+        formatter.field("comma", &self.comma);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Variant {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("Variant");
+        formatter.field("attrs", &self.attrs);
+        formatter.field("ident", &self.ident);
+        formatter.field("fields", &self.fields);
+        formatter.field("discriminant", &self.discriminant);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::VisRestricted {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.debug(formatter, "VisRestricted")
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+impl crate::VisRestricted {
+    fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+        let mut formatter = formatter.debug_struct(name);
+        formatter.field("pub_token", &self.pub_token);
+        formatter.field("paren_token", &self.paren_token);
+        formatter.field("in_token", &self.in_token);
+        formatter.field("path", &self.path);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::Visibility {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("Visibility::")?;
+        match self {
+            crate::Visibility::Public(v0) => {
+                let mut formatter = formatter.debug_tuple("Public");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::Visibility::Restricted(v0) => v0.debug(formatter, "Restricted"),
+            crate::Visibility::Inherited => formatter.write_str("Inherited"),
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::WhereClause {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut formatter = formatter.debug_struct("WhereClause");
+        formatter.field("where_token", &self.where_token);
+        formatter.field("predicates", &self.predicates);
+        formatter.finish()
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for crate::WherePredicate {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        formatter.write_str("WherePredicate::")?;
+        match self {
+            crate::WherePredicate::Lifetime(v0) => {
+                let mut formatter = formatter.debug_tuple("Lifetime");
+                formatter.field(v0);
+                formatter.finish()
+            }
+            crate::WherePredicate::Type(v0) => {
+                let mut formatter = formatter.debug_tuple("Type");
+                formatter.field(v0);
+                formatter.finish()
+            }
+        }
+    }
+}
diff --git a/rust/syn/gen/eq.rs b/rust/syn/gen/eq.rs
new file mode 100644
index 0000000000000000000000000000000000000000..cab23ce3c0b02c56594df616d5ef8c1e44f339be
--- /dev/null
+++ b/rust/syn/gen/eq.rs
@@ -0,0 +1,2241 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#[cfg(any(feature = "derive", feature = "full"))]
+use crate::tt::TokenStreamHelper;
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Abi {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Abi {
+    fn eq(&self, other: &Self) -> bool {
+        self.name == other.name
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::AngleBracketedGenericArguments {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::AngleBracketedGenericArguments {
+    fn eq(&self, other: &Self) -> bool {
+        self.colon2_token == other.colon2_token && self.args == other.args
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Arm {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Arm {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat && self.guard == other.guard
+            && self.body == other.body && self.comma == other.comma
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::AssocConst {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::AssocConst {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.generics == other.generics
+            && self.value == other.value
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::AssocType {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::AssocType {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.generics == other.generics
+            && self.ty == other.ty
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::AttrStyle {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::AttrStyle {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::AttrStyle::Outer, crate::AttrStyle::Outer) => true,
+            (crate::AttrStyle::Inner(_), crate::AttrStyle::Inner(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Attribute {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Attribute {
+    fn eq(&self, other: &Self) -> bool {
+        self.style == other.style && self.meta == other.meta
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::BareFnArg {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::BareFnArg {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.name == other.name && self.ty == other.ty
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::BareVariadic {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::BareVariadic {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.name == other.name && self.comma == other.comma
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::BinOp {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::BinOp {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::BinOp::Add(_), crate::BinOp::Add(_)) => true,
+            (crate::BinOp::Sub(_), crate::BinOp::Sub(_)) => true,
+            (crate::BinOp::Mul(_), crate::BinOp::Mul(_)) => true,
+            (crate::BinOp::Div(_), crate::BinOp::Div(_)) => true,
+            (crate::BinOp::Rem(_), crate::BinOp::Rem(_)) => true,
+            (crate::BinOp::And(_), crate::BinOp::And(_)) => true,
+            (crate::BinOp::Or(_), crate::BinOp::Or(_)) => true,
+            (crate::BinOp::BitXor(_), crate::BinOp::BitXor(_)) => true,
+            (crate::BinOp::BitAnd(_), crate::BinOp::BitAnd(_)) => true,
+            (crate::BinOp::BitOr(_), crate::BinOp::BitOr(_)) => true,
+            (crate::BinOp::Shl(_), crate::BinOp::Shl(_)) => true,
+            (crate::BinOp::Shr(_), crate::BinOp::Shr(_)) => true,
+            (crate::BinOp::Eq(_), crate::BinOp::Eq(_)) => true,
+            (crate::BinOp::Lt(_), crate::BinOp::Lt(_)) => true,
+            (crate::BinOp::Le(_), crate::BinOp::Le(_)) => true,
+            (crate::BinOp::Ne(_), crate::BinOp::Ne(_)) => true,
+            (crate::BinOp::Ge(_), crate::BinOp::Ge(_)) => true,
+            (crate::BinOp::Gt(_), crate::BinOp::Gt(_)) => true,
+            (crate::BinOp::AddAssign(_), crate::BinOp::AddAssign(_)) => true,
+            (crate::BinOp::SubAssign(_), crate::BinOp::SubAssign(_)) => true,
+            (crate::BinOp::MulAssign(_), crate::BinOp::MulAssign(_)) => true,
+            (crate::BinOp::DivAssign(_), crate::BinOp::DivAssign(_)) => true,
+            (crate::BinOp::RemAssign(_), crate::BinOp::RemAssign(_)) => true,
+            (crate::BinOp::BitXorAssign(_), crate::BinOp::BitXorAssign(_)) => true,
+            (crate::BinOp::BitAndAssign(_), crate::BinOp::BitAndAssign(_)) => true,
+            (crate::BinOp::BitOrAssign(_), crate::BinOp::BitOrAssign(_)) => true,
+            (crate::BinOp::ShlAssign(_), crate::BinOp::ShlAssign(_)) => true,
+            (crate::BinOp::ShrAssign(_), crate::BinOp::ShrAssign(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Block {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Block {
+    fn eq(&self, other: &Self) -> bool {
+        self.stmts == other.stmts
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::BoundLifetimes {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::BoundLifetimes {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetimes == other.lifetimes
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ConstParam {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ConstParam {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.ident == other.ident && self.ty == other.ty
+            && self.eq_token == other.eq_token && self.default == other.default
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Constraint {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Constraint {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.generics == other.generics
+            && self.bounds == other.bounds
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Data {}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Data {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::Data::Struct(self0), crate::Data::Struct(other0)) => self0 == other0,
+            (crate::Data::Enum(self0), crate::Data::Enum(other0)) => self0 == other0,
+            (crate::Data::Union(self0), crate::Data::Union(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::DataEnum {}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::DataEnum {
+    fn eq(&self, other: &Self) -> bool {
+        self.variants == other.variants
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::DataStruct {}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::DataStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.fields == other.fields && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::DataUnion {}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::DataUnion {
+    fn eq(&self, other: &Self) -> bool {
+        self.fields == other.fields
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::DeriveInput {}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::DeriveInput {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+            && self.generics == other.generics && self.data == other.data
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Expr {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Expr {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            #[cfg(feature = "full")]
+            (crate::Expr::Array(self0), crate::Expr::Array(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Assign(self0), crate::Expr::Assign(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Async(self0), crate::Expr::Async(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Await(self0), crate::Expr::Await(other0)) => self0 == other0,
+            (crate::Expr::Binary(self0), crate::Expr::Binary(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Block(self0), crate::Expr::Block(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Break(self0), crate::Expr::Break(other0)) => self0 == other0,
+            (crate::Expr::Call(self0), crate::Expr::Call(other0)) => self0 == other0,
+            (crate::Expr::Cast(self0), crate::Expr::Cast(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Closure(self0), crate::Expr::Closure(other0)) => {
+                self0 == other0
+            }
+            #[cfg(feature = "full")]
+            (crate::Expr::Const(self0), crate::Expr::Const(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Continue(self0), crate::Expr::Continue(other0)) => {
+                self0 == other0
+            }
+            (crate::Expr::Field(self0), crate::Expr::Field(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::ForLoop(self0), crate::Expr::ForLoop(other0)) => {
+                self0 == other0
+            }
+            (crate::Expr::Group(self0), crate::Expr::Group(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::If(self0), crate::Expr::If(other0)) => self0 == other0,
+            (crate::Expr::Index(self0), crate::Expr::Index(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Infer(self0), crate::Expr::Infer(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Let(self0), crate::Expr::Let(other0)) => self0 == other0,
+            (crate::Expr::Lit(self0), crate::Expr::Lit(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Loop(self0), crate::Expr::Loop(other0)) => self0 == other0,
+            (crate::Expr::Macro(self0), crate::Expr::Macro(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Match(self0), crate::Expr::Match(other0)) => self0 == other0,
+            (crate::Expr::MethodCall(self0), crate::Expr::MethodCall(other0)) => {
+                self0 == other0
+            }
+            (crate::Expr::Paren(self0), crate::Expr::Paren(other0)) => self0 == other0,
+            (crate::Expr::Path(self0), crate::Expr::Path(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Range(self0), crate::Expr::Range(other0)) => self0 == other0,
+            (crate::Expr::Reference(self0), crate::Expr::Reference(other0)) => {
+                self0 == other0
+            }
+            #[cfg(feature = "full")]
+            (crate::Expr::Repeat(self0), crate::Expr::Repeat(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Return(self0), crate::Expr::Return(other0)) => self0 == other0,
+            (crate::Expr::Struct(self0), crate::Expr::Struct(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Try(self0), crate::Expr::Try(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::TryBlock(self0), crate::Expr::TryBlock(other0)) => {
+                self0 == other0
+            }
+            #[cfg(feature = "full")]
+            (crate::Expr::Tuple(self0), crate::Expr::Tuple(other0)) => self0 == other0,
+            (crate::Expr::Unary(self0), crate::Expr::Unary(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Unsafe(self0), crate::Expr::Unsafe(other0)) => self0 == other0,
+            (crate::Expr::Verbatim(self0), crate::Expr::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            #[cfg(feature = "full")]
+            (crate::Expr::While(self0), crate::Expr::While(other0)) => self0 == other0,
+            #[cfg(feature = "full")]
+            (crate::Expr::Yield(self0), crate::Expr::Yield(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprArray {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprArray {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.elems == other.elems
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprAssign {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprAssign {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.left == other.left && self.right == other.right
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprAsync {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprAsync {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.capture == other.capture
+            && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprAwait {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprAwait {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.base == other.base
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprBinary {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprBinary {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.left == other.left && self.op == other.op
+            && self.right == other.right
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprBlock {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprBlock {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label
+            && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprBreak {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprBreak {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprCall {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprCall {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.func == other.func && self.args == other.args
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprCast {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprCast {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprClosure {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprClosure {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.lifetimes == other.lifetimes
+            && self.constness == other.constness && self.movability == other.movability
+            && self.asyncness == other.asyncness && self.capture == other.capture
+            && self.inputs == other.inputs && self.output == other.output
+            && self.body == other.body
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprConst {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprConst {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprContinue {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprContinue {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprField {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprField {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.base == other.base
+            && self.member == other.member
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprForLoop {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprForLoop {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label && self.pat == other.pat
+            && self.expr == other.expr && self.body == other.body
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprGroup {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprGroup {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprIf {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprIf {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.cond == other.cond
+            && self.then_branch == other.then_branch
+            && self.else_branch == other.else_branch
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprIndex {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprIndex {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr && self.index == other.index
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprInfer {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprInfer {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprLet {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprLet {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprLit {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprLit {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.lit == other.lit
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprLoop {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprLoop {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label && self.body == other.body
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprMacro {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprMatch {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprMatch {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr && self.arms == other.arms
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprMethodCall {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprMethodCall {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.receiver == other.receiver
+            && self.method == other.method && self.turbofish == other.turbofish
+            && self.args == other.args
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprParen {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprParen {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprPath {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprPath {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.qself == other.qself && self.path == other.path
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprRange {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprRange {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.start == other.start
+            && self.limits == other.limits && self.end == other.end
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprReference {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprReference {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mutability == other.mutability
+            && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprRepeat {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprRepeat {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr && self.len == other.len
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprReturn {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprReturn {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprStruct {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.qself == other.qself && self.path == other.path
+            && self.fields == other.fields && self.dot2_token == other.dot2_token
+            && self.rest == other.rest
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprTry {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprTry {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprTryBlock {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprTryBlock {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprTuple {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprTuple {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.elems == other.elems
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprUnary {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprUnary {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.op == other.op && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprUnsafe {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprUnsafe {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprWhile {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprWhile {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.label == other.label && self.cond == other.cond
+            && self.body == other.body
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ExprYield {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ExprYield {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Field {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Field {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis
+            && self.mutability == other.mutability && self.ident == other.ident
+            && self.colon_token == other.colon_token && self.ty == other.ty
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::FieldMutability {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::FieldMutability {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::FieldMutability::None, crate::FieldMutability::None) => true,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::FieldPat {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::FieldPat {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.member == other.member
+            && self.colon_token == other.colon_token && self.pat == other.pat
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::FieldValue {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::FieldValue {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.member == other.member
+            && self.colon_token == other.colon_token && self.expr == other.expr
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Fields {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Fields {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::Fields::Named(self0), crate::Fields::Named(other0)) => {
+                self0 == other0
+            }
+            (crate::Fields::Unnamed(self0), crate::Fields::Unnamed(other0)) => {
+                self0 == other0
+            }
+            (crate::Fields::Unit, crate::Fields::Unit) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::FieldsNamed {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::FieldsNamed {
+    fn eq(&self, other: &Self) -> bool {
+        self.named == other.named
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::FieldsUnnamed {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::FieldsUnnamed {
+    fn eq(&self, other: &Self) -> bool {
+        self.unnamed == other.unnamed
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::File {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::File {
+    fn eq(&self, other: &Self) -> bool {
+        self.shebang == other.shebang && self.attrs == other.attrs
+            && self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::FnArg {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::FnArg {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::FnArg::Receiver(self0), crate::FnArg::Receiver(other0)) => {
+                self0 == other0
+            }
+            (crate::FnArg::Typed(self0), crate::FnArg::Typed(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ForeignItem {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ForeignItem {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::ForeignItem::Fn(self0), crate::ForeignItem::Fn(other0)) => {
+                self0 == other0
+            }
+            (crate::ForeignItem::Static(self0), crate::ForeignItem::Static(other0)) => {
+                self0 == other0
+            }
+            (crate::ForeignItem::Type(self0), crate::ForeignItem::Type(other0)) => {
+                self0 == other0
+            }
+            (crate::ForeignItem::Macro(self0), crate::ForeignItem::Macro(other0)) => {
+                self0 == other0
+            }
+            (
+                crate::ForeignItem::Verbatim(self0),
+                crate::ForeignItem::Verbatim(other0),
+            ) => TokenStreamHelper(self0) == TokenStreamHelper(other0),
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ForeignItemFn {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ForeignItemFn {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.sig == other.sig
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ForeignItemMacro {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ForeignItemMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac
+            && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ForeignItemStatic {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ForeignItemStatic {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis
+            && self.mutability == other.mutability && self.ident == other.ident
+            && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ForeignItemType {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ForeignItemType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+            && self.generics == other.generics
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::GenericArgument {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::GenericArgument {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (
+                crate::GenericArgument::Lifetime(self0),
+                crate::GenericArgument::Lifetime(other0),
+            ) => self0 == other0,
+            (
+                crate::GenericArgument::Type(self0),
+                crate::GenericArgument::Type(other0),
+            ) => self0 == other0,
+            (
+                crate::GenericArgument::Const(self0),
+                crate::GenericArgument::Const(other0),
+            ) => self0 == other0,
+            (
+                crate::GenericArgument::AssocType(self0),
+                crate::GenericArgument::AssocType(other0),
+            ) => self0 == other0,
+            (
+                crate::GenericArgument::AssocConst(self0),
+                crate::GenericArgument::AssocConst(other0),
+            ) => self0 == other0,
+            (
+                crate::GenericArgument::Constraint(self0),
+                crate::GenericArgument::Constraint(other0),
+            ) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::GenericParam {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::GenericParam {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (
+                crate::GenericParam::Lifetime(self0),
+                crate::GenericParam::Lifetime(other0),
+            ) => self0 == other0,
+            (crate::GenericParam::Type(self0), crate::GenericParam::Type(other0)) => {
+                self0 == other0
+            }
+            (crate::GenericParam::Const(self0), crate::GenericParam::Const(other0)) => {
+                self0 == other0
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Generics {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Generics {
+    fn eq(&self, other: &Self) -> bool {
+        self.lt_token == other.lt_token && self.params == other.params
+            && self.gt_token == other.gt_token && self.where_clause == other.where_clause
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ImplItem {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ImplItem {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::ImplItem::Const(self0), crate::ImplItem::Const(other0)) => {
+                self0 == other0
+            }
+            (crate::ImplItem::Fn(self0), crate::ImplItem::Fn(other0)) => self0 == other0,
+            (crate::ImplItem::Type(self0), crate::ImplItem::Type(other0)) => {
+                self0 == other0
+            }
+            (crate::ImplItem::Macro(self0), crate::ImplItem::Macro(other0)) => {
+                self0 == other0
+            }
+            (crate::ImplItem::Verbatim(self0), crate::ImplItem::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ImplItemConst {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ImplItemConst {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis
+            && self.defaultness == other.defaultness && self.ident == other.ident
+            && self.generics == other.generics && self.ty == other.ty
+            && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ImplItemFn {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ImplItemFn {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis
+            && self.defaultness == other.defaultness && self.sig == other.sig
+            && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ImplItemMacro {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ImplItemMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac
+            && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ImplItemType {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ImplItemType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis
+            && self.defaultness == other.defaultness && self.ident == other.ident
+            && self.generics == other.generics && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ImplRestriction {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ImplRestriction {
+    fn eq(&self, _other: &Self) -> bool {
+        match *self {}
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Item {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Item {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::Item::Const(self0), crate::Item::Const(other0)) => self0 == other0,
+            (crate::Item::Enum(self0), crate::Item::Enum(other0)) => self0 == other0,
+            (crate::Item::ExternCrate(self0), crate::Item::ExternCrate(other0)) => {
+                self0 == other0
+            }
+            (crate::Item::Fn(self0), crate::Item::Fn(other0)) => self0 == other0,
+            (crate::Item::ForeignMod(self0), crate::Item::ForeignMod(other0)) => {
+                self0 == other0
+            }
+            (crate::Item::Impl(self0), crate::Item::Impl(other0)) => self0 == other0,
+            (crate::Item::Macro(self0), crate::Item::Macro(other0)) => self0 == other0,
+            (crate::Item::Mod(self0), crate::Item::Mod(other0)) => self0 == other0,
+            (crate::Item::Static(self0), crate::Item::Static(other0)) => self0 == other0,
+            (crate::Item::Struct(self0), crate::Item::Struct(other0)) => self0 == other0,
+            (crate::Item::Trait(self0), crate::Item::Trait(other0)) => self0 == other0,
+            (crate::Item::TraitAlias(self0), crate::Item::TraitAlias(other0)) => {
+                self0 == other0
+            }
+            (crate::Item::Type(self0), crate::Item::Type(other0)) => self0 == other0,
+            (crate::Item::Union(self0), crate::Item::Union(other0)) => self0 == other0,
+            (crate::Item::Use(self0), crate::Item::Use(other0)) => self0 == other0,
+            (crate::Item::Verbatim(self0), crate::Item::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemConst {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemConst {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+            && self.generics == other.generics && self.ty == other.ty
+            && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemEnum {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemEnum {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+            && self.generics == other.generics && self.variants == other.variants
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemExternCrate {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemExternCrate {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+            && self.rename == other.rename
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemFn {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemFn {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.sig == other.sig
+            && self.block == other.block
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemForeignMod {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemForeignMod {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.unsafety == other.unsafety
+            && self.abi == other.abi && self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemImpl {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemImpl {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.defaultness == other.defaultness
+            && self.unsafety == other.unsafety && self.generics == other.generics
+            && self.trait_ == other.trait_ && self.self_ty == other.self_ty
+            && self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemMacro {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.ident == other.ident && self.mac == other.mac
+            && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemMod {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemMod {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis
+            && self.unsafety == other.unsafety && self.ident == other.ident
+            && self.content == other.content && self.semi == other.semi
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemStatic {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemStatic {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis
+            && self.mutability == other.mutability && self.ident == other.ident
+            && self.ty == other.ty && self.expr == other.expr
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemStruct {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+            && self.generics == other.generics && self.fields == other.fields
+            && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemTrait {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemTrait {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis
+            && self.unsafety == other.unsafety && self.auto_token == other.auto_token
+            && self.restriction == other.restriction && self.ident == other.ident
+            && self.generics == other.generics && self.colon_token == other.colon_token
+            && self.supertraits == other.supertraits && self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemTraitAlias {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemTraitAlias {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+            && self.generics == other.generics && self.bounds == other.bounds
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemType {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+            && self.generics == other.generics && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemUnion {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemUnion {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis && self.ident == other.ident
+            && self.generics == other.generics && self.fields == other.fields
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ItemUse {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ItemUse {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.vis == other.vis
+            && self.leading_colon == other.leading_colon && self.tree == other.tree
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Label {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Label {
+    fn eq(&self, other: &Self) -> bool {
+        self.name == other.name
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::LifetimeParam {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::LifetimeParam {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.lifetime == other.lifetime
+            && self.colon_token == other.colon_token && self.bounds == other.bounds
+    }
+}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Lit {}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Lit {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::Lit::Str(self0), crate::Lit::Str(other0)) => self0 == other0,
+            (crate::Lit::ByteStr(self0), crate::Lit::ByteStr(other0)) => self0 == other0,
+            (crate::Lit::Byte(self0), crate::Lit::Byte(other0)) => self0 == other0,
+            (crate::Lit::Char(self0), crate::Lit::Char(other0)) => self0 == other0,
+            (crate::Lit::Int(self0), crate::Lit::Int(other0)) => self0 == other0,
+            (crate::Lit::Float(self0), crate::Lit::Float(other0)) => self0 == other0,
+            (crate::Lit::Bool(self0), crate::Lit::Bool(other0)) => self0 == other0,
+            (crate::Lit::Verbatim(self0), crate::Lit::Verbatim(other0)) => {
+                self0.to_string() == other0.to_string()
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::LitBool {}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::LitBool {
+    fn eq(&self, other: &Self) -> bool {
+        self.value == other.value
+    }
+}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::LitByte {}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::LitByteStr {}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::LitChar {}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::LitFloat {}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::LitInt {}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::LitStr {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Local {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Local {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat && self.init == other.init
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::LocalInit {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::LocalInit {
+    fn eq(&self, other: &Self) -> bool {
+        self.expr == other.expr && self.diverge == other.diverge
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Macro {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Macro {
+    fn eq(&self, other: &Self) -> bool {
+        self.path == other.path && self.delimiter == other.delimiter
+            && TokenStreamHelper(&self.tokens) == TokenStreamHelper(&other.tokens)
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::MacroDelimiter {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::MacroDelimiter {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::MacroDelimiter::Paren(_), crate::MacroDelimiter::Paren(_)) => true,
+            (crate::MacroDelimiter::Brace(_), crate::MacroDelimiter::Brace(_)) => true,
+            (crate::MacroDelimiter::Bracket(_), crate::MacroDelimiter::Bracket(_)) => {
+                true
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Meta {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Meta {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::Meta::Path(self0), crate::Meta::Path(other0)) => self0 == other0,
+            (crate::Meta::List(self0), crate::Meta::List(other0)) => self0 == other0,
+            (crate::Meta::NameValue(self0), crate::Meta::NameValue(other0)) => {
+                self0 == other0
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::MetaList {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::MetaList {
+    fn eq(&self, other: &Self) -> bool {
+        self.path == other.path && self.delimiter == other.delimiter
+            && TokenStreamHelper(&self.tokens) == TokenStreamHelper(&other.tokens)
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::MetaNameValue {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::MetaNameValue {
+    fn eq(&self, other: &Self) -> bool {
+        self.path == other.path && self.value == other.value
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ParenthesizedGenericArguments {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ParenthesizedGenericArguments {
+    fn eq(&self, other: &Self) -> bool {
+        self.inputs == other.inputs && self.output == other.output
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Pat {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Pat {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::Pat::Const(self0), crate::Pat::Const(other0)) => self0 == other0,
+            (crate::Pat::Ident(self0), crate::Pat::Ident(other0)) => self0 == other0,
+            (crate::Pat::Lit(self0), crate::Pat::Lit(other0)) => self0 == other0,
+            (crate::Pat::Macro(self0), crate::Pat::Macro(other0)) => self0 == other0,
+            (crate::Pat::Or(self0), crate::Pat::Or(other0)) => self0 == other0,
+            (crate::Pat::Paren(self0), crate::Pat::Paren(other0)) => self0 == other0,
+            (crate::Pat::Path(self0), crate::Pat::Path(other0)) => self0 == other0,
+            (crate::Pat::Range(self0), crate::Pat::Range(other0)) => self0 == other0,
+            (crate::Pat::Reference(self0), crate::Pat::Reference(other0)) => {
+                self0 == other0
+            }
+            (crate::Pat::Rest(self0), crate::Pat::Rest(other0)) => self0 == other0,
+            (crate::Pat::Slice(self0), crate::Pat::Slice(other0)) => self0 == other0,
+            (crate::Pat::Struct(self0), crate::Pat::Struct(other0)) => self0 == other0,
+            (crate::Pat::Tuple(self0), crate::Pat::Tuple(other0)) => self0 == other0,
+            (crate::Pat::TupleStruct(self0), crate::Pat::TupleStruct(other0)) => {
+                self0 == other0
+            }
+            (crate::Pat::Type(self0), crate::Pat::Type(other0)) => self0 == other0,
+            (crate::Pat::Verbatim(self0), crate::Pat::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            (crate::Pat::Wild(self0), crate::Pat::Wild(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatIdent {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatIdent {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.by_ref == other.by_ref
+            && self.mutability == other.mutability && self.ident == other.ident
+            && self.subpat == other.subpat
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatOr {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatOr {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.leading_vert == other.leading_vert
+            && self.cases == other.cases
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatParen {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatParen {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatReference {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatReference {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mutability == other.mutability
+            && self.pat == other.pat
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatRest {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatRest {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatSlice {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatSlice {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.elems == other.elems
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatStruct {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.qself == other.qself && self.path == other.path
+            && self.fields == other.fields && self.rest == other.rest
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatTuple {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatTuple {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.elems == other.elems
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatTupleStruct {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatTupleStruct {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.qself == other.qself && self.path == other.path
+            && self.elems == other.elems
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatType {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat && self.ty == other.ty
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PatWild {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PatWild {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Path {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Path {
+    fn eq(&self, other: &Self) -> bool {
+        self.leading_colon == other.leading_colon && self.segments == other.segments
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PathArguments {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PathArguments {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::PathArguments::None, crate::PathArguments::None) => true,
+            (
+                crate::PathArguments::AngleBracketed(self0),
+                crate::PathArguments::AngleBracketed(other0),
+            ) => self0 == other0,
+            (
+                crate::PathArguments::Parenthesized(self0),
+                crate::PathArguments::Parenthesized(other0),
+            ) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PathSegment {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PathSegment {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.arguments == other.arguments
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PredicateLifetime {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PredicateLifetime {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetime == other.lifetime && self.bounds == other.bounds
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::PredicateType {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::PredicateType {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetimes == other.lifetimes && self.bounded_ty == other.bounded_ty
+            && self.bounds == other.bounds
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::QSelf {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::QSelf {
+    fn eq(&self, other: &Self) -> bool {
+        self.ty == other.ty && self.position == other.position
+            && self.as_token == other.as_token
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::RangeLimits {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::RangeLimits {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::RangeLimits::HalfOpen(_), crate::RangeLimits::HalfOpen(_)) => true,
+            (crate::RangeLimits::Closed(_), crate::RangeLimits::Closed(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Receiver {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Receiver {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.reference == other.reference
+            && self.mutability == other.mutability
+            && self.colon_token == other.colon_token && self.ty == other.ty
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::ReturnType {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::ReturnType {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::ReturnType::Default, crate::ReturnType::Default) => true,
+            (crate::ReturnType::Type(_, self1), crate::ReturnType::Type(_, other1)) => {
+                self1 == other1
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Signature {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Signature {
+    fn eq(&self, other: &Self) -> bool {
+        self.constness == other.constness && self.asyncness == other.asyncness
+            && self.unsafety == other.unsafety && self.abi == other.abi
+            && self.ident == other.ident && self.generics == other.generics
+            && self.inputs == other.inputs && self.variadic == other.variadic
+            && self.output == other.output
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::StaticMutability {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::StaticMutability {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::StaticMutability::Mut(_), crate::StaticMutability::Mut(_)) => true,
+            (crate::StaticMutability::None, crate::StaticMutability::None) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Stmt {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Stmt {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::Stmt::Local(self0), crate::Stmt::Local(other0)) => self0 == other0,
+            (crate::Stmt::Item(self0), crate::Stmt::Item(other0)) => self0 == other0,
+            (crate::Stmt::Expr(self0, self1), crate::Stmt::Expr(other0, other1)) => {
+                self0 == other0 && self1 == other1
+            }
+            (crate::Stmt::Macro(self0), crate::Stmt::Macro(other0)) => self0 == other0,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::StmtMacro {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::StmtMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac
+            && self.semi_token == other.semi_token
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TraitBound {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TraitBound {
+    fn eq(&self, other: &Self) -> bool {
+        self.paren_token == other.paren_token && self.modifier == other.modifier
+            && self.lifetimes == other.lifetimes && self.path == other.path
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TraitBoundModifier {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TraitBoundModifier {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::TraitBoundModifier::None, crate::TraitBoundModifier::None) => true,
+            (
+                crate::TraitBoundModifier::Maybe(_),
+                crate::TraitBoundModifier::Maybe(_),
+            ) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TraitItem {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TraitItem {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::TraitItem::Const(self0), crate::TraitItem::Const(other0)) => {
+                self0 == other0
+            }
+            (crate::TraitItem::Fn(self0), crate::TraitItem::Fn(other0)) => {
+                self0 == other0
+            }
+            (crate::TraitItem::Type(self0), crate::TraitItem::Type(other0)) => {
+                self0 == other0
+            }
+            (crate::TraitItem::Macro(self0), crate::TraitItem::Macro(other0)) => {
+                self0 == other0
+            }
+            (crate::TraitItem::Verbatim(self0), crate::TraitItem::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TraitItemConst {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TraitItemConst {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.ident == other.ident
+            && self.generics == other.generics && self.ty == other.ty
+            && self.default == other.default
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TraitItemFn {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TraitItemFn {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.sig == other.sig
+            && self.default == other.default && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TraitItemMacro {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TraitItemMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.mac == other.mac
+            && self.semi_token == other.semi_token
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TraitItemType {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TraitItemType {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.ident == other.ident
+            && self.generics == other.generics && self.colon_token == other.colon_token
+            && self.bounds == other.bounds && self.default == other.default
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Type {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Type {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::Type::Array(self0), crate::Type::Array(other0)) => self0 == other0,
+            (crate::Type::BareFn(self0), crate::Type::BareFn(other0)) => self0 == other0,
+            (crate::Type::Group(self0), crate::Type::Group(other0)) => self0 == other0,
+            (crate::Type::ImplTrait(self0), crate::Type::ImplTrait(other0)) => {
+                self0 == other0
+            }
+            (crate::Type::Infer(self0), crate::Type::Infer(other0)) => self0 == other0,
+            (crate::Type::Macro(self0), crate::Type::Macro(other0)) => self0 == other0,
+            (crate::Type::Never(self0), crate::Type::Never(other0)) => self0 == other0,
+            (crate::Type::Paren(self0), crate::Type::Paren(other0)) => self0 == other0,
+            (crate::Type::Path(self0), crate::Type::Path(other0)) => self0 == other0,
+            (crate::Type::Ptr(self0), crate::Type::Ptr(other0)) => self0 == other0,
+            (crate::Type::Reference(self0), crate::Type::Reference(other0)) => {
+                self0 == other0
+            }
+            (crate::Type::Slice(self0), crate::Type::Slice(other0)) => self0 == other0,
+            (crate::Type::TraitObject(self0), crate::Type::TraitObject(other0)) => {
+                self0 == other0
+            }
+            (crate::Type::Tuple(self0), crate::Type::Tuple(other0)) => self0 == other0,
+            (crate::Type::Verbatim(self0), crate::Type::Verbatim(other0)) => {
+                TokenStreamHelper(self0) == TokenStreamHelper(other0)
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeArray {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeArray {
+    fn eq(&self, other: &Self) -> bool {
+        self.elem == other.elem && self.len == other.len
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeBareFn {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeBareFn {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetimes == other.lifetimes && self.unsafety == other.unsafety
+            && self.abi == other.abi && self.inputs == other.inputs
+            && self.variadic == other.variadic && self.output == other.output
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeGroup {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeGroup {
+    fn eq(&self, other: &Self) -> bool {
+        self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeImplTrait {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeImplTrait {
+    fn eq(&self, other: &Self) -> bool {
+        self.bounds == other.bounds
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeInfer {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeInfer {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeMacro {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeMacro {
+    fn eq(&self, other: &Self) -> bool {
+        self.mac == other.mac
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeNever {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeNever {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeParam {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeParam {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.ident == other.ident
+            && self.colon_token == other.colon_token && self.bounds == other.bounds
+            && self.eq_token == other.eq_token && self.default == other.default
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeParamBound {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeParamBound {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (
+                crate::TypeParamBound::Trait(self0),
+                crate::TypeParamBound::Trait(other0),
+            ) => self0 == other0,
+            (
+                crate::TypeParamBound::Lifetime(self0),
+                crate::TypeParamBound::Lifetime(other0),
+            ) => self0 == other0,
+            (
+                crate::TypeParamBound::Verbatim(self0),
+                crate::TypeParamBound::Verbatim(other0),
+            ) => TokenStreamHelper(self0) == TokenStreamHelper(other0),
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeParen {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeParen {
+    fn eq(&self, other: &Self) -> bool {
+        self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypePath {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypePath {
+    fn eq(&self, other: &Self) -> bool {
+        self.qself == other.qself && self.path == other.path
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypePtr {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypePtr {
+    fn eq(&self, other: &Self) -> bool {
+        self.const_token == other.const_token && self.mutability == other.mutability
+            && self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeReference {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeReference {
+    fn eq(&self, other: &Self) -> bool {
+        self.lifetime == other.lifetime && self.mutability == other.mutability
+            && self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeSlice {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeSlice {
+    fn eq(&self, other: &Self) -> bool {
+        self.elem == other.elem
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeTraitObject {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeTraitObject {
+    fn eq(&self, other: &Self) -> bool {
+        self.dyn_token == other.dyn_token && self.bounds == other.bounds
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::TypeTuple {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::TypeTuple {
+    fn eq(&self, other: &Self) -> bool {
+        self.elems == other.elems
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::UnOp {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::UnOp {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::UnOp::Deref(_), crate::UnOp::Deref(_)) => true,
+            (crate::UnOp::Not(_), crate::UnOp::Not(_)) => true,
+            (crate::UnOp::Neg(_), crate::UnOp::Neg(_)) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::UseGlob {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::UseGlob {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::UseGroup {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::UseGroup {
+    fn eq(&self, other: &Self) -> bool {
+        self.items == other.items
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::UseName {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::UseName {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::UsePath {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::UsePath {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.tree == other.tree
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::UseRename {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::UseRename {
+    fn eq(&self, other: &Self) -> bool {
+        self.ident == other.ident && self.rename == other.rename
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::UseTree {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::UseTree {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::UseTree::Path(self0), crate::UseTree::Path(other0)) => {
+                self0 == other0
+            }
+            (crate::UseTree::Name(self0), crate::UseTree::Name(other0)) => {
+                self0 == other0
+            }
+            (crate::UseTree::Rename(self0), crate::UseTree::Rename(other0)) => {
+                self0 == other0
+            }
+            (crate::UseTree::Glob(self0), crate::UseTree::Glob(other0)) => {
+                self0 == other0
+            }
+            (crate::UseTree::Group(self0), crate::UseTree::Group(other0)) => {
+                self0 == other0
+            }
+            _ => false,
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Variadic {}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Variadic {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.pat == other.pat && self.comma == other.comma
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Variant {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Variant {
+    fn eq(&self, other: &Self) -> bool {
+        self.attrs == other.attrs && self.ident == other.ident
+            && self.fields == other.fields && self.discriminant == other.discriminant
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::VisRestricted {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::VisRestricted {
+    fn eq(&self, other: &Self) -> bool {
+        self.in_token == other.in_token && self.path == other.path
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::Visibility {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::Visibility {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (crate::Visibility::Public(_), crate::Visibility::Public(_)) => true,
+            (
+                crate::Visibility::Restricted(self0),
+                crate::Visibility::Restricted(other0),
+            ) => self0 == other0,
+            (crate::Visibility::Inherited, crate::Visibility::Inherited) => true,
+            _ => false,
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::WhereClause {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::WhereClause {
+    fn eq(&self, other: &Self) -> bool {
+        self.predicates == other.predicates
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for crate::WherePredicate {}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for crate::WherePredicate {
+    fn eq(&self, other: &Self) -> bool {
+        match (self, other) {
+            (
+                crate::WherePredicate::Lifetime(self0),
+                crate::WherePredicate::Lifetime(other0),
+            ) => self0 == other0,
+            (crate::WherePredicate::Type(self0), crate::WherePredicate::Type(other0)) => {
+                self0 == other0
+            }
+            _ => false,
+        }
+    }
+}
diff --git a/rust/syn/gen/fold.rs b/rust/syn/gen/fold.rs
new file mode 100644
index 0000000000000000000000000000000000000000..8a1eab52712fcab7082409c044ab686e9f65d850
--- /dev/null
+++ b/rust/syn/gen/fold.rs
@@ -0,0 +1,3762 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#![allow(unreachable_code, unused_variables)]
+#![allow(
+    clippy::match_wildcard_for_single_variants,
+    clippy::needless_match,
+    clippy::needless_pass_by_ref_mut,
+)]
+#[cfg(any(feature = "full", feature = "derive"))]
+use crate::gen::helper::fold::FoldHelper;
+#[cfg(feature = "full")]
+macro_rules! full {
+    ($e:expr) => {
+        $e
+    };
+}
+#[cfg(all(feature = "derive", not(feature = "full")))]
+macro_rules! full {
+    ($e:expr) => {
+        unreachable!()
+    };
+}
+/// Syntax tree traversal to transform the nodes of an owned syntax tree.
+///
+/// See the [module documentation] for details.
+///
+/// [module documentation]: self
+pub trait Fold {
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_abi(&mut self, i: crate::Abi) -> crate::Abi {
+        fold_abi(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_angle_bracketed_generic_arguments(
+        &mut self,
+        i: crate::AngleBracketedGenericArguments,
+    ) -> crate::AngleBracketedGenericArguments {
+        fold_angle_bracketed_generic_arguments(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_arm(&mut self, i: crate::Arm) -> crate::Arm {
+        fold_arm(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_assoc_const(&mut self, i: crate::AssocConst) -> crate::AssocConst {
+        fold_assoc_const(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_assoc_type(&mut self, i: crate::AssocType) -> crate::AssocType {
+        fold_assoc_type(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_attr_style(&mut self, i: crate::AttrStyle) -> crate::AttrStyle {
+        fold_attr_style(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_attribute(&mut self, i: crate::Attribute) -> crate::Attribute {
+        fold_attribute(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_bare_fn_arg(&mut self, i: crate::BareFnArg) -> crate::BareFnArg {
+        fold_bare_fn_arg(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_bare_variadic(&mut self, i: crate::BareVariadic) -> crate::BareVariadic {
+        fold_bare_variadic(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_bin_op(&mut self, i: crate::BinOp) -> crate::BinOp {
+        fold_bin_op(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_block(&mut self, i: crate::Block) -> crate::Block {
+        fold_block(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_bound_lifetimes(
+        &mut self,
+        i: crate::BoundLifetimes,
+    ) -> crate::BoundLifetimes {
+        fold_bound_lifetimes(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_const_param(&mut self, i: crate::ConstParam) -> crate::ConstParam {
+        fold_const_param(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_constraint(&mut self, i: crate::Constraint) -> crate::Constraint {
+        fold_constraint(self, i)
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn fold_data(&mut self, i: crate::Data) -> crate::Data {
+        fold_data(self, i)
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn fold_data_enum(&mut self, i: crate::DataEnum) -> crate::DataEnum {
+        fold_data_enum(self, i)
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn fold_data_struct(&mut self, i: crate::DataStruct) -> crate::DataStruct {
+        fold_data_struct(self, i)
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn fold_data_union(&mut self, i: crate::DataUnion) -> crate::DataUnion {
+        fold_data_union(self, i)
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn fold_derive_input(&mut self, i: crate::DeriveInput) -> crate::DeriveInput {
+        fold_derive_input(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr(&mut self, i: crate::Expr) -> crate::Expr {
+        fold_expr(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_array(&mut self, i: crate::ExprArray) -> crate::ExprArray {
+        fold_expr_array(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_assign(&mut self, i: crate::ExprAssign) -> crate::ExprAssign {
+        fold_expr_assign(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_async(&mut self, i: crate::ExprAsync) -> crate::ExprAsync {
+        fold_expr_async(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_await(&mut self, i: crate::ExprAwait) -> crate::ExprAwait {
+        fold_expr_await(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_binary(&mut self, i: crate::ExprBinary) -> crate::ExprBinary {
+        fold_expr_binary(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_block(&mut self, i: crate::ExprBlock) -> crate::ExprBlock {
+        fold_expr_block(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_break(&mut self, i: crate::ExprBreak) -> crate::ExprBreak {
+        fold_expr_break(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_call(&mut self, i: crate::ExprCall) -> crate::ExprCall {
+        fold_expr_call(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_cast(&mut self, i: crate::ExprCast) -> crate::ExprCast {
+        fold_expr_cast(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_closure(&mut self, i: crate::ExprClosure) -> crate::ExprClosure {
+        fold_expr_closure(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_const(&mut self, i: crate::ExprConst) -> crate::ExprConst {
+        fold_expr_const(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_continue(&mut self, i: crate::ExprContinue) -> crate::ExprContinue {
+        fold_expr_continue(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_field(&mut self, i: crate::ExprField) -> crate::ExprField {
+        fold_expr_field(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_for_loop(&mut self, i: crate::ExprForLoop) -> crate::ExprForLoop {
+        fold_expr_for_loop(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_group(&mut self, i: crate::ExprGroup) -> crate::ExprGroup {
+        fold_expr_group(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_if(&mut self, i: crate::ExprIf) -> crate::ExprIf {
+        fold_expr_if(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_index(&mut self, i: crate::ExprIndex) -> crate::ExprIndex {
+        fold_expr_index(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_infer(&mut self, i: crate::ExprInfer) -> crate::ExprInfer {
+        fold_expr_infer(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_let(&mut self, i: crate::ExprLet) -> crate::ExprLet {
+        fold_expr_let(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_lit(&mut self, i: crate::ExprLit) -> crate::ExprLit {
+        fold_expr_lit(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_loop(&mut self, i: crate::ExprLoop) -> crate::ExprLoop {
+        fold_expr_loop(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_macro(&mut self, i: crate::ExprMacro) -> crate::ExprMacro {
+        fold_expr_macro(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_match(&mut self, i: crate::ExprMatch) -> crate::ExprMatch {
+        fold_expr_match(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_method_call(
+        &mut self,
+        i: crate::ExprMethodCall,
+    ) -> crate::ExprMethodCall {
+        fold_expr_method_call(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_paren(&mut self, i: crate::ExprParen) -> crate::ExprParen {
+        fold_expr_paren(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_path(&mut self, i: crate::ExprPath) -> crate::ExprPath {
+        fold_expr_path(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_range(&mut self, i: crate::ExprRange) -> crate::ExprRange {
+        fold_expr_range(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_reference(&mut self, i: crate::ExprReference) -> crate::ExprReference {
+        fold_expr_reference(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_repeat(&mut self, i: crate::ExprRepeat) -> crate::ExprRepeat {
+        fold_expr_repeat(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_return(&mut self, i: crate::ExprReturn) -> crate::ExprReturn {
+        fold_expr_return(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_struct(&mut self, i: crate::ExprStruct) -> crate::ExprStruct {
+        fold_expr_struct(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_try(&mut self, i: crate::ExprTry) -> crate::ExprTry {
+        fold_expr_try(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_try_block(&mut self, i: crate::ExprTryBlock) -> crate::ExprTryBlock {
+        fold_expr_try_block(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_tuple(&mut self, i: crate::ExprTuple) -> crate::ExprTuple {
+        fold_expr_tuple(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_expr_unary(&mut self, i: crate::ExprUnary) -> crate::ExprUnary {
+        fold_expr_unary(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_unsafe(&mut self, i: crate::ExprUnsafe) -> crate::ExprUnsafe {
+        fold_expr_unsafe(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_while(&mut self, i: crate::ExprWhile) -> crate::ExprWhile {
+        fold_expr_while(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_expr_yield(&mut self, i: crate::ExprYield) -> crate::ExprYield {
+        fold_expr_yield(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_field(&mut self, i: crate::Field) -> crate::Field {
+        fold_field(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_field_mutability(
+        &mut self,
+        i: crate::FieldMutability,
+    ) -> crate::FieldMutability {
+        fold_field_mutability(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_field_pat(&mut self, i: crate::FieldPat) -> crate::FieldPat {
+        fold_field_pat(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_field_value(&mut self, i: crate::FieldValue) -> crate::FieldValue {
+        fold_field_value(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_fields(&mut self, i: crate::Fields) -> crate::Fields {
+        fold_fields(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_fields_named(&mut self, i: crate::FieldsNamed) -> crate::FieldsNamed {
+        fold_fields_named(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_fields_unnamed(&mut self, i: crate::FieldsUnnamed) -> crate::FieldsUnnamed {
+        fold_fields_unnamed(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_file(&mut self, i: crate::File) -> crate::File {
+        fold_file(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_fn_arg(&mut self, i: crate::FnArg) -> crate::FnArg {
+        fold_fn_arg(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_foreign_item(&mut self, i: crate::ForeignItem) -> crate::ForeignItem {
+        fold_foreign_item(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_foreign_item_fn(&mut self, i: crate::ForeignItemFn) -> crate::ForeignItemFn {
+        fold_foreign_item_fn(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_foreign_item_macro(
+        &mut self,
+        i: crate::ForeignItemMacro,
+    ) -> crate::ForeignItemMacro {
+        fold_foreign_item_macro(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_foreign_item_static(
+        &mut self,
+        i: crate::ForeignItemStatic,
+    ) -> crate::ForeignItemStatic {
+        fold_foreign_item_static(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_foreign_item_type(
+        &mut self,
+        i: crate::ForeignItemType,
+    ) -> crate::ForeignItemType {
+        fold_foreign_item_type(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_generic_argument(
+        &mut self,
+        i: crate::GenericArgument,
+    ) -> crate::GenericArgument {
+        fold_generic_argument(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_generic_param(&mut self, i: crate::GenericParam) -> crate::GenericParam {
+        fold_generic_param(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_generics(&mut self, i: crate::Generics) -> crate::Generics {
+        fold_generics(self, i)
+    }
+    fn fold_ident(&mut self, i: proc_macro2::Ident) -> proc_macro2::Ident {
+        fold_ident(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_impl_item(&mut self, i: crate::ImplItem) -> crate::ImplItem {
+        fold_impl_item(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_impl_item_const(&mut self, i: crate::ImplItemConst) -> crate::ImplItemConst {
+        fold_impl_item_const(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_impl_item_fn(&mut self, i: crate::ImplItemFn) -> crate::ImplItemFn {
+        fold_impl_item_fn(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_impl_item_macro(&mut self, i: crate::ImplItemMacro) -> crate::ImplItemMacro {
+        fold_impl_item_macro(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_impl_item_type(&mut self, i: crate::ImplItemType) -> crate::ImplItemType {
+        fold_impl_item_type(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_impl_restriction(
+        &mut self,
+        i: crate::ImplRestriction,
+    ) -> crate::ImplRestriction {
+        fold_impl_restriction(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_index(&mut self, i: crate::Index) -> crate::Index {
+        fold_index(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item(&mut self, i: crate::Item) -> crate::Item {
+        fold_item(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_const(&mut self, i: crate::ItemConst) -> crate::ItemConst {
+        fold_item_const(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_enum(&mut self, i: crate::ItemEnum) -> crate::ItemEnum {
+        fold_item_enum(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_extern_crate(
+        &mut self,
+        i: crate::ItemExternCrate,
+    ) -> crate::ItemExternCrate {
+        fold_item_extern_crate(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_fn(&mut self, i: crate::ItemFn) -> crate::ItemFn {
+        fold_item_fn(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_foreign_mod(
+        &mut self,
+        i: crate::ItemForeignMod,
+    ) -> crate::ItemForeignMod {
+        fold_item_foreign_mod(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_impl(&mut self, i: crate::ItemImpl) -> crate::ItemImpl {
+        fold_item_impl(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_macro(&mut self, i: crate::ItemMacro) -> crate::ItemMacro {
+        fold_item_macro(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_mod(&mut self, i: crate::ItemMod) -> crate::ItemMod {
+        fold_item_mod(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_static(&mut self, i: crate::ItemStatic) -> crate::ItemStatic {
+        fold_item_static(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_struct(&mut self, i: crate::ItemStruct) -> crate::ItemStruct {
+        fold_item_struct(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_trait(&mut self, i: crate::ItemTrait) -> crate::ItemTrait {
+        fold_item_trait(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_trait_alias(
+        &mut self,
+        i: crate::ItemTraitAlias,
+    ) -> crate::ItemTraitAlias {
+        fold_item_trait_alias(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_type(&mut self, i: crate::ItemType) -> crate::ItemType {
+        fold_item_type(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_union(&mut self, i: crate::ItemUnion) -> crate::ItemUnion {
+        fold_item_union(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_item_use(&mut self, i: crate::ItemUse) -> crate::ItemUse {
+        fold_item_use(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_label(&mut self, i: crate::Label) -> crate::Label {
+        fold_label(self, i)
+    }
+    fn fold_lifetime(&mut self, i: crate::Lifetime) -> crate::Lifetime {
+        fold_lifetime(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_lifetime_param(&mut self, i: crate::LifetimeParam) -> crate::LifetimeParam {
+        fold_lifetime_param(self, i)
+    }
+    fn fold_lit(&mut self, i: crate::Lit) -> crate::Lit {
+        fold_lit(self, i)
+    }
+    fn fold_lit_bool(&mut self, i: crate::LitBool) -> crate::LitBool {
+        fold_lit_bool(self, i)
+    }
+    fn fold_lit_byte(&mut self, i: crate::LitByte) -> crate::LitByte {
+        fold_lit_byte(self, i)
+    }
+    fn fold_lit_byte_str(&mut self, i: crate::LitByteStr) -> crate::LitByteStr {
+        fold_lit_byte_str(self, i)
+    }
+    fn fold_lit_char(&mut self, i: crate::LitChar) -> crate::LitChar {
+        fold_lit_char(self, i)
+    }
+    fn fold_lit_float(&mut self, i: crate::LitFloat) -> crate::LitFloat {
+        fold_lit_float(self, i)
+    }
+    fn fold_lit_int(&mut self, i: crate::LitInt) -> crate::LitInt {
+        fold_lit_int(self, i)
+    }
+    fn fold_lit_str(&mut self, i: crate::LitStr) -> crate::LitStr {
+        fold_lit_str(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_local(&mut self, i: crate::Local) -> crate::Local {
+        fold_local(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_local_init(&mut self, i: crate::LocalInit) -> crate::LocalInit {
+        fold_local_init(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_macro(&mut self, i: crate::Macro) -> crate::Macro {
+        fold_macro(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_macro_delimiter(
+        &mut self,
+        i: crate::MacroDelimiter,
+    ) -> crate::MacroDelimiter {
+        fold_macro_delimiter(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_member(&mut self, i: crate::Member) -> crate::Member {
+        fold_member(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_meta(&mut self, i: crate::Meta) -> crate::Meta {
+        fold_meta(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_meta_list(&mut self, i: crate::MetaList) -> crate::MetaList {
+        fold_meta_list(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_meta_name_value(&mut self, i: crate::MetaNameValue) -> crate::MetaNameValue {
+        fold_meta_name_value(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_parenthesized_generic_arguments(
+        &mut self,
+        i: crate::ParenthesizedGenericArguments,
+    ) -> crate::ParenthesizedGenericArguments {
+        fold_parenthesized_generic_arguments(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat(&mut self, i: crate::Pat) -> crate::Pat {
+        fold_pat(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_ident(&mut self, i: crate::PatIdent) -> crate::PatIdent {
+        fold_pat_ident(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_or(&mut self, i: crate::PatOr) -> crate::PatOr {
+        fold_pat_or(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_paren(&mut self, i: crate::PatParen) -> crate::PatParen {
+        fold_pat_paren(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_reference(&mut self, i: crate::PatReference) -> crate::PatReference {
+        fold_pat_reference(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_rest(&mut self, i: crate::PatRest) -> crate::PatRest {
+        fold_pat_rest(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_slice(&mut self, i: crate::PatSlice) -> crate::PatSlice {
+        fold_pat_slice(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_struct(&mut self, i: crate::PatStruct) -> crate::PatStruct {
+        fold_pat_struct(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_tuple(&mut self, i: crate::PatTuple) -> crate::PatTuple {
+        fold_pat_tuple(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_tuple_struct(
+        &mut self,
+        i: crate::PatTupleStruct,
+    ) -> crate::PatTupleStruct {
+        fold_pat_tuple_struct(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_type(&mut self, i: crate::PatType) -> crate::PatType {
+        fold_pat_type(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_pat_wild(&mut self, i: crate::PatWild) -> crate::PatWild {
+        fold_pat_wild(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_path(&mut self, i: crate::Path) -> crate::Path {
+        fold_path(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_path_arguments(&mut self, i: crate::PathArguments) -> crate::PathArguments {
+        fold_path_arguments(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_path_segment(&mut self, i: crate::PathSegment) -> crate::PathSegment {
+        fold_path_segment(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_predicate_lifetime(
+        &mut self,
+        i: crate::PredicateLifetime,
+    ) -> crate::PredicateLifetime {
+        fold_predicate_lifetime(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_predicate_type(&mut self, i: crate::PredicateType) -> crate::PredicateType {
+        fold_predicate_type(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_qself(&mut self, i: crate::QSelf) -> crate::QSelf {
+        fold_qself(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_range_limits(&mut self, i: crate::RangeLimits) -> crate::RangeLimits {
+        fold_range_limits(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_receiver(&mut self, i: crate::Receiver) -> crate::Receiver {
+        fold_receiver(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_return_type(&mut self, i: crate::ReturnType) -> crate::ReturnType {
+        fold_return_type(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_signature(&mut self, i: crate::Signature) -> crate::Signature {
+        fold_signature(self, i)
+    }
+    fn fold_span(&mut self, i: proc_macro2::Span) -> proc_macro2::Span {
+        fold_span(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_static_mutability(
+        &mut self,
+        i: crate::StaticMutability,
+    ) -> crate::StaticMutability {
+        fold_static_mutability(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_stmt(&mut self, i: crate::Stmt) -> crate::Stmt {
+        fold_stmt(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_stmt_macro(&mut self, i: crate::StmtMacro) -> crate::StmtMacro {
+        fold_stmt_macro(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_trait_bound(&mut self, i: crate::TraitBound) -> crate::TraitBound {
+        fold_trait_bound(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_trait_bound_modifier(
+        &mut self,
+        i: crate::TraitBoundModifier,
+    ) -> crate::TraitBoundModifier {
+        fold_trait_bound_modifier(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_trait_item(&mut self, i: crate::TraitItem) -> crate::TraitItem {
+        fold_trait_item(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_trait_item_const(
+        &mut self,
+        i: crate::TraitItemConst,
+    ) -> crate::TraitItemConst {
+        fold_trait_item_const(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_trait_item_fn(&mut self, i: crate::TraitItemFn) -> crate::TraitItemFn {
+        fold_trait_item_fn(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_trait_item_macro(
+        &mut self,
+        i: crate::TraitItemMacro,
+    ) -> crate::TraitItemMacro {
+        fold_trait_item_macro(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_trait_item_type(&mut self, i: crate::TraitItemType) -> crate::TraitItemType {
+        fold_trait_item_type(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type(&mut self, i: crate::Type) -> crate::Type {
+        fold_type(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_array(&mut self, i: crate::TypeArray) -> crate::TypeArray {
+        fold_type_array(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_bare_fn(&mut self, i: crate::TypeBareFn) -> crate::TypeBareFn {
+        fold_type_bare_fn(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_group(&mut self, i: crate::TypeGroup) -> crate::TypeGroup {
+        fold_type_group(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_impl_trait(&mut self, i: crate::TypeImplTrait) -> crate::TypeImplTrait {
+        fold_type_impl_trait(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_infer(&mut self, i: crate::TypeInfer) -> crate::TypeInfer {
+        fold_type_infer(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_macro(&mut self, i: crate::TypeMacro) -> crate::TypeMacro {
+        fold_type_macro(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_never(&mut self, i: crate::TypeNever) -> crate::TypeNever {
+        fold_type_never(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_param(&mut self, i: crate::TypeParam) -> crate::TypeParam {
+        fold_type_param(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_param_bound(
+        &mut self,
+        i: crate::TypeParamBound,
+    ) -> crate::TypeParamBound {
+        fold_type_param_bound(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_paren(&mut self, i: crate::TypeParen) -> crate::TypeParen {
+        fold_type_paren(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_path(&mut self, i: crate::TypePath) -> crate::TypePath {
+        fold_type_path(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_ptr(&mut self, i: crate::TypePtr) -> crate::TypePtr {
+        fold_type_ptr(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_reference(&mut self, i: crate::TypeReference) -> crate::TypeReference {
+        fold_type_reference(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_slice(&mut self, i: crate::TypeSlice) -> crate::TypeSlice {
+        fold_type_slice(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_trait_object(
+        &mut self,
+        i: crate::TypeTraitObject,
+    ) -> crate::TypeTraitObject {
+        fold_type_trait_object(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_type_tuple(&mut self, i: crate::TypeTuple) -> crate::TypeTuple {
+        fold_type_tuple(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_un_op(&mut self, i: crate::UnOp) -> crate::UnOp {
+        fold_un_op(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_use_glob(&mut self, i: crate::UseGlob) -> crate::UseGlob {
+        fold_use_glob(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_use_group(&mut self, i: crate::UseGroup) -> crate::UseGroup {
+        fold_use_group(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_use_name(&mut self, i: crate::UseName) -> crate::UseName {
+        fold_use_name(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_use_path(&mut self, i: crate::UsePath) -> crate::UsePath {
+        fold_use_path(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_use_rename(&mut self, i: crate::UseRename) -> crate::UseRename {
+        fold_use_rename(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_use_tree(&mut self, i: crate::UseTree) -> crate::UseTree {
+        fold_use_tree(self, i)
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn fold_variadic(&mut self, i: crate::Variadic) -> crate::Variadic {
+        fold_variadic(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_variant(&mut self, i: crate::Variant) -> crate::Variant {
+        fold_variant(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_vis_restricted(&mut self, i: crate::VisRestricted) -> crate::VisRestricted {
+        fold_vis_restricted(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_visibility(&mut self, i: crate::Visibility) -> crate::Visibility {
+        fold_visibility(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_where_clause(&mut self, i: crate::WhereClause) -> crate::WhereClause {
+        fold_where_clause(self, i)
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn fold_where_predicate(
+        &mut self,
+        i: crate::WherePredicate,
+    ) -> crate::WherePredicate {
+        fold_where_predicate(self, i)
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_abi<F>(f: &mut F, node: crate::Abi) -> crate::Abi
+where
+    F: Fold + ?Sized,
+{
+    crate::Abi {
+        extern_token: node.extern_token,
+        name: (node.name).map(|it| f.fold_lit_str(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_angle_bracketed_generic_arguments<F>(
+    f: &mut F,
+    node: crate::AngleBracketedGenericArguments,
+) -> crate::AngleBracketedGenericArguments
+where
+    F: Fold + ?Sized,
+{
+    crate::AngleBracketedGenericArguments {
+        colon2_token: node.colon2_token,
+        lt_token: node.lt_token,
+        args: FoldHelper::lift(node.args, |it| f.fold_generic_argument(it)),
+        gt_token: node.gt_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_arm<F>(f: &mut F, node: crate::Arm) -> crate::Arm
+where
+    F: Fold + ?Sized,
+{
+    crate::Arm {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        pat: f.fold_pat(node.pat),
+        guard: (node.guard).map(|it| ((it).0, Box::new(f.fold_expr(*(it).1)))),
+        fat_arrow_token: node.fat_arrow_token,
+        body: Box::new(f.fold_expr(*node.body)),
+        comma: node.comma,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_assoc_const<F>(f: &mut F, node: crate::AssocConst) -> crate::AssocConst
+where
+    F: Fold + ?Sized,
+{
+    crate::AssocConst {
+        ident: f.fold_ident(node.ident),
+        generics: (node.generics).map(|it| f.fold_angle_bracketed_generic_arguments(it)),
+        eq_token: node.eq_token,
+        value: f.fold_expr(node.value),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_assoc_type<F>(f: &mut F, node: crate::AssocType) -> crate::AssocType
+where
+    F: Fold + ?Sized,
+{
+    crate::AssocType {
+        ident: f.fold_ident(node.ident),
+        generics: (node.generics).map(|it| f.fold_angle_bracketed_generic_arguments(it)),
+        eq_token: node.eq_token,
+        ty: f.fold_type(node.ty),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_attr_style<F>(f: &mut F, node: crate::AttrStyle) -> crate::AttrStyle
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::AttrStyle::Outer => crate::AttrStyle::Outer,
+        crate::AttrStyle::Inner(_binding_0) => crate::AttrStyle::Inner(_binding_0),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_attribute<F>(f: &mut F, node: crate::Attribute) -> crate::Attribute
+where
+    F: Fold + ?Sized,
+{
+    crate::Attribute {
+        pound_token: node.pound_token,
+        style: f.fold_attr_style(node.style),
+        bracket_token: node.bracket_token,
+        meta: f.fold_meta(node.meta),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_bare_fn_arg<F>(f: &mut F, node: crate::BareFnArg) -> crate::BareFnArg
+where
+    F: Fold + ?Sized,
+{
+    crate::BareFnArg {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        name: (node.name).map(|it| (f.fold_ident((it).0), (it).1)),
+        ty: f.fold_type(node.ty),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_bare_variadic<F>(f: &mut F, node: crate::BareVariadic) -> crate::BareVariadic
+where
+    F: Fold + ?Sized,
+{
+    crate::BareVariadic {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        name: (node.name).map(|it| (f.fold_ident((it).0), (it).1)),
+        dots: node.dots,
+        comma: node.comma,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_bin_op<F>(f: &mut F, node: crate::BinOp) -> crate::BinOp
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::BinOp::Add(_binding_0) => crate::BinOp::Add(_binding_0),
+        crate::BinOp::Sub(_binding_0) => crate::BinOp::Sub(_binding_0),
+        crate::BinOp::Mul(_binding_0) => crate::BinOp::Mul(_binding_0),
+        crate::BinOp::Div(_binding_0) => crate::BinOp::Div(_binding_0),
+        crate::BinOp::Rem(_binding_0) => crate::BinOp::Rem(_binding_0),
+        crate::BinOp::And(_binding_0) => crate::BinOp::And(_binding_0),
+        crate::BinOp::Or(_binding_0) => crate::BinOp::Or(_binding_0),
+        crate::BinOp::BitXor(_binding_0) => crate::BinOp::BitXor(_binding_0),
+        crate::BinOp::BitAnd(_binding_0) => crate::BinOp::BitAnd(_binding_0),
+        crate::BinOp::BitOr(_binding_0) => crate::BinOp::BitOr(_binding_0),
+        crate::BinOp::Shl(_binding_0) => crate::BinOp::Shl(_binding_0),
+        crate::BinOp::Shr(_binding_0) => crate::BinOp::Shr(_binding_0),
+        crate::BinOp::Eq(_binding_0) => crate::BinOp::Eq(_binding_0),
+        crate::BinOp::Lt(_binding_0) => crate::BinOp::Lt(_binding_0),
+        crate::BinOp::Le(_binding_0) => crate::BinOp::Le(_binding_0),
+        crate::BinOp::Ne(_binding_0) => crate::BinOp::Ne(_binding_0),
+        crate::BinOp::Ge(_binding_0) => crate::BinOp::Ge(_binding_0),
+        crate::BinOp::Gt(_binding_0) => crate::BinOp::Gt(_binding_0),
+        crate::BinOp::AddAssign(_binding_0) => crate::BinOp::AddAssign(_binding_0),
+        crate::BinOp::SubAssign(_binding_0) => crate::BinOp::SubAssign(_binding_0),
+        crate::BinOp::MulAssign(_binding_0) => crate::BinOp::MulAssign(_binding_0),
+        crate::BinOp::DivAssign(_binding_0) => crate::BinOp::DivAssign(_binding_0),
+        crate::BinOp::RemAssign(_binding_0) => crate::BinOp::RemAssign(_binding_0),
+        crate::BinOp::BitXorAssign(_binding_0) => crate::BinOp::BitXorAssign(_binding_0),
+        crate::BinOp::BitAndAssign(_binding_0) => crate::BinOp::BitAndAssign(_binding_0),
+        crate::BinOp::BitOrAssign(_binding_0) => crate::BinOp::BitOrAssign(_binding_0),
+        crate::BinOp::ShlAssign(_binding_0) => crate::BinOp::ShlAssign(_binding_0),
+        crate::BinOp::ShrAssign(_binding_0) => crate::BinOp::ShrAssign(_binding_0),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_block<F>(f: &mut F, node: crate::Block) -> crate::Block
+where
+    F: Fold + ?Sized,
+{
+    crate::Block {
+        brace_token: node.brace_token,
+        stmts: FoldHelper::lift(node.stmts, |it| f.fold_stmt(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_bound_lifetimes<F>(
+    f: &mut F,
+    node: crate::BoundLifetimes,
+) -> crate::BoundLifetimes
+where
+    F: Fold + ?Sized,
+{
+    crate::BoundLifetimes {
+        for_token: node.for_token,
+        lt_token: node.lt_token,
+        lifetimes: FoldHelper::lift(node.lifetimes, |it| f.fold_generic_param(it)),
+        gt_token: node.gt_token,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_const_param<F>(f: &mut F, node: crate::ConstParam) -> crate::ConstParam
+where
+    F: Fold + ?Sized,
+{
+    crate::ConstParam {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        const_token: node.const_token,
+        ident: f.fold_ident(node.ident),
+        colon_token: node.colon_token,
+        ty: f.fold_type(node.ty),
+        eq_token: node.eq_token,
+        default: (node.default).map(|it| f.fold_expr(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_constraint<F>(f: &mut F, node: crate::Constraint) -> crate::Constraint
+where
+    F: Fold + ?Sized,
+{
+    crate::Constraint {
+        ident: f.fold_ident(node.ident),
+        generics: (node.generics).map(|it| f.fold_angle_bracketed_generic_arguments(it)),
+        colon_token: node.colon_token,
+        bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn fold_data<F>(f: &mut F, node: crate::Data) -> crate::Data
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Data::Struct(_binding_0) => {
+            crate::Data::Struct(f.fold_data_struct(_binding_0))
+        }
+        crate::Data::Enum(_binding_0) => crate::Data::Enum(f.fold_data_enum(_binding_0)),
+        crate::Data::Union(_binding_0) => {
+            crate::Data::Union(f.fold_data_union(_binding_0))
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn fold_data_enum<F>(f: &mut F, node: crate::DataEnum) -> crate::DataEnum
+where
+    F: Fold + ?Sized,
+{
+    crate::DataEnum {
+        enum_token: node.enum_token,
+        brace_token: node.brace_token,
+        variants: FoldHelper::lift(node.variants, |it| f.fold_variant(it)),
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn fold_data_struct<F>(f: &mut F, node: crate::DataStruct) -> crate::DataStruct
+where
+    F: Fold + ?Sized,
+{
+    crate::DataStruct {
+        struct_token: node.struct_token,
+        fields: f.fold_fields(node.fields),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn fold_data_union<F>(f: &mut F, node: crate::DataUnion) -> crate::DataUnion
+where
+    F: Fold + ?Sized,
+{
+    crate::DataUnion {
+        union_token: node.union_token,
+        fields: f.fold_fields_named(node.fields),
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn fold_derive_input<F>(f: &mut F, node: crate::DeriveInput) -> crate::DeriveInput
+where
+    F: Fold + ?Sized,
+{
+    crate::DeriveInput {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        data: f.fold_data(node.data),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr<F>(f: &mut F, node: crate::Expr) -> crate::Expr
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Expr::Array(_binding_0) => {
+            crate::Expr::Array(full!(f.fold_expr_array(_binding_0)))
+        }
+        crate::Expr::Assign(_binding_0) => {
+            crate::Expr::Assign(full!(f.fold_expr_assign(_binding_0)))
+        }
+        crate::Expr::Async(_binding_0) => {
+            crate::Expr::Async(full!(f.fold_expr_async(_binding_0)))
+        }
+        crate::Expr::Await(_binding_0) => {
+            crate::Expr::Await(full!(f.fold_expr_await(_binding_0)))
+        }
+        crate::Expr::Binary(_binding_0) => {
+            crate::Expr::Binary(f.fold_expr_binary(_binding_0))
+        }
+        crate::Expr::Block(_binding_0) => {
+            crate::Expr::Block(full!(f.fold_expr_block(_binding_0)))
+        }
+        crate::Expr::Break(_binding_0) => {
+            crate::Expr::Break(full!(f.fold_expr_break(_binding_0)))
+        }
+        crate::Expr::Call(_binding_0) => crate::Expr::Call(f.fold_expr_call(_binding_0)),
+        crate::Expr::Cast(_binding_0) => crate::Expr::Cast(f.fold_expr_cast(_binding_0)),
+        crate::Expr::Closure(_binding_0) => {
+            crate::Expr::Closure(full!(f.fold_expr_closure(_binding_0)))
+        }
+        crate::Expr::Const(_binding_0) => {
+            crate::Expr::Const(full!(f.fold_expr_const(_binding_0)))
+        }
+        crate::Expr::Continue(_binding_0) => {
+            crate::Expr::Continue(full!(f.fold_expr_continue(_binding_0)))
+        }
+        crate::Expr::Field(_binding_0) => {
+            crate::Expr::Field(f.fold_expr_field(_binding_0))
+        }
+        crate::Expr::ForLoop(_binding_0) => {
+            crate::Expr::ForLoop(full!(f.fold_expr_for_loop(_binding_0)))
+        }
+        crate::Expr::Group(_binding_0) => {
+            crate::Expr::Group(f.fold_expr_group(_binding_0))
+        }
+        crate::Expr::If(_binding_0) => crate::Expr::If(full!(f.fold_expr_if(_binding_0))),
+        crate::Expr::Index(_binding_0) => {
+            crate::Expr::Index(f.fold_expr_index(_binding_0))
+        }
+        crate::Expr::Infer(_binding_0) => {
+            crate::Expr::Infer(full!(f.fold_expr_infer(_binding_0)))
+        }
+        crate::Expr::Let(_binding_0) => {
+            crate::Expr::Let(full!(f.fold_expr_let(_binding_0)))
+        }
+        crate::Expr::Lit(_binding_0) => crate::Expr::Lit(f.fold_expr_lit(_binding_0)),
+        crate::Expr::Loop(_binding_0) => {
+            crate::Expr::Loop(full!(f.fold_expr_loop(_binding_0)))
+        }
+        crate::Expr::Macro(_binding_0) => {
+            crate::Expr::Macro(f.fold_expr_macro(_binding_0))
+        }
+        crate::Expr::Match(_binding_0) => {
+            crate::Expr::Match(full!(f.fold_expr_match(_binding_0)))
+        }
+        crate::Expr::MethodCall(_binding_0) => {
+            crate::Expr::MethodCall(f.fold_expr_method_call(_binding_0))
+        }
+        crate::Expr::Paren(_binding_0) => {
+            crate::Expr::Paren(f.fold_expr_paren(_binding_0))
+        }
+        crate::Expr::Path(_binding_0) => crate::Expr::Path(f.fold_expr_path(_binding_0)),
+        crate::Expr::Range(_binding_0) => {
+            crate::Expr::Range(full!(f.fold_expr_range(_binding_0)))
+        }
+        crate::Expr::Reference(_binding_0) => {
+            crate::Expr::Reference(f.fold_expr_reference(_binding_0))
+        }
+        crate::Expr::Repeat(_binding_0) => {
+            crate::Expr::Repeat(full!(f.fold_expr_repeat(_binding_0)))
+        }
+        crate::Expr::Return(_binding_0) => {
+            crate::Expr::Return(full!(f.fold_expr_return(_binding_0)))
+        }
+        crate::Expr::Struct(_binding_0) => {
+            crate::Expr::Struct(f.fold_expr_struct(_binding_0))
+        }
+        crate::Expr::Try(_binding_0) => {
+            crate::Expr::Try(full!(f.fold_expr_try(_binding_0)))
+        }
+        crate::Expr::TryBlock(_binding_0) => {
+            crate::Expr::TryBlock(full!(f.fold_expr_try_block(_binding_0)))
+        }
+        crate::Expr::Tuple(_binding_0) => {
+            crate::Expr::Tuple(full!(f.fold_expr_tuple(_binding_0)))
+        }
+        crate::Expr::Unary(_binding_0) => {
+            crate::Expr::Unary(f.fold_expr_unary(_binding_0))
+        }
+        crate::Expr::Unsafe(_binding_0) => {
+            crate::Expr::Unsafe(full!(f.fold_expr_unsafe(_binding_0)))
+        }
+        crate::Expr::Verbatim(_binding_0) => crate::Expr::Verbatim(_binding_0),
+        crate::Expr::While(_binding_0) => {
+            crate::Expr::While(full!(f.fold_expr_while(_binding_0)))
+        }
+        crate::Expr::Yield(_binding_0) => {
+            crate::Expr::Yield(full!(f.fold_expr_yield(_binding_0)))
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_array<F>(f: &mut F, node: crate::ExprArray) -> crate::ExprArray
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprArray {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        bracket_token: node.bracket_token,
+        elems: FoldHelper::lift(node.elems, |it| f.fold_expr(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_assign<F>(f: &mut F, node: crate::ExprAssign) -> crate::ExprAssign
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprAssign {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        left: Box::new(f.fold_expr(*node.left)),
+        eq_token: node.eq_token,
+        right: Box::new(f.fold_expr(*node.right)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_async<F>(f: &mut F, node: crate::ExprAsync) -> crate::ExprAsync
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprAsync {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        async_token: node.async_token,
+        capture: node.capture,
+        block: f.fold_block(node.block),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_await<F>(f: &mut F, node: crate::ExprAwait) -> crate::ExprAwait
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprAwait {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        base: Box::new(f.fold_expr(*node.base)),
+        dot_token: node.dot_token,
+        await_token: node.await_token,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_binary<F>(f: &mut F, node: crate::ExprBinary) -> crate::ExprBinary
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprBinary {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        left: Box::new(f.fold_expr(*node.left)),
+        op: f.fold_bin_op(node.op),
+        right: Box::new(f.fold_expr(*node.right)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_block<F>(f: &mut F, node: crate::ExprBlock) -> crate::ExprBlock
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprBlock {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        label: (node.label).map(|it| f.fold_label(it)),
+        block: f.fold_block(node.block),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_break<F>(f: &mut F, node: crate::ExprBreak) -> crate::ExprBreak
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprBreak {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        break_token: node.break_token,
+        label: (node.label).map(|it| f.fold_lifetime(it)),
+        expr: (node.expr).map(|it| Box::new(f.fold_expr(*it))),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_call<F>(f: &mut F, node: crate::ExprCall) -> crate::ExprCall
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprCall {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        func: Box::new(f.fold_expr(*node.func)),
+        paren_token: node.paren_token,
+        args: FoldHelper::lift(node.args, |it| f.fold_expr(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_cast<F>(f: &mut F, node: crate::ExprCast) -> crate::ExprCast
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprCast {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        expr: Box::new(f.fold_expr(*node.expr)),
+        as_token: node.as_token,
+        ty: Box::new(f.fold_type(*node.ty)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_closure<F>(f: &mut F, node: crate::ExprClosure) -> crate::ExprClosure
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprClosure {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        lifetimes: (node.lifetimes).map(|it| f.fold_bound_lifetimes(it)),
+        constness: node.constness,
+        movability: node.movability,
+        asyncness: node.asyncness,
+        capture: node.capture,
+        or1_token: node.or1_token,
+        inputs: FoldHelper::lift(node.inputs, |it| f.fold_pat(it)),
+        or2_token: node.or2_token,
+        output: f.fold_return_type(node.output),
+        body: Box::new(f.fold_expr(*node.body)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_const<F>(f: &mut F, node: crate::ExprConst) -> crate::ExprConst
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprConst {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        const_token: node.const_token,
+        block: f.fold_block(node.block),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_continue<F>(f: &mut F, node: crate::ExprContinue) -> crate::ExprContinue
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprContinue {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        continue_token: node.continue_token,
+        label: (node.label).map(|it| f.fold_lifetime(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_field<F>(f: &mut F, node: crate::ExprField) -> crate::ExprField
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprField {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        base: Box::new(f.fold_expr(*node.base)),
+        dot_token: node.dot_token,
+        member: f.fold_member(node.member),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_for_loop<F>(f: &mut F, node: crate::ExprForLoop) -> crate::ExprForLoop
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprForLoop {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        label: (node.label).map(|it| f.fold_label(it)),
+        for_token: node.for_token,
+        pat: Box::new(f.fold_pat(*node.pat)),
+        in_token: node.in_token,
+        expr: Box::new(f.fold_expr(*node.expr)),
+        body: f.fold_block(node.body),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_group<F>(f: &mut F, node: crate::ExprGroup) -> crate::ExprGroup
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprGroup {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        group_token: node.group_token,
+        expr: Box::new(f.fold_expr(*node.expr)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_if<F>(f: &mut F, node: crate::ExprIf) -> crate::ExprIf
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprIf {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        if_token: node.if_token,
+        cond: Box::new(f.fold_expr(*node.cond)),
+        then_branch: f.fold_block(node.then_branch),
+        else_branch: (node.else_branch)
+            .map(|it| ((it).0, Box::new(f.fold_expr(*(it).1)))),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_index<F>(f: &mut F, node: crate::ExprIndex) -> crate::ExprIndex
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprIndex {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        expr: Box::new(f.fold_expr(*node.expr)),
+        bracket_token: node.bracket_token,
+        index: Box::new(f.fold_expr(*node.index)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_infer<F>(f: &mut F, node: crate::ExprInfer) -> crate::ExprInfer
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprInfer {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        underscore_token: node.underscore_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_let<F>(f: &mut F, node: crate::ExprLet) -> crate::ExprLet
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprLet {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        let_token: node.let_token,
+        pat: Box::new(f.fold_pat(*node.pat)),
+        eq_token: node.eq_token,
+        expr: Box::new(f.fold_expr(*node.expr)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_lit<F>(f: &mut F, node: crate::ExprLit) -> crate::ExprLit
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprLit {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        lit: f.fold_lit(node.lit),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_loop<F>(f: &mut F, node: crate::ExprLoop) -> crate::ExprLoop
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprLoop {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        label: (node.label).map(|it| f.fold_label(it)),
+        loop_token: node.loop_token,
+        body: f.fold_block(node.body),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_macro<F>(f: &mut F, node: crate::ExprMacro) -> crate::ExprMacro
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprMacro {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        mac: f.fold_macro(node.mac),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_match<F>(f: &mut F, node: crate::ExprMatch) -> crate::ExprMatch
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprMatch {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        match_token: node.match_token,
+        expr: Box::new(f.fold_expr(*node.expr)),
+        brace_token: node.brace_token,
+        arms: FoldHelper::lift(node.arms, |it| f.fold_arm(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_method_call<F>(
+    f: &mut F,
+    node: crate::ExprMethodCall,
+) -> crate::ExprMethodCall
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprMethodCall {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        receiver: Box::new(f.fold_expr(*node.receiver)),
+        dot_token: node.dot_token,
+        method: f.fold_ident(node.method),
+        turbofish: (node.turbofish)
+            .map(|it| f.fold_angle_bracketed_generic_arguments(it)),
+        paren_token: node.paren_token,
+        args: FoldHelper::lift(node.args, |it| f.fold_expr(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_paren<F>(f: &mut F, node: crate::ExprParen) -> crate::ExprParen
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprParen {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        paren_token: node.paren_token,
+        expr: Box::new(f.fold_expr(*node.expr)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_path<F>(f: &mut F, node: crate::ExprPath) -> crate::ExprPath
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprPath {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        qself: (node.qself).map(|it| f.fold_qself(it)),
+        path: f.fold_path(node.path),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_range<F>(f: &mut F, node: crate::ExprRange) -> crate::ExprRange
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprRange {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        start: (node.start).map(|it| Box::new(f.fold_expr(*it))),
+        limits: f.fold_range_limits(node.limits),
+        end: (node.end).map(|it| Box::new(f.fold_expr(*it))),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_reference<F>(
+    f: &mut F,
+    node: crate::ExprReference,
+) -> crate::ExprReference
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprReference {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        and_token: node.and_token,
+        mutability: node.mutability,
+        expr: Box::new(f.fold_expr(*node.expr)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_repeat<F>(f: &mut F, node: crate::ExprRepeat) -> crate::ExprRepeat
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprRepeat {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        bracket_token: node.bracket_token,
+        expr: Box::new(f.fold_expr(*node.expr)),
+        semi_token: node.semi_token,
+        len: Box::new(f.fold_expr(*node.len)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_return<F>(f: &mut F, node: crate::ExprReturn) -> crate::ExprReturn
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprReturn {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        return_token: node.return_token,
+        expr: (node.expr).map(|it| Box::new(f.fold_expr(*it))),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_struct<F>(f: &mut F, node: crate::ExprStruct) -> crate::ExprStruct
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprStruct {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        qself: (node.qself).map(|it| f.fold_qself(it)),
+        path: f.fold_path(node.path),
+        brace_token: node.brace_token,
+        fields: FoldHelper::lift(node.fields, |it| f.fold_field_value(it)),
+        dot2_token: node.dot2_token,
+        rest: (node.rest).map(|it| Box::new(f.fold_expr(*it))),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_try<F>(f: &mut F, node: crate::ExprTry) -> crate::ExprTry
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprTry {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        expr: Box::new(f.fold_expr(*node.expr)),
+        question_token: node.question_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_try_block<F>(
+    f: &mut F,
+    node: crate::ExprTryBlock,
+) -> crate::ExprTryBlock
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprTryBlock {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        try_token: node.try_token,
+        block: f.fold_block(node.block),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_tuple<F>(f: &mut F, node: crate::ExprTuple) -> crate::ExprTuple
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprTuple {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        paren_token: node.paren_token,
+        elems: FoldHelper::lift(node.elems, |it| f.fold_expr(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_expr_unary<F>(f: &mut F, node: crate::ExprUnary) -> crate::ExprUnary
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprUnary {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        op: f.fold_un_op(node.op),
+        expr: Box::new(f.fold_expr(*node.expr)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_unsafe<F>(f: &mut F, node: crate::ExprUnsafe) -> crate::ExprUnsafe
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprUnsafe {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        unsafe_token: node.unsafe_token,
+        block: f.fold_block(node.block),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_while<F>(f: &mut F, node: crate::ExprWhile) -> crate::ExprWhile
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprWhile {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        label: (node.label).map(|it| f.fold_label(it)),
+        while_token: node.while_token,
+        cond: Box::new(f.fold_expr(*node.cond)),
+        body: f.fold_block(node.body),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_expr_yield<F>(f: &mut F, node: crate::ExprYield) -> crate::ExprYield
+where
+    F: Fold + ?Sized,
+{
+    crate::ExprYield {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        yield_token: node.yield_token,
+        expr: (node.expr).map(|it| Box::new(f.fold_expr(*it))),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_field<F>(f: &mut F, node: crate::Field) -> crate::Field
+where
+    F: Fold + ?Sized,
+{
+    crate::Field {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        mutability: f.fold_field_mutability(node.mutability),
+        ident: (node.ident).map(|it| f.fold_ident(it)),
+        colon_token: node.colon_token,
+        ty: f.fold_type(node.ty),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_field_mutability<F>(
+    f: &mut F,
+    node: crate::FieldMutability,
+) -> crate::FieldMutability
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::FieldMutability::None => crate::FieldMutability::None,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_field_pat<F>(f: &mut F, node: crate::FieldPat) -> crate::FieldPat
+where
+    F: Fold + ?Sized,
+{
+    crate::FieldPat {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        member: f.fold_member(node.member),
+        colon_token: node.colon_token,
+        pat: Box::new(f.fold_pat(*node.pat)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_field_value<F>(f: &mut F, node: crate::FieldValue) -> crate::FieldValue
+where
+    F: Fold + ?Sized,
+{
+    crate::FieldValue {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        member: f.fold_member(node.member),
+        colon_token: node.colon_token,
+        expr: f.fold_expr(node.expr),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_fields<F>(f: &mut F, node: crate::Fields) -> crate::Fields
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Fields::Named(_binding_0) => {
+            crate::Fields::Named(f.fold_fields_named(_binding_0))
+        }
+        crate::Fields::Unnamed(_binding_0) => {
+            crate::Fields::Unnamed(f.fold_fields_unnamed(_binding_0))
+        }
+        crate::Fields::Unit => crate::Fields::Unit,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_fields_named<F>(f: &mut F, node: crate::FieldsNamed) -> crate::FieldsNamed
+where
+    F: Fold + ?Sized,
+{
+    crate::FieldsNamed {
+        brace_token: node.brace_token,
+        named: FoldHelper::lift(node.named, |it| f.fold_field(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_fields_unnamed<F>(
+    f: &mut F,
+    node: crate::FieldsUnnamed,
+) -> crate::FieldsUnnamed
+where
+    F: Fold + ?Sized,
+{
+    crate::FieldsUnnamed {
+        paren_token: node.paren_token,
+        unnamed: FoldHelper::lift(node.unnamed, |it| f.fold_field(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_file<F>(f: &mut F, node: crate::File) -> crate::File
+where
+    F: Fold + ?Sized,
+{
+    crate::File {
+        shebang: node.shebang,
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        items: FoldHelper::lift(node.items, |it| f.fold_item(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_fn_arg<F>(f: &mut F, node: crate::FnArg) -> crate::FnArg
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::FnArg::Receiver(_binding_0) => {
+            crate::FnArg::Receiver(f.fold_receiver(_binding_0))
+        }
+        crate::FnArg::Typed(_binding_0) => {
+            crate::FnArg::Typed(f.fold_pat_type(_binding_0))
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_foreign_item<F>(f: &mut F, node: crate::ForeignItem) -> crate::ForeignItem
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::ForeignItem::Fn(_binding_0) => {
+            crate::ForeignItem::Fn(f.fold_foreign_item_fn(_binding_0))
+        }
+        crate::ForeignItem::Static(_binding_0) => {
+            crate::ForeignItem::Static(f.fold_foreign_item_static(_binding_0))
+        }
+        crate::ForeignItem::Type(_binding_0) => {
+            crate::ForeignItem::Type(f.fold_foreign_item_type(_binding_0))
+        }
+        crate::ForeignItem::Macro(_binding_0) => {
+            crate::ForeignItem::Macro(f.fold_foreign_item_macro(_binding_0))
+        }
+        crate::ForeignItem::Verbatim(_binding_0) => {
+            crate::ForeignItem::Verbatim(_binding_0)
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_foreign_item_fn<F>(
+    f: &mut F,
+    node: crate::ForeignItemFn,
+) -> crate::ForeignItemFn
+where
+    F: Fold + ?Sized,
+{
+    crate::ForeignItemFn {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        sig: f.fold_signature(node.sig),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_foreign_item_macro<F>(
+    f: &mut F,
+    node: crate::ForeignItemMacro,
+) -> crate::ForeignItemMacro
+where
+    F: Fold + ?Sized,
+{
+    crate::ForeignItemMacro {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        mac: f.fold_macro(node.mac),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_foreign_item_static<F>(
+    f: &mut F,
+    node: crate::ForeignItemStatic,
+) -> crate::ForeignItemStatic
+where
+    F: Fold + ?Sized,
+{
+    crate::ForeignItemStatic {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        static_token: node.static_token,
+        mutability: f.fold_static_mutability(node.mutability),
+        ident: f.fold_ident(node.ident),
+        colon_token: node.colon_token,
+        ty: Box::new(f.fold_type(*node.ty)),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_foreign_item_type<F>(
+    f: &mut F,
+    node: crate::ForeignItemType,
+) -> crate::ForeignItemType
+where
+    F: Fold + ?Sized,
+{
+    crate::ForeignItemType {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        type_token: node.type_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_generic_argument<F>(
+    f: &mut F,
+    node: crate::GenericArgument,
+) -> crate::GenericArgument
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::GenericArgument::Lifetime(_binding_0) => {
+            crate::GenericArgument::Lifetime(f.fold_lifetime(_binding_0))
+        }
+        crate::GenericArgument::Type(_binding_0) => {
+            crate::GenericArgument::Type(f.fold_type(_binding_0))
+        }
+        crate::GenericArgument::Const(_binding_0) => {
+            crate::GenericArgument::Const(f.fold_expr(_binding_0))
+        }
+        crate::GenericArgument::AssocType(_binding_0) => {
+            crate::GenericArgument::AssocType(f.fold_assoc_type(_binding_0))
+        }
+        crate::GenericArgument::AssocConst(_binding_0) => {
+            crate::GenericArgument::AssocConst(f.fold_assoc_const(_binding_0))
+        }
+        crate::GenericArgument::Constraint(_binding_0) => {
+            crate::GenericArgument::Constraint(f.fold_constraint(_binding_0))
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_generic_param<F>(f: &mut F, node: crate::GenericParam) -> crate::GenericParam
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::GenericParam::Lifetime(_binding_0) => {
+            crate::GenericParam::Lifetime(f.fold_lifetime_param(_binding_0))
+        }
+        crate::GenericParam::Type(_binding_0) => {
+            crate::GenericParam::Type(f.fold_type_param(_binding_0))
+        }
+        crate::GenericParam::Const(_binding_0) => {
+            crate::GenericParam::Const(f.fold_const_param(_binding_0))
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_generics<F>(f: &mut F, node: crate::Generics) -> crate::Generics
+where
+    F: Fold + ?Sized,
+{
+    crate::Generics {
+        lt_token: node.lt_token,
+        params: FoldHelper::lift(node.params, |it| f.fold_generic_param(it)),
+        gt_token: node.gt_token,
+        where_clause: (node.where_clause).map(|it| f.fold_where_clause(it)),
+    }
+}
+pub fn fold_ident<F>(f: &mut F, node: proc_macro2::Ident) -> proc_macro2::Ident
+where
+    F: Fold + ?Sized,
+{
+    let mut node = node;
+    let span = f.fold_span(node.span());
+    node.set_span(span);
+    node
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_impl_item<F>(f: &mut F, node: crate::ImplItem) -> crate::ImplItem
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::ImplItem::Const(_binding_0) => {
+            crate::ImplItem::Const(f.fold_impl_item_const(_binding_0))
+        }
+        crate::ImplItem::Fn(_binding_0) => {
+            crate::ImplItem::Fn(f.fold_impl_item_fn(_binding_0))
+        }
+        crate::ImplItem::Type(_binding_0) => {
+            crate::ImplItem::Type(f.fold_impl_item_type(_binding_0))
+        }
+        crate::ImplItem::Macro(_binding_0) => {
+            crate::ImplItem::Macro(f.fold_impl_item_macro(_binding_0))
+        }
+        crate::ImplItem::Verbatim(_binding_0) => crate::ImplItem::Verbatim(_binding_0),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_impl_item_const<F>(
+    f: &mut F,
+    node: crate::ImplItemConst,
+) -> crate::ImplItemConst
+where
+    F: Fold + ?Sized,
+{
+    crate::ImplItemConst {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        defaultness: node.defaultness,
+        const_token: node.const_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        colon_token: node.colon_token,
+        ty: f.fold_type(node.ty),
+        eq_token: node.eq_token,
+        expr: f.fold_expr(node.expr),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_impl_item_fn<F>(f: &mut F, node: crate::ImplItemFn) -> crate::ImplItemFn
+where
+    F: Fold + ?Sized,
+{
+    crate::ImplItemFn {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        defaultness: node.defaultness,
+        sig: f.fold_signature(node.sig),
+        block: f.fold_block(node.block),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_impl_item_macro<F>(
+    f: &mut F,
+    node: crate::ImplItemMacro,
+) -> crate::ImplItemMacro
+where
+    F: Fold + ?Sized,
+{
+    crate::ImplItemMacro {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        mac: f.fold_macro(node.mac),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_impl_item_type<F>(
+    f: &mut F,
+    node: crate::ImplItemType,
+) -> crate::ImplItemType
+where
+    F: Fold + ?Sized,
+{
+    crate::ImplItemType {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        defaultness: node.defaultness,
+        type_token: node.type_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        eq_token: node.eq_token,
+        ty: f.fold_type(node.ty),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_impl_restriction<F>(
+    f: &mut F,
+    node: crate::ImplRestriction,
+) -> crate::ImplRestriction
+where
+    F: Fold + ?Sized,
+{
+    match node {}
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_index<F>(f: &mut F, node: crate::Index) -> crate::Index
+where
+    F: Fold + ?Sized,
+{
+    crate::Index {
+        index: node.index,
+        span: f.fold_span(node.span),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item<F>(f: &mut F, node: crate::Item) -> crate::Item
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Item::Const(_binding_0) => {
+            crate::Item::Const(f.fold_item_const(_binding_0))
+        }
+        crate::Item::Enum(_binding_0) => crate::Item::Enum(f.fold_item_enum(_binding_0)),
+        crate::Item::ExternCrate(_binding_0) => {
+            crate::Item::ExternCrate(f.fold_item_extern_crate(_binding_0))
+        }
+        crate::Item::Fn(_binding_0) => crate::Item::Fn(f.fold_item_fn(_binding_0)),
+        crate::Item::ForeignMod(_binding_0) => {
+            crate::Item::ForeignMod(f.fold_item_foreign_mod(_binding_0))
+        }
+        crate::Item::Impl(_binding_0) => crate::Item::Impl(f.fold_item_impl(_binding_0)),
+        crate::Item::Macro(_binding_0) => {
+            crate::Item::Macro(f.fold_item_macro(_binding_0))
+        }
+        crate::Item::Mod(_binding_0) => crate::Item::Mod(f.fold_item_mod(_binding_0)),
+        crate::Item::Static(_binding_0) => {
+            crate::Item::Static(f.fold_item_static(_binding_0))
+        }
+        crate::Item::Struct(_binding_0) => {
+            crate::Item::Struct(f.fold_item_struct(_binding_0))
+        }
+        crate::Item::Trait(_binding_0) => {
+            crate::Item::Trait(f.fold_item_trait(_binding_0))
+        }
+        crate::Item::TraitAlias(_binding_0) => {
+            crate::Item::TraitAlias(f.fold_item_trait_alias(_binding_0))
+        }
+        crate::Item::Type(_binding_0) => crate::Item::Type(f.fold_item_type(_binding_0)),
+        crate::Item::Union(_binding_0) => {
+            crate::Item::Union(f.fold_item_union(_binding_0))
+        }
+        crate::Item::Use(_binding_0) => crate::Item::Use(f.fold_item_use(_binding_0)),
+        crate::Item::Verbatim(_binding_0) => crate::Item::Verbatim(_binding_0),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_const<F>(f: &mut F, node: crate::ItemConst) -> crate::ItemConst
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemConst {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        const_token: node.const_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        colon_token: node.colon_token,
+        ty: Box::new(f.fold_type(*node.ty)),
+        eq_token: node.eq_token,
+        expr: Box::new(f.fold_expr(*node.expr)),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_enum<F>(f: &mut F, node: crate::ItemEnum) -> crate::ItemEnum
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemEnum {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        enum_token: node.enum_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        brace_token: node.brace_token,
+        variants: FoldHelper::lift(node.variants, |it| f.fold_variant(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_extern_crate<F>(
+    f: &mut F,
+    node: crate::ItemExternCrate,
+) -> crate::ItemExternCrate
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemExternCrate {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        extern_token: node.extern_token,
+        crate_token: node.crate_token,
+        ident: f.fold_ident(node.ident),
+        rename: (node.rename).map(|it| ((it).0, f.fold_ident((it).1))),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_fn<F>(f: &mut F, node: crate::ItemFn) -> crate::ItemFn
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemFn {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        sig: f.fold_signature(node.sig),
+        block: Box::new(f.fold_block(*node.block)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_foreign_mod<F>(
+    f: &mut F,
+    node: crate::ItemForeignMod,
+) -> crate::ItemForeignMod
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemForeignMod {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        unsafety: node.unsafety,
+        abi: f.fold_abi(node.abi),
+        brace_token: node.brace_token,
+        items: FoldHelper::lift(node.items, |it| f.fold_foreign_item(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_impl<F>(f: &mut F, node: crate::ItemImpl) -> crate::ItemImpl
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemImpl {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        defaultness: node.defaultness,
+        unsafety: node.unsafety,
+        impl_token: node.impl_token,
+        generics: f.fold_generics(node.generics),
+        trait_: (node.trait_).map(|it| ((it).0, f.fold_path((it).1), (it).2)),
+        self_ty: Box::new(f.fold_type(*node.self_ty)),
+        brace_token: node.brace_token,
+        items: FoldHelper::lift(node.items, |it| f.fold_impl_item(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_macro<F>(f: &mut F, node: crate::ItemMacro) -> crate::ItemMacro
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemMacro {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        ident: (node.ident).map(|it| f.fold_ident(it)),
+        mac: f.fold_macro(node.mac),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_mod<F>(f: &mut F, node: crate::ItemMod) -> crate::ItemMod
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemMod {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        unsafety: node.unsafety,
+        mod_token: node.mod_token,
+        ident: f.fold_ident(node.ident),
+        content: (node.content)
+            .map(|it| ((it).0, FoldHelper::lift((it).1, |it| f.fold_item(it)))),
+        semi: node.semi,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_static<F>(f: &mut F, node: crate::ItemStatic) -> crate::ItemStatic
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemStatic {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        static_token: node.static_token,
+        mutability: f.fold_static_mutability(node.mutability),
+        ident: f.fold_ident(node.ident),
+        colon_token: node.colon_token,
+        ty: Box::new(f.fold_type(*node.ty)),
+        eq_token: node.eq_token,
+        expr: Box::new(f.fold_expr(*node.expr)),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_struct<F>(f: &mut F, node: crate::ItemStruct) -> crate::ItemStruct
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemStruct {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        struct_token: node.struct_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        fields: f.fold_fields(node.fields),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_trait<F>(f: &mut F, node: crate::ItemTrait) -> crate::ItemTrait
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemTrait {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        unsafety: node.unsafety,
+        auto_token: node.auto_token,
+        restriction: (node.restriction).map(|it| f.fold_impl_restriction(it)),
+        trait_token: node.trait_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        colon_token: node.colon_token,
+        supertraits: FoldHelper::lift(
+            node.supertraits,
+            |it| f.fold_type_param_bound(it),
+        ),
+        brace_token: node.brace_token,
+        items: FoldHelper::lift(node.items, |it| f.fold_trait_item(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_trait_alias<F>(
+    f: &mut F,
+    node: crate::ItemTraitAlias,
+) -> crate::ItemTraitAlias
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemTraitAlias {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        trait_token: node.trait_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        eq_token: node.eq_token,
+        bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_type<F>(f: &mut F, node: crate::ItemType) -> crate::ItemType
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemType {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        type_token: node.type_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        eq_token: node.eq_token,
+        ty: Box::new(f.fold_type(*node.ty)),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_union<F>(f: &mut F, node: crate::ItemUnion) -> crate::ItemUnion
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemUnion {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        union_token: node.union_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        fields: f.fold_fields_named(node.fields),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_item_use<F>(f: &mut F, node: crate::ItemUse) -> crate::ItemUse
+where
+    F: Fold + ?Sized,
+{
+    crate::ItemUse {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        vis: f.fold_visibility(node.vis),
+        use_token: node.use_token,
+        leading_colon: node.leading_colon,
+        tree: f.fold_use_tree(node.tree),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_label<F>(f: &mut F, node: crate::Label) -> crate::Label
+where
+    F: Fold + ?Sized,
+{
+    crate::Label {
+        name: f.fold_lifetime(node.name),
+        colon_token: node.colon_token,
+    }
+}
+pub fn fold_lifetime<F>(f: &mut F, node: crate::Lifetime) -> crate::Lifetime
+where
+    F: Fold + ?Sized,
+{
+    crate::Lifetime {
+        apostrophe: f.fold_span(node.apostrophe),
+        ident: f.fold_ident(node.ident),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_lifetime_param<F>(
+    f: &mut F,
+    node: crate::LifetimeParam,
+) -> crate::LifetimeParam
+where
+    F: Fold + ?Sized,
+{
+    crate::LifetimeParam {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        lifetime: f.fold_lifetime(node.lifetime),
+        colon_token: node.colon_token,
+        bounds: FoldHelper::lift(node.bounds, |it| f.fold_lifetime(it)),
+    }
+}
+pub fn fold_lit<F>(f: &mut F, node: crate::Lit) -> crate::Lit
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Lit::Str(_binding_0) => crate::Lit::Str(f.fold_lit_str(_binding_0)),
+        crate::Lit::ByteStr(_binding_0) => {
+            crate::Lit::ByteStr(f.fold_lit_byte_str(_binding_0))
+        }
+        crate::Lit::Byte(_binding_0) => crate::Lit::Byte(f.fold_lit_byte(_binding_0)),
+        crate::Lit::Char(_binding_0) => crate::Lit::Char(f.fold_lit_char(_binding_0)),
+        crate::Lit::Int(_binding_0) => crate::Lit::Int(f.fold_lit_int(_binding_0)),
+        crate::Lit::Float(_binding_0) => crate::Lit::Float(f.fold_lit_float(_binding_0)),
+        crate::Lit::Bool(_binding_0) => crate::Lit::Bool(f.fold_lit_bool(_binding_0)),
+        crate::Lit::Verbatim(_binding_0) => crate::Lit::Verbatim(_binding_0),
+    }
+}
+pub fn fold_lit_bool<F>(f: &mut F, node: crate::LitBool) -> crate::LitBool
+where
+    F: Fold + ?Sized,
+{
+    crate::LitBool {
+        value: node.value,
+        span: f.fold_span(node.span),
+    }
+}
+pub fn fold_lit_byte<F>(f: &mut F, node: crate::LitByte) -> crate::LitByte
+where
+    F: Fold + ?Sized,
+{
+    let span = f.fold_span(node.span());
+    let mut node = node;
+    node.set_span(span);
+    node
+}
+pub fn fold_lit_byte_str<F>(f: &mut F, node: crate::LitByteStr) -> crate::LitByteStr
+where
+    F: Fold + ?Sized,
+{
+    let span = f.fold_span(node.span());
+    let mut node = node;
+    node.set_span(span);
+    node
+}
+pub fn fold_lit_char<F>(f: &mut F, node: crate::LitChar) -> crate::LitChar
+where
+    F: Fold + ?Sized,
+{
+    let span = f.fold_span(node.span());
+    let mut node = node;
+    node.set_span(span);
+    node
+}
+pub fn fold_lit_float<F>(f: &mut F, node: crate::LitFloat) -> crate::LitFloat
+where
+    F: Fold + ?Sized,
+{
+    let span = f.fold_span(node.span());
+    let mut node = node;
+    node.set_span(span);
+    node
+}
+pub fn fold_lit_int<F>(f: &mut F, node: crate::LitInt) -> crate::LitInt
+where
+    F: Fold + ?Sized,
+{
+    let span = f.fold_span(node.span());
+    let mut node = node;
+    node.set_span(span);
+    node
+}
+pub fn fold_lit_str<F>(f: &mut F, node: crate::LitStr) -> crate::LitStr
+where
+    F: Fold + ?Sized,
+{
+    let span = f.fold_span(node.span());
+    let mut node = node;
+    node.set_span(span);
+    node
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_local<F>(f: &mut F, node: crate::Local) -> crate::Local
+where
+    F: Fold + ?Sized,
+{
+    crate::Local {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        let_token: node.let_token,
+        pat: f.fold_pat(node.pat),
+        init: (node.init).map(|it| f.fold_local_init(it)),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_local_init<F>(f: &mut F, node: crate::LocalInit) -> crate::LocalInit
+where
+    F: Fold + ?Sized,
+{
+    crate::LocalInit {
+        eq_token: node.eq_token,
+        expr: Box::new(f.fold_expr(*node.expr)),
+        diverge: (node.diverge).map(|it| ((it).0, Box::new(f.fold_expr(*(it).1)))),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_macro<F>(f: &mut F, node: crate::Macro) -> crate::Macro
+where
+    F: Fold + ?Sized,
+{
+    crate::Macro {
+        path: f.fold_path(node.path),
+        bang_token: node.bang_token,
+        delimiter: f.fold_macro_delimiter(node.delimiter),
+        tokens: node.tokens,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_macro_delimiter<F>(
+    f: &mut F,
+    node: crate::MacroDelimiter,
+) -> crate::MacroDelimiter
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::MacroDelimiter::Paren(_binding_0) => {
+            crate::MacroDelimiter::Paren(_binding_0)
+        }
+        crate::MacroDelimiter::Brace(_binding_0) => {
+            crate::MacroDelimiter::Brace(_binding_0)
+        }
+        crate::MacroDelimiter::Bracket(_binding_0) => {
+            crate::MacroDelimiter::Bracket(_binding_0)
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_member<F>(f: &mut F, node: crate::Member) -> crate::Member
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Member::Named(_binding_0) => {
+            crate::Member::Named(f.fold_ident(_binding_0))
+        }
+        crate::Member::Unnamed(_binding_0) => {
+            crate::Member::Unnamed(f.fold_index(_binding_0))
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_meta<F>(f: &mut F, node: crate::Meta) -> crate::Meta
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Meta::Path(_binding_0) => crate::Meta::Path(f.fold_path(_binding_0)),
+        crate::Meta::List(_binding_0) => crate::Meta::List(f.fold_meta_list(_binding_0)),
+        crate::Meta::NameValue(_binding_0) => {
+            crate::Meta::NameValue(f.fold_meta_name_value(_binding_0))
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_meta_list<F>(f: &mut F, node: crate::MetaList) -> crate::MetaList
+where
+    F: Fold + ?Sized,
+{
+    crate::MetaList {
+        path: f.fold_path(node.path),
+        delimiter: f.fold_macro_delimiter(node.delimiter),
+        tokens: node.tokens,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_meta_name_value<F>(
+    f: &mut F,
+    node: crate::MetaNameValue,
+) -> crate::MetaNameValue
+where
+    F: Fold + ?Sized,
+{
+    crate::MetaNameValue {
+        path: f.fold_path(node.path),
+        eq_token: node.eq_token,
+        value: f.fold_expr(node.value),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_parenthesized_generic_arguments<F>(
+    f: &mut F,
+    node: crate::ParenthesizedGenericArguments,
+) -> crate::ParenthesizedGenericArguments
+where
+    F: Fold + ?Sized,
+{
+    crate::ParenthesizedGenericArguments {
+        paren_token: node.paren_token,
+        inputs: FoldHelper::lift(node.inputs, |it| f.fold_type(it)),
+        output: f.fold_return_type(node.output),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat<F>(f: &mut F, node: crate::Pat) -> crate::Pat
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Pat::Const(_binding_0) => crate::Pat::Const(f.fold_expr_const(_binding_0)),
+        crate::Pat::Ident(_binding_0) => crate::Pat::Ident(f.fold_pat_ident(_binding_0)),
+        crate::Pat::Lit(_binding_0) => crate::Pat::Lit(f.fold_expr_lit(_binding_0)),
+        crate::Pat::Macro(_binding_0) => crate::Pat::Macro(f.fold_expr_macro(_binding_0)),
+        crate::Pat::Or(_binding_0) => crate::Pat::Or(f.fold_pat_or(_binding_0)),
+        crate::Pat::Paren(_binding_0) => crate::Pat::Paren(f.fold_pat_paren(_binding_0)),
+        crate::Pat::Path(_binding_0) => crate::Pat::Path(f.fold_expr_path(_binding_0)),
+        crate::Pat::Range(_binding_0) => crate::Pat::Range(f.fold_expr_range(_binding_0)),
+        crate::Pat::Reference(_binding_0) => {
+            crate::Pat::Reference(f.fold_pat_reference(_binding_0))
+        }
+        crate::Pat::Rest(_binding_0) => crate::Pat::Rest(f.fold_pat_rest(_binding_0)),
+        crate::Pat::Slice(_binding_0) => crate::Pat::Slice(f.fold_pat_slice(_binding_0)),
+        crate::Pat::Struct(_binding_0) => {
+            crate::Pat::Struct(f.fold_pat_struct(_binding_0))
+        }
+        crate::Pat::Tuple(_binding_0) => crate::Pat::Tuple(f.fold_pat_tuple(_binding_0)),
+        crate::Pat::TupleStruct(_binding_0) => {
+            crate::Pat::TupleStruct(f.fold_pat_tuple_struct(_binding_0))
+        }
+        crate::Pat::Type(_binding_0) => crate::Pat::Type(f.fold_pat_type(_binding_0)),
+        crate::Pat::Verbatim(_binding_0) => crate::Pat::Verbatim(_binding_0),
+        crate::Pat::Wild(_binding_0) => crate::Pat::Wild(f.fold_pat_wild(_binding_0)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_ident<F>(f: &mut F, node: crate::PatIdent) -> crate::PatIdent
+where
+    F: Fold + ?Sized,
+{
+    crate::PatIdent {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        by_ref: node.by_ref,
+        mutability: node.mutability,
+        ident: f.fold_ident(node.ident),
+        subpat: (node.subpat).map(|it| ((it).0, Box::new(f.fold_pat(*(it).1)))),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_or<F>(f: &mut F, node: crate::PatOr) -> crate::PatOr
+where
+    F: Fold + ?Sized,
+{
+    crate::PatOr {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        leading_vert: node.leading_vert,
+        cases: FoldHelper::lift(node.cases, |it| f.fold_pat(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_paren<F>(f: &mut F, node: crate::PatParen) -> crate::PatParen
+where
+    F: Fold + ?Sized,
+{
+    crate::PatParen {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        paren_token: node.paren_token,
+        pat: Box::new(f.fold_pat(*node.pat)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_reference<F>(f: &mut F, node: crate::PatReference) -> crate::PatReference
+where
+    F: Fold + ?Sized,
+{
+    crate::PatReference {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        and_token: node.and_token,
+        mutability: node.mutability,
+        pat: Box::new(f.fold_pat(*node.pat)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_rest<F>(f: &mut F, node: crate::PatRest) -> crate::PatRest
+where
+    F: Fold + ?Sized,
+{
+    crate::PatRest {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        dot2_token: node.dot2_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_slice<F>(f: &mut F, node: crate::PatSlice) -> crate::PatSlice
+where
+    F: Fold + ?Sized,
+{
+    crate::PatSlice {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        bracket_token: node.bracket_token,
+        elems: FoldHelper::lift(node.elems, |it| f.fold_pat(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_struct<F>(f: &mut F, node: crate::PatStruct) -> crate::PatStruct
+where
+    F: Fold + ?Sized,
+{
+    crate::PatStruct {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        qself: (node.qself).map(|it| f.fold_qself(it)),
+        path: f.fold_path(node.path),
+        brace_token: node.brace_token,
+        fields: FoldHelper::lift(node.fields, |it| f.fold_field_pat(it)),
+        rest: (node.rest).map(|it| f.fold_pat_rest(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_tuple<F>(f: &mut F, node: crate::PatTuple) -> crate::PatTuple
+where
+    F: Fold + ?Sized,
+{
+    crate::PatTuple {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        paren_token: node.paren_token,
+        elems: FoldHelper::lift(node.elems, |it| f.fold_pat(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_tuple_struct<F>(
+    f: &mut F,
+    node: crate::PatTupleStruct,
+) -> crate::PatTupleStruct
+where
+    F: Fold + ?Sized,
+{
+    crate::PatTupleStruct {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        qself: (node.qself).map(|it| f.fold_qself(it)),
+        path: f.fold_path(node.path),
+        paren_token: node.paren_token,
+        elems: FoldHelper::lift(node.elems, |it| f.fold_pat(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_type<F>(f: &mut F, node: crate::PatType) -> crate::PatType
+where
+    F: Fold + ?Sized,
+{
+    crate::PatType {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        pat: Box::new(f.fold_pat(*node.pat)),
+        colon_token: node.colon_token,
+        ty: Box::new(f.fold_type(*node.ty)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_pat_wild<F>(f: &mut F, node: crate::PatWild) -> crate::PatWild
+where
+    F: Fold + ?Sized,
+{
+    crate::PatWild {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        underscore_token: node.underscore_token,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_path<F>(f: &mut F, node: crate::Path) -> crate::Path
+where
+    F: Fold + ?Sized,
+{
+    crate::Path {
+        leading_colon: node.leading_colon,
+        segments: FoldHelper::lift(node.segments, |it| f.fold_path_segment(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_path_arguments<F>(
+    f: &mut F,
+    node: crate::PathArguments,
+) -> crate::PathArguments
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::PathArguments::None => crate::PathArguments::None,
+        crate::PathArguments::AngleBracketed(_binding_0) => {
+            crate::PathArguments::AngleBracketed(
+                f.fold_angle_bracketed_generic_arguments(_binding_0),
+            )
+        }
+        crate::PathArguments::Parenthesized(_binding_0) => {
+            crate::PathArguments::Parenthesized(
+                f.fold_parenthesized_generic_arguments(_binding_0),
+            )
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_path_segment<F>(f: &mut F, node: crate::PathSegment) -> crate::PathSegment
+where
+    F: Fold + ?Sized,
+{
+    crate::PathSegment {
+        ident: f.fold_ident(node.ident),
+        arguments: f.fold_path_arguments(node.arguments),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_predicate_lifetime<F>(
+    f: &mut F,
+    node: crate::PredicateLifetime,
+) -> crate::PredicateLifetime
+where
+    F: Fold + ?Sized,
+{
+    crate::PredicateLifetime {
+        lifetime: f.fold_lifetime(node.lifetime),
+        colon_token: node.colon_token,
+        bounds: FoldHelper::lift(node.bounds, |it| f.fold_lifetime(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_predicate_type<F>(
+    f: &mut F,
+    node: crate::PredicateType,
+) -> crate::PredicateType
+where
+    F: Fold + ?Sized,
+{
+    crate::PredicateType {
+        lifetimes: (node.lifetimes).map(|it| f.fold_bound_lifetimes(it)),
+        bounded_ty: f.fold_type(node.bounded_ty),
+        colon_token: node.colon_token,
+        bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_qself<F>(f: &mut F, node: crate::QSelf) -> crate::QSelf
+where
+    F: Fold + ?Sized,
+{
+    crate::QSelf {
+        lt_token: node.lt_token,
+        ty: Box::new(f.fold_type(*node.ty)),
+        position: node.position,
+        as_token: node.as_token,
+        gt_token: node.gt_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_range_limits<F>(f: &mut F, node: crate::RangeLimits) -> crate::RangeLimits
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::RangeLimits::HalfOpen(_binding_0) => {
+            crate::RangeLimits::HalfOpen(_binding_0)
+        }
+        crate::RangeLimits::Closed(_binding_0) => crate::RangeLimits::Closed(_binding_0),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_receiver<F>(f: &mut F, node: crate::Receiver) -> crate::Receiver
+where
+    F: Fold + ?Sized,
+{
+    crate::Receiver {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        reference: (node.reference)
+            .map(|it| ((it).0, ((it).1).map(|it| f.fold_lifetime(it)))),
+        mutability: node.mutability,
+        self_token: node.self_token,
+        colon_token: node.colon_token,
+        ty: Box::new(f.fold_type(*node.ty)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_return_type<F>(f: &mut F, node: crate::ReturnType) -> crate::ReturnType
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::ReturnType::Default => crate::ReturnType::Default,
+        crate::ReturnType::Type(_binding_0, _binding_1) => {
+            crate::ReturnType::Type(_binding_0, Box::new(f.fold_type(*_binding_1)))
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_signature<F>(f: &mut F, node: crate::Signature) -> crate::Signature
+where
+    F: Fold + ?Sized,
+{
+    crate::Signature {
+        constness: node.constness,
+        asyncness: node.asyncness,
+        unsafety: node.unsafety,
+        abi: (node.abi).map(|it| f.fold_abi(it)),
+        fn_token: node.fn_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        paren_token: node.paren_token,
+        inputs: FoldHelper::lift(node.inputs, |it| f.fold_fn_arg(it)),
+        variadic: (node.variadic).map(|it| f.fold_variadic(it)),
+        output: f.fold_return_type(node.output),
+    }
+}
+pub fn fold_span<F>(f: &mut F, node: proc_macro2::Span) -> proc_macro2::Span
+where
+    F: Fold + ?Sized,
+{
+    node
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_static_mutability<F>(
+    f: &mut F,
+    node: crate::StaticMutability,
+) -> crate::StaticMutability
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::StaticMutability::Mut(_binding_0) => {
+            crate::StaticMutability::Mut(_binding_0)
+        }
+        crate::StaticMutability::None => crate::StaticMutability::None,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_stmt<F>(f: &mut F, node: crate::Stmt) -> crate::Stmt
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Stmt::Local(_binding_0) => crate::Stmt::Local(f.fold_local(_binding_0)),
+        crate::Stmt::Item(_binding_0) => crate::Stmt::Item(f.fold_item(_binding_0)),
+        crate::Stmt::Expr(_binding_0, _binding_1) => {
+            crate::Stmt::Expr(f.fold_expr(_binding_0), _binding_1)
+        }
+        crate::Stmt::Macro(_binding_0) => {
+            crate::Stmt::Macro(f.fold_stmt_macro(_binding_0))
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_stmt_macro<F>(f: &mut F, node: crate::StmtMacro) -> crate::StmtMacro
+where
+    F: Fold + ?Sized,
+{
+    crate::StmtMacro {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        mac: f.fold_macro(node.mac),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_trait_bound<F>(f: &mut F, node: crate::TraitBound) -> crate::TraitBound
+where
+    F: Fold + ?Sized,
+{
+    crate::TraitBound {
+        paren_token: node.paren_token,
+        modifier: f.fold_trait_bound_modifier(node.modifier),
+        lifetimes: (node.lifetimes).map(|it| f.fold_bound_lifetimes(it)),
+        path: f.fold_path(node.path),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_trait_bound_modifier<F>(
+    f: &mut F,
+    node: crate::TraitBoundModifier,
+) -> crate::TraitBoundModifier
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::TraitBoundModifier::None => crate::TraitBoundModifier::None,
+        crate::TraitBoundModifier::Maybe(_binding_0) => {
+            crate::TraitBoundModifier::Maybe(_binding_0)
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_trait_item<F>(f: &mut F, node: crate::TraitItem) -> crate::TraitItem
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::TraitItem::Const(_binding_0) => {
+            crate::TraitItem::Const(f.fold_trait_item_const(_binding_0))
+        }
+        crate::TraitItem::Fn(_binding_0) => {
+            crate::TraitItem::Fn(f.fold_trait_item_fn(_binding_0))
+        }
+        crate::TraitItem::Type(_binding_0) => {
+            crate::TraitItem::Type(f.fold_trait_item_type(_binding_0))
+        }
+        crate::TraitItem::Macro(_binding_0) => {
+            crate::TraitItem::Macro(f.fold_trait_item_macro(_binding_0))
+        }
+        crate::TraitItem::Verbatim(_binding_0) => crate::TraitItem::Verbatim(_binding_0),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_trait_item_const<F>(
+    f: &mut F,
+    node: crate::TraitItemConst,
+) -> crate::TraitItemConst
+where
+    F: Fold + ?Sized,
+{
+    crate::TraitItemConst {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        const_token: node.const_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        colon_token: node.colon_token,
+        ty: f.fold_type(node.ty),
+        default: (node.default).map(|it| ((it).0, f.fold_expr((it).1))),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_trait_item_fn<F>(f: &mut F, node: crate::TraitItemFn) -> crate::TraitItemFn
+where
+    F: Fold + ?Sized,
+{
+    crate::TraitItemFn {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        sig: f.fold_signature(node.sig),
+        default: (node.default).map(|it| f.fold_block(it)),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_trait_item_macro<F>(
+    f: &mut F,
+    node: crate::TraitItemMacro,
+) -> crate::TraitItemMacro
+where
+    F: Fold + ?Sized,
+{
+    crate::TraitItemMacro {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        mac: f.fold_macro(node.mac),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_trait_item_type<F>(
+    f: &mut F,
+    node: crate::TraitItemType,
+) -> crate::TraitItemType
+where
+    F: Fold + ?Sized,
+{
+    crate::TraitItemType {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        type_token: node.type_token,
+        ident: f.fold_ident(node.ident),
+        generics: f.fold_generics(node.generics),
+        colon_token: node.colon_token,
+        bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
+        default: (node.default).map(|it| ((it).0, f.fold_type((it).1))),
+        semi_token: node.semi_token,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type<F>(f: &mut F, node: crate::Type) -> crate::Type
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Type::Array(_binding_0) => {
+            crate::Type::Array(f.fold_type_array(_binding_0))
+        }
+        crate::Type::BareFn(_binding_0) => {
+            crate::Type::BareFn(f.fold_type_bare_fn(_binding_0))
+        }
+        crate::Type::Group(_binding_0) => {
+            crate::Type::Group(f.fold_type_group(_binding_0))
+        }
+        crate::Type::ImplTrait(_binding_0) => {
+            crate::Type::ImplTrait(f.fold_type_impl_trait(_binding_0))
+        }
+        crate::Type::Infer(_binding_0) => {
+            crate::Type::Infer(f.fold_type_infer(_binding_0))
+        }
+        crate::Type::Macro(_binding_0) => {
+            crate::Type::Macro(f.fold_type_macro(_binding_0))
+        }
+        crate::Type::Never(_binding_0) => {
+            crate::Type::Never(f.fold_type_never(_binding_0))
+        }
+        crate::Type::Paren(_binding_0) => {
+            crate::Type::Paren(f.fold_type_paren(_binding_0))
+        }
+        crate::Type::Path(_binding_0) => crate::Type::Path(f.fold_type_path(_binding_0)),
+        crate::Type::Ptr(_binding_0) => crate::Type::Ptr(f.fold_type_ptr(_binding_0)),
+        crate::Type::Reference(_binding_0) => {
+            crate::Type::Reference(f.fold_type_reference(_binding_0))
+        }
+        crate::Type::Slice(_binding_0) => {
+            crate::Type::Slice(f.fold_type_slice(_binding_0))
+        }
+        crate::Type::TraitObject(_binding_0) => {
+            crate::Type::TraitObject(f.fold_type_trait_object(_binding_0))
+        }
+        crate::Type::Tuple(_binding_0) => {
+            crate::Type::Tuple(f.fold_type_tuple(_binding_0))
+        }
+        crate::Type::Verbatim(_binding_0) => crate::Type::Verbatim(_binding_0),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_array<F>(f: &mut F, node: crate::TypeArray) -> crate::TypeArray
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeArray {
+        bracket_token: node.bracket_token,
+        elem: Box::new(f.fold_type(*node.elem)),
+        semi_token: node.semi_token,
+        len: f.fold_expr(node.len),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_bare_fn<F>(f: &mut F, node: crate::TypeBareFn) -> crate::TypeBareFn
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeBareFn {
+        lifetimes: (node.lifetimes).map(|it| f.fold_bound_lifetimes(it)),
+        unsafety: node.unsafety,
+        abi: (node.abi).map(|it| f.fold_abi(it)),
+        fn_token: node.fn_token,
+        paren_token: node.paren_token,
+        inputs: FoldHelper::lift(node.inputs, |it| f.fold_bare_fn_arg(it)),
+        variadic: (node.variadic).map(|it| f.fold_bare_variadic(it)),
+        output: f.fold_return_type(node.output),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_group<F>(f: &mut F, node: crate::TypeGroup) -> crate::TypeGroup
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeGroup {
+        group_token: node.group_token,
+        elem: Box::new(f.fold_type(*node.elem)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_impl_trait<F>(
+    f: &mut F,
+    node: crate::TypeImplTrait,
+) -> crate::TypeImplTrait
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeImplTrait {
+        impl_token: node.impl_token,
+        bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_infer<F>(f: &mut F, node: crate::TypeInfer) -> crate::TypeInfer
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeInfer {
+        underscore_token: node.underscore_token,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_macro<F>(f: &mut F, node: crate::TypeMacro) -> crate::TypeMacro
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeMacro {
+        mac: f.fold_macro(node.mac),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_never<F>(f: &mut F, node: crate::TypeNever) -> crate::TypeNever
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeNever {
+        bang_token: node.bang_token,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_param<F>(f: &mut F, node: crate::TypeParam) -> crate::TypeParam
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeParam {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        ident: f.fold_ident(node.ident),
+        colon_token: node.colon_token,
+        bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
+        eq_token: node.eq_token,
+        default: (node.default).map(|it| f.fold_type(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_param_bound<F>(
+    f: &mut F,
+    node: crate::TypeParamBound,
+) -> crate::TypeParamBound
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::TypeParamBound::Trait(_binding_0) => {
+            crate::TypeParamBound::Trait(f.fold_trait_bound(_binding_0))
+        }
+        crate::TypeParamBound::Lifetime(_binding_0) => {
+            crate::TypeParamBound::Lifetime(f.fold_lifetime(_binding_0))
+        }
+        crate::TypeParamBound::Verbatim(_binding_0) => {
+            crate::TypeParamBound::Verbatim(_binding_0)
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_paren<F>(f: &mut F, node: crate::TypeParen) -> crate::TypeParen
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeParen {
+        paren_token: node.paren_token,
+        elem: Box::new(f.fold_type(*node.elem)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_path<F>(f: &mut F, node: crate::TypePath) -> crate::TypePath
+where
+    F: Fold + ?Sized,
+{
+    crate::TypePath {
+        qself: (node.qself).map(|it| f.fold_qself(it)),
+        path: f.fold_path(node.path),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_ptr<F>(f: &mut F, node: crate::TypePtr) -> crate::TypePtr
+where
+    F: Fold + ?Sized,
+{
+    crate::TypePtr {
+        star_token: node.star_token,
+        const_token: node.const_token,
+        mutability: node.mutability,
+        elem: Box::new(f.fold_type(*node.elem)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_reference<F>(
+    f: &mut F,
+    node: crate::TypeReference,
+) -> crate::TypeReference
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeReference {
+        and_token: node.and_token,
+        lifetime: (node.lifetime).map(|it| f.fold_lifetime(it)),
+        mutability: node.mutability,
+        elem: Box::new(f.fold_type(*node.elem)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_slice<F>(f: &mut F, node: crate::TypeSlice) -> crate::TypeSlice
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeSlice {
+        bracket_token: node.bracket_token,
+        elem: Box::new(f.fold_type(*node.elem)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_trait_object<F>(
+    f: &mut F,
+    node: crate::TypeTraitObject,
+) -> crate::TypeTraitObject
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeTraitObject {
+        dyn_token: node.dyn_token,
+        bounds: FoldHelper::lift(node.bounds, |it| f.fold_type_param_bound(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_type_tuple<F>(f: &mut F, node: crate::TypeTuple) -> crate::TypeTuple
+where
+    F: Fold + ?Sized,
+{
+    crate::TypeTuple {
+        paren_token: node.paren_token,
+        elems: FoldHelper::lift(node.elems, |it| f.fold_type(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_un_op<F>(f: &mut F, node: crate::UnOp) -> crate::UnOp
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::UnOp::Deref(_binding_0) => crate::UnOp::Deref(_binding_0),
+        crate::UnOp::Not(_binding_0) => crate::UnOp::Not(_binding_0),
+        crate::UnOp::Neg(_binding_0) => crate::UnOp::Neg(_binding_0),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_use_glob<F>(f: &mut F, node: crate::UseGlob) -> crate::UseGlob
+where
+    F: Fold + ?Sized,
+{
+    crate::UseGlob {
+        star_token: node.star_token,
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_use_group<F>(f: &mut F, node: crate::UseGroup) -> crate::UseGroup
+where
+    F: Fold + ?Sized,
+{
+    crate::UseGroup {
+        brace_token: node.brace_token,
+        items: FoldHelper::lift(node.items, |it| f.fold_use_tree(it)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_use_name<F>(f: &mut F, node: crate::UseName) -> crate::UseName
+where
+    F: Fold + ?Sized,
+{
+    crate::UseName {
+        ident: f.fold_ident(node.ident),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_use_path<F>(f: &mut F, node: crate::UsePath) -> crate::UsePath
+where
+    F: Fold + ?Sized,
+{
+    crate::UsePath {
+        ident: f.fold_ident(node.ident),
+        colon2_token: node.colon2_token,
+        tree: Box::new(f.fold_use_tree(*node.tree)),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_use_rename<F>(f: &mut F, node: crate::UseRename) -> crate::UseRename
+where
+    F: Fold + ?Sized,
+{
+    crate::UseRename {
+        ident: f.fold_ident(node.ident),
+        as_token: node.as_token,
+        rename: f.fold_ident(node.rename),
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_use_tree<F>(f: &mut F, node: crate::UseTree) -> crate::UseTree
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::UseTree::Path(_binding_0) => {
+            crate::UseTree::Path(f.fold_use_path(_binding_0))
+        }
+        crate::UseTree::Name(_binding_0) => {
+            crate::UseTree::Name(f.fold_use_name(_binding_0))
+        }
+        crate::UseTree::Rename(_binding_0) => {
+            crate::UseTree::Rename(f.fold_use_rename(_binding_0))
+        }
+        crate::UseTree::Glob(_binding_0) => {
+            crate::UseTree::Glob(f.fold_use_glob(_binding_0))
+        }
+        crate::UseTree::Group(_binding_0) => {
+            crate::UseTree::Group(f.fold_use_group(_binding_0))
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn fold_variadic<F>(f: &mut F, node: crate::Variadic) -> crate::Variadic
+where
+    F: Fold + ?Sized,
+{
+    crate::Variadic {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        pat: (node.pat).map(|it| (Box::new(f.fold_pat(*(it).0)), (it).1)),
+        dots: node.dots,
+        comma: node.comma,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_variant<F>(f: &mut F, node: crate::Variant) -> crate::Variant
+where
+    F: Fold + ?Sized,
+{
+    crate::Variant {
+        attrs: FoldHelper::lift(node.attrs, |it| f.fold_attribute(it)),
+        ident: f.fold_ident(node.ident),
+        fields: f.fold_fields(node.fields),
+        discriminant: (node.discriminant).map(|it| ((it).0, f.fold_expr((it).1))),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_vis_restricted<F>(
+    f: &mut F,
+    node: crate::VisRestricted,
+) -> crate::VisRestricted
+where
+    F: Fold + ?Sized,
+{
+    crate::VisRestricted {
+        pub_token: node.pub_token,
+        paren_token: node.paren_token,
+        in_token: node.in_token,
+        path: Box::new(f.fold_path(*node.path)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_visibility<F>(f: &mut F, node: crate::Visibility) -> crate::Visibility
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::Visibility::Public(_binding_0) => crate::Visibility::Public(_binding_0),
+        crate::Visibility::Restricted(_binding_0) => {
+            crate::Visibility::Restricted(f.fold_vis_restricted(_binding_0))
+        }
+        crate::Visibility::Inherited => crate::Visibility::Inherited,
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_where_clause<F>(f: &mut F, node: crate::WhereClause) -> crate::WhereClause
+where
+    F: Fold + ?Sized,
+{
+    crate::WhereClause {
+        where_token: node.where_token,
+        predicates: FoldHelper::lift(node.predicates, |it| f.fold_where_predicate(it)),
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn fold_where_predicate<F>(
+    f: &mut F,
+    node: crate::WherePredicate,
+) -> crate::WherePredicate
+where
+    F: Fold + ?Sized,
+{
+    match node {
+        crate::WherePredicate::Lifetime(_binding_0) => {
+            crate::WherePredicate::Lifetime(f.fold_predicate_lifetime(_binding_0))
+        }
+        crate::WherePredicate::Type(_binding_0) => {
+            crate::WherePredicate::Type(f.fold_predicate_type(_binding_0))
+        }
+    }
+}
diff --git a/rust/syn/gen/hash.rs b/rust/syn/gen/hash.rs
new file mode 100644
index 0000000000000000000000000000000000000000..9d8f0fc0f70b3efeacede4f9607bcf7dec1f54e4
--- /dev/null
+++ b/rust/syn/gen/hash.rs
@@ -0,0 +1,2805 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#[cfg(any(feature = "derive", feature = "full"))]
+use crate::tt::TokenStreamHelper;
+use std::hash::{Hash, Hasher};
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Abi {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.name.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::AngleBracketedGenericArguments {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.colon2_token.hash(state);
+        self.args.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Arm {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+        self.guard.hash(state);
+        self.body.hash(state);
+        self.comma.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::AssocConst {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.value.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::AssocType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::AttrStyle {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::AttrStyle::Outer => {
+                state.write_u8(0u8);
+            }
+            crate::AttrStyle::Inner(_) => {
+                state.write_u8(1u8);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Attribute {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.style.hash(state);
+        self.meta.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::BareFnArg {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.name.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::BareVariadic {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.name.hash(state);
+        self.comma.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::BinOp {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::BinOp::Add(_) => {
+                state.write_u8(0u8);
+            }
+            crate::BinOp::Sub(_) => {
+                state.write_u8(1u8);
+            }
+            crate::BinOp::Mul(_) => {
+                state.write_u8(2u8);
+            }
+            crate::BinOp::Div(_) => {
+                state.write_u8(3u8);
+            }
+            crate::BinOp::Rem(_) => {
+                state.write_u8(4u8);
+            }
+            crate::BinOp::And(_) => {
+                state.write_u8(5u8);
+            }
+            crate::BinOp::Or(_) => {
+                state.write_u8(6u8);
+            }
+            crate::BinOp::BitXor(_) => {
+                state.write_u8(7u8);
+            }
+            crate::BinOp::BitAnd(_) => {
+                state.write_u8(8u8);
+            }
+            crate::BinOp::BitOr(_) => {
+                state.write_u8(9u8);
+            }
+            crate::BinOp::Shl(_) => {
+                state.write_u8(10u8);
+            }
+            crate::BinOp::Shr(_) => {
+                state.write_u8(11u8);
+            }
+            crate::BinOp::Eq(_) => {
+                state.write_u8(12u8);
+            }
+            crate::BinOp::Lt(_) => {
+                state.write_u8(13u8);
+            }
+            crate::BinOp::Le(_) => {
+                state.write_u8(14u8);
+            }
+            crate::BinOp::Ne(_) => {
+                state.write_u8(15u8);
+            }
+            crate::BinOp::Ge(_) => {
+                state.write_u8(16u8);
+            }
+            crate::BinOp::Gt(_) => {
+                state.write_u8(17u8);
+            }
+            crate::BinOp::AddAssign(_) => {
+                state.write_u8(18u8);
+            }
+            crate::BinOp::SubAssign(_) => {
+                state.write_u8(19u8);
+            }
+            crate::BinOp::MulAssign(_) => {
+                state.write_u8(20u8);
+            }
+            crate::BinOp::DivAssign(_) => {
+                state.write_u8(21u8);
+            }
+            crate::BinOp::RemAssign(_) => {
+                state.write_u8(22u8);
+            }
+            crate::BinOp::BitXorAssign(_) => {
+                state.write_u8(23u8);
+            }
+            crate::BinOp::BitAndAssign(_) => {
+                state.write_u8(24u8);
+            }
+            crate::BinOp::BitOrAssign(_) => {
+                state.write_u8(25u8);
+            }
+            crate::BinOp::ShlAssign(_) => {
+                state.write_u8(26u8);
+            }
+            crate::BinOp::ShrAssign(_) => {
+                state.write_u8(27u8);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Block {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.stmts.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::BoundLifetimes {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetimes.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ConstParam {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.ty.hash(state);
+        self.eq_token.hash(state);
+        self.default.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Constraint {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Data {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::Data::Struct(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::Data::Enum(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::Data::Union(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::DataEnum {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.variants.hash(state);
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::DataStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.fields.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::DataUnion {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.fields.hash(state);
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::DeriveInput {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.data.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Expr {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            #[cfg(feature = "full")]
+            crate::Expr::Array(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Assign(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Async(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Await(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::Expr::Binary(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Block(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Break(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            crate::Expr::Call(v0) => {
+                state.write_u8(7u8);
+                v0.hash(state);
+            }
+            crate::Expr::Cast(v0) => {
+                state.write_u8(8u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Closure(v0) => {
+                state.write_u8(9u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Const(v0) => {
+                state.write_u8(10u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Continue(v0) => {
+                state.write_u8(11u8);
+                v0.hash(state);
+            }
+            crate::Expr::Field(v0) => {
+                state.write_u8(12u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::ForLoop(v0) => {
+                state.write_u8(13u8);
+                v0.hash(state);
+            }
+            crate::Expr::Group(v0) => {
+                state.write_u8(14u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::If(v0) => {
+                state.write_u8(15u8);
+                v0.hash(state);
+            }
+            crate::Expr::Index(v0) => {
+                state.write_u8(16u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Infer(v0) => {
+                state.write_u8(17u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Let(v0) => {
+                state.write_u8(18u8);
+                v0.hash(state);
+            }
+            crate::Expr::Lit(v0) => {
+                state.write_u8(19u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Loop(v0) => {
+                state.write_u8(20u8);
+                v0.hash(state);
+            }
+            crate::Expr::Macro(v0) => {
+                state.write_u8(21u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Match(v0) => {
+                state.write_u8(22u8);
+                v0.hash(state);
+            }
+            crate::Expr::MethodCall(v0) => {
+                state.write_u8(23u8);
+                v0.hash(state);
+            }
+            crate::Expr::Paren(v0) => {
+                state.write_u8(24u8);
+                v0.hash(state);
+            }
+            crate::Expr::Path(v0) => {
+                state.write_u8(25u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Range(v0) => {
+                state.write_u8(26u8);
+                v0.hash(state);
+            }
+            crate::Expr::Reference(v0) => {
+                state.write_u8(27u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Repeat(v0) => {
+                state.write_u8(28u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Return(v0) => {
+                state.write_u8(29u8);
+                v0.hash(state);
+            }
+            crate::Expr::Struct(v0) => {
+                state.write_u8(30u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Try(v0) => {
+                state.write_u8(31u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::TryBlock(v0) => {
+                state.write_u8(32u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Tuple(v0) => {
+                state.write_u8(33u8);
+                v0.hash(state);
+            }
+            crate::Expr::Unary(v0) => {
+                state.write_u8(34u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Unsafe(v0) => {
+                state.write_u8(35u8);
+                v0.hash(state);
+            }
+            crate::Expr::Verbatim(v0) => {
+                state.write_u8(36u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::While(v0) => {
+                state.write_u8(37u8);
+                v0.hash(state);
+            }
+            #[cfg(feature = "full")]
+            crate::Expr::Yield(v0) => {
+                state.write_u8(38u8);
+                v0.hash(state);
+            }
+            #[cfg(not(feature = "full"))]
+            _ => unreachable!(),
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprArray {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.elems.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprAssign {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.left.hash(state);
+        self.right.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprAsync {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.capture.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprAwait {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.base.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprBinary {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.left.hash(state);
+        self.op.hash(state);
+        self.right.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprBlock {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprBreak {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprCall {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.func.hash(state);
+        self.args.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprCast {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprClosure {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.lifetimes.hash(state);
+        self.constness.hash(state);
+        self.movability.hash(state);
+        self.asyncness.hash(state);
+        self.capture.hash(state);
+        self.inputs.hash(state);
+        self.output.hash(state);
+        self.body.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprConst {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprContinue {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprField {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.base.hash(state);
+        self.member.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprForLoop {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.pat.hash(state);
+        self.expr.hash(state);
+        self.body.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprGroup {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprIf {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.cond.hash(state);
+        self.then_branch.hash(state);
+        self.else_branch.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprIndex {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+        self.index.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprInfer {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprLet {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprLit {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.lit.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprLoop {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.body.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprMatch {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+        self.arms.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprMethodCall {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.receiver.hash(state);
+        self.method.hash(state);
+        self.turbofish.hash(state);
+        self.args.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprParen {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprPath {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.qself.hash(state);
+        self.path.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprRange {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.start.hash(state);
+        self.limits.hash(state);
+        self.end.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprReference {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mutability.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprRepeat {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+        self.len.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprReturn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.qself.hash(state);
+        self.path.hash(state);
+        self.fields.hash(state);
+        self.dot2_token.hash(state);
+        self.rest.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprTry {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprTryBlock {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprTuple {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.elems.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprUnary {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.op.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprUnsafe {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprWhile {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.label.hash(state);
+        self.cond.hash(state);
+        self.body.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ExprYield {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Field {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.mutability.hash(state);
+        self.ident.hash(state);
+        self.colon_token.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::FieldMutability {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::FieldMutability::None => {
+                state.write_u8(0u8);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::FieldPat {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.member.hash(state);
+        self.colon_token.hash(state);
+        self.pat.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::FieldValue {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.member.hash(state);
+        self.colon_token.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Fields {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::Fields::Named(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::Fields::Unnamed(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::Fields::Unit => {
+                state.write_u8(2u8);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::FieldsNamed {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.named.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::FieldsUnnamed {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.unnamed.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::File {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.shebang.hash(state);
+        self.attrs.hash(state);
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::FnArg {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::FnArg::Receiver(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::FnArg::Typed(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ForeignItem {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::ForeignItem::Fn(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::ForeignItem::Static(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::ForeignItem::Type(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            crate::ForeignItem::Macro(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::ForeignItem::Verbatim(v0) => {
+                state.write_u8(4u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ForeignItemFn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.sig.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ForeignItemMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ForeignItemStatic {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.mutability.hash(state);
+        self.ident.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ForeignItemType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::GenericArgument {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::GenericArgument::Lifetime(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::GenericArgument::Type(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::GenericArgument::Const(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            crate::GenericArgument::AssocType(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::GenericArgument::AssocConst(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            crate::GenericArgument::Constraint(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::GenericParam {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::GenericParam::Lifetime(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::GenericParam::Type(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::GenericParam::Const(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Generics {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lt_token.hash(state);
+        self.params.hash(state);
+        self.gt_token.hash(state);
+        self.where_clause.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ImplItem {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::ImplItem::Const(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::ImplItem::Fn(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::ImplItem::Type(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            crate::ImplItem::Macro(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::ImplItem::Verbatim(v0) => {
+                state.write_u8(4u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ImplItemConst {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.defaultness.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.ty.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ImplItemFn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.defaultness.hash(state);
+        self.sig.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ImplItemMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ImplItemType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.defaultness.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ImplRestriction {
+    fn hash<H>(&self, _state: &mut H)
+    where
+        H: Hasher,
+    {
+        match *self {}
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Item {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::Item::Const(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::Item::Enum(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::Item::ExternCrate(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            crate::Item::Fn(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::Item::ForeignMod(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            crate::Item::Impl(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            crate::Item::Macro(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            crate::Item::Mod(v0) => {
+                state.write_u8(7u8);
+                v0.hash(state);
+            }
+            crate::Item::Static(v0) => {
+                state.write_u8(8u8);
+                v0.hash(state);
+            }
+            crate::Item::Struct(v0) => {
+                state.write_u8(9u8);
+                v0.hash(state);
+            }
+            crate::Item::Trait(v0) => {
+                state.write_u8(10u8);
+                v0.hash(state);
+            }
+            crate::Item::TraitAlias(v0) => {
+                state.write_u8(11u8);
+                v0.hash(state);
+            }
+            crate::Item::Type(v0) => {
+                state.write_u8(12u8);
+                v0.hash(state);
+            }
+            crate::Item::Union(v0) => {
+                state.write_u8(13u8);
+                v0.hash(state);
+            }
+            crate::Item::Use(v0) => {
+                state.write_u8(14u8);
+                v0.hash(state);
+            }
+            crate::Item::Verbatim(v0) => {
+                state.write_u8(15u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemConst {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.ty.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemEnum {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.variants.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemExternCrate {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.rename.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemFn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.sig.hash(state);
+        self.block.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemForeignMod {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.unsafety.hash(state);
+        self.abi.hash(state);
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemImpl {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.defaultness.hash(state);
+        self.unsafety.hash(state);
+        self.generics.hash(state);
+        self.trait_.hash(state);
+        self.self_ty.hash(state);
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.mac.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemMod {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.unsafety.hash(state);
+        self.ident.hash(state);
+        self.content.hash(state);
+        self.semi.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemStatic {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.mutability.hash(state);
+        self.ident.hash(state);
+        self.ty.hash(state);
+        self.expr.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.fields.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemTrait {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.unsafety.hash(state);
+        self.auto_token.hash(state);
+        self.restriction.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.colon_token.hash(state);
+        self.supertraits.hash(state);
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemTraitAlias {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemUnion {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.fields.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ItemUse {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.vis.hash(state);
+        self.leading_colon.hash(state);
+        self.tree.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Label {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.name.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::LifetimeParam {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.lifetime.hash(state);
+        self.colon_token.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Lit {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::Lit::Str(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::Lit::ByteStr(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::Lit::Byte(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            crate::Lit::Char(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::Lit::Int(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            crate::Lit::Float(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            crate::Lit::Bool(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            crate::Lit::Verbatim(v0) => {
+                state.write_u8(7u8);
+                v0.to_string().hash(state);
+            }
+        }
+    }
+}
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::LitBool {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.value.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Local {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+        self.init.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::LocalInit {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.expr.hash(state);
+        self.diverge.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Macro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.path.hash(state);
+        self.delimiter.hash(state);
+        TokenStreamHelper(&self.tokens).hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::MacroDelimiter {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::MacroDelimiter::Paren(_) => {
+                state.write_u8(0u8);
+            }
+            crate::MacroDelimiter::Brace(_) => {
+                state.write_u8(1u8);
+            }
+            crate::MacroDelimiter::Bracket(_) => {
+                state.write_u8(2u8);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Meta {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::Meta::Path(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::Meta::List(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::Meta::NameValue(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::MetaList {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.path.hash(state);
+        self.delimiter.hash(state);
+        TokenStreamHelper(&self.tokens).hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::MetaNameValue {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.path.hash(state);
+        self.value.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ParenthesizedGenericArguments {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.inputs.hash(state);
+        self.output.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Pat {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::Pat::Const(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::Pat::Ident(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::Pat::Lit(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            crate::Pat::Macro(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::Pat::Or(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            crate::Pat::Paren(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            crate::Pat::Path(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            crate::Pat::Range(v0) => {
+                state.write_u8(7u8);
+                v0.hash(state);
+            }
+            crate::Pat::Reference(v0) => {
+                state.write_u8(8u8);
+                v0.hash(state);
+            }
+            crate::Pat::Rest(v0) => {
+                state.write_u8(9u8);
+                v0.hash(state);
+            }
+            crate::Pat::Slice(v0) => {
+                state.write_u8(10u8);
+                v0.hash(state);
+            }
+            crate::Pat::Struct(v0) => {
+                state.write_u8(11u8);
+                v0.hash(state);
+            }
+            crate::Pat::Tuple(v0) => {
+                state.write_u8(12u8);
+                v0.hash(state);
+            }
+            crate::Pat::TupleStruct(v0) => {
+                state.write_u8(13u8);
+                v0.hash(state);
+            }
+            crate::Pat::Type(v0) => {
+                state.write_u8(14u8);
+                v0.hash(state);
+            }
+            crate::Pat::Verbatim(v0) => {
+                state.write_u8(15u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+            crate::Pat::Wild(v0) => {
+                state.write_u8(16u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatIdent {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.by_ref.hash(state);
+        self.mutability.hash(state);
+        self.ident.hash(state);
+        self.subpat.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatOr {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.leading_vert.hash(state);
+        self.cases.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatParen {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatReference {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mutability.hash(state);
+        self.pat.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatRest {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatSlice {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.elems.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.qself.hash(state);
+        self.path.hash(state);
+        self.fields.hash(state);
+        self.rest.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatTuple {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.elems.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatTupleStruct {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.qself.hash(state);
+        self.path.hash(state);
+        self.elems.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PatWild {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Path {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.leading_colon.hash(state);
+        self.segments.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PathArguments {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::PathArguments::None => {
+                state.write_u8(0u8);
+            }
+            crate::PathArguments::AngleBracketed(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::PathArguments::Parenthesized(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PathSegment {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.arguments.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PredicateLifetime {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetime.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::PredicateType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetimes.hash(state);
+        self.bounded_ty.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::QSelf {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ty.hash(state);
+        self.position.hash(state);
+        self.as_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::RangeLimits {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::RangeLimits::HalfOpen(_) => {
+                state.write_u8(0u8);
+            }
+            crate::RangeLimits::Closed(_) => {
+                state.write_u8(1u8);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Receiver {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.reference.hash(state);
+        self.mutability.hash(state);
+        self.colon_token.hash(state);
+        self.ty.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::ReturnType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::ReturnType::Default => {
+                state.write_u8(0u8);
+            }
+            crate::ReturnType::Type(_, v1) => {
+                state.write_u8(1u8);
+                v1.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Signature {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.constness.hash(state);
+        self.asyncness.hash(state);
+        self.unsafety.hash(state);
+        self.abi.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.inputs.hash(state);
+        self.variadic.hash(state);
+        self.output.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::StaticMutability {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::StaticMutability::Mut(_) => {
+                state.write_u8(0u8);
+            }
+            crate::StaticMutability::None => {
+                state.write_u8(1u8);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Stmt {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::Stmt::Local(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::Stmt::Item(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::Stmt::Expr(v0, v1) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+                v1.hash(state);
+            }
+            crate::Stmt::Macro(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::StmtMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TraitBound {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.paren_token.hash(state);
+        self.modifier.hash(state);
+        self.lifetimes.hash(state);
+        self.path.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TraitBoundModifier {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::TraitBoundModifier::None => {
+                state.write_u8(0u8);
+            }
+            crate::TraitBoundModifier::Maybe(_) => {
+                state.write_u8(1u8);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TraitItem {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::TraitItem::Const(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::TraitItem::Fn(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::TraitItem::Type(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            crate::TraitItem::Macro(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::TraitItem::Verbatim(v0) => {
+                state.write_u8(4u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TraitItemConst {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.ty.hash(state);
+        self.default.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TraitItemFn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.sig.hash(state);
+        self.default.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TraitItemMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.mac.hash(state);
+        self.semi_token.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TraitItemType {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.generics.hash(state);
+        self.colon_token.hash(state);
+        self.bounds.hash(state);
+        self.default.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Type {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::Type::Array(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::Type::BareFn(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::Type::Group(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            crate::Type::ImplTrait(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::Type::Infer(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+            crate::Type::Macro(v0) => {
+                state.write_u8(5u8);
+                v0.hash(state);
+            }
+            crate::Type::Never(v0) => {
+                state.write_u8(6u8);
+                v0.hash(state);
+            }
+            crate::Type::Paren(v0) => {
+                state.write_u8(7u8);
+                v0.hash(state);
+            }
+            crate::Type::Path(v0) => {
+                state.write_u8(8u8);
+                v0.hash(state);
+            }
+            crate::Type::Ptr(v0) => {
+                state.write_u8(9u8);
+                v0.hash(state);
+            }
+            crate::Type::Reference(v0) => {
+                state.write_u8(10u8);
+                v0.hash(state);
+            }
+            crate::Type::Slice(v0) => {
+                state.write_u8(11u8);
+                v0.hash(state);
+            }
+            crate::Type::TraitObject(v0) => {
+                state.write_u8(12u8);
+                v0.hash(state);
+            }
+            crate::Type::Tuple(v0) => {
+                state.write_u8(13u8);
+                v0.hash(state);
+            }
+            crate::Type::Verbatim(v0) => {
+                state.write_u8(14u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeArray {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elem.hash(state);
+        self.len.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeBareFn {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetimes.hash(state);
+        self.unsafety.hash(state);
+        self.abi.hash(state);
+        self.inputs.hash(state);
+        self.variadic.hash(state);
+        self.output.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeGroup {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeImplTrait {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.bounds.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeInfer {
+    fn hash<H>(&self, _state: &mut H)
+    where
+        H: Hasher,
+    {}
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeMacro {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.mac.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeNever {
+    fn hash<H>(&self, _state: &mut H)
+    where
+        H: Hasher,
+    {}
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeParam {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.colon_token.hash(state);
+        self.bounds.hash(state);
+        self.eq_token.hash(state);
+        self.default.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeParamBound {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::TypeParamBound::Trait(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::TypeParamBound::Lifetime(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::TypeParamBound::Verbatim(v0) => {
+                state.write_u8(2u8);
+                TokenStreamHelper(v0).hash(state);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeParen {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypePath {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.qself.hash(state);
+        self.path.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypePtr {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.const_token.hash(state);
+        self.mutability.hash(state);
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeReference {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.lifetime.hash(state);
+        self.mutability.hash(state);
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeSlice {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elem.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeTraitObject {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.dyn_token.hash(state);
+        self.bounds.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::TypeTuple {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.elems.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::UnOp {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::UnOp::Deref(_) => {
+                state.write_u8(0u8);
+            }
+            crate::UnOp::Not(_) => {
+                state.write_u8(1u8);
+            }
+            crate::UnOp::Neg(_) => {
+                state.write_u8(2u8);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::UseGlob {
+    fn hash<H>(&self, _state: &mut H)
+    where
+        H: Hasher,
+    {}
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::UseGroup {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.items.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::UseName {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::UsePath {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.tree.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::UseRename {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.ident.hash(state);
+        self.rename.hash(state);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::UseTree {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::UseTree::Path(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::UseTree::Name(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::UseTree::Rename(v0) => {
+                state.write_u8(2u8);
+                v0.hash(state);
+            }
+            crate::UseTree::Glob(v0) => {
+                state.write_u8(3u8);
+                v0.hash(state);
+            }
+            crate::UseTree::Group(v0) => {
+                state.write_u8(4u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Variadic {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.pat.hash(state);
+        self.comma.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Variant {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.attrs.hash(state);
+        self.ident.hash(state);
+        self.fields.hash(state);
+        self.discriminant.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::VisRestricted {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.in_token.hash(state);
+        self.path.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::Visibility {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::Visibility::Public(_) => {
+                state.write_u8(0u8);
+            }
+            crate::Visibility::Restricted(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+            crate::Visibility::Inherited => {
+                state.write_u8(2u8);
+            }
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::WhereClause {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        self.predicates.hash(state);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for crate::WherePredicate {
+    fn hash<H>(&self, state: &mut H)
+    where
+        H: Hasher,
+    {
+        match self {
+            crate::WherePredicate::Lifetime(v0) => {
+                state.write_u8(0u8);
+                v0.hash(state);
+            }
+            crate::WherePredicate::Type(v0) => {
+                state.write_u8(1u8);
+                v0.hash(state);
+            }
+        }
+    }
+}
diff --git a/rust/syn/gen/visit.rs b/rust/syn/gen/visit.rs
new file mode 100644
index 0000000000000000000000000000000000000000..ca270a9a64081d39861186fe01120873d8659e91
--- /dev/null
+++ b/rust/syn/gen/visit.rs
@@ -0,0 +1,3850 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#![allow(unused_variables)]
+#![allow(clippy::needless_pass_by_ref_mut)]
+#[cfg(any(feature = "full", feature = "derive"))]
+use crate::punctuated::Punctuated;
+#[cfg(feature = "full")]
+macro_rules! full {
+    ($e:expr) => {
+        $e
+    };
+}
+#[cfg(all(feature = "derive", not(feature = "full")))]
+macro_rules! full {
+    ($e:expr) => {
+        unreachable!()
+    };
+}
+macro_rules! skip {
+    ($($tt:tt)*) => {};
+}
+/// Syntax tree traversal to walk a shared borrow of a syntax tree.
+///
+/// See the [module documentation] for details.
+///
+/// [module documentation]: self
+pub trait Visit<'ast> {
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_abi(&mut self, i: &'ast crate::Abi) {
+        visit_abi(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_angle_bracketed_generic_arguments(
+        &mut self,
+        i: &'ast crate::AngleBracketedGenericArguments,
+    ) {
+        visit_angle_bracketed_generic_arguments(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_arm(&mut self, i: &'ast crate::Arm) {
+        visit_arm(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_assoc_const(&mut self, i: &'ast crate::AssocConst) {
+        visit_assoc_const(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_assoc_type(&mut self, i: &'ast crate::AssocType) {
+        visit_assoc_type(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_attr_style(&mut self, i: &'ast crate::AttrStyle) {
+        visit_attr_style(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_attribute(&mut self, i: &'ast crate::Attribute) {
+        visit_attribute(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_bare_fn_arg(&mut self, i: &'ast crate::BareFnArg) {
+        visit_bare_fn_arg(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_bare_variadic(&mut self, i: &'ast crate::BareVariadic) {
+        visit_bare_variadic(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_bin_op(&mut self, i: &'ast crate::BinOp) {
+        visit_bin_op(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_block(&mut self, i: &'ast crate::Block) {
+        visit_block(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_bound_lifetimes(&mut self, i: &'ast crate::BoundLifetimes) {
+        visit_bound_lifetimes(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_const_param(&mut self, i: &'ast crate::ConstParam) {
+        visit_const_param(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_constraint(&mut self, i: &'ast crate::Constraint) {
+        visit_constraint(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_data(&mut self, i: &'ast crate::Data) {
+        visit_data(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_data_enum(&mut self, i: &'ast crate::DataEnum) {
+        visit_data_enum(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_data_struct(&mut self, i: &'ast crate::DataStruct) {
+        visit_data_struct(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_data_union(&mut self, i: &'ast crate::DataUnion) {
+        visit_data_union(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_derive_input(&mut self, i: &'ast crate::DeriveInput) {
+        visit_derive_input(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr(&mut self, i: &'ast crate::Expr) {
+        visit_expr(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_array(&mut self, i: &'ast crate::ExprArray) {
+        visit_expr_array(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_assign(&mut self, i: &'ast crate::ExprAssign) {
+        visit_expr_assign(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_async(&mut self, i: &'ast crate::ExprAsync) {
+        visit_expr_async(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_await(&mut self, i: &'ast crate::ExprAwait) {
+        visit_expr_await(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_binary(&mut self, i: &'ast crate::ExprBinary) {
+        visit_expr_binary(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_block(&mut self, i: &'ast crate::ExprBlock) {
+        visit_expr_block(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_break(&mut self, i: &'ast crate::ExprBreak) {
+        visit_expr_break(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_call(&mut self, i: &'ast crate::ExprCall) {
+        visit_expr_call(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_cast(&mut self, i: &'ast crate::ExprCast) {
+        visit_expr_cast(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_closure(&mut self, i: &'ast crate::ExprClosure) {
+        visit_expr_closure(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_const(&mut self, i: &'ast crate::ExprConst) {
+        visit_expr_const(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_continue(&mut self, i: &'ast crate::ExprContinue) {
+        visit_expr_continue(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_field(&mut self, i: &'ast crate::ExprField) {
+        visit_expr_field(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_for_loop(&mut self, i: &'ast crate::ExprForLoop) {
+        visit_expr_for_loop(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_group(&mut self, i: &'ast crate::ExprGroup) {
+        visit_expr_group(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_if(&mut self, i: &'ast crate::ExprIf) {
+        visit_expr_if(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_index(&mut self, i: &'ast crate::ExprIndex) {
+        visit_expr_index(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_infer(&mut self, i: &'ast crate::ExprInfer) {
+        visit_expr_infer(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_let(&mut self, i: &'ast crate::ExprLet) {
+        visit_expr_let(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_lit(&mut self, i: &'ast crate::ExprLit) {
+        visit_expr_lit(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_loop(&mut self, i: &'ast crate::ExprLoop) {
+        visit_expr_loop(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_macro(&mut self, i: &'ast crate::ExprMacro) {
+        visit_expr_macro(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_match(&mut self, i: &'ast crate::ExprMatch) {
+        visit_expr_match(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_method_call(&mut self, i: &'ast crate::ExprMethodCall) {
+        visit_expr_method_call(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_paren(&mut self, i: &'ast crate::ExprParen) {
+        visit_expr_paren(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_path(&mut self, i: &'ast crate::ExprPath) {
+        visit_expr_path(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_range(&mut self, i: &'ast crate::ExprRange) {
+        visit_expr_range(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_reference(&mut self, i: &'ast crate::ExprReference) {
+        visit_expr_reference(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_repeat(&mut self, i: &'ast crate::ExprRepeat) {
+        visit_expr_repeat(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_return(&mut self, i: &'ast crate::ExprReturn) {
+        visit_expr_return(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_struct(&mut self, i: &'ast crate::ExprStruct) {
+        visit_expr_struct(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_try(&mut self, i: &'ast crate::ExprTry) {
+        visit_expr_try(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_try_block(&mut self, i: &'ast crate::ExprTryBlock) {
+        visit_expr_try_block(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_tuple(&mut self, i: &'ast crate::ExprTuple) {
+        visit_expr_tuple(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_unary(&mut self, i: &'ast crate::ExprUnary) {
+        visit_expr_unary(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_unsafe(&mut self, i: &'ast crate::ExprUnsafe) {
+        visit_expr_unsafe(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_while(&mut self, i: &'ast crate::ExprWhile) {
+        visit_expr_while(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_yield(&mut self, i: &'ast crate::ExprYield) {
+        visit_expr_yield(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_field(&mut self, i: &'ast crate::Field) {
+        visit_field(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_field_mutability(&mut self, i: &'ast crate::FieldMutability) {
+        visit_field_mutability(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_field_pat(&mut self, i: &'ast crate::FieldPat) {
+        visit_field_pat(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_field_value(&mut self, i: &'ast crate::FieldValue) {
+        visit_field_value(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_fields(&mut self, i: &'ast crate::Fields) {
+        visit_fields(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_fields_named(&mut self, i: &'ast crate::FieldsNamed) {
+        visit_fields_named(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_fields_unnamed(&mut self, i: &'ast crate::FieldsUnnamed) {
+        visit_fields_unnamed(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_file(&mut self, i: &'ast crate::File) {
+        visit_file(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_fn_arg(&mut self, i: &'ast crate::FnArg) {
+        visit_fn_arg(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item(&mut self, i: &'ast crate::ForeignItem) {
+        visit_foreign_item(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item_fn(&mut self, i: &'ast crate::ForeignItemFn) {
+        visit_foreign_item_fn(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item_macro(&mut self, i: &'ast crate::ForeignItemMacro) {
+        visit_foreign_item_macro(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item_static(&mut self, i: &'ast crate::ForeignItemStatic) {
+        visit_foreign_item_static(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item_type(&mut self, i: &'ast crate::ForeignItemType) {
+        visit_foreign_item_type(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_generic_argument(&mut self, i: &'ast crate::GenericArgument) {
+        visit_generic_argument(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_generic_param(&mut self, i: &'ast crate::GenericParam) {
+        visit_generic_param(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_generics(&mut self, i: &'ast crate::Generics) {
+        visit_generics(self, i);
+    }
+    fn visit_ident(&mut self, i: &'ast proc_macro2::Ident) {
+        visit_ident(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item(&mut self, i: &'ast crate::ImplItem) {
+        visit_impl_item(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item_const(&mut self, i: &'ast crate::ImplItemConst) {
+        visit_impl_item_const(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item_fn(&mut self, i: &'ast crate::ImplItemFn) {
+        visit_impl_item_fn(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item_macro(&mut self, i: &'ast crate::ImplItemMacro) {
+        visit_impl_item_macro(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item_type(&mut self, i: &'ast crate::ImplItemType) {
+        visit_impl_item_type(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_restriction(&mut self, i: &'ast crate::ImplRestriction) {
+        visit_impl_restriction(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_index(&mut self, i: &'ast crate::Index) {
+        visit_index(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item(&mut self, i: &'ast crate::Item) {
+        visit_item(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_const(&mut self, i: &'ast crate::ItemConst) {
+        visit_item_const(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_enum(&mut self, i: &'ast crate::ItemEnum) {
+        visit_item_enum(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_extern_crate(&mut self, i: &'ast crate::ItemExternCrate) {
+        visit_item_extern_crate(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_fn(&mut self, i: &'ast crate::ItemFn) {
+        visit_item_fn(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_foreign_mod(&mut self, i: &'ast crate::ItemForeignMod) {
+        visit_item_foreign_mod(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_impl(&mut self, i: &'ast crate::ItemImpl) {
+        visit_item_impl(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_macro(&mut self, i: &'ast crate::ItemMacro) {
+        visit_item_macro(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_mod(&mut self, i: &'ast crate::ItemMod) {
+        visit_item_mod(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_static(&mut self, i: &'ast crate::ItemStatic) {
+        visit_item_static(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_struct(&mut self, i: &'ast crate::ItemStruct) {
+        visit_item_struct(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_trait(&mut self, i: &'ast crate::ItemTrait) {
+        visit_item_trait(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_trait_alias(&mut self, i: &'ast crate::ItemTraitAlias) {
+        visit_item_trait_alias(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_type(&mut self, i: &'ast crate::ItemType) {
+        visit_item_type(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_union(&mut self, i: &'ast crate::ItemUnion) {
+        visit_item_union(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_use(&mut self, i: &'ast crate::ItemUse) {
+        visit_item_use(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_label(&mut self, i: &'ast crate::Label) {
+        visit_label(self, i);
+    }
+    fn visit_lifetime(&mut self, i: &'ast crate::Lifetime) {
+        visit_lifetime(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_lifetime_param(&mut self, i: &'ast crate::LifetimeParam) {
+        visit_lifetime_param(self, i);
+    }
+    fn visit_lit(&mut self, i: &'ast crate::Lit) {
+        visit_lit(self, i);
+    }
+    fn visit_lit_bool(&mut self, i: &'ast crate::LitBool) {
+        visit_lit_bool(self, i);
+    }
+    fn visit_lit_byte(&mut self, i: &'ast crate::LitByte) {
+        visit_lit_byte(self, i);
+    }
+    fn visit_lit_byte_str(&mut self, i: &'ast crate::LitByteStr) {
+        visit_lit_byte_str(self, i);
+    }
+    fn visit_lit_char(&mut self, i: &'ast crate::LitChar) {
+        visit_lit_char(self, i);
+    }
+    fn visit_lit_float(&mut self, i: &'ast crate::LitFloat) {
+        visit_lit_float(self, i);
+    }
+    fn visit_lit_int(&mut self, i: &'ast crate::LitInt) {
+        visit_lit_int(self, i);
+    }
+    fn visit_lit_str(&mut self, i: &'ast crate::LitStr) {
+        visit_lit_str(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_local(&mut self, i: &'ast crate::Local) {
+        visit_local(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_local_init(&mut self, i: &'ast crate::LocalInit) {
+        visit_local_init(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_macro(&mut self, i: &'ast crate::Macro) {
+        visit_macro(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_macro_delimiter(&mut self, i: &'ast crate::MacroDelimiter) {
+        visit_macro_delimiter(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_member(&mut self, i: &'ast crate::Member) {
+        visit_member(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_meta(&mut self, i: &'ast crate::Meta) {
+        visit_meta(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_meta_list(&mut self, i: &'ast crate::MetaList) {
+        visit_meta_list(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_meta_name_value(&mut self, i: &'ast crate::MetaNameValue) {
+        visit_meta_name_value(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_parenthesized_generic_arguments(
+        &mut self,
+        i: &'ast crate::ParenthesizedGenericArguments,
+    ) {
+        visit_parenthesized_generic_arguments(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat(&mut self, i: &'ast crate::Pat) {
+        visit_pat(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_ident(&mut self, i: &'ast crate::PatIdent) {
+        visit_pat_ident(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_or(&mut self, i: &'ast crate::PatOr) {
+        visit_pat_or(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_paren(&mut self, i: &'ast crate::PatParen) {
+        visit_pat_paren(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_reference(&mut self, i: &'ast crate::PatReference) {
+        visit_pat_reference(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_rest(&mut self, i: &'ast crate::PatRest) {
+        visit_pat_rest(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_slice(&mut self, i: &'ast crate::PatSlice) {
+        visit_pat_slice(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_struct(&mut self, i: &'ast crate::PatStruct) {
+        visit_pat_struct(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_tuple(&mut self, i: &'ast crate::PatTuple) {
+        visit_pat_tuple(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_tuple_struct(&mut self, i: &'ast crate::PatTupleStruct) {
+        visit_pat_tuple_struct(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_type(&mut self, i: &'ast crate::PatType) {
+        visit_pat_type(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_wild(&mut self, i: &'ast crate::PatWild) {
+        visit_pat_wild(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_path(&mut self, i: &'ast crate::Path) {
+        visit_path(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_path_arguments(&mut self, i: &'ast crate::PathArguments) {
+        visit_path_arguments(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_path_segment(&mut self, i: &'ast crate::PathSegment) {
+        visit_path_segment(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_predicate_lifetime(&mut self, i: &'ast crate::PredicateLifetime) {
+        visit_predicate_lifetime(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_predicate_type(&mut self, i: &'ast crate::PredicateType) {
+        visit_predicate_type(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_qself(&mut self, i: &'ast crate::QSelf) {
+        visit_qself(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_range_limits(&mut self, i: &'ast crate::RangeLimits) {
+        visit_range_limits(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_receiver(&mut self, i: &'ast crate::Receiver) {
+        visit_receiver(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_return_type(&mut self, i: &'ast crate::ReturnType) {
+        visit_return_type(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_signature(&mut self, i: &'ast crate::Signature) {
+        visit_signature(self, i);
+    }
+    fn visit_span(&mut self, i: &proc_macro2::Span) {
+        visit_span(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_static_mutability(&mut self, i: &'ast crate::StaticMutability) {
+        visit_static_mutability(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_stmt(&mut self, i: &'ast crate::Stmt) {
+        visit_stmt(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_stmt_macro(&mut self, i: &'ast crate::StmtMacro) {
+        visit_stmt_macro(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_trait_bound(&mut self, i: &'ast crate::TraitBound) {
+        visit_trait_bound(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_trait_bound_modifier(&mut self, i: &'ast crate::TraitBoundModifier) {
+        visit_trait_bound_modifier(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item(&mut self, i: &'ast crate::TraitItem) {
+        visit_trait_item(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item_const(&mut self, i: &'ast crate::TraitItemConst) {
+        visit_trait_item_const(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item_fn(&mut self, i: &'ast crate::TraitItemFn) {
+        visit_trait_item_fn(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item_macro(&mut self, i: &'ast crate::TraitItemMacro) {
+        visit_trait_item_macro(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item_type(&mut self, i: &'ast crate::TraitItemType) {
+        visit_trait_item_type(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type(&mut self, i: &'ast crate::Type) {
+        visit_type(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_array(&mut self, i: &'ast crate::TypeArray) {
+        visit_type_array(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_bare_fn(&mut self, i: &'ast crate::TypeBareFn) {
+        visit_type_bare_fn(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_group(&mut self, i: &'ast crate::TypeGroup) {
+        visit_type_group(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_impl_trait(&mut self, i: &'ast crate::TypeImplTrait) {
+        visit_type_impl_trait(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_infer(&mut self, i: &'ast crate::TypeInfer) {
+        visit_type_infer(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_macro(&mut self, i: &'ast crate::TypeMacro) {
+        visit_type_macro(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_never(&mut self, i: &'ast crate::TypeNever) {
+        visit_type_never(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_param(&mut self, i: &'ast crate::TypeParam) {
+        visit_type_param(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_param_bound(&mut self, i: &'ast crate::TypeParamBound) {
+        visit_type_param_bound(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_paren(&mut self, i: &'ast crate::TypeParen) {
+        visit_type_paren(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_path(&mut self, i: &'ast crate::TypePath) {
+        visit_type_path(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_ptr(&mut self, i: &'ast crate::TypePtr) {
+        visit_type_ptr(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_reference(&mut self, i: &'ast crate::TypeReference) {
+        visit_type_reference(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_slice(&mut self, i: &'ast crate::TypeSlice) {
+        visit_type_slice(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_trait_object(&mut self, i: &'ast crate::TypeTraitObject) {
+        visit_type_trait_object(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_tuple(&mut self, i: &'ast crate::TypeTuple) {
+        visit_type_tuple(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_un_op(&mut self, i: &'ast crate::UnOp) {
+        visit_un_op(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_glob(&mut self, i: &'ast crate::UseGlob) {
+        visit_use_glob(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_group(&mut self, i: &'ast crate::UseGroup) {
+        visit_use_group(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_name(&mut self, i: &'ast crate::UseName) {
+        visit_use_name(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_path(&mut self, i: &'ast crate::UsePath) {
+        visit_use_path(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_rename(&mut self, i: &'ast crate::UseRename) {
+        visit_use_rename(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_tree(&mut self, i: &'ast crate::UseTree) {
+        visit_use_tree(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_variadic(&mut self, i: &'ast crate::Variadic) {
+        visit_variadic(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_variant(&mut self, i: &'ast crate::Variant) {
+        visit_variant(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_vis_restricted(&mut self, i: &'ast crate::VisRestricted) {
+        visit_vis_restricted(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_visibility(&mut self, i: &'ast crate::Visibility) {
+        visit_visibility(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_where_clause(&mut self, i: &'ast crate::WhereClause) {
+        visit_where_clause(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_where_predicate(&mut self, i: &'ast crate::WherePredicate) {
+        visit_where_predicate(self, i);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_abi<'ast, V>(v: &mut V, node: &'ast crate::Abi)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.extern_token);
+    if let Some(it) = &node.name {
+        v.visit_lit_str(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_angle_bracketed_generic_arguments<'ast, V>(
+    v: &mut V,
+    node: &'ast crate::AngleBracketedGenericArguments,
+)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.colon2_token);
+    skip!(node.lt_token);
+    for el in Punctuated::pairs(&node.args) {
+        let it = el.value();
+        v.visit_generic_argument(it);
+    }
+    skip!(node.gt_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_arm<'ast, V>(v: &mut V, node: &'ast crate::Arm)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_pat(&node.pat);
+    if let Some(it) = &node.guard {
+        skip!((it).0);
+        v.visit_expr(&*(it).1);
+    }
+    skip!(node.fat_arrow_token);
+    v.visit_expr(&*node.body);
+    skip!(node.comma);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_assoc_const<'ast, V>(v: &mut V, node: &'ast crate::AssocConst)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_ident(&node.ident);
+    if let Some(it) = &node.generics {
+        v.visit_angle_bracketed_generic_arguments(it);
+    }
+    skip!(node.eq_token);
+    v.visit_expr(&node.value);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_assoc_type<'ast, V>(v: &mut V, node: &'ast crate::AssocType)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_ident(&node.ident);
+    if let Some(it) = &node.generics {
+        v.visit_angle_bracketed_generic_arguments(it);
+    }
+    skip!(node.eq_token);
+    v.visit_type(&node.ty);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_attr_style<'ast, V>(v: &mut V, node: &'ast crate::AttrStyle)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::AttrStyle::Outer => {}
+        crate::AttrStyle::Inner(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_attribute<'ast, V>(v: &mut V, node: &'ast crate::Attribute)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.pound_token);
+    v.visit_attr_style(&node.style);
+    skip!(node.bracket_token);
+    v.visit_meta(&node.meta);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_bare_fn_arg<'ast, V>(v: &mut V, node: &'ast crate::BareFnArg)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.name {
+        v.visit_ident(&(it).0);
+        skip!((it).1);
+    }
+    v.visit_type(&node.ty);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_bare_variadic<'ast, V>(v: &mut V, node: &'ast crate::BareVariadic)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.name {
+        v.visit_ident(&(it).0);
+        skip!((it).1);
+    }
+    skip!(node.dots);
+    skip!(node.comma);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_bin_op<'ast, V>(v: &mut V, node: &'ast crate::BinOp)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::BinOp::Add(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Sub(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Mul(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Div(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Rem(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::And(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Or(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitXor(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitAnd(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitOr(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Shl(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Shr(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Eq(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Lt(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Le(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Ne(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Ge(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Gt(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::AddAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::SubAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::MulAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::DivAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::RemAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitXorAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitAndAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitOrAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::ShlAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::ShrAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_block<'ast, V>(v: &mut V, node: &'ast crate::Block)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.brace_token);
+    for it in &node.stmts {
+        v.visit_stmt(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_bound_lifetimes<'ast, V>(v: &mut V, node: &'ast crate::BoundLifetimes)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.for_token);
+    skip!(node.lt_token);
+    for el in Punctuated::pairs(&node.lifetimes) {
+        let it = el.value();
+        v.visit_generic_param(it);
+    }
+    skip!(node.gt_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_const_param<'ast, V>(v: &mut V, node: &'ast crate::ConstParam)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.const_token);
+    v.visit_ident(&node.ident);
+    skip!(node.colon_token);
+    v.visit_type(&node.ty);
+    skip!(node.eq_token);
+    if let Some(it) = &node.default {
+        v.visit_expr(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_constraint<'ast, V>(v: &mut V, node: &'ast crate::Constraint)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_ident(&node.ident);
+    if let Some(it) = &node.generics {
+        v.visit_angle_bracketed_generic_arguments(it);
+    }
+    skip!(node.colon_token);
+    for el in Punctuated::pairs(&node.bounds) {
+        let it = el.value();
+        v.visit_type_param_bound(it);
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_data<'ast, V>(v: &mut V, node: &'ast crate::Data)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Data::Struct(_binding_0) => {
+            v.visit_data_struct(_binding_0);
+        }
+        crate::Data::Enum(_binding_0) => {
+            v.visit_data_enum(_binding_0);
+        }
+        crate::Data::Union(_binding_0) => {
+            v.visit_data_union(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_data_enum<'ast, V>(v: &mut V, node: &'ast crate::DataEnum)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.enum_token);
+    skip!(node.brace_token);
+    for el in Punctuated::pairs(&node.variants) {
+        let it = el.value();
+        v.visit_variant(it);
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_data_struct<'ast, V>(v: &mut V, node: &'ast crate::DataStruct)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.struct_token);
+    v.visit_fields(&node.fields);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_data_union<'ast, V>(v: &mut V, node: &'ast crate::DataUnion)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.union_token);
+    v.visit_fields_named(&node.fields);
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_derive_input<'ast, V>(v: &mut V, node: &'ast crate::DeriveInput)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    v.visit_data(&node.data);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr<'ast, V>(v: &mut V, node: &'ast crate::Expr)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Expr::Array(_binding_0) => {
+            full!(v.visit_expr_array(_binding_0));
+        }
+        crate::Expr::Assign(_binding_0) => {
+            full!(v.visit_expr_assign(_binding_0));
+        }
+        crate::Expr::Async(_binding_0) => {
+            full!(v.visit_expr_async(_binding_0));
+        }
+        crate::Expr::Await(_binding_0) => {
+            full!(v.visit_expr_await(_binding_0));
+        }
+        crate::Expr::Binary(_binding_0) => {
+            v.visit_expr_binary(_binding_0);
+        }
+        crate::Expr::Block(_binding_0) => {
+            full!(v.visit_expr_block(_binding_0));
+        }
+        crate::Expr::Break(_binding_0) => {
+            full!(v.visit_expr_break(_binding_0));
+        }
+        crate::Expr::Call(_binding_0) => {
+            v.visit_expr_call(_binding_0);
+        }
+        crate::Expr::Cast(_binding_0) => {
+            v.visit_expr_cast(_binding_0);
+        }
+        crate::Expr::Closure(_binding_0) => {
+            full!(v.visit_expr_closure(_binding_0));
+        }
+        crate::Expr::Const(_binding_0) => {
+            full!(v.visit_expr_const(_binding_0));
+        }
+        crate::Expr::Continue(_binding_0) => {
+            full!(v.visit_expr_continue(_binding_0));
+        }
+        crate::Expr::Field(_binding_0) => {
+            v.visit_expr_field(_binding_0);
+        }
+        crate::Expr::ForLoop(_binding_0) => {
+            full!(v.visit_expr_for_loop(_binding_0));
+        }
+        crate::Expr::Group(_binding_0) => {
+            v.visit_expr_group(_binding_0);
+        }
+        crate::Expr::If(_binding_0) => {
+            full!(v.visit_expr_if(_binding_0));
+        }
+        crate::Expr::Index(_binding_0) => {
+            v.visit_expr_index(_binding_0);
+        }
+        crate::Expr::Infer(_binding_0) => {
+            full!(v.visit_expr_infer(_binding_0));
+        }
+        crate::Expr::Let(_binding_0) => {
+            full!(v.visit_expr_let(_binding_0));
+        }
+        crate::Expr::Lit(_binding_0) => {
+            v.visit_expr_lit(_binding_0);
+        }
+        crate::Expr::Loop(_binding_0) => {
+            full!(v.visit_expr_loop(_binding_0));
+        }
+        crate::Expr::Macro(_binding_0) => {
+            v.visit_expr_macro(_binding_0);
+        }
+        crate::Expr::Match(_binding_0) => {
+            full!(v.visit_expr_match(_binding_0));
+        }
+        crate::Expr::MethodCall(_binding_0) => {
+            v.visit_expr_method_call(_binding_0);
+        }
+        crate::Expr::Paren(_binding_0) => {
+            v.visit_expr_paren(_binding_0);
+        }
+        crate::Expr::Path(_binding_0) => {
+            v.visit_expr_path(_binding_0);
+        }
+        crate::Expr::Range(_binding_0) => {
+            full!(v.visit_expr_range(_binding_0));
+        }
+        crate::Expr::Reference(_binding_0) => {
+            v.visit_expr_reference(_binding_0);
+        }
+        crate::Expr::Repeat(_binding_0) => {
+            full!(v.visit_expr_repeat(_binding_0));
+        }
+        crate::Expr::Return(_binding_0) => {
+            full!(v.visit_expr_return(_binding_0));
+        }
+        crate::Expr::Struct(_binding_0) => {
+            v.visit_expr_struct(_binding_0);
+        }
+        crate::Expr::Try(_binding_0) => {
+            full!(v.visit_expr_try(_binding_0));
+        }
+        crate::Expr::TryBlock(_binding_0) => {
+            full!(v.visit_expr_try_block(_binding_0));
+        }
+        crate::Expr::Tuple(_binding_0) => {
+            full!(v.visit_expr_tuple(_binding_0));
+        }
+        crate::Expr::Unary(_binding_0) => {
+            v.visit_expr_unary(_binding_0);
+        }
+        crate::Expr::Unsafe(_binding_0) => {
+            full!(v.visit_expr_unsafe(_binding_0));
+        }
+        crate::Expr::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::Expr::While(_binding_0) => {
+            full!(v.visit_expr_while(_binding_0));
+        }
+        crate::Expr::Yield(_binding_0) => {
+            full!(v.visit_expr_yield(_binding_0));
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_array<'ast, V>(v: &mut V, node: &'ast crate::ExprArray)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.bracket_token);
+    for el in Punctuated::pairs(&node.elems) {
+        let it = el.value();
+        v.visit_expr(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_assign<'ast, V>(v: &mut V, node: &'ast crate::ExprAssign)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_expr(&*node.left);
+    skip!(node.eq_token);
+    v.visit_expr(&*node.right);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_async<'ast, V>(v: &mut V, node: &'ast crate::ExprAsync)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.async_token);
+    skip!(node.capture);
+    v.visit_block(&node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_await<'ast, V>(v: &mut V, node: &'ast crate::ExprAwait)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_expr(&*node.base);
+    skip!(node.dot_token);
+    skip!(node.await_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_binary<'ast, V>(v: &mut V, node: &'ast crate::ExprBinary)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_expr(&*node.left);
+    v.visit_bin_op(&node.op);
+    v.visit_expr(&*node.right);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_block<'ast, V>(v: &mut V, node: &'ast crate::ExprBlock)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.label {
+        v.visit_label(it);
+    }
+    v.visit_block(&node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_break<'ast, V>(v: &mut V, node: &'ast crate::ExprBreak)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.break_token);
+    if let Some(it) = &node.label {
+        v.visit_lifetime(it);
+    }
+    if let Some(it) = &node.expr {
+        v.visit_expr(&**it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_call<'ast, V>(v: &mut V, node: &'ast crate::ExprCall)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_expr(&*node.func);
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.args) {
+        let it = el.value();
+        v.visit_expr(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_cast<'ast, V>(v: &mut V, node: &'ast crate::ExprCast)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_expr(&*node.expr);
+    skip!(node.as_token);
+    v.visit_type(&*node.ty);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_closure<'ast, V>(v: &mut V, node: &'ast crate::ExprClosure)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.lifetimes {
+        v.visit_bound_lifetimes(it);
+    }
+    skip!(node.constness);
+    skip!(node.movability);
+    skip!(node.asyncness);
+    skip!(node.capture);
+    skip!(node.or1_token);
+    for el in Punctuated::pairs(&node.inputs) {
+        let it = el.value();
+        v.visit_pat(it);
+    }
+    skip!(node.or2_token);
+    v.visit_return_type(&node.output);
+    v.visit_expr(&*node.body);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_const<'ast, V>(v: &mut V, node: &'ast crate::ExprConst)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.const_token);
+    v.visit_block(&node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_continue<'ast, V>(v: &mut V, node: &'ast crate::ExprContinue)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.continue_token);
+    if let Some(it) = &node.label {
+        v.visit_lifetime(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_field<'ast, V>(v: &mut V, node: &'ast crate::ExprField)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_expr(&*node.base);
+    skip!(node.dot_token);
+    v.visit_member(&node.member);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_for_loop<'ast, V>(v: &mut V, node: &'ast crate::ExprForLoop)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.label {
+        v.visit_label(it);
+    }
+    skip!(node.for_token);
+    v.visit_pat(&*node.pat);
+    skip!(node.in_token);
+    v.visit_expr(&*node.expr);
+    v.visit_block(&node.body);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_group<'ast, V>(v: &mut V, node: &'ast crate::ExprGroup)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.group_token);
+    v.visit_expr(&*node.expr);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_if<'ast, V>(v: &mut V, node: &'ast crate::ExprIf)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.if_token);
+    v.visit_expr(&*node.cond);
+    v.visit_block(&node.then_branch);
+    if let Some(it) = &node.else_branch {
+        skip!((it).0);
+        v.visit_expr(&*(it).1);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_index<'ast, V>(v: &mut V, node: &'ast crate::ExprIndex)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_expr(&*node.expr);
+    skip!(node.bracket_token);
+    v.visit_expr(&*node.index);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_infer<'ast, V>(v: &mut V, node: &'ast crate::ExprInfer)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.underscore_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_let<'ast, V>(v: &mut V, node: &'ast crate::ExprLet)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.let_token);
+    v.visit_pat(&*node.pat);
+    skip!(node.eq_token);
+    v.visit_expr(&*node.expr);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_lit<'ast, V>(v: &mut V, node: &'ast crate::ExprLit)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_lit(&node.lit);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_loop<'ast, V>(v: &mut V, node: &'ast crate::ExprLoop)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.label {
+        v.visit_label(it);
+    }
+    skip!(node.loop_token);
+    v.visit_block(&node.body);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_macro<'ast, V>(v: &mut V, node: &'ast crate::ExprMacro)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_macro(&node.mac);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_match<'ast, V>(v: &mut V, node: &'ast crate::ExprMatch)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.match_token);
+    v.visit_expr(&*node.expr);
+    skip!(node.brace_token);
+    for it in &node.arms {
+        v.visit_arm(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_method_call<'ast, V>(v: &mut V, node: &'ast crate::ExprMethodCall)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_expr(&*node.receiver);
+    skip!(node.dot_token);
+    v.visit_ident(&node.method);
+    if let Some(it) = &node.turbofish {
+        v.visit_angle_bracketed_generic_arguments(it);
+    }
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.args) {
+        let it = el.value();
+        v.visit_expr(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_paren<'ast, V>(v: &mut V, node: &'ast crate::ExprParen)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.paren_token);
+    v.visit_expr(&*node.expr);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_path<'ast, V>(v: &mut V, node: &'ast crate::ExprPath)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.qself {
+        v.visit_qself(it);
+    }
+    v.visit_path(&node.path);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_range<'ast, V>(v: &mut V, node: &'ast crate::ExprRange)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.start {
+        v.visit_expr(&**it);
+    }
+    v.visit_range_limits(&node.limits);
+    if let Some(it) = &node.end {
+        v.visit_expr(&**it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_reference<'ast, V>(v: &mut V, node: &'ast crate::ExprReference)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.and_token);
+    skip!(node.mutability);
+    v.visit_expr(&*node.expr);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_repeat<'ast, V>(v: &mut V, node: &'ast crate::ExprRepeat)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.bracket_token);
+    v.visit_expr(&*node.expr);
+    skip!(node.semi_token);
+    v.visit_expr(&*node.len);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_return<'ast, V>(v: &mut V, node: &'ast crate::ExprReturn)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.return_token);
+    if let Some(it) = &node.expr {
+        v.visit_expr(&**it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_struct<'ast, V>(v: &mut V, node: &'ast crate::ExprStruct)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.qself {
+        v.visit_qself(it);
+    }
+    v.visit_path(&node.path);
+    skip!(node.brace_token);
+    for el in Punctuated::pairs(&node.fields) {
+        let it = el.value();
+        v.visit_field_value(it);
+    }
+    skip!(node.dot2_token);
+    if let Some(it) = &node.rest {
+        v.visit_expr(&**it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_try<'ast, V>(v: &mut V, node: &'ast crate::ExprTry)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_expr(&*node.expr);
+    skip!(node.question_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_try_block<'ast, V>(v: &mut V, node: &'ast crate::ExprTryBlock)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.try_token);
+    v.visit_block(&node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_tuple<'ast, V>(v: &mut V, node: &'ast crate::ExprTuple)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.elems) {
+        let it = el.value();
+        v.visit_expr(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_unary<'ast, V>(v: &mut V, node: &'ast crate::ExprUnary)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_un_op(&node.op);
+    v.visit_expr(&*node.expr);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_unsafe<'ast, V>(v: &mut V, node: &'ast crate::ExprUnsafe)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.unsafe_token);
+    v.visit_block(&node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_while<'ast, V>(v: &mut V, node: &'ast crate::ExprWhile)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.label {
+        v.visit_label(it);
+    }
+    skip!(node.while_token);
+    v.visit_expr(&*node.cond);
+    v.visit_block(&node.body);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_yield<'ast, V>(v: &mut V, node: &'ast crate::ExprYield)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.yield_token);
+    if let Some(it) = &node.expr {
+        v.visit_expr(&**it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_field<'ast, V>(v: &mut V, node: &'ast crate::Field)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    v.visit_field_mutability(&node.mutability);
+    if let Some(it) = &node.ident {
+        v.visit_ident(it);
+    }
+    skip!(node.colon_token);
+    v.visit_type(&node.ty);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_field_mutability<'ast, V>(v: &mut V, node: &'ast crate::FieldMutability)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::FieldMutability::None => {}
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_field_pat<'ast, V>(v: &mut V, node: &'ast crate::FieldPat)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_member(&node.member);
+    skip!(node.colon_token);
+    v.visit_pat(&*node.pat);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_field_value<'ast, V>(v: &mut V, node: &'ast crate::FieldValue)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_member(&node.member);
+    skip!(node.colon_token);
+    v.visit_expr(&node.expr);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_fields<'ast, V>(v: &mut V, node: &'ast crate::Fields)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Fields::Named(_binding_0) => {
+            v.visit_fields_named(_binding_0);
+        }
+        crate::Fields::Unnamed(_binding_0) => {
+            v.visit_fields_unnamed(_binding_0);
+        }
+        crate::Fields::Unit => {}
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_fields_named<'ast, V>(v: &mut V, node: &'ast crate::FieldsNamed)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.brace_token);
+    for el in Punctuated::pairs(&node.named) {
+        let it = el.value();
+        v.visit_field(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_fields_unnamed<'ast, V>(v: &mut V, node: &'ast crate::FieldsUnnamed)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.unnamed) {
+        let it = el.value();
+        v.visit_field(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_file<'ast, V>(v: &mut V, node: &'ast crate::File)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.shebang);
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    for it in &node.items {
+        v.visit_item(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_fn_arg<'ast, V>(v: &mut V, node: &'ast crate::FnArg)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::FnArg::Receiver(_binding_0) => {
+            v.visit_receiver(_binding_0);
+        }
+        crate::FnArg::Typed(_binding_0) => {
+            v.visit_pat_type(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item<'ast, V>(v: &mut V, node: &'ast crate::ForeignItem)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::ForeignItem::Fn(_binding_0) => {
+            v.visit_foreign_item_fn(_binding_0);
+        }
+        crate::ForeignItem::Static(_binding_0) => {
+            v.visit_foreign_item_static(_binding_0);
+        }
+        crate::ForeignItem::Type(_binding_0) => {
+            v.visit_foreign_item_type(_binding_0);
+        }
+        crate::ForeignItem::Macro(_binding_0) => {
+            v.visit_foreign_item_macro(_binding_0);
+        }
+        crate::ForeignItem::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item_fn<'ast, V>(v: &mut V, node: &'ast crate::ForeignItemFn)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    v.visit_signature(&node.sig);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item_macro<'ast, V>(v: &mut V, node: &'ast crate::ForeignItemMacro)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_macro(&node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item_static<'ast, V>(
+    v: &mut V,
+    node: &'ast crate::ForeignItemStatic,
+)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.static_token);
+    v.visit_static_mutability(&node.mutability);
+    v.visit_ident(&node.ident);
+    skip!(node.colon_token);
+    v.visit_type(&*node.ty);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item_type<'ast, V>(v: &mut V, node: &'ast crate::ForeignItemType)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.type_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.semi_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_generic_argument<'ast, V>(v: &mut V, node: &'ast crate::GenericArgument)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::GenericArgument::Lifetime(_binding_0) => {
+            v.visit_lifetime(_binding_0);
+        }
+        crate::GenericArgument::Type(_binding_0) => {
+            v.visit_type(_binding_0);
+        }
+        crate::GenericArgument::Const(_binding_0) => {
+            v.visit_expr(_binding_0);
+        }
+        crate::GenericArgument::AssocType(_binding_0) => {
+            v.visit_assoc_type(_binding_0);
+        }
+        crate::GenericArgument::AssocConst(_binding_0) => {
+            v.visit_assoc_const(_binding_0);
+        }
+        crate::GenericArgument::Constraint(_binding_0) => {
+            v.visit_constraint(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_generic_param<'ast, V>(v: &mut V, node: &'ast crate::GenericParam)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::GenericParam::Lifetime(_binding_0) => {
+            v.visit_lifetime_param(_binding_0);
+        }
+        crate::GenericParam::Type(_binding_0) => {
+            v.visit_type_param(_binding_0);
+        }
+        crate::GenericParam::Const(_binding_0) => {
+            v.visit_const_param(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_generics<'ast, V>(v: &mut V, node: &'ast crate::Generics)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.lt_token);
+    for el in Punctuated::pairs(&node.params) {
+        let it = el.value();
+        v.visit_generic_param(it);
+    }
+    skip!(node.gt_token);
+    if let Some(it) = &node.where_clause {
+        v.visit_where_clause(it);
+    }
+}
+pub fn visit_ident<'ast, V>(v: &mut V, node: &'ast proc_macro2::Ident)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_span(&node.span());
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item<'ast, V>(v: &mut V, node: &'ast crate::ImplItem)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::ImplItem::Const(_binding_0) => {
+            v.visit_impl_item_const(_binding_0);
+        }
+        crate::ImplItem::Fn(_binding_0) => {
+            v.visit_impl_item_fn(_binding_0);
+        }
+        crate::ImplItem::Type(_binding_0) => {
+            v.visit_impl_item_type(_binding_0);
+        }
+        crate::ImplItem::Macro(_binding_0) => {
+            v.visit_impl_item_macro(_binding_0);
+        }
+        crate::ImplItem::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item_const<'ast, V>(v: &mut V, node: &'ast crate::ImplItemConst)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.defaultness);
+    skip!(node.const_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.colon_token);
+    v.visit_type(&node.ty);
+    skip!(node.eq_token);
+    v.visit_expr(&node.expr);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item_fn<'ast, V>(v: &mut V, node: &'ast crate::ImplItemFn)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.defaultness);
+    v.visit_signature(&node.sig);
+    v.visit_block(&node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item_macro<'ast, V>(v: &mut V, node: &'ast crate::ImplItemMacro)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_macro(&node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item_type<'ast, V>(v: &mut V, node: &'ast crate::ImplItemType)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.defaultness);
+    skip!(node.type_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.eq_token);
+    v.visit_type(&node.ty);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_restriction<'ast, V>(v: &mut V, node: &'ast crate::ImplRestriction)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match *node {}
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_index<'ast, V>(v: &mut V, node: &'ast crate::Index)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.index);
+    v.visit_span(&node.span);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item<'ast, V>(v: &mut V, node: &'ast crate::Item)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Item::Const(_binding_0) => {
+            v.visit_item_const(_binding_0);
+        }
+        crate::Item::Enum(_binding_0) => {
+            v.visit_item_enum(_binding_0);
+        }
+        crate::Item::ExternCrate(_binding_0) => {
+            v.visit_item_extern_crate(_binding_0);
+        }
+        crate::Item::Fn(_binding_0) => {
+            v.visit_item_fn(_binding_0);
+        }
+        crate::Item::ForeignMod(_binding_0) => {
+            v.visit_item_foreign_mod(_binding_0);
+        }
+        crate::Item::Impl(_binding_0) => {
+            v.visit_item_impl(_binding_0);
+        }
+        crate::Item::Macro(_binding_0) => {
+            v.visit_item_macro(_binding_0);
+        }
+        crate::Item::Mod(_binding_0) => {
+            v.visit_item_mod(_binding_0);
+        }
+        crate::Item::Static(_binding_0) => {
+            v.visit_item_static(_binding_0);
+        }
+        crate::Item::Struct(_binding_0) => {
+            v.visit_item_struct(_binding_0);
+        }
+        crate::Item::Trait(_binding_0) => {
+            v.visit_item_trait(_binding_0);
+        }
+        crate::Item::TraitAlias(_binding_0) => {
+            v.visit_item_trait_alias(_binding_0);
+        }
+        crate::Item::Type(_binding_0) => {
+            v.visit_item_type(_binding_0);
+        }
+        crate::Item::Union(_binding_0) => {
+            v.visit_item_union(_binding_0);
+        }
+        crate::Item::Use(_binding_0) => {
+            v.visit_item_use(_binding_0);
+        }
+        crate::Item::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_const<'ast, V>(v: &mut V, node: &'ast crate::ItemConst)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.const_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.colon_token);
+    v.visit_type(&*node.ty);
+    skip!(node.eq_token);
+    v.visit_expr(&*node.expr);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_enum<'ast, V>(v: &mut V, node: &'ast crate::ItemEnum)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.enum_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.brace_token);
+    for el in Punctuated::pairs(&node.variants) {
+        let it = el.value();
+        v.visit_variant(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_extern_crate<'ast, V>(v: &mut V, node: &'ast crate::ItemExternCrate)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.extern_token);
+    skip!(node.crate_token);
+    v.visit_ident(&node.ident);
+    if let Some(it) = &node.rename {
+        skip!((it).0);
+        v.visit_ident(&(it).1);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_fn<'ast, V>(v: &mut V, node: &'ast crate::ItemFn)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    v.visit_signature(&node.sig);
+    v.visit_block(&*node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_foreign_mod<'ast, V>(v: &mut V, node: &'ast crate::ItemForeignMod)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.unsafety);
+    v.visit_abi(&node.abi);
+    skip!(node.brace_token);
+    for it in &node.items {
+        v.visit_foreign_item(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_impl<'ast, V>(v: &mut V, node: &'ast crate::ItemImpl)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.defaultness);
+    skip!(node.unsafety);
+    skip!(node.impl_token);
+    v.visit_generics(&node.generics);
+    if let Some(it) = &node.trait_ {
+        skip!((it).0);
+        v.visit_path(&(it).1);
+        skip!((it).2);
+    }
+    v.visit_type(&*node.self_ty);
+    skip!(node.brace_token);
+    for it in &node.items {
+        v.visit_impl_item(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_macro<'ast, V>(v: &mut V, node: &'ast crate::ItemMacro)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.ident {
+        v.visit_ident(it);
+    }
+    v.visit_macro(&node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_mod<'ast, V>(v: &mut V, node: &'ast crate::ItemMod)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.unsafety);
+    skip!(node.mod_token);
+    v.visit_ident(&node.ident);
+    if let Some(it) = &node.content {
+        skip!((it).0);
+        for it in &(it).1 {
+            v.visit_item(it);
+        }
+    }
+    skip!(node.semi);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_static<'ast, V>(v: &mut V, node: &'ast crate::ItemStatic)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.static_token);
+    v.visit_static_mutability(&node.mutability);
+    v.visit_ident(&node.ident);
+    skip!(node.colon_token);
+    v.visit_type(&*node.ty);
+    skip!(node.eq_token);
+    v.visit_expr(&*node.expr);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_struct<'ast, V>(v: &mut V, node: &'ast crate::ItemStruct)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.struct_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    v.visit_fields(&node.fields);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_trait<'ast, V>(v: &mut V, node: &'ast crate::ItemTrait)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.unsafety);
+    skip!(node.auto_token);
+    if let Some(it) = &node.restriction {
+        v.visit_impl_restriction(it);
+    }
+    skip!(node.trait_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.colon_token);
+    for el in Punctuated::pairs(&node.supertraits) {
+        let it = el.value();
+        v.visit_type_param_bound(it);
+    }
+    skip!(node.brace_token);
+    for it in &node.items {
+        v.visit_trait_item(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_trait_alias<'ast, V>(v: &mut V, node: &'ast crate::ItemTraitAlias)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.trait_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.eq_token);
+    for el in Punctuated::pairs(&node.bounds) {
+        let it = el.value();
+        v.visit_type_param_bound(it);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_type<'ast, V>(v: &mut V, node: &'ast crate::ItemType)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.type_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.eq_token);
+    v.visit_type(&*node.ty);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_union<'ast, V>(v: &mut V, node: &'ast crate::ItemUnion)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.union_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    v.visit_fields_named(&node.fields);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_use<'ast, V>(v: &mut V, node: &'ast crate::ItemUse)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_visibility(&node.vis);
+    skip!(node.use_token);
+    skip!(node.leading_colon);
+    v.visit_use_tree(&node.tree);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_label<'ast, V>(v: &mut V, node: &'ast crate::Label)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_lifetime(&node.name);
+    skip!(node.colon_token);
+}
+pub fn visit_lifetime<'ast, V>(v: &mut V, node: &'ast crate::Lifetime)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_span(&node.apostrophe);
+    v.visit_ident(&node.ident);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_lifetime_param<'ast, V>(v: &mut V, node: &'ast crate::LifetimeParam)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_lifetime(&node.lifetime);
+    skip!(node.colon_token);
+    for el in Punctuated::pairs(&node.bounds) {
+        let it = el.value();
+        v.visit_lifetime(it);
+    }
+}
+pub fn visit_lit<'ast, V>(v: &mut V, node: &'ast crate::Lit)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Lit::Str(_binding_0) => {
+            v.visit_lit_str(_binding_0);
+        }
+        crate::Lit::ByteStr(_binding_0) => {
+            v.visit_lit_byte_str(_binding_0);
+        }
+        crate::Lit::Byte(_binding_0) => {
+            v.visit_lit_byte(_binding_0);
+        }
+        crate::Lit::Char(_binding_0) => {
+            v.visit_lit_char(_binding_0);
+        }
+        crate::Lit::Int(_binding_0) => {
+            v.visit_lit_int(_binding_0);
+        }
+        crate::Lit::Float(_binding_0) => {
+            v.visit_lit_float(_binding_0);
+        }
+        crate::Lit::Bool(_binding_0) => {
+            v.visit_lit_bool(_binding_0);
+        }
+        crate::Lit::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+pub fn visit_lit_bool<'ast, V>(v: &mut V, node: &'ast crate::LitBool)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.value);
+    v.visit_span(&node.span);
+}
+pub fn visit_lit_byte<'ast, V>(v: &mut V, node: &'ast crate::LitByte)
+where
+    V: Visit<'ast> + ?Sized,
+{}
+pub fn visit_lit_byte_str<'ast, V>(v: &mut V, node: &'ast crate::LitByteStr)
+where
+    V: Visit<'ast> + ?Sized,
+{}
+pub fn visit_lit_char<'ast, V>(v: &mut V, node: &'ast crate::LitChar)
+where
+    V: Visit<'ast> + ?Sized,
+{}
+pub fn visit_lit_float<'ast, V>(v: &mut V, node: &'ast crate::LitFloat)
+where
+    V: Visit<'ast> + ?Sized,
+{}
+pub fn visit_lit_int<'ast, V>(v: &mut V, node: &'ast crate::LitInt)
+where
+    V: Visit<'ast> + ?Sized,
+{}
+pub fn visit_lit_str<'ast, V>(v: &mut V, node: &'ast crate::LitStr)
+where
+    V: Visit<'ast> + ?Sized,
+{}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_local<'ast, V>(v: &mut V, node: &'ast crate::Local)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.let_token);
+    v.visit_pat(&node.pat);
+    if let Some(it) = &node.init {
+        v.visit_local_init(it);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_local_init<'ast, V>(v: &mut V, node: &'ast crate::LocalInit)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.eq_token);
+    v.visit_expr(&*node.expr);
+    if let Some(it) = &node.diverge {
+        skip!((it).0);
+        v.visit_expr(&*(it).1);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_macro<'ast, V>(v: &mut V, node: &'ast crate::Macro)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_path(&node.path);
+    skip!(node.bang_token);
+    v.visit_macro_delimiter(&node.delimiter);
+    skip!(node.tokens);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_macro_delimiter<'ast, V>(v: &mut V, node: &'ast crate::MacroDelimiter)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::MacroDelimiter::Paren(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::MacroDelimiter::Brace(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::MacroDelimiter::Bracket(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_member<'ast, V>(v: &mut V, node: &'ast crate::Member)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Member::Named(_binding_0) => {
+            v.visit_ident(_binding_0);
+        }
+        crate::Member::Unnamed(_binding_0) => {
+            v.visit_index(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_meta<'ast, V>(v: &mut V, node: &'ast crate::Meta)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Meta::Path(_binding_0) => {
+            v.visit_path(_binding_0);
+        }
+        crate::Meta::List(_binding_0) => {
+            v.visit_meta_list(_binding_0);
+        }
+        crate::Meta::NameValue(_binding_0) => {
+            v.visit_meta_name_value(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_meta_list<'ast, V>(v: &mut V, node: &'ast crate::MetaList)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_path(&node.path);
+    v.visit_macro_delimiter(&node.delimiter);
+    skip!(node.tokens);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_meta_name_value<'ast, V>(v: &mut V, node: &'ast crate::MetaNameValue)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_path(&node.path);
+    skip!(node.eq_token);
+    v.visit_expr(&node.value);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_parenthesized_generic_arguments<'ast, V>(
+    v: &mut V,
+    node: &'ast crate::ParenthesizedGenericArguments,
+)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.inputs) {
+        let it = el.value();
+        v.visit_type(it);
+    }
+    v.visit_return_type(&node.output);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat<'ast, V>(v: &mut V, node: &'ast crate::Pat)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Pat::Const(_binding_0) => {
+            v.visit_expr_const(_binding_0);
+        }
+        crate::Pat::Ident(_binding_0) => {
+            v.visit_pat_ident(_binding_0);
+        }
+        crate::Pat::Lit(_binding_0) => {
+            v.visit_expr_lit(_binding_0);
+        }
+        crate::Pat::Macro(_binding_0) => {
+            v.visit_expr_macro(_binding_0);
+        }
+        crate::Pat::Or(_binding_0) => {
+            v.visit_pat_or(_binding_0);
+        }
+        crate::Pat::Paren(_binding_0) => {
+            v.visit_pat_paren(_binding_0);
+        }
+        crate::Pat::Path(_binding_0) => {
+            v.visit_expr_path(_binding_0);
+        }
+        crate::Pat::Range(_binding_0) => {
+            v.visit_expr_range(_binding_0);
+        }
+        crate::Pat::Reference(_binding_0) => {
+            v.visit_pat_reference(_binding_0);
+        }
+        crate::Pat::Rest(_binding_0) => {
+            v.visit_pat_rest(_binding_0);
+        }
+        crate::Pat::Slice(_binding_0) => {
+            v.visit_pat_slice(_binding_0);
+        }
+        crate::Pat::Struct(_binding_0) => {
+            v.visit_pat_struct(_binding_0);
+        }
+        crate::Pat::Tuple(_binding_0) => {
+            v.visit_pat_tuple(_binding_0);
+        }
+        crate::Pat::TupleStruct(_binding_0) => {
+            v.visit_pat_tuple_struct(_binding_0);
+        }
+        crate::Pat::Type(_binding_0) => {
+            v.visit_pat_type(_binding_0);
+        }
+        crate::Pat::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::Pat::Wild(_binding_0) => {
+            v.visit_pat_wild(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_ident<'ast, V>(v: &mut V, node: &'ast crate::PatIdent)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.by_ref);
+    skip!(node.mutability);
+    v.visit_ident(&node.ident);
+    if let Some(it) = &node.subpat {
+        skip!((it).0);
+        v.visit_pat(&*(it).1);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_or<'ast, V>(v: &mut V, node: &'ast crate::PatOr)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.leading_vert);
+    for el in Punctuated::pairs(&node.cases) {
+        let it = el.value();
+        v.visit_pat(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_paren<'ast, V>(v: &mut V, node: &'ast crate::PatParen)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.paren_token);
+    v.visit_pat(&*node.pat);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_reference<'ast, V>(v: &mut V, node: &'ast crate::PatReference)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.and_token);
+    skip!(node.mutability);
+    v.visit_pat(&*node.pat);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_rest<'ast, V>(v: &mut V, node: &'ast crate::PatRest)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.dot2_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_slice<'ast, V>(v: &mut V, node: &'ast crate::PatSlice)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.bracket_token);
+    for el in Punctuated::pairs(&node.elems) {
+        let it = el.value();
+        v.visit_pat(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_struct<'ast, V>(v: &mut V, node: &'ast crate::PatStruct)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.qself {
+        v.visit_qself(it);
+    }
+    v.visit_path(&node.path);
+    skip!(node.brace_token);
+    for el in Punctuated::pairs(&node.fields) {
+        let it = el.value();
+        v.visit_field_pat(it);
+    }
+    if let Some(it) = &node.rest {
+        v.visit_pat_rest(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_tuple<'ast, V>(v: &mut V, node: &'ast crate::PatTuple)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.elems) {
+        let it = el.value();
+        v.visit_pat(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_tuple_struct<'ast, V>(v: &mut V, node: &'ast crate::PatTupleStruct)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.qself {
+        v.visit_qself(it);
+    }
+    v.visit_path(&node.path);
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.elems) {
+        let it = el.value();
+        v.visit_pat(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_type<'ast, V>(v: &mut V, node: &'ast crate::PatType)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_pat(&*node.pat);
+    skip!(node.colon_token);
+    v.visit_type(&*node.ty);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_wild<'ast, V>(v: &mut V, node: &'ast crate::PatWild)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.underscore_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_path<'ast, V>(v: &mut V, node: &'ast crate::Path)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.leading_colon);
+    for el in Punctuated::pairs(&node.segments) {
+        let it = el.value();
+        v.visit_path_segment(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_path_arguments<'ast, V>(v: &mut V, node: &'ast crate::PathArguments)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::PathArguments::None => {}
+        crate::PathArguments::AngleBracketed(_binding_0) => {
+            v.visit_angle_bracketed_generic_arguments(_binding_0);
+        }
+        crate::PathArguments::Parenthesized(_binding_0) => {
+            v.visit_parenthesized_generic_arguments(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_path_segment<'ast, V>(v: &mut V, node: &'ast crate::PathSegment)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_ident(&node.ident);
+    v.visit_path_arguments(&node.arguments);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_predicate_lifetime<'ast, V>(v: &mut V, node: &'ast crate::PredicateLifetime)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_lifetime(&node.lifetime);
+    skip!(node.colon_token);
+    for el in Punctuated::pairs(&node.bounds) {
+        let it = el.value();
+        v.visit_lifetime(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_predicate_type<'ast, V>(v: &mut V, node: &'ast crate::PredicateType)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    if let Some(it) = &node.lifetimes {
+        v.visit_bound_lifetimes(it);
+    }
+    v.visit_type(&node.bounded_ty);
+    skip!(node.colon_token);
+    for el in Punctuated::pairs(&node.bounds) {
+        let it = el.value();
+        v.visit_type_param_bound(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_qself<'ast, V>(v: &mut V, node: &'ast crate::QSelf)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.lt_token);
+    v.visit_type(&*node.ty);
+    skip!(node.position);
+    skip!(node.as_token);
+    skip!(node.gt_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_range_limits<'ast, V>(v: &mut V, node: &'ast crate::RangeLimits)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::RangeLimits::HalfOpen(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::RangeLimits::Closed(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_receiver<'ast, V>(v: &mut V, node: &'ast crate::Receiver)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.reference {
+        skip!((it).0);
+        if let Some(it) = &(it).1 {
+            v.visit_lifetime(it);
+        }
+    }
+    skip!(node.mutability);
+    skip!(node.self_token);
+    skip!(node.colon_token);
+    v.visit_type(&*node.ty);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_return_type<'ast, V>(v: &mut V, node: &'ast crate::ReturnType)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::ReturnType::Default => {}
+        crate::ReturnType::Type(_binding_0, _binding_1) => {
+            skip!(_binding_0);
+            v.visit_type(&**_binding_1);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_signature<'ast, V>(v: &mut V, node: &'ast crate::Signature)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.constness);
+    skip!(node.asyncness);
+    skip!(node.unsafety);
+    if let Some(it) = &node.abi {
+        v.visit_abi(it);
+    }
+    skip!(node.fn_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.inputs) {
+        let it = el.value();
+        v.visit_fn_arg(it);
+    }
+    if let Some(it) = &node.variadic {
+        v.visit_variadic(it);
+    }
+    v.visit_return_type(&node.output);
+}
+pub fn visit_span<'ast, V>(v: &mut V, node: &proc_macro2::Span)
+where
+    V: Visit<'ast> + ?Sized,
+{}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_static_mutability<'ast, V>(v: &mut V, node: &'ast crate::StaticMutability)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::StaticMutability::Mut(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::StaticMutability::None => {}
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_stmt<'ast, V>(v: &mut V, node: &'ast crate::Stmt)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Stmt::Local(_binding_0) => {
+            v.visit_local(_binding_0);
+        }
+        crate::Stmt::Item(_binding_0) => {
+            v.visit_item(_binding_0);
+        }
+        crate::Stmt::Expr(_binding_0, _binding_1) => {
+            v.visit_expr(_binding_0);
+            skip!(_binding_1);
+        }
+        crate::Stmt::Macro(_binding_0) => {
+            v.visit_stmt_macro(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_stmt_macro<'ast, V>(v: &mut V, node: &'ast crate::StmtMacro)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_macro(&node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_trait_bound<'ast, V>(v: &mut V, node: &'ast crate::TraitBound)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.paren_token);
+    v.visit_trait_bound_modifier(&node.modifier);
+    if let Some(it) = &node.lifetimes {
+        v.visit_bound_lifetimes(it);
+    }
+    v.visit_path(&node.path);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_trait_bound_modifier<'ast, V>(
+    v: &mut V,
+    node: &'ast crate::TraitBoundModifier,
+)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::TraitBoundModifier::None => {}
+        crate::TraitBoundModifier::Maybe(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item<'ast, V>(v: &mut V, node: &'ast crate::TraitItem)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::TraitItem::Const(_binding_0) => {
+            v.visit_trait_item_const(_binding_0);
+        }
+        crate::TraitItem::Fn(_binding_0) => {
+            v.visit_trait_item_fn(_binding_0);
+        }
+        crate::TraitItem::Type(_binding_0) => {
+            v.visit_trait_item_type(_binding_0);
+        }
+        crate::TraitItem::Macro(_binding_0) => {
+            v.visit_trait_item_macro(_binding_0);
+        }
+        crate::TraitItem::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item_const<'ast, V>(v: &mut V, node: &'ast crate::TraitItemConst)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.const_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.colon_token);
+    v.visit_type(&node.ty);
+    if let Some(it) = &node.default {
+        skip!((it).0);
+        v.visit_expr(&(it).1);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item_fn<'ast, V>(v: &mut V, node: &'ast crate::TraitItemFn)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_signature(&node.sig);
+    if let Some(it) = &node.default {
+        v.visit_block(it);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item_macro<'ast, V>(v: &mut V, node: &'ast crate::TraitItemMacro)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_macro(&node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item_type<'ast, V>(v: &mut V, node: &'ast crate::TraitItemType)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    skip!(node.type_token);
+    v.visit_ident(&node.ident);
+    v.visit_generics(&node.generics);
+    skip!(node.colon_token);
+    for el in Punctuated::pairs(&node.bounds) {
+        let it = el.value();
+        v.visit_type_param_bound(it);
+    }
+    if let Some(it) = &node.default {
+        skip!((it).0);
+        v.visit_type(&(it).1);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type<'ast, V>(v: &mut V, node: &'ast crate::Type)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Type::Array(_binding_0) => {
+            v.visit_type_array(_binding_0);
+        }
+        crate::Type::BareFn(_binding_0) => {
+            v.visit_type_bare_fn(_binding_0);
+        }
+        crate::Type::Group(_binding_0) => {
+            v.visit_type_group(_binding_0);
+        }
+        crate::Type::ImplTrait(_binding_0) => {
+            v.visit_type_impl_trait(_binding_0);
+        }
+        crate::Type::Infer(_binding_0) => {
+            v.visit_type_infer(_binding_0);
+        }
+        crate::Type::Macro(_binding_0) => {
+            v.visit_type_macro(_binding_0);
+        }
+        crate::Type::Never(_binding_0) => {
+            v.visit_type_never(_binding_0);
+        }
+        crate::Type::Paren(_binding_0) => {
+            v.visit_type_paren(_binding_0);
+        }
+        crate::Type::Path(_binding_0) => {
+            v.visit_type_path(_binding_0);
+        }
+        crate::Type::Ptr(_binding_0) => {
+            v.visit_type_ptr(_binding_0);
+        }
+        crate::Type::Reference(_binding_0) => {
+            v.visit_type_reference(_binding_0);
+        }
+        crate::Type::Slice(_binding_0) => {
+            v.visit_type_slice(_binding_0);
+        }
+        crate::Type::TraitObject(_binding_0) => {
+            v.visit_type_trait_object(_binding_0);
+        }
+        crate::Type::Tuple(_binding_0) => {
+            v.visit_type_tuple(_binding_0);
+        }
+        crate::Type::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_array<'ast, V>(v: &mut V, node: &'ast crate::TypeArray)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.bracket_token);
+    v.visit_type(&*node.elem);
+    skip!(node.semi_token);
+    v.visit_expr(&node.len);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_bare_fn<'ast, V>(v: &mut V, node: &'ast crate::TypeBareFn)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    if let Some(it) = &node.lifetimes {
+        v.visit_bound_lifetimes(it);
+    }
+    skip!(node.unsafety);
+    if let Some(it) = &node.abi {
+        v.visit_abi(it);
+    }
+    skip!(node.fn_token);
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.inputs) {
+        let it = el.value();
+        v.visit_bare_fn_arg(it);
+    }
+    if let Some(it) = &node.variadic {
+        v.visit_bare_variadic(it);
+    }
+    v.visit_return_type(&node.output);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_group<'ast, V>(v: &mut V, node: &'ast crate::TypeGroup)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.group_token);
+    v.visit_type(&*node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_impl_trait<'ast, V>(v: &mut V, node: &'ast crate::TypeImplTrait)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.impl_token);
+    for el in Punctuated::pairs(&node.bounds) {
+        let it = el.value();
+        v.visit_type_param_bound(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_infer<'ast, V>(v: &mut V, node: &'ast crate::TypeInfer)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.underscore_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_macro<'ast, V>(v: &mut V, node: &'ast crate::TypeMacro)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_macro(&node.mac);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_never<'ast, V>(v: &mut V, node: &'ast crate::TypeNever)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.bang_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_param<'ast, V>(v: &mut V, node: &'ast crate::TypeParam)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_ident(&node.ident);
+    skip!(node.colon_token);
+    for el in Punctuated::pairs(&node.bounds) {
+        let it = el.value();
+        v.visit_type_param_bound(it);
+    }
+    skip!(node.eq_token);
+    if let Some(it) = &node.default {
+        v.visit_type(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_param_bound<'ast, V>(v: &mut V, node: &'ast crate::TypeParamBound)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::TypeParamBound::Trait(_binding_0) => {
+            v.visit_trait_bound(_binding_0);
+        }
+        crate::TypeParamBound::Lifetime(_binding_0) => {
+            v.visit_lifetime(_binding_0);
+        }
+        crate::TypeParamBound::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_paren<'ast, V>(v: &mut V, node: &'ast crate::TypeParen)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.paren_token);
+    v.visit_type(&*node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_path<'ast, V>(v: &mut V, node: &'ast crate::TypePath)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    if let Some(it) = &node.qself {
+        v.visit_qself(it);
+    }
+    v.visit_path(&node.path);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_ptr<'ast, V>(v: &mut V, node: &'ast crate::TypePtr)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.star_token);
+    skip!(node.const_token);
+    skip!(node.mutability);
+    v.visit_type(&*node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_reference<'ast, V>(v: &mut V, node: &'ast crate::TypeReference)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.and_token);
+    if let Some(it) = &node.lifetime {
+        v.visit_lifetime(it);
+    }
+    skip!(node.mutability);
+    v.visit_type(&*node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_slice<'ast, V>(v: &mut V, node: &'ast crate::TypeSlice)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.bracket_token);
+    v.visit_type(&*node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_trait_object<'ast, V>(v: &mut V, node: &'ast crate::TypeTraitObject)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.dyn_token);
+    for el in Punctuated::pairs(&node.bounds) {
+        let it = el.value();
+        v.visit_type_param_bound(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_tuple<'ast, V>(v: &mut V, node: &'ast crate::TypeTuple)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.paren_token);
+    for el in Punctuated::pairs(&node.elems) {
+        let it = el.value();
+        v.visit_type(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_un_op<'ast, V>(v: &mut V, node: &'ast crate::UnOp)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::UnOp::Deref(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::UnOp::Not(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::UnOp::Neg(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_glob<'ast, V>(v: &mut V, node: &'ast crate::UseGlob)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.star_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_group<'ast, V>(v: &mut V, node: &'ast crate::UseGroup)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.brace_token);
+    for el in Punctuated::pairs(&node.items) {
+        let it = el.value();
+        v.visit_use_tree(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_name<'ast, V>(v: &mut V, node: &'ast crate::UseName)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_ident(&node.ident);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_path<'ast, V>(v: &mut V, node: &'ast crate::UsePath)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_ident(&node.ident);
+    skip!(node.colon2_token);
+    v.visit_use_tree(&*node.tree);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_rename<'ast, V>(v: &mut V, node: &'ast crate::UseRename)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    v.visit_ident(&node.ident);
+    skip!(node.as_token);
+    v.visit_ident(&node.rename);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_tree<'ast, V>(v: &mut V, node: &'ast crate::UseTree)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::UseTree::Path(_binding_0) => {
+            v.visit_use_path(_binding_0);
+        }
+        crate::UseTree::Name(_binding_0) => {
+            v.visit_use_name(_binding_0);
+        }
+        crate::UseTree::Rename(_binding_0) => {
+            v.visit_use_rename(_binding_0);
+        }
+        crate::UseTree::Glob(_binding_0) => {
+            v.visit_use_glob(_binding_0);
+        }
+        crate::UseTree::Group(_binding_0) => {
+            v.visit_use_group(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_variadic<'ast, V>(v: &mut V, node: &'ast crate::Variadic)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    if let Some(it) = &node.pat {
+        v.visit_pat(&*(it).0);
+        skip!((it).1);
+    }
+    skip!(node.dots);
+    skip!(node.comma);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_variant<'ast, V>(v: &mut V, node: &'ast crate::Variant)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    for it in &node.attrs {
+        v.visit_attribute(it);
+    }
+    v.visit_ident(&node.ident);
+    v.visit_fields(&node.fields);
+    if let Some(it) = &node.discriminant {
+        skip!((it).0);
+        v.visit_expr(&(it).1);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_vis_restricted<'ast, V>(v: &mut V, node: &'ast crate::VisRestricted)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.pub_token);
+    skip!(node.paren_token);
+    skip!(node.in_token);
+    v.visit_path(&*node.path);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_visibility<'ast, V>(v: &mut V, node: &'ast crate::Visibility)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::Visibility::Public(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::Visibility::Restricted(_binding_0) => {
+            v.visit_vis_restricted(_binding_0);
+        }
+        crate::Visibility::Inherited => {}
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_where_clause<'ast, V>(v: &mut V, node: &'ast crate::WhereClause)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    skip!(node.where_token);
+    for el in Punctuated::pairs(&node.predicates) {
+        let it = el.value();
+        v.visit_where_predicate(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_where_predicate<'ast, V>(v: &mut V, node: &'ast crate::WherePredicate)
+where
+    V: Visit<'ast> + ?Sized,
+{
+    match node {
+        crate::WherePredicate::Lifetime(_binding_0) => {
+            v.visit_predicate_lifetime(_binding_0);
+        }
+        crate::WherePredicate::Type(_binding_0) => {
+            v.visit_predicate_type(_binding_0);
+        }
+    }
+}
diff --git a/rust/syn/gen/visit_mut.rs b/rust/syn/gen/visit_mut.rs
new file mode 100644
index 0000000000000000000000000000000000000000..a04743717d573b706ba4a528631e46faf36c4f39
--- /dev/null
+++ b/rust/syn/gen/visit_mut.rs
@@ -0,0 +1,3847 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+// This file is @generated by syn-internal-codegen.
+// It is not intended for manual editing.
+
+#![allow(unused_variables)]
+#![allow(clippy::needless_pass_by_ref_mut)]
+#[cfg(any(feature = "full", feature = "derive"))]
+use crate::punctuated::Punctuated;
+#[cfg(feature = "full")]
+macro_rules! full {
+    ($e:expr) => {
+        $e
+    };
+}
+#[cfg(all(feature = "derive", not(feature = "full")))]
+macro_rules! full {
+    ($e:expr) => {
+        unreachable!()
+    };
+}
+macro_rules! skip {
+    ($($tt:tt)*) => {};
+}
+/// Syntax tree traversal to mutate an exclusive borrow of a syntax tree in
+/// place.
+///
+/// See the [module documentation] for details.
+///
+/// [module documentation]: self
+pub trait VisitMut {
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_abi_mut(&mut self, i: &mut crate::Abi) {
+        visit_abi_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_angle_bracketed_generic_arguments_mut(
+        &mut self,
+        i: &mut crate::AngleBracketedGenericArguments,
+    ) {
+        visit_angle_bracketed_generic_arguments_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_arm_mut(&mut self, i: &mut crate::Arm) {
+        visit_arm_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_assoc_const_mut(&mut self, i: &mut crate::AssocConst) {
+        visit_assoc_const_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_assoc_type_mut(&mut self, i: &mut crate::AssocType) {
+        visit_assoc_type_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_attr_style_mut(&mut self, i: &mut crate::AttrStyle) {
+        visit_attr_style_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_attribute_mut(&mut self, i: &mut crate::Attribute) {
+        visit_attribute_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_bare_fn_arg_mut(&mut self, i: &mut crate::BareFnArg) {
+        visit_bare_fn_arg_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_bare_variadic_mut(&mut self, i: &mut crate::BareVariadic) {
+        visit_bare_variadic_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_bin_op_mut(&mut self, i: &mut crate::BinOp) {
+        visit_bin_op_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_block_mut(&mut self, i: &mut crate::Block) {
+        visit_block_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_bound_lifetimes_mut(&mut self, i: &mut crate::BoundLifetimes) {
+        visit_bound_lifetimes_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_const_param_mut(&mut self, i: &mut crate::ConstParam) {
+        visit_const_param_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_constraint_mut(&mut self, i: &mut crate::Constraint) {
+        visit_constraint_mut(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_data_mut(&mut self, i: &mut crate::Data) {
+        visit_data_mut(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_data_enum_mut(&mut self, i: &mut crate::DataEnum) {
+        visit_data_enum_mut(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_data_struct_mut(&mut self, i: &mut crate::DataStruct) {
+        visit_data_struct_mut(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_data_union_mut(&mut self, i: &mut crate::DataUnion) {
+        visit_data_union_mut(self, i);
+    }
+    #[cfg(feature = "derive")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+    fn visit_derive_input_mut(&mut self, i: &mut crate::DeriveInput) {
+        visit_derive_input_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_mut(&mut self, i: &mut crate::Expr) {
+        visit_expr_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_array_mut(&mut self, i: &mut crate::ExprArray) {
+        visit_expr_array_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_assign_mut(&mut self, i: &mut crate::ExprAssign) {
+        visit_expr_assign_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_async_mut(&mut self, i: &mut crate::ExprAsync) {
+        visit_expr_async_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_await_mut(&mut self, i: &mut crate::ExprAwait) {
+        visit_expr_await_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_binary_mut(&mut self, i: &mut crate::ExprBinary) {
+        visit_expr_binary_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_block_mut(&mut self, i: &mut crate::ExprBlock) {
+        visit_expr_block_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_break_mut(&mut self, i: &mut crate::ExprBreak) {
+        visit_expr_break_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_call_mut(&mut self, i: &mut crate::ExprCall) {
+        visit_expr_call_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_cast_mut(&mut self, i: &mut crate::ExprCast) {
+        visit_expr_cast_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_closure_mut(&mut self, i: &mut crate::ExprClosure) {
+        visit_expr_closure_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_const_mut(&mut self, i: &mut crate::ExprConst) {
+        visit_expr_const_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_continue_mut(&mut self, i: &mut crate::ExprContinue) {
+        visit_expr_continue_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_field_mut(&mut self, i: &mut crate::ExprField) {
+        visit_expr_field_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_for_loop_mut(&mut self, i: &mut crate::ExprForLoop) {
+        visit_expr_for_loop_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_group_mut(&mut self, i: &mut crate::ExprGroup) {
+        visit_expr_group_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_if_mut(&mut self, i: &mut crate::ExprIf) {
+        visit_expr_if_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_index_mut(&mut self, i: &mut crate::ExprIndex) {
+        visit_expr_index_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_infer_mut(&mut self, i: &mut crate::ExprInfer) {
+        visit_expr_infer_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_let_mut(&mut self, i: &mut crate::ExprLet) {
+        visit_expr_let_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_lit_mut(&mut self, i: &mut crate::ExprLit) {
+        visit_expr_lit_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_loop_mut(&mut self, i: &mut crate::ExprLoop) {
+        visit_expr_loop_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_macro_mut(&mut self, i: &mut crate::ExprMacro) {
+        visit_expr_macro_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_match_mut(&mut self, i: &mut crate::ExprMatch) {
+        visit_expr_match_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_method_call_mut(&mut self, i: &mut crate::ExprMethodCall) {
+        visit_expr_method_call_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_paren_mut(&mut self, i: &mut crate::ExprParen) {
+        visit_expr_paren_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_path_mut(&mut self, i: &mut crate::ExprPath) {
+        visit_expr_path_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_range_mut(&mut self, i: &mut crate::ExprRange) {
+        visit_expr_range_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_reference_mut(&mut self, i: &mut crate::ExprReference) {
+        visit_expr_reference_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_repeat_mut(&mut self, i: &mut crate::ExprRepeat) {
+        visit_expr_repeat_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_return_mut(&mut self, i: &mut crate::ExprReturn) {
+        visit_expr_return_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_struct_mut(&mut self, i: &mut crate::ExprStruct) {
+        visit_expr_struct_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_try_mut(&mut self, i: &mut crate::ExprTry) {
+        visit_expr_try_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_try_block_mut(&mut self, i: &mut crate::ExprTryBlock) {
+        visit_expr_try_block_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_tuple_mut(&mut self, i: &mut crate::ExprTuple) {
+        visit_expr_tuple_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_expr_unary_mut(&mut self, i: &mut crate::ExprUnary) {
+        visit_expr_unary_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_unsafe_mut(&mut self, i: &mut crate::ExprUnsafe) {
+        visit_expr_unsafe_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_while_mut(&mut self, i: &mut crate::ExprWhile) {
+        visit_expr_while_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_expr_yield_mut(&mut self, i: &mut crate::ExprYield) {
+        visit_expr_yield_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_field_mut(&mut self, i: &mut crate::Field) {
+        visit_field_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_field_mutability_mut(&mut self, i: &mut crate::FieldMutability) {
+        visit_field_mutability_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_field_pat_mut(&mut self, i: &mut crate::FieldPat) {
+        visit_field_pat_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_field_value_mut(&mut self, i: &mut crate::FieldValue) {
+        visit_field_value_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_fields_mut(&mut self, i: &mut crate::Fields) {
+        visit_fields_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_fields_named_mut(&mut self, i: &mut crate::FieldsNamed) {
+        visit_fields_named_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_fields_unnamed_mut(&mut self, i: &mut crate::FieldsUnnamed) {
+        visit_fields_unnamed_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_file_mut(&mut self, i: &mut crate::File) {
+        visit_file_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_fn_arg_mut(&mut self, i: &mut crate::FnArg) {
+        visit_fn_arg_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item_mut(&mut self, i: &mut crate::ForeignItem) {
+        visit_foreign_item_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item_fn_mut(&mut self, i: &mut crate::ForeignItemFn) {
+        visit_foreign_item_fn_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item_macro_mut(&mut self, i: &mut crate::ForeignItemMacro) {
+        visit_foreign_item_macro_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item_static_mut(&mut self, i: &mut crate::ForeignItemStatic) {
+        visit_foreign_item_static_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_foreign_item_type_mut(&mut self, i: &mut crate::ForeignItemType) {
+        visit_foreign_item_type_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_generic_argument_mut(&mut self, i: &mut crate::GenericArgument) {
+        visit_generic_argument_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_generic_param_mut(&mut self, i: &mut crate::GenericParam) {
+        visit_generic_param_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_generics_mut(&mut self, i: &mut crate::Generics) {
+        visit_generics_mut(self, i);
+    }
+    fn visit_ident_mut(&mut self, i: &mut proc_macro2::Ident) {
+        visit_ident_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item_mut(&mut self, i: &mut crate::ImplItem) {
+        visit_impl_item_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item_const_mut(&mut self, i: &mut crate::ImplItemConst) {
+        visit_impl_item_const_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item_fn_mut(&mut self, i: &mut crate::ImplItemFn) {
+        visit_impl_item_fn_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item_macro_mut(&mut self, i: &mut crate::ImplItemMacro) {
+        visit_impl_item_macro_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_item_type_mut(&mut self, i: &mut crate::ImplItemType) {
+        visit_impl_item_type_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_impl_restriction_mut(&mut self, i: &mut crate::ImplRestriction) {
+        visit_impl_restriction_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_index_mut(&mut self, i: &mut crate::Index) {
+        visit_index_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_mut(&mut self, i: &mut crate::Item) {
+        visit_item_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_const_mut(&mut self, i: &mut crate::ItemConst) {
+        visit_item_const_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_enum_mut(&mut self, i: &mut crate::ItemEnum) {
+        visit_item_enum_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_extern_crate_mut(&mut self, i: &mut crate::ItemExternCrate) {
+        visit_item_extern_crate_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_fn_mut(&mut self, i: &mut crate::ItemFn) {
+        visit_item_fn_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_foreign_mod_mut(&mut self, i: &mut crate::ItemForeignMod) {
+        visit_item_foreign_mod_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_impl_mut(&mut self, i: &mut crate::ItemImpl) {
+        visit_item_impl_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_macro_mut(&mut self, i: &mut crate::ItemMacro) {
+        visit_item_macro_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_mod_mut(&mut self, i: &mut crate::ItemMod) {
+        visit_item_mod_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_static_mut(&mut self, i: &mut crate::ItemStatic) {
+        visit_item_static_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_struct_mut(&mut self, i: &mut crate::ItemStruct) {
+        visit_item_struct_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_trait_mut(&mut self, i: &mut crate::ItemTrait) {
+        visit_item_trait_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_trait_alias_mut(&mut self, i: &mut crate::ItemTraitAlias) {
+        visit_item_trait_alias_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_type_mut(&mut self, i: &mut crate::ItemType) {
+        visit_item_type_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_union_mut(&mut self, i: &mut crate::ItemUnion) {
+        visit_item_union_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_item_use_mut(&mut self, i: &mut crate::ItemUse) {
+        visit_item_use_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_label_mut(&mut self, i: &mut crate::Label) {
+        visit_label_mut(self, i);
+    }
+    fn visit_lifetime_mut(&mut self, i: &mut crate::Lifetime) {
+        visit_lifetime_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_lifetime_param_mut(&mut self, i: &mut crate::LifetimeParam) {
+        visit_lifetime_param_mut(self, i);
+    }
+    fn visit_lit_mut(&mut self, i: &mut crate::Lit) {
+        visit_lit_mut(self, i);
+    }
+    fn visit_lit_bool_mut(&mut self, i: &mut crate::LitBool) {
+        visit_lit_bool_mut(self, i);
+    }
+    fn visit_lit_byte_mut(&mut self, i: &mut crate::LitByte) {
+        visit_lit_byte_mut(self, i);
+    }
+    fn visit_lit_byte_str_mut(&mut self, i: &mut crate::LitByteStr) {
+        visit_lit_byte_str_mut(self, i);
+    }
+    fn visit_lit_char_mut(&mut self, i: &mut crate::LitChar) {
+        visit_lit_char_mut(self, i);
+    }
+    fn visit_lit_float_mut(&mut self, i: &mut crate::LitFloat) {
+        visit_lit_float_mut(self, i);
+    }
+    fn visit_lit_int_mut(&mut self, i: &mut crate::LitInt) {
+        visit_lit_int_mut(self, i);
+    }
+    fn visit_lit_str_mut(&mut self, i: &mut crate::LitStr) {
+        visit_lit_str_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_local_mut(&mut self, i: &mut crate::Local) {
+        visit_local_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_local_init_mut(&mut self, i: &mut crate::LocalInit) {
+        visit_local_init_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_macro_mut(&mut self, i: &mut crate::Macro) {
+        visit_macro_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_macro_delimiter_mut(&mut self, i: &mut crate::MacroDelimiter) {
+        visit_macro_delimiter_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_member_mut(&mut self, i: &mut crate::Member) {
+        visit_member_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_meta_mut(&mut self, i: &mut crate::Meta) {
+        visit_meta_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_meta_list_mut(&mut self, i: &mut crate::MetaList) {
+        visit_meta_list_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_meta_name_value_mut(&mut self, i: &mut crate::MetaNameValue) {
+        visit_meta_name_value_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_parenthesized_generic_arguments_mut(
+        &mut self,
+        i: &mut crate::ParenthesizedGenericArguments,
+    ) {
+        visit_parenthesized_generic_arguments_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_mut(&mut self, i: &mut crate::Pat) {
+        visit_pat_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_ident_mut(&mut self, i: &mut crate::PatIdent) {
+        visit_pat_ident_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_or_mut(&mut self, i: &mut crate::PatOr) {
+        visit_pat_or_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_paren_mut(&mut self, i: &mut crate::PatParen) {
+        visit_pat_paren_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_reference_mut(&mut self, i: &mut crate::PatReference) {
+        visit_pat_reference_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_rest_mut(&mut self, i: &mut crate::PatRest) {
+        visit_pat_rest_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_slice_mut(&mut self, i: &mut crate::PatSlice) {
+        visit_pat_slice_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_struct_mut(&mut self, i: &mut crate::PatStruct) {
+        visit_pat_struct_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_tuple_mut(&mut self, i: &mut crate::PatTuple) {
+        visit_pat_tuple_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_tuple_struct_mut(&mut self, i: &mut crate::PatTupleStruct) {
+        visit_pat_tuple_struct_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_type_mut(&mut self, i: &mut crate::PatType) {
+        visit_pat_type_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_pat_wild_mut(&mut self, i: &mut crate::PatWild) {
+        visit_pat_wild_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_path_mut(&mut self, i: &mut crate::Path) {
+        visit_path_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_path_arguments_mut(&mut self, i: &mut crate::PathArguments) {
+        visit_path_arguments_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_path_segment_mut(&mut self, i: &mut crate::PathSegment) {
+        visit_path_segment_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_predicate_lifetime_mut(&mut self, i: &mut crate::PredicateLifetime) {
+        visit_predicate_lifetime_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_predicate_type_mut(&mut self, i: &mut crate::PredicateType) {
+        visit_predicate_type_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_qself_mut(&mut self, i: &mut crate::QSelf) {
+        visit_qself_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_range_limits_mut(&mut self, i: &mut crate::RangeLimits) {
+        visit_range_limits_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_receiver_mut(&mut self, i: &mut crate::Receiver) {
+        visit_receiver_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_return_type_mut(&mut self, i: &mut crate::ReturnType) {
+        visit_return_type_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_signature_mut(&mut self, i: &mut crate::Signature) {
+        visit_signature_mut(self, i);
+    }
+    fn visit_span_mut(&mut self, i: &mut proc_macro2::Span) {
+        visit_span_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_static_mutability_mut(&mut self, i: &mut crate::StaticMutability) {
+        visit_static_mutability_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_stmt_mut(&mut self, i: &mut crate::Stmt) {
+        visit_stmt_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_stmt_macro_mut(&mut self, i: &mut crate::StmtMacro) {
+        visit_stmt_macro_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_trait_bound_mut(&mut self, i: &mut crate::TraitBound) {
+        visit_trait_bound_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_trait_bound_modifier_mut(&mut self, i: &mut crate::TraitBoundModifier) {
+        visit_trait_bound_modifier_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item_mut(&mut self, i: &mut crate::TraitItem) {
+        visit_trait_item_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item_const_mut(&mut self, i: &mut crate::TraitItemConst) {
+        visit_trait_item_const_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item_fn_mut(&mut self, i: &mut crate::TraitItemFn) {
+        visit_trait_item_fn_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item_macro_mut(&mut self, i: &mut crate::TraitItemMacro) {
+        visit_trait_item_macro_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_trait_item_type_mut(&mut self, i: &mut crate::TraitItemType) {
+        visit_trait_item_type_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_mut(&mut self, i: &mut crate::Type) {
+        visit_type_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_array_mut(&mut self, i: &mut crate::TypeArray) {
+        visit_type_array_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_bare_fn_mut(&mut self, i: &mut crate::TypeBareFn) {
+        visit_type_bare_fn_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_group_mut(&mut self, i: &mut crate::TypeGroup) {
+        visit_type_group_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_impl_trait_mut(&mut self, i: &mut crate::TypeImplTrait) {
+        visit_type_impl_trait_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_infer_mut(&mut self, i: &mut crate::TypeInfer) {
+        visit_type_infer_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_macro_mut(&mut self, i: &mut crate::TypeMacro) {
+        visit_type_macro_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_never_mut(&mut self, i: &mut crate::TypeNever) {
+        visit_type_never_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_param_mut(&mut self, i: &mut crate::TypeParam) {
+        visit_type_param_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_param_bound_mut(&mut self, i: &mut crate::TypeParamBound) {
+        visit_type_param_bound_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_paren_mut(&mut self, i: &mut crate::TypeParen) {
+        visit_type_paren_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_path_mut(&mut self, i: &mut crate::TypePath) {
+        visit_type_path_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_ptr_mut(&mut self, i: &mut crate::TypePtr) {
+        visit_type_ptr_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_reference_mut(&mut self, i: &mut crate::TypeReference) {
+        visit_type_reference_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_slice_mut(&mut self, i: &mut crate::TypeSlice) {
+        visit_type_slice_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_trait_object_mut(&mut self, i: &mut crate::TypeTraitObject) {
+        visit_type_trait_object_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_type_tuple_mut(&mut self, i: &mut crate::TypeTuple) {
+        visit_type_tuple_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_un_op_mut(&mut self, i: &mut crate::UnOp) {
+        visit_un_op_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_glob_mut(&mut self, i: &mut crate::UseGlob) {
+        visit_use_glob_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_group_mut(&mut self, i: &mut crate::UseGroup) {
+        visit_use_group_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_name_mut(&mut self, i: &mut crate::UseName) {
+        visit_use_name_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_path_mut(&mut self, i: &mut crate::UsePath) {
+        visit_use_path_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_rename_mut(&mut self, i: &mut crate::UseRename) {
+        visit_use_rename_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_use_tree_mut(&mut self, i: &mut crate::UseTree) {
+        visit_use_tree_mut(self, i);
+    }
+    #[cfg(feature = "full")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    fn visit_variadic_mut(&mut self, i: &mut crate::Variadic) {
+        visit_variadic_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_variant_mut(&mut self, i: &mut crate::Variant) {
+        visit_variant_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_vis_restricted_mut(&mut self, i: &mut crate::VisRestricted) {
+        visit_vis_restricted_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_visibility_mut(&mut self, i: &mut crate::Visibility) {
+        visit_visibility_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_where_clause_mut(&mut self, i: &mut crate::WhereClause) {
+        visit_where_clause_mut(self, i);
+    }
+    #[cfg(any(feature = "derive", feature = "full"))]
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+    fn visit_where_predicate_mut(&mut self, i: &mut crate::WherePredicate) {
+        visit_where_predicate_mut(self, i);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_abi_mut<V>(v: &mut V, node: &mut crate::Abi)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.extern_token);
+    if let Some(it) = &mut node.name {
+        v.visit_lit_str_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_angle_bracketed_generic_arguments_mut<V>(
+    v: &mut V,
+    node: &mut crate::AngleBracketedGenericArguments,
+)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.colon2_token);
+    skip!(node.lt_token);
+    for mut el in Punctuated::pairs_mut(&mut node.args) {
+        let it = el.value_mut();
+        v.visit_generic_argument_mut(it);
+    }
+    skip!(node.gt_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_arm_mut<V>(v: &mut V, node: &mut crate::Arm)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_pat_mut(&mut node.pat);
+    if let Some(it) = &mut node.guard {
+        skip!((it).0);
+        v.visit_expr_mut(&mut *(it).1);
+    }
+    skip!(node.fat_arrow_token);
+    v.visit_expr_mut(&mut *node.body);
+    skip!(node.comma);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_assoc_const_mut<V>(v: &mut V, node: &mut crate::AssocConst)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_ident_mut(&mut node.ident);
+    if let Some(it) = &mut node.generics {
+        v.visit_angle_bracketed_generic_arguments_mut(it);
+    }
+    skip!(node.eq_token);
+    v.visit_expr_mut(&mut node.value);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_assoc_type_mut<V>(v: &mut V, node: &mut crate::AssocType)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_ident_mut(&mut node.ident);
+    if let Some(it) = &mut node.generics {
+        v.visit_angle_bracketed_generic_arguments_mut(it);
+    }
+    skip!(node.eq_token);
+    v.visit_type_mut(&mut node.ty);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_attr_style_mut<V>(v: &mut V, node: &mut crate::AttrStyle)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::AttrStyle::Outer => {}
+        crate::AttrStyle::Inner(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_attribute_mut<V>(v: &mut V, node: &mut crate::Attribute)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.pound_token);
+    v.visit_attr_style_mut(&mut node.style);
+    skip!(node.bracket_token);
+    v.visit_meta_mut(&mut node.meta);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_bare_fn_arg_mut<V>(v: &mut V, node: &mut crate::BareFnArg)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.name {
+        v.visit_ident_mut(&mut (it).0);
+        skip!((it).1);
+    }
+    v.visit_type_mut(&mut node.ty);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_bare_variadic_mut<V>(v: &mut V, node: &mut crate::BareVariadic)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.name {
+        v.visit_ident_mut(&mut (it).0);
+        skip!((it).1);
+    }
+    skip!(node.dots);
+    skip!(node.comma);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_bin_op_mut<V>(v: &mut V, node: &mut crate::BinOp)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::BinOp::Add(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Sub(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Mul(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Div(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Rem(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::And(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Or(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitXor(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitAnd(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitOr(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Shl(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Shr(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Eq(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Lt(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Le(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Ne(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Ge(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::Gt(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::AddAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::SubAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::MulAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::DivAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::RemAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitXorAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitAndAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::BitOrAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::ShlAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::BinOp::ShrAssign(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_block_mut<V>(v: &mut V, node: &mut crate::Block)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.brace_token);
+    for it in &mut node.stmts {
+        v.visit_stmt_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_bound_lifetimes_mut<V>(v: &mut V, node: &mut crate::BoundLifetimes)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.for_token);
+    skip!(node.lt_token);
+    for mut el in Punctuated::pairs_mut(&mut node.lifetimes) {
+        let it = el.value_mut();
+        v.visit_generic_param_mut(it);
+    }
+    skip!(node.gt_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_const_param_mut<V>(v: &mut V, node: &mut crate::ConstParam)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.const_token);
+    v.visit_ident_mut(&mut node.ident);
+    skip!(node.colon_token);
+    v.visit_type_mut(&mut node.ty);
+    skip!(node.eq_token);
+    if let Some(it) = &mut node.default {
+        v.visit_expr_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_constraint_mut<V>(v: &mut V, node: &mut crate::Constraint)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_ident_mut(&mut node.ident);
+    if let Some(it) = &mut node.generics {
+        v.visit_angle_bracketed_generic_arguments_mut(it);
+    }
+    skip!(node.colon_token);
+    for mut el in Punctuated::pairs_mut(&mut node.bounds) {
+        let it = el.value_mut();
+        v.visit_type_param_bound_mut(it);
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_data_mut<V>(v: &mut V, node: &mut crate::Data)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Data::Struct(_binding_0) => {
+            v.visit_data_struct_mut(_binding_0);
+        }
+        crate::Data::Enum(_binding_0) => {
+            v.visit_data_enum_mut(_binding_0);
+        }
+        crate::Data::Union(_binding_0) => {
+            v.visit_data_union_mut(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_data_enum_mut<V>(v: &mut V, node: &mut crate::DataEnum)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.enum_token);
+    skip!(node.brace_token);
+    for mut el in Punctuated::pairs_mut(&mut node.variants) {
+        let it = el.value_mut();
+        v.visit_variant_mut(it);
+    }
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_data_struct_mut<V>(v: &mut V, node: &mut crate::DataStruct)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.struct_token);
+    v.visit_fields_mut(&mut node.fields);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_data_union_mut<V>(v: &mut V, node: &mut crate::DataUnion)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.union_token);
+    v.visit_fields_named_mut(&mut node.fields);
+}
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub fn visit_derive_input_mut<V>(v: &mut V, node: &mut crate::DeriveInput)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    v.visit_data_mut(&mut node.data);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_mut<V>(v: &mut V, node: &mut crate::Expr)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Expr::Array(_binding_0) => {
+            full!(v.visit_expr_array_mut(_binding_0));
+        }
+        crate::Expr::Assign(_binding_0) => {
+            full!(v.visit_expr_assign_mut(_binding_0));
+        }
+        crate::Expr::Async(_binding_0) => {
+            full!(v.visit_expr_async_mut(_binding_0));
+        }
+        crate::Expr::Await(_binding_0) => {
+            full!(v.visit_expr_await_mut(_binding_0));
+        }
+        crate::Expr::Binary(_binding_0) => {
+            v.visit_expr_binary_mut(_binding_0);
+        }
+        crate::Expr::Block(_binding_0) => {
+            full!(v.visit_expr_block_mut(_binding_0));
+        }
+        crate::Expr::Break(_binding_0) => {
+            full!(v.visit_expr_break_mut(_binding_0));
+        }
+        crate::Expr::Call(_binding_0) => {
+            v.visit_expr_call_mut(_binding_0);
+        }
+        crate::Expr::Cast(_binding_0) => {
+            v.visit_expr_cast_mut(_binding_0);
+        }
+        crate::Expr::Closure(_binding_0) => {
+            full!(v.visit_expr_closure_mut(_binding_0));
+        }
+        crate::Expr::Const(_binding_0) => {
+            full!(v.visit_expr_const_mut(_binding_0));
+        }
+        crate::Expr::Continue(_binding_0) => {
+            full!(v.visit_expr_continue_mut(_binding_0));
+        }
+        crate::Expr::Field(_binding_0) => {
+            v.visit_expr_field_mut(_binding_0);
+        }
+        crate::Expr::ForLoop(_binding_0) => {
+            full!(v.visit_expr_for_loop_mut(_binding_0));
+        }
+        crate::Expr::Group(_binding_0) => {
+            v.visit_expr_group_mut(_binding_0);
+        }
+        crate::Expr::If(_binding_0) => {
+            full!(v.visit_expr_if_mut(_binding_0));
+        }
+        crate::Expr::Index(_binding_0) => {
+            v.visit_expr_index_mut(_binding_0);
+        }
+        crate::Expr::Infer(_binding_0) => {
+            full!(v.visit_expr_infer_mut(_binding_0));
+        }
+        crate::Expr::Let(_binding_0) => {
+            full!(v.visit_expr_let_mut(_binding_0));
+        }
+        crate::Expr::Lit(_binding_0) => {
+            v.visit_expr_lit_mut(_binding_0);
+        }
+        crate::Expr::Loop(_binding_0) => {
+            full!(v.visit_expr_loop_mut(_binding_0));
+        }
+        crate::Expr::Macro(_binding_0) => {
+            v.visit_expr_macro_mut(_binding_0);
+        }
+        crate::Expr::Match(_binding_0) => {
+            full!(v.visit_expr_match_mut(_binding_0));
+        }
+        crate::Expr::MethodCall(_binding_0) => {
+            v.visit_expr_method_call_mut(_binding_0);
+        }
+        crate::Expr::Paren(_binding_0) => {
+            v.visit_expr_paren_mut(_binding_0);
+        }
+        crate::Expr::Path(_binding_0) => {
+            v.visit_expr_path_mut(_binding_0);
+        }
+        crate::Expr::Range(_binding_0) => {
+            full!(v.visit_expr_range_mut(_binding_0));
+        }
+        crate::Expr::Reference(_binding_0) => {
+            v.visit_expr_reference_mut(_binding_0);
+        }
+        crate::Expr::Repeat(_binding_0) => {
+            full!(v.visit_expr_repeat_mut(_binding_0));
+        }
+        crate::Expr::Return(_binding_0) => {
+            full!(v.visit_expr_return_mut(_binding_0));
+        }
+        crate::Expr::Struct(_binding_0) => {
+            v.visit_expr_struct_mut(_binding_0);
+        }
+        crate::Expr::Try(_binding_0) => {
+            full!(v.visit_expr_try_mut(_binding_0));
+        }
+        crate::Expr::TryBlock(_binding_0) => {
+            full!(v.visit_expr_try_block_mut(_binding_0));
+        }
+        crate::Expr::Tuple(_binding_0) => {
+            full!(v.visit_expr_tuple_mut(_binding_0));
+        }
+        crate::Expr::Unary(_binding_0) => {
+            v.visit_expr_unary_mut(_binding_0);
+        }
+        crate::Expr::Unsafe(_binding_0) => {
+            full!(v.visit_expr_unsafe_mut(_binding_0));
+        }
+        crate::Expr::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::Expr::While(_binding_0) => {
+            full!(v.visit_expr_while_mut(_binding_0));
+        }
+        crate::Expr::Yield(_binding_0) => {
+            full!(v.visit_expr_yield_mut(_binding_0));
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_array_mut<V>(v: &mut V, node: &mut crate::ExprArray)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.bracket_token);
+    for mut el in Punctuated::pairs_mut(&mut node.elems) {
+        let it = el.value_mut();
+        v.visit_expr_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_assign_mut<V>(v: &mut V, node: &mut crate::ExprAssign)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_expr_mut(&mut *node.left);
+    skip!(node.eq_token);
+    v.visit_expr_mut(&mut *node.right);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_async_mut<V>(v: &mut V, node: &mut crate::ExprAsync)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.async_token);
+    skip!(node.capture);
+    v.visit_block_mut(&mut node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_await_mut<V>(v: &mut V, node: &mut crate::ExprAwait)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_expr_mut(&mut *node.base);
+    skip!(node.dot_token);
+    skip!(node.await_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_binary_mut<V>(v: &mut V, node: &mut crate::ExprBinary)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_expr_mut(&mut *node.left);
+    v.visit_bin_op_mut(&mut node.op);
+    v.visit_expr_mut(&mut *node.right);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_block_mut<V>(v: &mut V, node: &mut crate::ExprBlock)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.label {
+        v.visit_label_mut(it);
+    }
+    v.visit_block_mut(&mut node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_break_mut<V>(v: &mut V, node: &mut crate::ExprBreak)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.break_token);
+    if let Some(it) = &mut node.label {
+        v.visit_lifetime_mut(it);
+    }
+    if let Some(it) = &mut node.expr {
+        v.visit_expr_mut(&mut **it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_call_mut<V>(v: &mut V, node: &mut crate::ExprCall)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_expr_mut(&mut *node.func);
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.args) {
+        let it = el.value_mut();
+        v.visit_expr_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_cast_mut<V>(v: &mut V, node: &mut crate::ExprCast)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_expr_mut(&mut *node.expr);
+    skip!(node.as_token);
+    v.visit_type_mut(&mut *node.ty);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_closure_mut<V>(v: &mut V, node: &mut crate::ExprClosure)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.lifetimes {
+        v.visit_bound_lifetimes_mut(it);
+    }
+    skip!(node.constness);
+    skip!(node.movability);
+    skip!(node.asyncness);
+    skip!(node.capture);
+    skip!(node.or1_token);
+    for mut el in Punctuated::pairs_mut(&mut node.inputs) {
+        let it = el.value_mut();
+        v.visit_pat_mut(it);
+    }
+    skip!(node.or2_token);
+    v.visit_return_type_mut(&mut node.output);
+    v.visit_expr_mut(&mut *node.body);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_const_mut<V>(v: &mut V, node: &mut crate::ExprConst)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.const_token);
+    v.visit_block_mut(&mut node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_continue_mut<V>(v: &mut V, node: &mut crate::ExprContinue)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.continue_token);
+    if let Some(it) = &mut node.label {
+        v.visit_lifetime_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_field_mut<V>(v: &mut V, node: &mut crate::ExprField)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_expr_mut(&mut *node.base);
+    skip!(node.dot_token);
+    v.visit_member_mut(&mut node.member);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_for_loop_mut<V>(v: &mut V, node: &mut crate::ExprForLoop)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.label {
+        v.visit_label_mut(it);
+    }
+    skip!(node.for_token);
+    v.visit_pat_mut(&mut *node.pat);
+    skip!(node.in_token);
+    v.visit_expr_mut(&mut *node.expr);
+    v.visit_block_mut(&mut node.body);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_group_mut<V>(v: &mut V, node: &mut crate::ExprGroup)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.group_token);
+    v.visit_expr_mut(&mut *node.expr);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_if_mut<V>(v: &mut V, node: &mut crate::ExprIf)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.if_token);
+    v.visit_expr_mut(&mut *node.cond);
+    v.visit_block_mut(&mut node.then_branch);
+    if let Some(it) = &mut node.else_branch {
+        skip!((it).0);
+        v.visit_expr_mut(&mut *(it).1);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_index_mut<V>(v: &mut V, node: &mut crate::ExprIndex)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_expr_mut(&mut *node.expr);
+    skip!(node.bracket_token);
+    v.visit_expr_mut(&mut *node.index);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_infer_mut<V>(v: &mut V, node: &mut crate::ExprInfer)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.underscore_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_let_mut<V>(v: &mut V, node: &mut crate::ExprLet)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.let_token);
+    v.visit_pat_mut(&mut *node.pat);
+    skip!(node.eq_token);
+    v.visit_expr_mut(&mut *node.expr);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_lit_mut<V>(v: &mut V, node: &mut crate::ExprLit)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_lit_mut(&mut node.lit);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_loop_mut<V>(v: &mut V, node: &mut crate::ExprLoop)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.label {
+        v.visit_label_mut(it);
+    }
+    skip!(node.loop_token);
+    v.visit_block_mut(&mut node.body);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_macro_mut<V>(v: &mut V, node: &mut crate::ExprMacro)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_macro_mut(&mut node.mac);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_match_mut<V>(v: &mut V, node: &mut crate::ExprMatch)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.match_token);
+    v.visit_expr_mut(&mut *node.expr);
+    skip!(node.brace_token);
+    for it in &mut node.arms {
+        v.visit_arm_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_method_call_mut<V>(v: &mut V, node: &mut crate::ExprMethodCall)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_expr_mut(&mut *node.receiver);
+    skip!(node.dot_token);
+    v.visit_ident_mut(&mut node.method);
+    if let Some(it) = &mut node.turbofish {
+        v.visit_angle_bracketed_generic_arguments_mut(it);
+    }
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.args) {
+        let it = el.value_mut();
+        v.visit_expr_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_paren_mut<V>(v: &mut V, node: &mut crate::ExprParen)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.paren_token);
+    v.visit_expr_mut(&mut *node.expr);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_path_mut<V>(v: &mut V, node: &mut crate::ExprPath)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.qself {
+        v.visit_qself_mut(it);
+    }
+    v.visit_path_mut(&mut node.path);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_range_mut<V>(v: &mut V, node: &mut crate::ExprRange)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.start {
+        v.visit_expr_mut(&mut **it);
+    }
+    v.visit_range_limits_mut(&mut node.limits);
+    if let Some(it) = &mut node.end {
+        v.visit_expr_mut(&mut **it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_reference_mut<V>(v: &mut V, node: &mut crate::ExprReference)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.and_token);
+    skip!(node.mutability);
+    v.visit_expr_mut(&mut *node.expr);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_repeat_mut<V>(v: &mut V, node: &mut crate::ExprRepeat)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.bracket_token);
+    v.visit_expr_mut(&mut *node.expr);
+    skip!(node.semi_token);
+    v.visit_expr_mut(&mut *node.len);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_return_mut<V>(v: &mut V, node: &mut crate::ExprReturn)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.return_token);
+    if let Some(it) = &mut node.expr {
+        v.visit_expr_mut(&mut **it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_struct_mut<V>(v: &mut V, node: &mut crate::ExprStruct)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.qself {
+        v.visit_qself_mut(it);
+    }
+    v.visit_path_mut(&mut node.path);
+    skip!(node.brace_token);
+    for mut el in Punctuated::pairs_mut(&mut node.fields) {
+        let it = el.value_mut();
+        v.visit_field_value_mut(it);
+    }
+    skip!(node.dot2_token);
+    if let Some(it) = &mut node.rest {
+        v.visit_expr_mut(&mut **it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_try_mut<V>(v: &mut V, node: &mut crate::ExprTry)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_expr_mut(&mut *node.expr);
+    skip!(node.question_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_try_block_mut<V>(v: &mut V, node: &mut crate::ExprTryBlock)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.try_token);
+    v.visit_block_mut(&mut node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_tuple_mut<V>(v: &mut V, node: &mut crate::ExprTuple)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.elems) {
+        let it = el.value_mut();
+        v.visit_expr_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_expr_unary_mut<V>(v: &mut V, node: &mut crate::ExprUnary)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_un_op_mut(&mut node.op);
+    v.visit_expr_mut(&mut *node.expr);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_unsafe_mut<V>(v: &mut V, node: &mut crate::ExprUnsafe)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.unsafe_token);
+    v.visit_block_mut(&mut node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_while_mut<V>(v: &mut V, node: &mut crate::ExprWhile)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.label {
+        v.visit_label_mut(it);
+    }
+    skip!(node.while_token);
+    v.visit_expr_mut(&mut *node.cond);
+    v.visit_block_mut(&mut node.body);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_expr_yield_mut<V>(v: &mut V, node: &mut crate::ExprYield)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.yield_token);
+    if let Some(it) = &mut node.expr {
+        v.visit_expr_mut(&mut **it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_field_mut<V>(v: &mut V, node: &mut crate::Field)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    v.visit_field_mutability_mut(&mut node.mutability);
+    if let Some(it) = &mut node.ident {
+        v.visit_ident_mut(it);
+    }
+    skip!(node.colon_token);
+    v.visit_type_mut(&mut node.ty);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_field_mutability_mut<V>(v: &mut V, node: &mut crate::FieldMutability)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::FieldMutability::None => {}
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_field_pat_mut<V>(v: &mut V, node: &mut crate::FieldPat)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_member_mut(&mut node.member);
+    skip!(node.colon_token);
+    v.visit_pat_mut(&mut *node.pat);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_field_value_mut<V>(v: &mut V, node: &mut crate::FieldValue)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_member_mut(&mut node.member);
+    skip!(node.colon_token);
+    v.visit_expr_mut(&mut node.expr);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_fields_mut<V>(v: &mut V, node: &mut crate::Fields)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Fields::Named(_binding_0) => {
+            v.visit_fields_named_mut(_binding_0);
+        }
+        crate::Fields::Unnamed(_binding_0) => {
+            v.visit_fields_unnamed_mut(_binding_0);
+        }
+        crate::Fields::Unit => {}
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_fields_named_mut<V>(v: &mut V, node: &mut crate::FieldsNamed)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.brace_token);
+    for mut el in Punctuated::pairs_mut(&mut node.named) {
+        let it = el.value_mut();
+        v.visit_field_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_fields_unnamed_mut<V>(v: &mut V, node: &mut crate::FieldsUnnamed)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.unnamed) {
+        let it = el.value_mut();
+        v.visit_field_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_file_mut<V>(v: &mut V, node: &mut crate::File)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.shebang);
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    for it in &mut node.items {
+        v.visit_item_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_fn_arg_mut<V>(v: &mut V, node: &mut crate::FnArg)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::FnArg::Receiver(_binding_0) => {
+            v.visit_receiver_mut(_binding_0);
+        }
+        crate::FnArg::Typed(_binding_0) => {
+            v.visit_pat_type_mut(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item_mut<V>(v: &mut V, node: &mut crate::ForeignItem)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::ForeignItem::Fn(_binding_0) => {
+            v.visit_foreign_item_fn_mut(_binding_0);
+        }
+        crate::ForeignItem::Static(_binding_0) => {
+            v.visit_foreign_item_static_mut(_binding_0);
+        }
+        crate::ForeignItem::Type(_binding_0) => {
+            v.visit_foreign_item_type_mut(_binding_0);
+        }
+        crate::ForeignItem::Macro(_binding_0) => {
+            v.visit_foreign_item_macro_mut(_binding_0);
+        }
+        crate::ForeignItem::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item_fn_mut<V>(v: &mut V, node: &mut crate::ForeignItemFn)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    v.visit_signature_mut(&mut node.sig);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item_macro_mut<V>(v: &mut V, node: &mut crate::ForeignItemMacro)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_macro_mut(&mut node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item_static_mut<V>(v: &mut V, node: &mut crate::ForeignItemStatic)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.static_token);
+    v.visit_static_mutability_mut(&mut node.mutability);
+    v.visit_ident_mut(&mut node.ident);
+    skip!(node.colon_token);
+    v.visit_type_mut(&mut *node.ty);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_foreign_item_type_mut<V>(v: &mut V, node: &mut crate::ForeignItemType)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.type_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.semi_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_generic_argument_mut<V>(v: &mut V, node: &mut crate::GenericArgument)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::GenericArgument::Lifetime(_binding_0) => {
+            v.visit_lifetime_mut(_binding_0);
+        }
+        crate::GenericArgument::Type(_binding_0) => {
+            v.visit_type_mut(_binding_0);
+        }
+        crate::GenericArgument::Const(_binding_0) => {
+            v.visit_expr_mut(_binding_0);
+        }
+        crate::GenericArgument::AssocType(_binding_0) => {
+            v.visit_assoc_type_mut(_binding_0);
+        }
+        crate::GenericArgument::AssocConst(_binding_0) => {
+            v.visit_assoc_const_mut(_binding_0);
+        }
+        crate::GenericArgument::Constraint(_binding_0) => {
+            v.visit_constraint_mut(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_generic_param_mut<V>(v: &mut V, node: &mut crate::GenericParam)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::GenericParam::Lifetime(_binding_0) => {
+            v.visit_lifetime_param_mut(_binding_0);
+        }
+        crate::GenericParam::Type(_binding_0) => {
+            v.visit_type_param_mut(_binding_0);
+        }
+        crate::GenericParam::Const(_binding_0) => {
+            v.visit_const_param_mut(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_generics_mut<V>(v: &mut V, node: &mut crate::Generics)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.lt_token);
+    for mut el in Punctuated::pairs_mut(&mut node.params) {
+        let it = el.value_mut();
+        v.visit_generic_param_mut(it);
+    }
+    skip!(node.gt_token);
+    if let Some(it) = &mut node.where_clause {
+        v.visit_where_clause_mut(it);
+    }
+}
+pub fn visit_ident_mut<V>(v: &mut V, node: &mut proc_macro2::Ident)
+where
+    V: VisitMut + ?Sized,
+{
+    let mut span = node.span();
+    v.visit_span_mut(&mut span);
+    node.set_span(span);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item_mut<V>(v: &mut V, node: &mut crate::ImplItem)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::ImplItem::Const(_binding_0) => {
+            v.visit_impl_item_const_mut(_binding_0);
+        }
+        crate::ImplItem::Fn(_binding_0) => {
+            v.visit_impl_item_fn_mut(_binding_0);
+        }
+        crate::ImplItem::Type(_binding_0) => {
+            v.visit_impl_item_type_mut(_binding_0);
+        }
+        crate::ImplItem::Macro(_binding_0) => {
+            v.visit_impl_item_macro_mut(_binding_0);
+        }
+        crate::ImplItem::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item_const_mut<V>(v: &mut V, node: &mut crate::ImplItemConst)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.defaultness);
+    skip!(node.const_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.colon_token);
+    v.visit_type_mut(&mut node.ty);
+    skip!(node.eq_token);
+    v.visit_expr_mut(&mut node.expr);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item_fn_mut<V>(v: &mut V, node: &mut crate::ImplItemFn)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.defaultness);
+    v.visit_signature_mut(&mut node.sig);
+    v.visit_block_mut(&mut node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item_macro_mut<V>(v: &mut V, node: &mut crate::ImplItemMacro)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_macro_mut(&mut node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_item_type_mut<V>(v: &mut V, node: &mut crate::ImplItemType)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.defaultness);
+    skip!(node.type_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.eq_token);
+    v.visit_type_mut(&mut node.ty);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_impl_restriction_mut<V>(v: &mut V, node: &mut crate::ImplRestriction)
+where
+    V: VisitMut + ?Sized,
+{
+    match *node {}
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_index_mut<V>(v: &mut V, node: &mut crate::Index)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.index);
+    v.visit_span_mut(&mut node.span);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_mut<V>(v: &mut V, node: &mut crate::Item)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Item::Const(_binding_0) => {
+            v.visit_item_const_mut(_binding_0);
+        }
+        crate::Item::Enum(_binding_0) => {
+            v.visit_item_enum_mut(_binding_0);
+        }
+        crate::Item::ExternCrate(_binding_0) => {
+            v.visit_item_extern_crate_mut(_binding_0);
+        }
+        crate::Item::Fn(_binding_0) => {
+            v.visit_item_fn_mut(_binding_0);
+        }
+        crate::Item::ForeignMod(_binding_0) => {
+            v.visit_item_foreign_mod_mut(_binding_0);
+        }
+        crate::Item::Impl(_binding_0) => {
+            v.visit_item_impl_mut(_binding_0);
+        }
+        crate::Item::Macro(_binding_0) => {
+            v.visit_item_macro_mut(_binding_0);
+        }
+        crate::Item::Mod(_binding_0) => {
+            v.visit_item_mod_mut(_binding_0);
+        }
+        crate::Item::Static(_binding_0) => {
+            v.visit_item_static_mut(_binding_0);
+        }
+        crate::Item::Struct(_binding_0) => {
+            v.visit_item_struct_mut(_binding_0);
+        }
+        crate::Item::Trait(_binding_0) => {
+            v.visit_item_trait_mut(_binding_0);
+        }
+        crate::Item::TraitAlias(_binding_0) => {
+            v.visit_item_trait_alias_mut(_binding_0);
+        }
+        crate::Item::Type(_binding_0) => {
+            v.visit_item_type_mut(_binding_0);
+        }
+        crate::Item::Union(_binding_0) => {
+            v.visit_item_union_mut(_binding_0);
+        }
+        crate::Item::Use(_binding_0) => {
+            v.visit_item_use_mut(_binding_0);
+        }
+        crate::Item::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_const_mut<V>(v: &mut V, node: &mut crate::ItemConst)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.const_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.colon_token);
+    v.visit_type_mut(&mut *node.ty);
+    skip!(node.eq_token);
+    v.visit_expr_mut(&mut *node.expr);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_enum_mut<V>(v: &mut V, node: &mut crate::ItemEnum)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.enum_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.brace_token);
+    for mut el in Punctuated::pairs_mut(&mut node.variants) {
+        let it = el.value_mut();
+        v.visit_variant_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_extern_crate_mut<V>(v: &mut V, node: &mut crate::ItemExternCrate)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.extern_token);
+    skip!(node.crate_token);
+    v.visit_ident_mut(&mut node.ident);
+    if let Some(it) = &mut node.rename {
+        skip!((it).0);
+        v.visit_ident_mut(&mut (it).1);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_fn_mut<V>(v: &mut V, node: &mut crate::ItemFn)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    v.visit_signature_mut(&mut node.sig);
+    v.visit_block_mut(&mut *node.block);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_foreign_mod_mut<V>(v: &mut V, node: &mut crate::ItemForeignMod)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.unsafety);
+    v.visit_abi_mut(&mut node.abi);
+    skip!(node.brace_token);
+    for it in &mut node.items {
+        v.visit_foreign_item_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_impl_mut<V>(v: &mut V, node: &mut crate::ItemImpl)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.defaultness);
+    skip!(node.unsafety);
+    skip!(node.impl_token);
+    v.visit_generics_mut(&mut node.generics);
+    if let Some(it) = &mut node.trait_ {
+        skip!((it).0);
+        v.visit_path_mut(&mut (it).1);
+        skip!((it).2);
+    }
+    v.visit_type_mut(&mut *node.self_ty);
+    skip!(node.brace_token);
+    for it in &mut node.items {
+        v.visit_impl_item_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_macro_mut<V>(v: &mut V, node: &mut crate::ItemMacro)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.ident {
+        v.visit_ident_mut(it);
+    }
+    v.visit_macro_mut(&mut node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_mod_mut<V>(v: &mut V, node: &mut crate::ItemMod)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.unsafety);
+    skip!(node.mod_token);
+    v.visit_ident_mut(&mut node.ident);
+    if let Some(it) = &mut node.content {
+        skip!((it).0);
+        for it in &mut (it).1 {
+            v.visit_item_mut(it);
+        }
+    }
+    skip!(node.semi);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_static_mut<V>(v: &mut V, node: &mut crate::ItemStatic)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.static_token);
+    v.visit_static_mutability_mut(&mut node.mutability);
+    v.visit_ident_mut(&mut node.ident);
+    skip!(node.colon_token);
+    v.visit_type_mut(&mut *node.ty);
+    skip!(node.eq_token);
+    v.visit_expr_mut(&mut *node.expr);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_struct_mut<V>(v: &mut V, node: &mut crate::ItemStruct)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.struct_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    v.visit_fields_mut(&mut node.fields);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_trait_mut<V>(v: &mut V, node: &mut crate::ItemTrait)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.unsafety);
+    skip!(node.auto_token);
+    if let Some(it) = &mut node.restriction {
+        v.visit_impl_restriction_mut(it);
+    }
+    skip!(node.trait_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.colon_token);
+    for mut el in Punctuated::pairs_mut(&mut node.supertraits) {
+        let it = el.value_mut();
+        v.visit_type_param_bound_mut(it);
+    }
+    skip!(node.brace_token);
+    for it in &mut node.items {
+        v.visit_trait_item_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_trait_alias_mut<V>(v: &mut V, node: &mut crate::ItemTraitAlias)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.trait_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.eq_token);
+    for mut el in Punctuated::pairs_mut(&mut node.bounds) {
+        let it = el.value_mut();
+        v.visit_type_param_bound_mut(it);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_type_mut<V>(v: &mut V, node: &mut crate::ItemType)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.type_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.eq_token);
+    v.visit_type_mut(&mut *node.ty);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_union_mut<V>(v: &mut V, node: &mut crate::ItemUnion)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.union_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    v.visit_fields_named_mut(&mut node.fields);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_item_use_mut<V>(v: &mut V, node: &mut crate::ItemUse)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_visibility_mut(&mut node.vis);
+    skip!(node.use_token);
+    skip!(node.leading_colon);
+    v.visit_use_tree_mut(&mut node.tree);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_label_mut<V>(v: &mut V, node: &mut crate::Label)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_lifetime_mut(&mut node.name);
+    skip!(node.colon_token);
+}
+pub fn visit_lifetime_mut<V>(v: &mut V, node: &mut crate::Lifetime)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_span_mut(&mut node.apostrophe);
+    v.visit_ident_mut(&mut node.ident);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_lifetime_param_mut<V>(v: &mut V, node: &mut crate::LifetimeParam)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_lifetime_mut(&mut node.lifetime);
+    skip!(node.colon_token);
+    for mut el in Punctuated::pairs_mut(&mut node.bounds) {
+        let it = el.value_mut();
+        v.visit_lifetime_mut(it);
+    }
+}
+pub fn visit_lit_mut<V>(v: &mut V, node: &mut crate::Lit)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Lit::Str(_binding_0) => {
+            v.visit_lit_str_mut(_binding_0);
+        }
+        crate::Lit::ByteStr(_binding_0) => {
+            v.visit_lit_byte_str_mut(_binding_0);
+        }
+        crate::Lit::Byte(_binding_0) => {
+            v.visit_lit_byte_mut(_binding_0);
+        }
+        crate::Lit::Char(_binding_0) => {
+            v.visit_lit_char_mut(_binding_0);
+        }
+        crate::Lit::Int(_binding_0) => {
+            v.visit_lit_int_mut(_binding_0);
+        }
+        crate::Lit::Float(_binding_0) => {
+            v.visit_lit_float_mut(_binding_0);
+        }
+        crate::Lit::Bool(_binding_0) => {
+            v.visit_lit_bool_mut(_binding_0);
+        }
+        crate::Lit::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+pub fn visit_lit_bool_mut<V>(v: &mut V, node: &mut crate::LitBool)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.value);
+    v.visit_span_mut(&mut node.span);
+}
+pub fn visit_lit_byte_mut<V>(v: &mut V, node: &mut crate::LitByte)
+where
+    V: VisitMut + ?Sized,
+{}
+pub fn visit_lit_byte_str_mut<V>(v: &mut V, node: &mut crate::LitByteStr)
+where
+    V: VisitMut + ?Sized,
+{}
+pub fn visit_lit_char_mut<V>(v: &mut V, node: &mut crate::LitChar)
+where
+    V: VisitMut + ?Sized,
+{}
+pub fn visit_lit_float_mut<V>(v: &mut V, node: &mut crate::LitFloat)
+where
+    V: VisitMut + ?Sized,
+{}
+pub fn visit_lit_int_mut<V>(v: &mut V, node: &mut crate::LitInt)
+where
+    V: VisitMut + ?Sized,
+{}
+pub fn visit_lit_str_mut<V>(v: &mut V, node: &mut crate::LitStr)
+where
+    V: VisitMut + ?Sized,
+{}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_local_mut<V>(v: &mut V, node: &mut crate::Local)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.let_token);
+    v.visit_pat_mut(&mut node.pat);
+    if let Some(it) = &mut node.init {
+        v.visit_local_init_mut(it);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_local_init_mut<V>(v: &mut V, node: &mut crate::LocalInit)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.eq_token);
+    v.visit_expr_mut(&mut *node.expr);
+    if let Some(it) = &mut node.diverge {
+        skip!((it).0);
+        v.visit_expr_mut(&mut *(it).1);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_macro_mut<V>(v: &mut V, node: &mut crate::Macro)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_path_mut(&mut node.path);
+    skip!(node.bang_token);
+    v.visit_macro_delimiter_mut(&mut node.delimiter);
+    skip!(node.tokens);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_macro_delimiter_mut<V>(v: &mut V, node: &mut crate::MacroDelimiter)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::MacroDelimiter::Paren(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::MacroDelimiter::Brace(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::MacroDelimiter::Bracket(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_member_mut<V>(v: &mut V, node: &mut crate::Member)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Member::Named(_binding_0) => {
+            v.visit_ident_mut(_binding_0);
+        }
+        crate::Member::Unnamed(_binding_0) => {
+            v.visit_index_mut(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_meta_mut<V>(v: &mut V, node: &mut crate::Meta)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Meta::Path(_binding_0) => {
+            v.visit_path_mut(_binding_0);
+        }
+        crate::Meta::List(_binding_0) => {
+            v.visit_meta_list_mut(_binding_0);
+        }
+        crate::Meta::NameValue(_binding_0) => {
+            v.visit_meta_name_value_mut(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_meta_list_mut<V>(v: &mut V, node: &mut crate::MetaList)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_path_mut(&mut node.path);
+    v.visit_macro_delimiter_mut(&mut node.delimiter);
+    skip!(node.tokens);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_meta_name_value_mut<V>(v: &mut V, node: &mut crate::MetaNameValue)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_path_mut(&mut node.path);
+    skip!(node.eq_token);
+    v.visit_expr_mut(&mut node.value);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_parenthesized_generic_arguments_mut<V>(
+    v: &mut V,
+    node: &mut crate::ParenthesizedGenericArguments,
+)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.inputs) {
+        let it = el.value_mut();
+        v.visit_type_mut(it);
+    }
+    v.visit_return_type_mut(&mut node.output);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_mut<V>(v: &mut V, node: &mut crate::Pat)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Pat::Const(_binding_0) => {
+            v.visit_expr_const_mut(_binding_0);
+        }
+        crate::Pat::Ident(_binding_0) => {
+            v.visit_pat_ident_mut(_binding_0);
+        }
+        crate::Pat::Lit(_binding_0) => {
+            v.visit_expr_lit_mut(_binding_0);
+        }
+        crate::Pat::Macro(_binding_0) => {
+            v.visit_expr_macro_mut(_binding_0);
+        }
+        crate::Pat::Or(_binding_0) => {
+            v.visit_pat_or_mut(_binding_0);
+        }
+        crate::Pat::Paren(_binding_0) => {
+            v.visit_pat_paren_mut(_binding_0);
+        }
+        crate::Pat::Path(_binding_0) => {
+            v.visit_expr_path_mut(_binding_0);
+        }
+        crate::Pat::Range(_binding_0) => {
+            v.visit_expr_range_mut(_binding_0);
+        }
+        crate::Pat::Reference(_binding_0) => {
+            v.visit_pat_reference_mut(_binding_0);
+        }
+        crate::Pat::Rest(_binding_0) => {
+            v.visit_pat_rest_mut(_binding_0);
+        }
+        crate::Pat::Slice(_binding_0) => {
+            v.visit_pat_slice_mut(_binding_0);
+        }
+        crate::Pat::Struct(_binding_0) => {
+            v.visit_pat_struct_mut(_binding_0);
+        }
+        crate::Pat::Tuple(_binding_0) => {
+            v.visit_pat_tuple_mut(_binding_0);
+        }
+        crate::Pat::TupleStruct(_binding_0) => {
+            v.visit_pat_tuple_struct_mut(_binding_0);
+        }
+        crate::Pat::Type(_binding_0) => {
+            v.visit_pat_type_mut(_binding_0);
+        }
+        crate::Pat::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::Pat::Wild(_binding_0) => {
+            v.visit_pat_wild_mut(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_ident_mut<V>(v: &mut V, node: &mut crate::PatIdent)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.by_ref);
+    skip!(node.mutability);
+    v.visit_ident_mut(&mut node.ident);
+    if let Some(it) = &mut node.subpat {
+        skip!((it).0);
+        v.visit_pat_mut(&mut *(it).1);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_or_mut<V>(v: &mut V, node: &mut crate::PatOr)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.leading_vert);
+    for mut el in Punctuated::pairs_mut(&mut node.cases) {
+        let it = el.value_mut();
+        v.visit_pat_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_paren_mut<V>(v: &mut V, node: &mut crate::PatParen)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.paren_token);
+    v.visit_pat_mut(&mut *node.pat);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_reference_mut<V>(v: &mut V, node: &mut crate::PatReference)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.and_token);
+    skip!(node.mutability);
+    v.visit_pat_mut(&mut *node.pat);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_rest_mut<V>(v: &mut V, node: &mut crate::PatRest)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.dot2_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_slice_mut<V>(v: &mut V, node: &mut crate::PatSlice)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.bracket_token);
+    for mut el in Punctuated::pairs_mut(&mut node.elems) {
+        let it = el.value_mut();
+        v.visit_pat_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_struct_mut<V>(v: &mut V, node: &mut crate::PatStruct)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.qself {
+        v.visit_qself_mut(it);
+    }
+    v.visit_path_mut(&mut node.path);
+    skip!(node.brace_token);
+    for mut el in Punctuated::pairs_mut(&mut node.fields) {
+        let it = el.value_mut();
+        v.visit_field_pat_mut(it);
+    }
+    if let Some(it) = &mut node.rest {
+        v.visit_pat_rest_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_tuple_mut<V>(v: &mut V, node: &mut crate::PatTuple)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.elems) {
+        let it = el.value_mut();
+        v.visit_pat_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_tuple_struct_mut<V>(v: &mut V, node: &mut crate::PatTupleStruct)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.qself {
+        v.visit_qself_mut(it);
+    }
+    v.visit_path_mut(&mut node.path);
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.elems) {
+        let it = el.value_mut();
+        v.visit_pat_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_type_mut<V>(v: &mut V, node: &mut crate::PatType)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_pat_mut(&mut *node.pat);
+    skip!(node.colon_token);
+    v.visit_type_mut(&mut *node.ty);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_pat_wild_mut<V>(v: &mut V, node: &mut crate::PatWild)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.underscore_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_path_mut<V>(v: &mut V, node: &mut crate::Path)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.leading_colon);
+    for mut el in Punctuated::pairs_mut(&mut node.segments) {
+        let it = el.value_mut();
+        v.visit_path_segment_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_path_arguments_mut<V>(v: &mut V, node: &mut crate::PathArguments)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::PathArguments::None => {}
+        crate::PathArguments::AngleBracketed(_binding_0) => {
+            v.visit_angle_bracketed_generic_arguments_mut(_binding_0);
+        }
+        crate::PathArguments::Parenthesized(_binding_0) => {
+            v.visit_parenthesized_generic_arguments_mut(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_path_segment_mut<V>(v: &mut V, node: &mut crate::PathSegment)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_path_arguments_mut(&mut node.arguments);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_predicate_lifetime_mut<V>(v: &mut V, node: &mut crate::PredicateLifetime)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_lifetime_mut(&mut node.lifetime);
+    skip!(node.colon_token);
+    for mut el in Punctuated::pairs_mut(&mut node.bounds) {
+        let it = el.value_mut();
+        v.visit_lifetime_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_predicate_type_mut<V>(v: &mut V, node: &mut crate::PredicateType)
+where
+    V: VisitMut + ?Sized,
+{
+    if let Some(it) = &mut node.lifetimes {
+        v.visit_bound_lifetimes_mut(it);
+    }
+    v.visit_type_mut(&mut node.bounded_ty);
+    skip!(node.colon_token);
+    for mut el in Punctuated::pairs_mut(&mut node.bounds) {
+        let it = el.value_mut();
+        v.visit_type_param_bound_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_qself_mut<V>(v: &mut V, node: &mut crate::QSelf)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.lt_token);
+    v.visit_type_mut(&mut *node.ty);
+    skip!(node.position);
+    skip!(node.as_token);
+    skip!(node.gt_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_range_limits_mut<V>(v: &mut V, node: &mut crate::RangeLimits)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::RangeLimits::HalfOpen(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::RangeLimits::Closed(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_receiver_mut<V>(v: &mut V, node: &mut crate::Receiver)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.reference {
+        skip!((it).0);
+        if let Some(it) = &mut (it).1 {
+            v.visit_lifetime_mut(it);
+        }
+    }
+    skip!(node.mutability);
+    skip!(node.self_token);
+    skip!(node.colon_token);
+    v.visit_type_mut(&mut *node.ty);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_return_type_mut<V>(v: &mut V, node: &mut crate::ReturnType)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::ReturnType::Default => {}
+        crate::ReturnType::Type(_binding_0, _binding_1) => {
+            skip!(_binding_0);
+            v.visit_type_mut(&mut **_binding_1);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_signature_mut<V>(v: &mut V, node: &mut crate::Signature)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.constness);
+    skip!(node.asyncness);
+    skip!(node.unsafety);
+    if let Some(it) = &mut node.abi {
+        v.visit_abi_mut(it);
+    }
+    skip!(node.fn_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.inputs) {
+        let it = el.value_mut();
+        v.visit_fn_arg_mut(it);
+    }
+    if let Some(it) = &mut node.variadic {
+        v.visit_variadic_mut(it);
+    }
+    v.visit_return_type_mut(&mut node.output);
+}
+pub fn visit_span_mut<V>(v: &mut V, node: &mut proc_macro2::Span)
+where
+    V: VisitMut + ?Sized,
+{}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_static_mutability_mut<V>(v: &mut V, node: &mut crate::StaticMutability)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::StaticMutability::Mut(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::StaticMutability::None => {}
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_stmt_mut<V>(v: &mut V, node: &mut crate::Stmt)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Stmt::Local(_binding_0) => {
+            v.visit_local_mut(_binding_0);
+        }
+        crate::Stmt::Item(_binding_0) => {
+            v.visit_item_mut(_binding_0);
+        }
+        crate::Stmt::Expr(_binding_0, _binding_1) => {
+            v.visit_expr_mut(_binding_0);
+            skip!(_binding_1);
+        }
+        crate::Stmt::Macro(_binding_0) => {
+            v.visit_stmt_macro_mut(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_stmt_macro_mut<V>(v: &mut V, node: &mut crate::StmtMacro)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_macro_mut(&mut node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_trait_bound_mut<V>(v: &mut V, node: &mut crate::TraitBound)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.paren_token);
+    v.visit_trait_bound_modifier_mut(&mut node.modifier);
+    if let Some(it) = &mut node.lifetimes {
+        v.visit_bound_lifetimes_mut(it);
+    }
+    v.visit_path_mut(&mut node.path);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_trait_bound_modifier_mut<V>(v: &mut V, node: &mut crate::TraitBoundModifier)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::TraitBoundModifier::None => {}
+        crate::TraitBoundModifier::Maybe(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item_mut<V>(v: &mut V, node: &mut crate::TraitItem)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::TraitItem::Const(_binding_0) => {
+            v.visit_trait_item_const_mut(_binding_0);
+        }
+        crate::TraitItem::Fn(_binding_0) => {
+            v.visit_trait_item_fn_mut(_binding_0);
+        }
+        crate::TraitItem::Type(_binding_0) => {
+            v.visit_trait_item_type_mut(_binding_0);
+        }
+        crate::TraitItem::Macro(_binding_0) => {
+            v.visit_trait_item_macro_mut(_binding_0);
+        }
+        crate::TraitItem::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item_const_mut<V>(v: &mut V, node: &mut crate::TraitItemConst)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.const_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.colon_token);
+    v.visit_type_mut(&mut node.ty);
+    if let Some(it) = &mut node.default {
+        skip!((it).0);
+        v.visit_expr_mut(&mut (it).1);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item_fn_mut<V>(v: &mut V, node: &mut crate::TraitItemFn)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_signature_mut(&mut node.sig);
+    if let Some(it) = &mut node.default {
+        v.visit_block_mut(it);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item_macro_mut<V>(v: &mut V, node: &mut crate::TraitItemMacro)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_macro_mut(&mut node.mac);
+    skip!(node.semi_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_trait_item_type_mut<V>(v: &mut V, node: &mut crate::TraitItemType)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    skip!(node.type_token);
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_generics_mut(&mut node.generics);
+    skip!(node.colon_token);
+    for mut el in Punctuated::pairs_mut(&mut node.bounds) {
+        let it = el.value_mut();
+        v.visit_type_param_bound_mut(it);
+    }
+    if let Some(it) = &mut node.default {
+        skip!((it).0);
+        v.visit_type_mut(&mut (it).1);
+    }
+    skip!(node.semi_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_mut<V>(v: &mut V, node: &mut crate::Type)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Type::Array(_binding_0) => {
+            v.visit_type_array_mut(_binding_0);
+        }
+        crate::Type::BareFn(_binding_0) => {
+            v.visit_type_bare_fn_mut(_binding_0);
+        }
+        crate::Type::Group(_binding_0) => {
+            v.visit_type_group_mut(_binding_0);
+        }
+        crate::Type::ImplTrait(_binding_0) => {
+            v.visit_type_impl_trait_mut(_binding_0);
+        }
+        crate::Type::Infer(_binding_0) => {
+            v.visit_type_infer_mut(_binding_0);
+        }
+        crate::Type::Macro(_binding_0) => {
+            v.visit_type_macro_mut(_binding_0);
+        }
+        crate::Type::Never(_binding_0) => {
+            v.visit_type_never_mut(_binding_0);
+        }
+        crate::Type::Paren(_binding_0) => {
+            v.visit_type_paren_mut(_binding_0);
+        }
+        crate::Type::Path(_binding_0) => {
+            v.visit_type_path_mut(_binding_0);
+        }
+        crate::Type::Ptr(_binding_0) => {
+            v.visit_type_ptr_mut(_binding_0);
+        }
+        crate::Type::Reference(_binding_0) => {
+            v.visit_type_reference_mut(_binding_0);
+        }
+        crate::Type::Slice(_binding_0) => {
+            v.visit_type_slice_mut(_binding_0);
+        }
+        crate::Type::TraitObject(_binding_0) => {
+            v.visit_type_trait_object_mut(_binding_0);
+        }
+        crate::Type::Tuple(_binding_0) => {
+            v.visit_type_tuple_mut(_binding_0);
+        }
+        crate::Type::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_array_mut<V>(v: &mut V, node: &mut crate::TypeArray)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.bracket_token);
+    v.visit_type_mut(&mut *node.elem);
+    skip!(node.semi_token);
+    v.visit_expr_mut(&mut node.len);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_bare_fn_mut<V>(v: &mut V, node: &mut crate::TypeBareFn)
+where
+    V: VisitMut + ?Sized,
+{
+    if let Some(it) = &mut node.lifetimes {
+        v.visit_bound_lifetimes_mut(it);
+    }
+    skip!(node.unsafety);
+    if let Some(it) = &mut node.abi {
+        v.visit_abi_mut(it);
+    }
+    skip!(node.fn_token);
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.inputs) {
+        let it = el.value_mut();
+        v.visit_bare_fn_arg_mut(it);
+    }
+    if let Some(it) = &mut node.variadic {
+        v.visit_bare_variadic_mut(it);
+    }
+    v.visit_return_type_mut(&mut node.output);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_group_mut<V>(v: &mut V, node: &mut crate::TypeGroup)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.group_token);
+    v.visit_type_mut(&mut *node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_impl_trait_mut<V>(v: &mut V, node: &mut crate::TypeImplTrait)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.impl_token);
+    for mut el in Punctuated::pairs_mut(&mut node.bounds) {
+        let it = el.value_mut();
+        v.visit_type_param_bound_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_infer_mut<V>(v: &mut V, node: &mut crate::TypeInfer)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.underscore_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_macro_mut<V>(v: &mut V, node: &mut crate::TypeMacro)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_macro_mut(&mut node.mac);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_never_mut<V>(v: &mut V, node: &mut crate::TypeNever)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.bang_token);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_param_mut<V>(v: &mut V, node: &mut crate::TypeParam)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_ident_mut(&mut node.ident);
+    skip!(node.colon_token);
+    for mut el in Punctuated::pairs_mut(&mut node.bounds) {
+        let it = el.value_mut();
+        v.visit_type_param_bound_mut(it);
+    }
+    skip!(node.eq_token);
+    if let Some(it) = &mut node.default {
+        v.visit_type_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_param_bound_mut<V>(v: &mut V, node: &mut crate::TypeParamBound)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::TypeParamBound::Trait(_binding_0) => {
+            v.visit_trait_bound_mut(_binding_0);
+        }
+        crate::TypeParamBound::Lifetime(_binding_0) => {
+            v.visit_lifetime_mut(_binding_0);
+        }
+        crate::TypeParamBound::Verbatim(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_paren_mut<V>(v: &mut V, node: &mut crate::TypeParen)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.paren_token);
+    v.visit_type_mut(&mut *node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_path_mut<V>(v: &mut V, node: &mut crate::TypePath)
+where
+    V: VisitMut + ?Sized,
+{
+    if let Some(it) = &mut node.qself {
+        v.visit_qself_mut(it);
+    }
+    v.visit_path_mut(&mut node.path);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_ptr_mut<V>(v: &mut V, node: &mut crate::TypePtr)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.star_token);
+    skip!(node.const_token);
+    skip!(node.mutability);
+    v.visit_type_mut(&mut *node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_reference_mut<V>(v: &mut V, node: &mut crate::TypeReference)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.and_token);
+    if let Some(it) = &mut node.lifetime {
+        v.visit_lifetime_mut(it);
+    }
+    skip!(node.mutability);
+    v.visit_type_mut(&mut *node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_slice_mut<V>(v: &mut V, node: &mut crate::TypeSlice)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.bracket_token);
+    v.visit_type_mut(&mut *node.elem);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_trait_object_mut<V>(v: &mut V, node: &mut crate::TypeTraitObject)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.dyn_token);
+    for mut el in Punctuated::pairs_mut(&mut node.bounds) {
+        let it = el.value_mut();
+        v.visit_type_param_bound_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_type_tuple_mut<V>(v: &mut V, node: &mut crate::TypeTuple)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.paren_token);
+    for mut el in Punctuated::pairs_mut(&mut node.elems) {
+        let it = el.value_mut();
+        v.visit_type_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_un_op_mut<V>(v: &mut V, node: &mut crate::UnOp)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::UnOp::Deref(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::UnOp::Not(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::UnOp::Neg(_binding_0) => {
+            skip!(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_glob_mut<V>(v: &mut V, node: &mut crate::UseGlob)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.star_token);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_group_mut<V>(v: &mut V, node: &mut crate::UseGroup)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.brace_token);
+    for mut el in Punctuated::pairs_mut(&mut node.items) {
+        let it = el.value_mut();
+        v.visit_use_tree_mut(it);
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_name_mut<V>(v: &mut V, node: &mut crate::UseName)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_ident_mut(&mut node.ident);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_path_mut<V>(v: &mut V, node: &mut crate::UsePath)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_ident_mut(&mut node.ident);
+    skip!(node.colon2_token);
+    v.visit_use_tree_mut(&mut *node.tree);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_rename_mut<V>(v: &mut V, node: &mut crate::UseRename)
+where
+    V: VisitMut + ?Sized,
+{
+    v.visit_ident_mut(&mut node.ident);
+    skip!(node.as_token);
+    v.visit_ident_mut(&mut node.rename);
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_use_tree_mut<V>(v: &mut V, node: &mut crate::UseTree)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::UseTree::Path(_binding_0) => {
+            v.visit_use_path_mut(_binding_0);
+        }
+        crate::UseTree::Name(_binding_0) => {
+            v.visit_use_name_mut(_binding_0);
+        }
+        crate::UseTree::Rename(_binding_0) => {
+            v.visit_use_rename_mut(_binding_0);
+        }
+        crate::UseTree::Glob(_binding_0) => {
+            v.visit_use_glob_mut(_binding_0);
+        }
+        crate::UseTree::Group(_binding_0) => {
+            v.visit_use_group_mut(_binding_0);
+        }
+    }
+}
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub fn visit_variadic_mut<V>(v: &mut V, node: &mut crate::Variadic)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    if let Some(it) = &mut node.pat {
+        v.visit_pat_mut(&mut *(it).0);
+        skip!((it).1);
+    }
+    skip!(node.dots);
+    skip!(node.comma);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_variant_mut<V>(v: &mut V, node: &mut crate::Variant)
+where
+    V: VisitMut + ?Sized,
+{
+    for it in &mut node.attrs {
+        v.visit_attribute_mut(it);
+    }
+    v.visit_ident_mut(&mut node.ident);
+    v.visit_fields_mut(&mut node.fields);
+    if let Some(it) = &mut node.discriminant {
+        skip!((it).0);
+        v.visit_expr_mut(&mut (it).1);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_vis_restricted_mut<V>(v: &mut V, node: &mut crate::VisRestricted)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.pub_token);
+    skip!(node.paren_token);
+    skip!(node.in_token);
+    v.visit_path_mut(&mut *node.path);
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_visibility_mut<V>(v: &mut V, node: &mut crate::Visibility)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::Visibility::Public(_binding_0) => {
+            skip!(_binding_0);
+        }
+        crate::Visibility::Restricted(_binding_0) => {
+            v.visit_vis_restricted_mut(_binding_0);
+        }
+        crate::Visibility::Inherited => {}
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_where_clause_mut<V>(v: &mut V, node: &mut crate::WhereClause)
+where
+    V: VisitMut + ?Sized,
+{
+    skip!(node.where_token);
+    for mut el in Punctuated::pairs_mut(&mut node.predicates) {
+        let it = el.value_mut();
+        v.visit_where_predicate_mut(it);
+    }
+}
+#[cfg(any(feature = "derive", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "derive", feature = "full"))))]
+pub fn visit_where_predicate_mut<V>(v: &mut V, node: &mut crate::WherePredicate)
+where
+    V: VisitMut + ?Sized,
+{
+    match node {
+        crate::WherePredicate::Lifetime(_binding_0) => {
+            v.visit_predicate_lifetime_mut(_binding_0);
+        }
+        crate::WherePredicate::Type(_binding_0) => {
+            v.visit_predicate_type_mut(_binding_0);
+        }
+    }
+}
diff --git a/rust/syn/gen_helper.rs b/rust/syn/gen_helper.rs
new file mode 100644
index 0000000000000000000000000000000000000000..908f6fc24feffc134a66b10a32738dc270f2c375
--- /dev/null
+++ b/rust/syn/gen_helper.rs
@@ -0,0 +1,36 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "fold")]
+pub(crate) mod fold {
+    use crate::punctuated::{Pair, Punctuated};
+
+    pub(crate) trait FoldHelper {
+        type Item;
+        fn lift<F>(self, f: F) -> Self
+        where
+            F: FnMut(Self::Item) -> Self::Item;
+    }
+
+    impl<T> FoldHelper for Vec<T> {
+        type Item = T;
+        fn lift<F>(self, f: F) -> Self
+        where
+            F: FnMut(Self::Item) -> Self::Item,
+        {
+            self.into_iter().map(f).collect()
+        }
+    }
+
+    impl<T, U> FoldHelper for Punctuated<T, U> {
+        type Item = T;
+        fn lift<F>(self, mut f: F) -> Self
+        where
+            F: FnMut(Self::Item) -> Self::Item,
+        {
+            self.into_pairs()
+                .map(Pair::into_tuple)
+                .map(|(t, u)| Pair::new(f(t), u))
+                .collect()
+        }
+    }
+}
diff --git a/rust/syn/generics.rs b/rust/syn/generics.rs
new file mode 100644
index 0000000000000000000000000000000000000000..5a2bc0feab782a1bfe85a6c4892e4b4d2fab456f
--- /dev/null
+++ b/rust/syn/generics.rs
@@ -0,0 +1,1252 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+use crate::expr::Expr;
+use crate::ident::Ident;
+use crate::lifetime::Lifetime;
+use crate::path::Path;
+use crate::punctuated::{Iter, IterMut, Punctuated};
+use crate::token;
+use crate::ty::Type;
+use proc_macro2::TokenStream;
+#[cfg(all(feature = "printing", feature = "extra-traits"))]
+use std::fmt::{self, Debug};
+#[cfg(all(feature = "printing", feature = "extra-traits"))]
+use std::hash::{Hash, Hasher};
+
+ast_struct! {
+    /// Lifetimes and type parameters attached to a declaration of a function,
+    /// enum, trait, etc.
+    ///
+    /// This struct represents two distinct optional syntactic elements,
+    /// [generic parameters] and [where clause]. In some locations of the
+    /// grammar, there may be other tokens in between these two things.
+    ///
+    /// [generic parameters]: https://doc.rust-lang.org/stable/reference/items/generics.html#generic-parameters
+    /// [where clause]: https://doc.rust-lang.org/stable/reference/items/generics.html#where-clauses
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct Generics {
+        pub lt_token: Option<Token![<]>,
+        pub params: Punctuated<GenericParam, Token![,]>,
+        pub gt_token: Option<Token![>]>,
+        pub where_clause: Option<WhereClause>,
+    }
+}
+
+ast_enum_of_structs! {
+    /// A generic type parameter, lifetime, or const generic: `T: Into<String>`,
+    /// `'a: 'b`, `const LEN: usize`.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum GenericParam {
+        /// A lifetime parameter: `'a: 'b + 'c + 'd`.
+        Lifetime(LifetimeParam),
+
+        /// A generic type parameter: `T: Into<String>`.
+        Type(TypeParam),
+
+        /// A const generic parameter: `const LENGTH: usize`.
+        Const(ConstParam),
+    }
+}
+
+ast_struct! {
+    /// A lifetime definition: `'a: 'b + 'c + 'd`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct LifetimeParam {
+        pub attrs: Vec<Attribute>,
+        pub lifetime: Lifetime,
+        pub colon_token: Option<Token![:]>,
+        pub bounds: Punctuated<Lifetime, Token![+]>,
+    }
+}
+
+ast_struct! {
+    /// A generic type parameter: `T: Into<String>`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeParam {
+        pub attrs: Vec<Attribute>,
+        pub ident: Ident,
+        pub colon_token: Option<Token![:]>,
+        pub bounds: Punctuated<TypeParamBound, Token![+]>,
+        pub eq_token: Option<Token![=]>,
+        pub default: Option<Type>,
+    }
+}
+
+ast_struct! {
+    /// A const generic parameter: `const LENGTH: usize`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ConstParam {
+        pub attrs: Vec<Attribute>,
+        pub const_token: Token![const],
+        pub ident: Ident,
+        pub colon_token: Token![:],
+        pub ty: Type,
+        pub eq_token: Option<Token![=]>,
+        pub default: Option<Expr>,
+    }
+}
+
+impl Default for Generics {
+    fn default() -> Self {
+        Generics {
+            lt_token: None,
+            params: Punctuated::new(),
+            gt_token: None,
+            where_clause: None,
+        }
+    }
+}
+
+impl Generics {
+    /// Returns an
+    /// <code
+    ///   style="padding-right:0;">Iterator&lt;Item = &amp;</code><a
+    ///   href="struct.LifetimeParam.html"><code
+    ///   style="padding-left:0;padding-right:0;">LifetimeParam</code></a><code
+    ///   style="padding-left:0;">&gt;</code>
+    /// over the lifetime parameters in `self.params`.
+    pub fn lifetimes(&self) -> Lifetimes {
+        Lifetimes(self.params.iter())
+    }
+
+    /// Returns an
+    /// <code
+    ///   style="padding-right:0;">Iterator&lt;Item = &amp;mut </code><a
+    ///   href="struct.LifetimeParam.html"><code
+    ///   style="padding-left:0;padding-right:0;">LifetimeParam</code></a><code
+    ///   style="padding-left:0;">&gt;</code>
+    /// over the lifetime parameters in `self.params`.
+    pub fn lifetimes_mut(&mut self) -> LifetimesMut {
+        LifetimesMut(self.params.iter_mut())
+    }
+
+    /// Returns an
+    /// <code
+    ///   style="padding-right:0;">Iterator&lt;Item = &amp;</code><a
+    ///   href="struct.TypeParam.html"><code
+    ///   style="padding-left:0;padding-right:0;">TypeParam</code></a><code
+    ///   style="padding-left:0;">&gt;</code>
+    /// over the type parameters in `self.params`.
+    pub fn type_params(&self) -> TypeParams {
+        TypeParams(self.params.iter())
+    }
+
+    /// Returns an
+    /// <code
+    ///   style="padding-right:0;">Iterator&lt;Item = &amp;mut </code><a
+    ///   href="struct.TypeParam.html"><code
+    ///   style="padding-left:0;padding-right:0;">TypeParam</code></a><code
+    ///   style="padding-left:0;">&gt;</code>
+    /// over the type parameters in `self.params`.
+    pub fn type_params_mut(&mut self) -> TypeParamsMut {
+        TypeParamsMut(self.params.iter_mut())
+    }
+
+    /// Returns an
+    /// <code
+    ///   style="padding-right:0;">Iterator&lt;Item = &amp;</code><a
+    ///   href="struct.ConstParam.html"><code
+    ///   style="padding-left:0;padding-right:0;">ConstParam</code></a><code
+    ///   style="padding-left:0;">&gt;</code>
+    /// over the constant parameters in `self.params`.
+    pub fn const_params(&self) -> ConstParams {
+        ConstParams(self.params.iter())
+    }
+
+    /// Returns an
+    /// <code
+    ///   style="padding-right:0;">Iterator&lt;Item = &amp;mut </code><a
+    ///   href="struct.ConstParam.html"><code
+    ///   style="padding-left:0;padding-right:0;">ConstParam</code></a><code
+    ///   style="padding-left:0;">&gt;</code>
+    /// over the constant parameters in `self.params`.
+    pub fn const_params_mut(&mut self) -> ConstParamsMut {
+        ConstParamsMut(self.params.iter_mut())
+    }
+
+    /// Initializes an empty `where`-clause if there is not one present already.
+    pub fn make_where_clause(&mut self) -> &mut WhereClause {
+        self.where_clause.get_or_insert_with(|| WhereClause {
+            where_token: <Token![where]>::default(),
+            predicates: Punctuated::new(),
+        })
+    }
+}
+
+pub struct Lifetimes<'a>(Iter<'a, GenericParam>);
+
+impl<'a> Iterator for Lifetimes<'a> {
+    type Item = &'a LifetimeParam;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let next = match self.0.next() {
+            Some(item) => item,
+            None => return None,
+        };
+        if let GenericParam::Lifetime(lifetime) = next {
+            Some(lifetime)
+        } else {
+            self.next()
+        }
+    }
+}
+
+pub struct LifetimesMut<'a>(IterMut<'a, GenericParam>);
+
+impl<'a> Iterator for LifetimesMut<'a> {
+    type Item = &'a mut LifetimeParam;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let next = match self.0.next() {
+            Some(item) => item,
+            None => return None,
+        };
+        if let GenericParam::Lifetime(lifetime) = next {
+            Some(lifetime)
+        } else {
+            self.next()
+        }
+    }
+}
+
+pub struct TypeParams<'a>(Iter<'a, GenericParam>);
+
+impl<'a> Iterator for TypeParams<'a> {
+    type Item = &'a TypeParam;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let next = match self.0.next() {
+            Some(item) => item,
+            None => return None,
+        };
+        if let GenericParam::Type(type_param) = next {
+            Some(type_param)
+        } else {
+            self.next()
+        }
+    }
+}
+
+pub struct TypeParamsMut<'a>(IterMut<'a, GenericParam>);
+
+impl<'a> Iterator for TypeParamsMut<'a> {
+    type Item = &'a mut TypeParam;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let next = match self.0.next() {
+            Some(item) => item,
+            None => return None,
+        };
+        if let GenericParam::Type(type_param) = next {
+            Some(type_param)
+        } else {
+            self.next()
+        }
+    }
+}
+
+pub struct ConstParams<'a>(Iter<'a, GenericParam>);
+
+impl<'a> Iterator for ConstParams<'a> {
+    type Item = &'a ConstParam;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let next = match self.0.next() {
+            Some(item) => item,
+            None => return None,
+        };
+        if let GenericParam::Const(const_param) = next {
+            Some(const_param)
+        } else {
+            self.next()
+        }
+    }
+}
+
+pub struct ConstParamsMut<'a>(IterMut<'a, GenericParam>);
+
+impl<'a> Iterator for ConstParamsMut<'a> {
+    type Item = &'a mut ConstParam;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let next = match self.0.next() {
+            Some(item) => item,
+            None => return None,
+        };
+        if let GenericParam::Const(const_param) = next {
+            Some(const_param)
+        } else {
+            self.next()
+        }
+    }
+}
+
+/// Returned by `Generics::split_for_impl`.
+#[cfg(feature = "printing")]
+#[cfg_attr(
+    doc_cfg,
+    doc(cfg(all(any(feature = "full", feature = "derive"), feature = "printing")))
+)]
+pub struct ImplGenerics<'a>(&'a Generics);
+
+/// Returned by `Generics::split_for_impl`.
+#[cfg(feature = "printing")]
+#[cfg_attr(
+    doc_cfg,
+    doc(cfg(all(any(feature = "full", feature = "derive"), feature = "printing")))
+)]
+pub struct TypeGenerics<'a>(&'a Generics);
+
+/// Returned by `TypeGenerics::as_turbofish`.
+#[cfg(feature = "printing")]
+#[cfg_attr(
+    doc_cfg,
+    doc(cfg(all(any(feature = "full", feature = "derive"), feature = "printing")))
+)]
+pub struct Turbofish<'a>(&'a Generics);
+
+#[cfg(feature = "printing")]
+impl Generics {
+    /// Split a type's generics into the pieces required for impl'ing a trait
+    /// for that type.
+    ///
+    /// ```
+    /// # use proc_macro2::{Span, Ident};
+    /// # use quote::quote;
+    /// #
+    /// # let generics: syn::Generics = Default::default();
+    /// # let name = Ident::new("MyType", Span::call_site());
+    /// #
+    /// let (impl_generics, ty_generics, where_clause) = generics.split_for_impl();
+    /// quote! {
+    ///     impl #impl_generics MyTrait for #name #ty_generics #where_clause {
+    ///         // ...
+    ///     }
+    /// }
+    /// # ;
+    /// ```
+    #[cfg_attr(
+        doc_cfg,
+        doc(cfg(all(any(feature = "full", feature = "derive"), feature = "printing")))
+    )]
+    pub fn split_for_impl(&self) -> (ImplGenerics, TypeGenerics, Option<&WhereClause>) {
+        (
+            ImplGenerics(self),
+            TypeGenerics(self),
+            self.where_clause.as_ref(),
+        )
+    }
+}
+
+#[cfg(feature = "printing")]
+macro_rules! generics_wrapper_impls {
+    ($ty:ident) => {
+        #[cfg(feature = "clone-impls")]
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+        impl<'a> Clone for $ty<'a> {
+            fn clone(&self) -> Self {
+                $ty(self.0)
+            }
+        }
+
+        #[cfg(feature = "extra-traits")]
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+        impl<'a> Debug for $ty<'a> {
+            fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+                formatter
+                    .debug_tuple(stringify!($ty))
+                    .field(self.0)
+                    .finish()
+            }
+        }
+
+        #[cfg(feature = "extra-traits")]
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+        impl<'a> Eq for $ty<'a> {}
+
+        #[cfg(feature = "extra-traits")]
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+        impl<'a> PartialEq for $ty<'a> {
+            fn eq(&self, other: &Self) -> bool {
+                self.0 == other.0
+            }
+        }
+
+        #[cfg(feature = "extra-traits")]
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+        impl<'a> Hash for $ty<'a> {
+            fn hash<H: Hasher>(&self, state: &mut H) {
+                self.0.hash(state);
+            }
+        }
+    };
+}
+
+#[cfg(feature = "printing")]
+generics_wrapper_impls!(ImplGenerics);
+#[cfg(feature = "printing")]
+generics_wrapper_impls!(TypeGenerics);
+#[cfg(feature = "printing")]
+generics_wrapper_impls!(Turbofish);
+
+#[cfg(feature = "printing")]
+impl<'a> TypeGenerics<'a> {
+    /// Turn a type's generics like `<X, Y>` into a turbofish like `::<X, Y>`.
+    pub fn as_turbofish(&self) -> Turbofish {
+        Turbofish(self.0)
+    }
+}
+
+ast_struct! {
+    /// A set of bound lifetimes: `for<'a, 'b, 'c>`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct BoundLifetimes {
+        pub for_token: Token![for],
+        pub lt_token: Token![<],
+        pub lifetimes: Punctuated<GenericParam, Token![,]>,
+        pub gt_token: Token![>],
+    }
+}
+
+impl Default for BoundLifetimes {
+    fn default() -> Self {
+        BoundLifetimes {
+            for_token: Default::default(),
+            lt_token: Default::default(),
+            lifetimes: Punctuated::new(),
+            gt_token: Default::default(),
+        }
+    }
+}
+
+impl LifetimeParam {
+    pub fn new(lifetime: Lifetime) -> Self {
+        LifetimeParam {
+            attrs: Vec::new(),
+            lifetime,
+            colon_token: None,
+            bounds: Punctuated::new(),
+        }
+    }
+}
+
+impl From<Ident> for TypeParam {
+    fn from(ident: Ident) -> Self {
+        TypeParam {
+            attrs: vec![],
+            ident,
+            colon_token: None,
+            bounds: Punctuated::new(),
+            eq_token: None,
+            default: None,
+        }
+    }
+}
+
+ast_enum_of_structs! {
+    /// A trait or lifetime used as a bound on a type parameter.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum TypeParamBound {
+        Trait(TraitBound),
+        Lifetime(Lifetime),
+        Verbatim(TokenStream),
+    }
+}
+
+ast_struct! {
+    /// A trait used as a bound on a type parameter.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TraitBound {
+        pub paren_token: Option<token::Paren>,
+        pub modifier: TraitBoundModifier,
+        /// The `for<'a>` in `for<'a> Foo<&'a T>`
+        pub lifetimes: Option<BoundLifetimes>,
+        /// The `Foo<&'a T>` in `for<'a> Foo<&'a T>`
+        pub path: Path,
+    }
+}
+
+ast_enum! {
+    /// A modifier on a trait bound, currently only used for the `?` in
+    /// `?Sized`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum TraitBoundModifier {
+        None,
+        Maybe(Token![?]),
+    }
+}
+
+ast_struct! {
+    /// A `where` clause in a definition: `where T: Deserialize<'de>, D:
+    /// 'static`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct WhereClause {
+        pub where_token: Token![where],
+        pub predicates: Punctuated<WherePredicate, Token![,]>,
+    }
+}
+
+ast_enum_of_structs! {
+    /// A single predicate in a `where` clause: `T: Deserialize<'de>`.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum WherePredicate {
+        /// A lifetime predicate in a `where` clause: `'a: 'b + 'c`.
+        Lifetime(PredicateLifetime),
+
+        /// A type predicate in a `where` clause: `for<'c> Foo<'c>: Trait<'c>`.
+        Type(PredicateType),
+    }
+}
+
+ast_struct! {
+    /// A lifetime predicate in a `where` clause: `'a: 'b + 'c`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct PredicateLifetime {
+        pub lifetime: Lifetime,
+        pub colon_token: Token![:],
+        pub bounds: Punctuated<Lifetime, Token![+]>,
+    }
+}
+
+ast_struct! {
+    /// A type predicate in a `where` clause: `for<'c> Foo<'c>: Trait<'c>`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct PredicateType {
+        /// Any lifetimes from a `for` binding
+        pub lifetimes: Option<BoundLifetimes>,
+        /// The type being bounded
+        pub bounded_ty: Type,
+        pub colon_token: Token![:],
+        /// Trait and lifetime bounds (`Clone+Send+'static`)
+        pub bounds: Punctuated<TypeParamBound, Token![+]>,
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::Attribute;
+    use crate::error::Result;
+    use crate::ext::IdentExt as _;
+    use crate::generics::{
+        BoundLifetimes, ConstParam, GenericParam, Generics, LifetimeParam, PredicateLifetime,
+        PredicateType, TraitBound, TraitBoundModifier, TypeParam, TypeParamBound, WhereClause,
+        WherePredicate,
+    };
+    use crate::ident::Ident;
+    use crate::lifetime::Lifetime;
+    use crate::parse::{Parse, ParseStream};
+    use crate::path::{self, ParenthesizedGenericArguments, Path, PathArguments};
+    use crate::punctuated::Punctuated;
+    use crate::token;
+    use crate::ty::Type;
+    use crate::verbatim;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Generics {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if !input.peek(Token![<]) {
+                return Ok(Generics::default());
+            }
+
+            let lt_token: Token![<] = input.parse()?;
+
+            let mut params = Punctuated::new();
+            loop {
+                if input.peek(Token![>]) {
+                    break;
+                }
+
+                let attrs = input.call(Attribute::parse_outer)?;
+                let lookahead = input.lookahead1();
+                if lookahead.peek(Lifetime) {
+                    params.push_value(GenericParam::Lifetime(LifetimeParam {
+                        attrs,
+                        ..input.parse()?
+                    }));
+                } else if lookahead.peek(Ident) {
+                    params.push_value(GenericParam::Type(TypeParam {
+                        attrs,
+                        ..input.parse()?
+                    }));
+                } else if lookahead.peek(Token![const]) {
+                    params.push_value(GenericParam::Const(ConstParam {
+                        attrs,
+                        ..input.parse()?
+                    }));
+                } else if input.peek(Token![_]) {
+                    params.push_value(GenericParam::Type(TypeParam {
+                        attrs,
+                        ident: input.call(Ident::parse_any)?,
+                        colon_token: None,
+                        bounds: Punctuated::new(),
+                        eq_token: None,
+                        default: None,
+                    }));
+                } else {
+                    return Err(lookahead.error());
+                }
+
+                if input.peek(Token![>]) {
+                    break;
+                }
+                let punct = input.parse()?;
+                params.push_punct(punct);
+            }
+
+            let gt_token: Token![>] = input.parse()?;
+
+            Ok(Generics {
+                lt_token: Some(lt_token),
+                params,
+                gt_token: Some(gt_token),
+                where_clause: None,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for GenericParam {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Ident) {
+                Ok(GenericParam::Type(TypeParam {
+                    attrs,
+                    ..input.parse()?
+                }))
+            } else if lookahead.peek(Lifetime) {
+                Ok(GenericParam::Lifetime(LifetimeParam {
+                    attrs,
+                    ..input.parse()?
+                }))
+            } else if lookahead.peek(Token![const]) {
+                Ok(GenericParam::Const(ConstParam {
+                    attrs,
+                    ..input.parse()?
+                }))
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for LifetimeParam {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let has_colon;
+            Ok(LifetimeParam {
+                attrs: input.call(Attribute::parse_outer)?,
+                lifetime: input.parse()?,
+                colon_token: {
+                    if input.peek(Token![:]) {
+                        has_colon = true;
+                        Some(input.parse()?)
+                    } else {
+                        has_colon = false;
+                        None
+                    }
+                },
+                bounds: {
+                    let mut bounds = Punctuated::new();
+                    if has_colon {
+                        loop {
+                            if input.peek(Token![,]) || input.peek(Token![>]) {
+                                break;
+                            }
+                            let value = input.parse()?;
+                            bounds.push_value(value);
+                            if !input.peek(Token![+]) {
+                                break;
+                            }
+                            let punct = input.parse()?;
+                            bounds.push_punct(punct);
+                        }
+                    }
+                    bounds
+                },
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for BoundLifetimes {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(BoundLifetimes {
+                for_token: input.parse()?,
+                lt_token: input.parse()?,
+                lifetimes: {
+                    let mut lifetimes = Punctuated::new();
+                    while !input.peek(Token![>]) {
+                        let attrs = input.call(Attribute::parse_outer)?;
+                        let lifetime: Lifetime = input.parse()?;
+                        lifetimes.push_value(GenericParam::Lifetime(LifetimeParam {
+                            attrs,
+                            lifetime,
+                            colon_token: None,
+                            bounds: Punctuated::new(),
+                        }));
+                        if input.peek(Token![>]) {
+                            break;
+                        }
+                        lifetimes.push_punct(input.parse()?);
+                    }
+                    lifetimes
+                },
+                gt_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Option<BoundLifetimes> {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Token![for]) {
+                input.parse().map(Some)
+            } else {
+                Ok(None)
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeParam {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let ident: Ident = input.parse()?;
+            let colon_token: Option<Token![:]> = input.parse()?;
+
+            let mut bounds = Punctuated::new();
+            if colon_token.is_some() {
+                loop {
+                    if input.peek(Token![,]) || input.peek(Token![>]) || input.peek(Token![=]) {
+                        break;
+                    }
+                    let value: TypeParamBound = input.parse()?;
+                    bounds.push_value(value);
+                    if !input.peek(Token![+]) {
+                        break;
+                    }
+                    let punct: Token![+] = input.parse()?;
+                    bounds.push_punct(punct);
+                }
+            }
+
+            let eq_token: Option<Token![=]> = input.parse()?;
+            let default = if eq_token.is_some() {
+                Some(input.parse::<Type>()?)
+            } else {
+                None
+            };
+
+            Ok(TypeParam {
+                attrs,
+                ident,
+                colon_token,
+                bounds,
+                eq_token,
+                default,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeParamBound {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Lifetime) {
+                return input.parse().map(TypeParamBound::Lifetime);
+            }
+
+            let begin = input.fork();
+
+            let content;
+            let (paren_token, content) = if input.peek(token::Paren) {
+                (Some(parenthesized!(content in input)), &content)
+            } else {
+                (None, input)
+            };
+
+            let is_tilde_const =
+                cfg!(feature = "full") && content.peek(Token![~]) && content.peek2(Token![const]);
+            if is_tilde_const {
+                content.parse::<Token![~]>()?;
+                content.parse::<Token![const]>()?;
+            }
+
+            let mut bound: TraitBound = content.parse()?;
+            bound.paren_token = paren_token;
+
+            if is_tilde_const {
+                Ok(TypeParamBound::Verbatim(verbatim::between(&begin, input)))
+            } else {
+                Ok(TypeParamBound::Trait(bound))
+            }
+        }
+    }
+
+    impl TypeParamBound {
+        pub(crate) fn parse_multiple(
+            input: ParseStream,
+            allow_plus: bool,
+        ) -> Result<Punctuated<Self, Token![+]>> {
+            let mut bounds = Punctuated::new();
+            loop {
+                bounds.push_value(input.parse()?);
+                if !(allow_plus && input.peek(Token![+])) {
+                    break;
+                }
+                bounds.push_punct(input.parse()?);
+                if !(input.peek(Ident::peek_any)
+                    || input.peek(Token![::])
+                    || input.peek(Token![?])
+                    || input.peek(Lifetime)
+                    || input.peek(token::Paren)
+                    || input.peek(Token![~]))
+                {
+                    break;
+                }
+            }
+            Ok(bounds)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitBound {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let modifier: TraitBoundModifier = input.parse()?;
+            let lifetimes: Option<BoundLifetimes> = input.parse()?;
+
+            let mut path: Path = input.parse()?;
+            if path.segments.last().unwrap().arguments.is_empty()
+                && (input.peek(token::Paren) || input.peek(Token![::]) && input.peek3(token::Paren))
+            {
+                input.parse::<Option<Token![::]>>()?;
+                let args: ParenthesizedGenericArguments = input.parse()?;
+                let parenthesized = PathArguments::Parenthesized(args);
+                path.segments.last_mut().unwrap().arguments = parenthesized;
+            }
+
+            Ok(TraitBound {
+                paren_token: None,
+                modifier,
+                lifetimes,
+                path,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitBoundModifier {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Token![?]) {
+                input.parse().map(TraitBoundModifier::Maybe)
+            } else {
+                Ok(TraitBoundModifier::None)
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ConstParam {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut default = None;
+            Ok(ConstParam {
+                attrs: input.call(Attribute::parse_outer)?,
+                const_token: input.parse()?,
+                ident: input.parse()?,
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+                eq_token: {
+                    if input.peek(Token![=]) {
+                        let eq_token = input.parse()?;
+                        default = Some(path::parsing::const_argument(input)?);
+                        Some(eq_token)
+                    } else {
+                        None
+                    }
+                },
+                default,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for WhereClause {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(WhereClause {
+                where_token: input.parse()?,
+                predicates: {
+                    let mut predicates = Punctuated::new();
+                    loop {
+                        if input.is_empty()
+                            || input.peek(token::Brace)
+                            || input.peek(Token![,])
+                            || input.peek(Token![;])
+                            || input.peek(Token![:]) && !input.peek(Token![::])
+                            || input.peek(Token![=])
+                        {
+                            break;
+                        }
+                        let value = input.parse()?;
+                        predicates.push_value(value);
+                        if !input.peek(Token![,]) {
+                            break;
+                        }
+                        let punct = input.parse()?;
+                        predicates.push_punct(punct);
+                    }
+                    predicates
+                },
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Option<WhereClause> {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Token![where]) {
+                input.parse().map(Some)
+            } else {
+                Ok(None)
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for WherePredicate {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Lifetime) && input.peek2(Token![:]) {
+                Ok(WherePredicate::Lifetime(PredicateLifetime {
+                    lifetime: input.parse()?,
+                    colon_token: input.parse()?,
+                    bounds: {
+                        let mut bounds = Punctuated::new();
+                        loop {
+                            if input.is_empty()
+                                || input.peek(token::Brace)
+                                || input.peek(Token![,])
+                                || input.peek(Token![;])
+                                || input.peek(Token![:])
+                                || input.peek(Token![=])
+                            {
+                                break;
+                            }
+                            let value = input.parse()?;
+                            bounds.push_value(value);
+                            if !input.peek(Token![+]) {
+                                break;
+                            }
+                            let punct = input.parse()?;
+                            bounds.push_punct(punct);
+                        }
+                        bounds
+                    },
+                }))
+            } else {
+                Ok(WherePredicate::Type(PredicateType {
+                    lifetimes: input.parse()?,
+                    bounded_ty: input.parse()?,
+                    colon_token: input.parse()?,
+                    bounds: {
+                        let mut bounds = Punctuated::new();
+                        loop {
+                            if input.is_empty()
+                                || input.peek(token::Brace)
+                                || input.peek(Token![,])
+                                || input.peek(Token![;])
+                                || input.peek(Token![:]) && !input.peek(Token![::])
+                                || input.peek(Token![=])
+                            {
+                                break;
+                            }
+                            let value = input.parse()?;
+                            bounds.push_value(value);
+                            if !input.peek(Token![+]) {
+                                break;
+                            }
+                            let punct = input.parse()?;
+                            bounds.push_punct(punct);
+                        }
+                        bounds
+                    },
+                }))
+            }
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::attr::FilterAttrs;
+    use crate::generics::{
+        BoundLifetimes, ConstParam, GenericParam, Generics, ImplGenerics, LifetimeParam,
+        PredicateLifetime, PredicateType, TraitBound, TraitBoundModifier, Turbofish, TypeGenerics,
+        TypeParam, WhereClause,
+    };
+    use crate::print::TokensOrDefault;
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Generics {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            if self.params.is_empty() {
+                return;
+            }
+
+            TokensOrDefault(&self.lt_token).to_tokens(tokens);
+
+            // Print lifetimes before types and consts, regardless of their
+            // order in self.params.
+            let mut trailing_or_empty = true;
+            for param in self.params.pairs() {
+                if let GenericParam::Lifetime(_) = **param.value() {
+                    param.to_tokens(tokens);
+                    trailing_or_empty = param.punct().is_some();
+                }
+            }
+            for param in self.params.pairs() {
+                match param.value() {
+                    GenericParam::Type(_) | GenericParam::Const(_) => {
+                        if !trailing_or_empty {
+                            <Token![,]>::default().to_tokens(tokens);
+                            trailing_or_empty = true;
+                        }
+                        param.to_tokens(tokens);
+                    }
+                    GenericParam::Lifetime(_) => {}
+                }
+            }
+
+            TokensOrDefault(&self.gt_token).to_tokens(tokens);
+        }
+    }
+
+    impl<'a> ToTokens for ImplGenerics<'a> {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            if self.0.params.is_empty() {
+                return;
+            }
+
+            TokensOrDefault(&self.0.lt_token).to_tokens(tokens);
+
+            // Print lifetimes before types and consts, regardless of their
+            // order in self.params.
+            let mut trailing_or_empty = true;
+            for param in self.0.params.pairs() {
+                if let GenericParam::Lifetime(_) = **param.value() {
+                    param.to_tokens(tokens);
+                    trailing_or_empty = param.punct().is_some();
+                }
+            }
+            for param in self.0.params.pairs() {
+                if let GenericParam::Lifetime(_) = **param.value() {
+                    continue;
+                }
+                if !trailing_or_empty {
+                    <Token![,]>::default().to_tokens(tokens);
+                    trailing_or_empty = true;
+                }
+                match param.value() {
+                    GenericParam::Lifetime(_) => unreachable!(),
+                    GenericParam::Type(param) => {
+                        // Leave off the type parameter defaults
+                        tokens.append_all(param.attrs.outer());
+                        param.ident.to_tokens(tokens);
+                        if !param.bounds.is_empty() {
+                            TokensOrDefault(&param.colon_token).to_tokens(tokens);
+                            param.bounds.to_tokens(tokens);
+                        }
+                    }
+                    GenericParam::Const(param) => {
+                        // Leave off the const parameter defaults
+                        tokens.append_all(param.attrs.outer());
+                        param.const_token.to_tokens(tokens);
+                        param.ident.to_tokens(tokens);
+                        param.colon_token.to_tokens(tokens);
+                        param.ty.to_tokens(tokens);
+                    }
+                }
+                param.punct().to_tokens(tokens);
+            }
+
+            TokensOrDefault(&self.0.gt_token).to_tokens(tokens);
+        }
+    }
+
+    impl<'a> ToTokens for TypeGenerics<'a> {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            if self.0.params.is_empty() {
+                return;
+            }
+
+            TokensOrDefault(&self.0.lt_token).to_tokens(tokens);
+
+            // Print lifetimes before types and consts, regardless of their
+            // order in self.params.
+            let mut trailing_or_empty = true;
+            for param in self.0.params.pairs() {
+                if let GenericParam::Lifetime(def) = *param.value() {
+                    // Leave off the lifetime bounds and attributes
+                    def.lifetime.to_tokens(tokens);
+                    param.punct().to_tokens(tokens);
+                    trailing_or_empty = param.punct().is_some();
+                }
+            }
+            for param in self.0.params.pairs() {
+                if let GenericParam::Lifetime(_) = **param.value() {
+                    continue;
+                }
+                if !trailing_or_empty {
+                    <Token![,]>::default().to_tokens(tokens);
+                    trailing_or_empty = true;
+                }
+                match param.value() {
+                    GenericParam::Lifetime(_) => unreachable!(),
+                    GenericParam::Type(param) => {
+                        // Leave off the type parameter defaults
+                        param.ident.to_tokens(tokens);
+                    }
+                    GenericParam::Const(param) => {
+                        // Leave off the const parameter defaults
+                        param.ident.to_tokens(tokens);
+                    }
+                }
+                param.punct().to_tokens(tokens);
+            }
+
+            TokensOrDefault(&self.0.gt_token).to_tokens(tokens);
+        }
+    }
+
+    impl<'a> ToTokens for Turbofish<'a> {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            if !self.0.params.is_empty() {
+                <Token![::]>::default().to_tokens(tokens);
+                TypeGenerics(self.0).to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for BoundLifetimes {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.for_token.to_tokens(tokens);
+            self.lt_token.to_tokens(tokens);
+            self.lifetimes.to_tokens(tokens);
+            self.gt_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for LifetimeParam {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.lifetime.to_tokens(tokens);
+            if !self.bounds.is_empty() {
+                TokensOrDefault(&self.colon_token).to_tokens(tokens);
+                self.bounds.to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeParam {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.ident.to_tokens(tokens);
+            if !self.bounds.is_empty() {
+                TokensOrDefault(&self.colon_token).to_tokens(tokens);
+                self.bounds.to_tokens(tokens);
+            }
+            if let Some(default) = &self.default {
+                TokensOrDefault(&self.eq_token).to_tokens(tokens);
+                default.to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitBound {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            let to_tokens = |tokens: &mut TokenStream| {
+                self.modifier.to_tokens(tokens);
+                self.lifetimes.to_tokens(tokens);
+                self.path.to_tokens(tokens);
+            };
+            match &self.paren_token {
+                Some(paren) => paren.surround(tokens, to_tokens),
+                None => to_tokens(tokens),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitBoundModifier {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                TraitBoundModifier::None => {}
+                TraitBoundModifier::Maybe(t) => t.to_tokens(tokens),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ConstParam {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.const_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            if let Some(default) = &self.default {
+                TokensOrDefault(&self.eq_token).to_tokens(tokens);
+                default.to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for WhereClause {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            if !self.predicates.is_empty() {
+                self.where_token.to_tokens(tokens);
+                self.predicates.to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PredicateLifetime {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.lifetime.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.bounds.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PredicateType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.lifetimes.to_tokens(tokens);
+            self.bounded_ty.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.bounds.to_tokens(tokens);
+        }
+    }
+}
diff --git a/rust/syn/group.rs b/rust/syn/group.rs
new file mode 100644
index 0000000000000000000000000000000000000000..52a79d650909b43e2272b777cb4c43f5485ec0ae
--- /dev/null
+++ b/rust/syn/group.rs
@@ -0,0 +1,293 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::error::Result;
+use crate::parse::ParseBuffer;
+use crate::token;
+use proc_macro2::extra::DelimSpan;
+use proc_macro2::Delimiter;
+
+// Not public API.
+#[doc(hidden)]
+pub struct Parens<'a> {
+    #[doc(hidden)]
+    pub token: token::Paren,
+    #[doc(hidden)]
+    pub content: ParseBuffer<'a>,
+}
+
+// Not public API.
+#[doc(hidden)]
+pub struct Braces<'a> {
+    #[doc(hidden)]
+    pub token: token::Brace,
+    #[doc(hidden)]
+    pub content: ParseBuffer<'a>,
+}
+
+// Not public API.
+#[doc(hidden)]
+pub struct Brackets<'a> {
+    #[doc(hidden)]
+    pub token: token::Bracket,
+    #[doc(hidden)]
+    pub content: ParseBuffer<'a>,
+}
+
+// Not public API.
+#[cfg(any(feature = "full", feature = "derive"))]
+#[doc(hidden)]
+pub struct Group<'a> {
+    #[doc(hidden)]
+    pub token: token::Group,
+    #[doc(hidden)]
+    pub content: ParseBuffer<'a>,
+}
+
+// Not public API.
+#[doc(hidden)]
+pub fn parse_parens<'a>(input: &ParseBuffer<'a>) -> Result<Parens<'a>> {
+    parse_delimited(input, Delimiter::Parenthesis).map(|(span, content)| Parens {
+        token: token::Paren(span),
+        content,
+    })
+}
+
+// Not public API.
+#[doc(hidden)]
+pub fn parse_braces<'a>(input: &ParseBuffer<'a>) -> Result<Braces<'a>> {
+    parse_delimited(input, Delimiter::Brace).map(|(span, content)| Braces {
+        token: token::Brace(span),
+        content,
+    })
+}
+
+// Not public API.
+#[doc(hidden)]
+pub fn parse_brackets<'a>(input: &ParseBuffer<'a>) -> Result<Brackets<'a>> {
+    parse_delimited(input, Delimiter::Bracket).map(|(span, content)| Brackets {
+        token: token::Bracket(span),
+        content,
+    })
+}
+
+#[cfg(any(feature = "full", feature = "derive"))]
+pub(crate) fn parse_group<'a>(input: &ParseBuffer<'a>) -> Result<Group<'a>> {
+    parse_delimited(input, Delimiter::None).map(|(span, content)| Group {
+        token: token::Group(span.join()),
+        content,
+    })
+}
+
+fn parse_delimited<'a>(
+    input: &ParseBuffer<'a>,
+    delimiter: Delimiter,
+) -> Result<(DelimSpan, ParseBuffer<'a>)> {
+    input.step(|cursor| {
+        if let Some((content, span, rest)) = cursor.group(delimiter) {
+            let scope = crate::buffer::close_span_of_group(*cursor);
+            let nested = crate::parse::advance_step_cursor(cursor, content);
+            let unexpected = crate::parse::get_unexpected(input);
+            let content = crate::parse::new_parse_buffer(scope, nested, unexpected);
+            Ok(((span, content), rest))
+        } else {
+            let message = match delimiter {
+                Delimiter::Parenthesis => "expected parentheses",
+                Delimiter::Brace => "expected curly braces",
+                Delimiter::Bracket => "expected square brackets",
+                Delimiter::None => "expected invisible group",
+            };
+            Err(cursor.error(message))
+        }
+    })
+}
+
+/// Parse a set of parentheses and expose their content to subsequent parsers.
+///
+/// # Example
+///
+/// ```
+/// # use quote::quote;
+/// #
+/// use syn::{parenthesized, token, Ident, Result, Token, Type};
+/// use syn::parse::{Parse, ParseStream};
+/// use syn::punctuated::Punctuated;
+///
+/// // Parse a simplified tuple struct syntax like:
+/// //
+/// //     struct S(A, B);
+/// struct TupleStruct {
+///     struct_token: Token![struct],
+///     ident: Ident,
+///     paren_token: token::Paren,
+///     fields: Punctuated<Type, Token![,]>,
+///     semi_token: Token![;],
+/// }
+///
+/// impl Parse for TupleStruct {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         let content;
+///         Ok(TupleStruct {
+///             struct_token: input.parse()?,
+///             ident: input.parse()?,
+///             paren_token: parenthesized!(content in input),
+///             fields: content.parse_terminated(Type::parse, Token![,])?,
+///             semi_token: input.parse()?,
+///         })
+///     }
+/// }
+/// #
+/// # fn main() {
+/// #     let input = quote! {
+/// #         struct S(A, B);
+/// #     };
+/// #     syn::parse2::<TupleStruct>(input).unwrap();
+/// # }
+/// ```
+#[macro_export]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+macro_rules! parenthesized {
+    ($content:ident in $cursor:expr) => {
+        match $crate::__private::parse_parens(&$cursor) {
+            $crate::__private::Ok(parens) => {
+                $content = parens.content;
+                parens.token
+            }
+            $crate::__private::Err(error) => {
+                return $crate::__private::Err(error);
+            }
+        }
+    };
+}
+
+/// Parse a set of curly braces and expose their content to subsequent parsers.
+///
+/// # Example
+///
+/// ```
+/// # use quote::quote;
+/// #
+/// use syn::{braced, token, Ident, Result, Token, Type};
+/// use syn::parse::{Parse, ParseStream};
+/// use syn::punctuated::Punctuated;
+///
+/// // Parse a simplified struct syntax like:
+/// //
+/// //     struct S {
+/// //         a: A,
+/// //         b: B,
+/// //     }
+/// struct Struct {
+///     struct_token: Token![struct],
+///     ident: Ident,
+///     brace_token: token::Brace,
+///     fields: Punctuated<Field, Token![,]>,
+/// }
+///
+/// struct Field {
+///     name: Ident,
+///     colon_token: Token![:],
+///     ty: Type,
+/// }
+///
+/// impl Parse for Struct {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         let content;
+///         Ok(Struct {
+///             struct_token: input.parse()?,
+///             ident: input.parse()?,
+///             brace_token: braced!(content in input),
+///             fields: content.parse_terminated(Field::parse, Token![,])?,
+///         })
+///     }
+/// }
+///
+/// impl Parse for Field {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         Ok(Field {
+///             name: input.parse()?,
+///             colon_token: input.parse()?,
+///             ty: input.parse()?,
+///         })
+///     }
+/// }
+/// #
+/// # fn main() {
+/// #     let input = quote! {
+/// #         struct S {
+/// #             a: A,
+/// #             b: B,
+/// #         }
+/// #     };
+/// #     syn::parse2::<Struct>(input).unwrap();
+/// # }
+/// ```
+#[macro_export]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+macro_rules! braced {
+    ($content:ident in $cursor:expr) => {
+        match $crate::__private::parse_braces(&$cursor) {
+            $crate::__private::Ok(braces) => {
+                $content = braces.content;
+                braces.token
+            }
+            $crate::__private::Err(error) => {
+                return $crate::__private::Err(error);
+            }
+        }
+    };
+}
+
+/// Parse a set of square brackets and expose their content to subsequent
+/// parsers.
+///
+/// # Example
+///
+/// ```
+/// # use quote::quote;
+/// #
+/// use proc_macro2::TokenStream;
+/// use syn::{bracketed, token, Result, Token};
+/// use syn::parse::{Parse, ParseStream};
+///
+/// // Parse an outer attribute like:
+/// //
+/// //     #[repr(C, packed)]
+/// struct OuterAttribute {
+///     pound_token: Token![#],
+///     bracket_token: token::Bracket,
+///     content: TokenStream,
+/// }
+///
+/// impl Parse for OuterAttribute {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         let content;
+///         Ok(OuterAttribute {
+///             pound_token: input.parse()?,
+///             bracket_token: bracketed!(content in input),
+///             content: content.parse()?,
+///         })
+///     }
+/// }
+/// #
+/// # fn main() {
+/// #     let input = quote! {
+/// #         #[repr(C, packed)]
+/// #     };
+/// #     syn::parse2::<OuterAttribute>(input).unwrap();
+/// # }
+/// ```
+#[macro_export]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+macro_rules! bracketed {
+    ($content:ident in $cursor:expr) => {
+        match $crate::__private::parse_brackets(&$cursor) {
+            $crate::__private::Ok(brackets) => {
+                $content = brackets.content;
+                brackets.token
+            }
+            $crate::__private::Err(error) => {
+                return $crate::__private::Err(error);
+            }
+        }
+    };
+}
diff --git a/rust/syn/ident.rs b/rust/syn/ident.rs
new file mode 100644
index 0000000000000000000000000000000000000000..b2137467cfbe50b3a536bbe3ca3dde163fde5aa8
--- /dev/null
+++ b/rust/syn/ident.rs
@@ -0,0 +1,110 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "parsing")]
+use crate::lookahead;
+
+pub use proc_macro2::Ident;
+
+#[cfg(feature = "parsing")]
+pub_if_not_doc! {
+    #[doc(hidden)]
+    #[allow(non_snake_case)]
+    pub fn Ident(marker: lookahead::TokenMarker) -> Ident {
+        match marker {}
+    }
+}
+
+macro_rules! ident_from_token {
+    ($token:ident) => {
+        impl From<Token![$token]> for Ident {
+            fn from(token: Token![$token]) -> Ident {
+                Ident::new(stringify!($token), token.span)
+            }
+        }
+    };
+}
+
+ident_from_token!(self);
+ident_from_token!(Self);
+ident_from_token!(super);
+ident_from_token!(crate);
+ident_from_token!(extern);
+
+impl From<Token![_]> for Ident {
+    fn from(token: Token![_]) -> Ident {
+        Ident::new("_", token.span)
+    }
+}
+
+pub(crate) fn xid_ok(symbol: &str) -> bool {
+    let mut chars = symbol.chars();
+    let first = chars.next().unwrap();
+    if !(first == '_' || first.is_ascii_alphabetic()) {
+        return false;
+    }
+    for ch in chars {
+        if !(ch == '_' || ch.is_ascii_alphanumeric()) {
+            return false;
+        }
+    }
+    true
+}
+
+#[cfg(feature = "parsing")]
+mod parsing {
+    use crate::buffer::Cursor;
+    use crate::error::Result;
+    use crate::parse::{Parse, ParseStream};
+    use crate::token::Token;
+    use proc_macro2::Ident;
+
+    fn accept_as_ident(ident: &Ident) -> bool {
+        match ident.to_string().as_str() {
+            "_" |
+            // Based on https://doc.rust-lang.org/1.65.0/reference/keywords.html
+            "abstract" | "as" | "async" | "await" | "become" | "box" | "break" |
+            "const" | "continue" | "crate" | "do" | "dyn" | "else" | "enum" |
+            "extern" | "false" | "final" | "fn" | "for" | "if" | "impl" | "in" |
+            "let" | "loop" | "macro" | "match" | "mod" | "move" | "mut" |
+            "override" | "priv" | "pub" | "ref" | "return" | "Self" | "self" |
+            "static" | "struct" | "super" | "trait" | "true" | "try" | "type" |
+            "typeof" | "unsafe" | "unsized" | "use" | "virtual" | "where" |
+            "while" | "yield" => false,
+            _ => true,
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Ident {
+        fn parse(input: ParseStream) -> Result<Self> {
+            input.step(|cursor| {
+                if let Some((ident, rest)) = cursor.ident() {
+                    if accept_as_ident(&ident) {
+                        Ok((ident, rest))
+                    } else {
+                        Err(cursor.error(format_args!(
+                            "expected identifier, found keyword `{}`",
+                            ident,
+                        )))
+                    }
+                } else {
+                    Err(cursor.error("expected identifier"))
+                }
+            })
+        }
+    }
+
+    impl Token for Ident {
+        fn peek(cursor: Cursor) -> bool {
+            if let Some((ident, _rest)) = cursor.ident() {
+                accept_as_ident(&ident)
+            } else {
+                false
+            }
+        }
+
+        fn display() -> &'static str {
+            "identifier"
+        }
+    }
+}
diff --git a/rust/syn/item.rs b/rust/syn/item.rs
new file mode 100644
index 0000000000000000000000000000000000000000..52a8ab4854714fa437c976a2fd49bbad64a2c4ad
--- /dev/null
+++ b/rust/syn/item.rs
@@ -0,0 +1,3452 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+use crate::data::{Fields, FieldsNamed, Variant};
+use crate::derive::{Data, DataEnum, DataStruct, DataUnion, DeriveInput};
+use crate::expr::Expr;
+use crate::generics::{Generics, TypeParamBound};
+use crate::ident::Ident;
+use crate::lifetime::Lifetime;
+use crate::mac::Macro;
+use crate::pat::{Pat, PatType};
+use crate::path::Path;
+use crate::punctuated::Punctuated;
+use crate::restriction::Visibility;
+use crate::stmt::Block;
+use crate::token;
+use crate::ty::{Abi, ReturnType, Type};
+use proc_macro2::TokenStream;
+#[cfg(feature = "parsing")]
+use std::mem;
+
+ast_enum_of_structs! {
+    /// Things that can appear directly inside of a module or scope.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[non_exhaustive]
+    pub enum Item {
+        /// A constant item: `const MAX: u16 = 65535`.
+        Const(ItemConst),
+
+        /// An enum definition: `enum Foo<A, B> { A(A), B(B) }`.
+        Enum(ItemEnum),
+
+        /// An `extern crate` item: `extern crate serde`.
+        ExternCrate(ItemExternCrate),
+
+        /// A free-standing function: `fn process(n: usize) -> Result<()> { ...
+        /// }`.
+        Fn(ItemFn),
+
+        /// A block of foreign items: `extern "C" { ... }`.
+        ForeignMod(ItemForeignMod),
+
+        /// An impl block providing trait or associated items: `impl<A> Trait
+        /// for Data<A> { ... }`.
+        Impl(ItemImpl),
+
+        /// A macro invocation, which includes `macro_rules!` definitions.
+        Macro(ItemMacro),
+
+        /// A module or module declaration: `mod m` or `mod m { ... }`.
+        Mod(ItemMod),
+
+        /// A static item: `static BIKE: Shed = Shed(42)`.
+        Static(ItemStatic),
+
+        /// A struct definition: `struct Foo<A> { x: A }`.
+        Struct(ItemStruct),
+
+        /// A trait definition: `pub trait Iterator { ... }`.
+        Trait(ItemTrait),
+
+        /// A trait alias: `pub trait SharableIterator = Iterator + Sync`.
+        TraitAlias(ItemTraitAlias),
+
+        /// A type alias: `type Result<T> = std::result::Result<T, MyError>`.
+        Type(ItemType),
+
+        /// A union definition: `union Foo<A, B> { x: A, y: B }`.
+        Union(ItemUnion),
+
+        /// A use declaration: `use std::collections::HashMap`.
+        Use(ItemUse),
+
+        /// Tokens forming an item not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match item {
+        //         #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //
+        //         Item::Const(item) => {...}
+        //         Item::Enum(item) => {...}
+        //         ...
+        //         Item::Verbatim(item) => {...}
+        //
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+    }
+}
+
+ast_struct! {
+    /// A constant item: `const MAX: u16 = 65535`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemConst {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub const_token: Token![const],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub colon_token: Token![:],
+        pub ty: Box<Type>,
+        pub eq_token: Token![=],
+        pub expr: Box<Expr>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// An enum definition: `enum Foo<A, B> { A(A), B(B) }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemEnum {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub enum_token: Token![enum],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub brace_token: token::Brace,
+        pub variants: Punctuated<Variant, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// An `extern crate` item: `extern crate serde`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemExternCrate {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub extern_token: Token![extern],
+        pub crate_token: Token![crate],
+        pub ident: Ident,
+        pub rename: Option<(Token![as], Ident)>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A free-standing function: `fn process(n: usize) -> Result<()> { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemFn {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub sig: Signature,
+        pub block: Box<Block>,
+    }
+}
+
+ast_struct! {
+    /// A block of foreign items: `extern "C" { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemForeignMod {
+        pub attrs: Vec<Attribute>,
+        pub unsafety: Option<Token![unsafe]>,
+        pub abi: Abi,
+        pub brace_token: token::Brace,
+        pub items: Vec<ForeignItem>,
+    }
+}
+
+ast_struct! {
+    /// An impl block providing trait or associated items: `impl<A> Trait
+    /// for Data<A> { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemImpl {
+        pub attrs: Vec<Attribute>,
+        pub defaultness: Option<Token![default]>,
+        pub unsafety: Option<Token![unsafe]>,
+        pub impl_token: Token![impl],
+        pub generics: Generics,
+        /// Trait this impl implements.
+        pub trait_: Option<(Option<Token![!]>, Path, Token![for])>,
+        /// The Self type of the impl.
+        pub self_ty: Box<Type>,
+        pub brace_token: token::Brace,
+        pub items: Vec<ImplItem>,
+    }
+}
+
+ast_struct! {
+    /// A macro invocation, which includes `macro_rules!` definitions.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemMacro {
+        pub attrs: Vec<Attribute>,
+        /// The `example` in `macro_rules! example { ... }`.
+        pub ident: Option<Ident>,
+        pub mac: Macro,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// A module or module declaration: `mod m` or `mod m { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemMod {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub unsafety: Option<Token![unsafe]>,
+        pub mod_token: Token![mod],
+        pub ident: Ident,
+        pub content: Option<(token::Brace, Vec<Item>)>,
+        pub semi: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// A static item: `static BIKE: Shed = Shed(42)`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemStatic {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub static_token: Token![static],
+        pub mutability: StaticMutability,
+        pub ident: Ident,
+        pub colon_token: Token![:],
+        pub ty: Box<Type>,
+        pub eq_token: Token![=],
+        pub expr: Box<Expr>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A struct definition: `struct Foo<A> { x: A }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemStruct {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub struct_token: Token![struct],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub fields: Fields,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// A trait definition: `pub trait Iterator { ... }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemTrait {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub unsafety: Option<Token![unsafe]>,
+        pub auto_token: Option<Token![auto]>,
+        pub restriction: Option<ImplRestriction>,
+        pub trait_token: Token![trait],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub colon_token: Option<Token![:]>,
+        pub supertraits: Punctuated<TypeParamBound, Token![+]>,
+        pub brace_token: token::Brace,
+        pub items: Vec<TraitItem>,
+    }
+}
+
+ast_struct! {
+    /// A trait alias: `pub trait SharableIterator = Iterator + Sync`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemTraitAlias {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub trait_token: Token![trait],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub eq_token: Token![=],
+        pub bounds: Punctuated<TypeParamBound, Token![+]>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A type alias: `type Result<T> = std::result::Result<T, MyError>`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemType {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub type_token: Token![type],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub eq_token: Token![=],
+        pub ty: Box<Type>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A union definition: `union Foo<A, B> { x: A, y: B }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemUnion {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub union_token: Token![union],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub fields: FieldsNamed,
+    }
+}
+
+ast_struct! {
+    /// A use declaration: `use std::collections::HashMap`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ItemUse {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub use_token: Token![use],
+        pub leading_colon: Option<Token![::]>,
+        pub tree: UseTree,
+        pub semi_token: Token![;],
+    }
+}
+
+impl Item {
+    #[cfg(feature = "parsing")]
+    pub(crate) fn replace_attrs(&mut self, new: Vec<Attribute>) -> Vec<Attribute> {
+        match self {
+            Item::Const(ItemConst { attrs, .. })
+            | Item::Enum(ItemEnum { attrs, .. })
+            | Item::ExternCrate(ItemExternCrate { attrs, .. })
+            | Item::Fn(ItemFn { attrs, .. })
+            | Item::ForeignMod(ItemForeignMod { attrs, .. })
+            | Item::Impl(ItemImpl { attrs, .. })
+            | Item::Macro(ItemMacro { attrs, .. })
+            | Item::Mod(ItemMod { attrs, .. })
+            | Item::Static(ItemStatic { attrs, .. })
+            | Item::Struct(ItemStruct { attrs, .. })
+            | Item::Trait(ItemTrait { attrs, .. })
+            | Item::TraitAlias(ItemTraitAlias { attrs, .. })
+            | Item::Type(ItemType { attrs, .. })
+            | Item::Union(ItemUnion { attrs, .. })
+            | Item::Use(ItemUse { attrs, .. }) => mem::replace(attrs, new),
+            Item::Verbatim(_) => Vec::new(),
+        }
+    }
+}
+
+impl From<DeriveInput> for Item {
+    fn from(input: DeriveInput) -> Item {
+        match input.data {
+            Data::Struct(data) => Item::Struct(ItemStruct {
+                attrs: input.attrs,
+                vis: input.vis,
+                struct_token: data.struct_token,
+                ident: input.ident,
+                generics: input.generics,
+                fields: data.fields,
+                semi_token: data.semi_token,
+            }),
+            Data::Enum(data) => Item::Enum(ItemEnum {
+                attrs: input.attrs,
+                vis: input.vis,
+                enum_token: data.enum_token,
+                ident: input.ident,
+                generics: input.generics,
+                brace_token: data.brace_token,
+                variants: data.variants,
+            }),
+            Data::Union(data) => Item::Union(ItemUnion {
+                attrs: input.attrs,
+                vis: input.vis,
+                union_token: data.union_token,
+                ident: input.ident,
+                generics: input.generics,
+                fields: data.fields,
+            }),
+        }
+    }
+}
+
+impl From<ItemStruct> for DeriveInput {
+    fn from(input: ItemStruct) -> DeriveInput {
+        DeriveInput {
+            attrs: input.attrs,
+            vis: input.vis,
+            ident: input.ident,
+            generics: input.generics,
+            data: Data::Struct(DataStruct {
+                struct_token: input.struct_token,
+                fields: input.fields,
+                semi_token: input.semi_token,
+            }),
+        }
+    }
+}
+
+impl From<ItemEnum> for DeriveInput {
+    fn from(input: ItemEnum) -> DeriveInput {
+        DeriveInput {
+            attrs: input.attrs,
+            vis: input.vis,
+            ident: input.ident,
+            generics: input.generics,
+            data: Data::Enum(DataEnum {
+                enum_token: input.enum_token,
+                brace_token: input.brace_token,
+                variants: input.variants,
+            }),
+        }
+    }
+}
+
+impl From<ItemUnion> for DeriveInput {
+    fn from(input: ItemUnion) -> DeriveInput {
+        DeriveInput {
+            attrs: input.attrs,
+            vis: input.vis,
+            ident: input.ident,
+            generics: input.generics,
+            data: Data::Union(DataUnion {
+                union_token: input.union_token,
+                fields: input.fields,
+            }),
+        }
+    }
+}
+
+ast_enum_of_structs! {
+    /// A suffix of an import tree in a `use` item: `Type as Renamed` or `*`.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub enum UseTree {
+        /// A path prefix of imports in a `use` item: `std::...`.
+        Path(UsePath),
+
+        /// An identifier imported by a `use` item: `HashMap`.
+        Name(UseName),
+
+        /// An renamed identifier imported by a `use` item: `HashMap as Map`.
+        Rename(UseRename),
+
+        /// A glob import in a `use` item: `*`.
+        Glob(UseGlob),
+
+        /// A braced group of imports in a `use` item: `{A, B, C}`.
+        Group(UseGroup),
+    }
+}
+
+ast_struct! {
+    /// A path prefix of imports in a `use` item: `std::...`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UsePath {
+        pub ident: Ident,
+        pub colon2_token: Token![::],
+        pub tree: Box<UseTree>,
+    }
+}
+
+ast_struct! {
+    /// An identifier imported by a `use` item: `HashMap`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UseName {
+        pub ident: Ident,
+    }
+}
+
+ast_struct! {
+    /// An renamed identifier imported by a `use` item: `HashMap as Map`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UseRename {
+        pub ident: Ident,
+        pub as_token: Token![as],
+        pub rename: Ident,
+    }
+}
+
+ast_struct! {
+    /// A glob import in a `use` item: `*`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UseGlob {
+        pub star_token: Token![*],
+    }
+}
+
+ast_struct! {
+    /// A braced group of imports in a `use` item: `{A, B, C}`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct UseGroup {
+        pub brace_token: token::Brace,
+        pub items: Punctuated<UseTree, Token![,]>,
+    }
+}
+
+ast_enum_of_structs! {
+    /// An item within an `extern` block.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[non_exhaustive]
+    pub enum ForeignItem {
+        /// A foreign function in an `extern` block.
+        Fn(ForeignItemFn),
+
+        /// A foreign static item in an `extern` block: `static ext: u8`.
+        Static(ForeignItemStatic),
+
+        /// A foreign type in an `extern` block: `type void`.
+        Type(ForeignItemType),
+
+        /// A macro invocation within an extern block.
+        Macro(ForeignItemMacro),
+
+        /// Tokens in an `extern` block not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match item {
+        //         #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //
+        //         ForeignItem::Fn(item) => {...}
+        //         ForeignItem::Static(item) => {...}
+        //         ...
+        //         ForeignItem::Verbatim(item) => {...}
+        //
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+    }
+}
+
+ast_struct! {
+    /// A foreign function in an `extern` block.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ForeignItemFn {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub sig: Signature,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A foreign static item in an `extern` block: `static ext: u8`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ForeignItemStatic {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub static_token: Token![static],
+        pub mutability: StaticMutability,
+        pub ident: Ident,
+        pub colon_token: Token![:],
+        pub ty: Box<Type>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A foreign type in an `extern` block: `type void`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ForeignItemType {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub type_token: Token![type],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A macro invocation within an extern block.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ForeignItemMacro {
+        pub attrs: Vec<Attribute>,
+        pub mac: Macro,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_enum_of_structs! {
+    /// An item declaration within the definition of a trait.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[non_exhaustive]
+    pub enum TraitItem {
+        /// An associated constant within the definition of a trait.
+        Const(TraitItemConst),
+
+        /// An associated function within the definition of a trait.
+        Fn(TraitItemFn),
+
+        /// An associated type within the definition of a trait.
+        Type(TraitItemType),
+
+        /// A macro invocation within the definition of a trait.
+        Macro(TraitItemMacro),
+
+        /// Tokens within the definition of a trait not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match item {
+        //         #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //
+        //         TraitItem::Const(item) => {...}
+        //         TraitItem::Fn(item) => {...}
+        //         ...
+        //         TraitItem::Verbatim(item) => {...}
+        //
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+    }
+}
+
+ast_struct! {
+    /// An associated constant within the definition of a trait.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct TraitItemConst {
+        pub attrs: Vec<Attribute>,
+        pub const_token: Token![const],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub colon_token: Token![:],
+        pub ty: Type,
+        pub default: Option<(Token![=], Expr)>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// An associated function within the definition of a trait.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct TraitItemFn {
+        pub attrs: Vec<Attribute>,
+        pub sig: Signature,
+        pub default: Option<Block>,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// An associated type within the definition of a trait.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct TraitItemType {
+        pub attrs: Vec<Attribute>,
+        pub type_token: Token![type],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub colon_token: Option<Token![:]>,
+        pub bounds: Punctuated<TypeParamBound, Token![+]>,
+        pub default: Option<(Token![=], Type)>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A macro invocation within the definition of a trait.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct TraitItemMacro {
+        pub attrs: Vec<Attribute>,
+        pub mac: Macro,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_enum_of_structs! {
+    /// An item within an impl block.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[non_exhaustive]
+    pub enum ImplItem {
+        /// An associated constant within an impl block.
+        Const(ImplItemConst),
+
+        /// An associated function within an impl block.
+        Fn(ImplItemFn),
+
+        /// An associated type within an impl block.
+        Type(ImplItemType),
+
+        /// A macro invocation within an impl block.
+        Macro(ImplItemMacro),
+
+        /// Tokens within an impl block not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match item {
+        //         #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //
+        //         ImplItem::Const(item) => {...}
+        //         ImplItem::Fn(item) => {...}
+        //         ...
+        //         ImplItem::Verbatim(item) => {...}
+        //
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+    }
+}
+
+ast_struct! {
+    /// An associated constant within an impl block.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ImplItemConst {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub defaultness: Option<Token![default]>,
+        pub const_token: Token![const],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub colon_token: Token![:],
+        pub ty: Type,
+        pub eq_token: Token![=],
+        pub expr: Expr,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// An associated function within an impl block.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ImplItemFn {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub defaultness: Option<Token![default]>,
+        pub sig: Signature,
+        pub block: Block,
+    }
+}
+
+ast_struct! {
+    /// An associated type within an impl block.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ImplItemType {
+        pub attrs: Vec<Attribute>,
+        pub vis: Visibility,
+        pub defaultness: Option<Token![default]>,
+        pub type_token: Token![type],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub eq_token: Token![=],
+        pub ty: Type,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// A macro invocation within an impl block.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct ImplItemMacro {
+        pub attrs: Vec<Attribute>,
+        pub mac: Macro,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+ast_struct! {
+    /// A function signature in a trait or implementation: `unsafe fn
+    /// initialize(&self)`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct Signature {
+        pub constness: Option<Token![const]>,
+        pub asyncness: Option<Token![async]>,
+        pub unsafety: Option<Token![unsafe]>,
+        pub abi: Option<Abi>,
+        pub fn_token: Token![fn],
+        pub ident: Ident,
+        pub generics: Generics,
+        pub paren_token: token::Paren,
+        pub inputs: Punctuated<FnArg, Token![,]>,
+        pub variadic: Option<Variadic>,
+        pub output: ReturnType,
+    }
+}
+
+impl Signature {
+    /// A method's `self` receiver, such as `&self` or `self: Box<Self>`.
+    pub fn receiver(&self) -> Option<&Receiver> {
+        let arg = self.inputs.first()?;
+        match arg {
+            FnArg::Receiver(receiver) => Some(receiver),
+            FnArg::Typed(_) => None,
+        }
+    }
+}
+
+ast_enum_of_structs! {
+    /// An argument in a function signature: the `n: usize` in `fn f(n: usize)`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub enum FnArg {
+        /// The `self` argument of an associated method.
+        Receiver(Receiver),
+
+        /// A function argument accepted by pattern and type.
+        Typed(PatType),
+    }
+}
+
+ast_struct! {
+    /// The `self` argument of an associated method.
+    ///
+    /// If `colon_token` is present, the receiver is written with an explicit
+    /// type such as `self: Box<Self>`. If `colon_token` is absent, the receiver
+    /// is written in shorthand such as `self` or `&self` or `&mut self`. In the
+    /// shorthand case, the type in `ty` is reconstructed as one of `Self`,
+    /// `&Self`, or `&mut Self`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct Receiver {
+        pub attrs: Vec<Attribute>,
+        pub reference: Option<(Token![&], Option<Lifetime>)>,
+        pub mutability: Option<Token![mut]>,
+        pub self_token: Token![self],
+        pub colon_token: Option<Token![:]>,
+        pub ty: Box<Type>,
+    }
+}
+
+impl Receiver {
+    pub fn lifetime(&self) -> Option<&Lifetime> {
+        self.reference.as_ref()?.1.as_ref()
+    }
+}
+
+ast_struct! {
+    /// The variadic argument of a foreign function.
+    ///
+    /// ```rust
+    /// # struct c_char;
+    /// # struct c_int;
+    /// #
+    /// extern "C" {
+    ///     fn printf(format: *const c_char, ...) -> c_int;
+    ///     //                               ^^^
+    /// }
+    /// ```
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct Variadic {
+        pub attrs: Vec<Attribute>,
+        pub pat: Option<(Box<Pat>, Token![:])>,
+        pub dots: Token![...],
+        pub comma: Option<Token![,]>,
+    }
+}
+
+ast_enum! {
+    /// The mutability of an `Item::Static` or `ForeignItem::Static`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[non_exhaustive]
+    pub enum StaticMutability {
+        Mut(Token![mut]),
+        None,
+    }
+}
+
+ast_enum! {
+    /// Unused, but reserved for RFC 3323 restrictions.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[non_exhaustive]
+    pub enum ImplRestriction {}
+
+
+    // TODO: https://rust-lang.github.io/rfcs/3323-restrictions.html
+    //
+    // pub struct ImplRestriction {
+    //     pub impl_token: Token![impl],
+    //     pub paren_token: token::Paren,
+    //     pub in_token: Option<Token![in]>,
+    //     pub path: Box<Path>,
+    // }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::{self, Attribute};
+    use crate::derive;
+    use crate::error::{Error, Result};
+    use crate::expr::Expr;
+    use crate::ext::IdentExt as _;
+    use crate::generics::{Generics, TypeParamBound};
+    use crate::ident::Ident;
+    use crate::item::{
+        FnArg, ForeignItem, ForeignItemFn, ForeignItemMacro, ForeignItemStatic, ForeignItemType,
+        ImplItem, ImplItemConst, ImplItemFn, ImplItemMacro, ImplItemType, Item, ItemConst,
+        ItemEnum, ItemExternCrate, ItemFn, ItemForeignMod, ItemImpl, ItemMacro, ItemMod,
+        ItemStatic, ItemStruct, ItemTrait, ItemTraitAlias, ItemType, ItemUnion, ItemUse, Receiver,
+        Signature, StaticMutability, TraitItem, TraitItemConst, TraitItemFn, TraitItemMacro,
+        TraitItemType, UseGlob, UseGroup, UseName, UsePath, UseRename, UseTree, Variadic,
+    };
+    use crate::lifetime::Lifetime;
+    use crate::lit::LitStr;
+    use crate::mac::{self, Macro, MacroDelimiter};
+    use crate::parse::discouraged::Speculative as _;
+    use crate::parse::{Parse, ParseBuffer, ParseStream};
+    use crate::pat::{Pat, PatType, PatWild};
+    use crate::path::Path;
+    use crate::punctuated::Punctuated;
+    use crate::restriction::Visibility;
+    use crate::stmt::Block;
+    use crate::token;
+    use crate::ty::{Abi, ReturnType, Type, TypePath, TypeReference};
+    use crate::verbatim;
+    use proc_macro2::TokenStream;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Item {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let attrs = input.call(Attribute::parse_outer)?;
+            parse_rest_of_item(begin, attrs, input)
+        }
+    }
+
+    pub(crate) fn parse_rest_of_item(
+        begin: ParseBuffer,
+        mut attrs: Vec<Attribute>,
+        input: ParseStream,
+    ) -> Result<Item> {
+        let ahead = input.fork();
+        let vis: Visibility = ahead.parse()?;
+
+        let lookahead = ahead.lookahead1();
+        let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+            let vis: Visibility = input.parse()?;
+            let sig: Signature = input.parse()?;
+            if input.peek(Token![;]) {
+                input.parse::<Token![;]>()?;
+                Ok(Item::Verbatim(verbatim::between(&begin, input)))
+            } else {
+                parse_rest_of_fn(input, Vec::new(), vis, sig).map(Item::Fn)
+            }
+        } else if lookahead.peek(Token![extern]) {
+            ahead.parse::<Token![extern]>()?;
+            let lookahead = ahead.lookahead1();
+            if lookahead.peek(Token![crate]) {
+                input.parse().map(Item::ExternCrate)
+            } else if lookahead.peek(token::Brace) {
+                input.parse().map(Item::ForeignMod)
+            } else if lookahead.peek(LitStr) {
+                ahead.parse::<LitStr>()?;
+                let lookahead = ahead.lookahead1();
+                if lookahead.peek(token::Brace) {
+                    input.parse().map(Item::ForeignMod)
+                } else {
+                    Err(lookahead.error())
+                }
+            } else {
+                Err(lookahead.error())
+            }
+        } else if lookahead.peek(Token![use]) {
+            let allow_crate_root_in_path = true;
+            match parse_item_use(input, allow_crate_root_in_path)? {
+                Some(item_use) => Ok(Item::Use(item_use)),
+                None => Ok(Item::Verbatim(verbatim::between(&begin, input))),
+            }
+        } else if lookahead.peek(Token![static]) {
+            let vis = input.parse()?;
+            let static_token = input.parse()?;
+            let mutability = input.parse()?;
+            let ident = input.parse()?;
+            if input.peek(Token![=]) {
+                input.parse::<Token![=]>()?;
+                input.parse::<Expr>()?;
+                input.parse::<Token![;]>()?;
+                Ok(Item::Verbatim(verbatim::between(&begin, input)))
+            } else {
+                let colon_token = input.parse()?;
+                let ty = input.parse()?;
+                if input.peek(Token![;]) {
+                    input.parse::<Token![;]>()?;
+                    Ok(Item::Verbatim(verbatim::between(&begin, input)))
+                } else {
+                    Ok(Item::Static(ItemStatic {
+                        attrs: Vec::new(),
+                        vis,
+                        static_token,
+                        mutability,
+                        ident,
+                        colon_token,
+                        ty,
+                        eq_token: input.parse()?,
+                        expr: input.parse()?,
+                        semi_token: input.parse()?,
+                    }))
+                }
+            }
+        } else if lookahead.peek(Token![const]) {
+            let vis = input.parse()?;
+            let const_token: Token![const] = input.parse()?;
+            let lookahead = input.lookahead1();
+            let ident = if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                input.call(Ident::parse_any)?
+            } else {
+                return Err(lookahead.error());
+            };
+            let mut generics: Generics = input.parse()?;
+            let colon_token = input.parse()?;
+            let ty = input.parse()?;
+            let value = if let Some(eq_token) = input.parse::<Option<Token![=]>>()? {
+                let expr: Expr = input.parse()?;
+                Some((eq_token, expr))
+            } else {
+                None
+            };
+            generics.where_clause = input.parse()?;
+            let semi_token: Token![;] = input.parse()?;
+            match value {
+                Some((eq_token, expr))
+                    if generics.lt_token.is_none() && generics.where_clause.is_none() =>
+                {
+                    Ok(Item::Const(ItemConst {
+                        attrs: Vec::new(),
+                        vis,
+                        const_token,
+                        ident,
+                        generics,
+                        colon_token,
+                        ty,
+                        eq_token,
+                        expr: Box::new(expr),
+                        semi_token,
+                    }))
+                }
+                _ => Ok(Item::Verbatim(verbatim::between(&begin, input))),
+            }
+        } else if lookahead.peek(Token![unsafe]) {
+            ahead.parse::<Token![unsafe]>()?;
+            let lookahead = ahead.lookahead1();
+            if lookahead.peek(Token![trait])
+                || lookahead.peek(Token![auto]) && ahead.peek2(Token![trait])
+            {
+                input.parse().map(Item::Trait)
+            } else if lookahead.peek(Token![impl]) {
+                let allow_verbatim_impl = true;
+                if let Some(item) = parse_impl(input, allow_verbatim_impl)? {
+                    Ok(Item::Impl(item))
+                } else {
+                    Ok(Item::Verbatim(verbatim::between(&begin, input)))
+                }
+            } else if lookahead.peek(Token![extern]) {
+                input.parse().map(Item::ForeignMod)
+            } else if lookahead.peek(Token![mod]) {
+                input.parse().map(Item::Mod)
+            } else {
+                Err(lookahead.error())
+            }
+        } else if lookahead.peek(Token![mod]) {
+            input.parse().map(Item::Mod)
+        } else if lookahead.peek(Token![type]) {
+            parse_item_type(begin, input)
+        } else if lookahead.peek(Token![struct]) {
+            input.parse().map(Item::Struct)
+        } else if lookahead.peek(Token![enum]) {
+            input.parse().map(Item::Enum)
+        } else if lookahead.peek(Token![union]) && ahead.peek2(Ident) {
+            input.parse().map(Item::Union)
+        } else if lookahead.peek(Token![trait]) {
+            input.call(parse_trait_or_trait_alias)
+        } else if lookahead.peek(Token![auto]) && ahead.peek2(Token![trait]) {
+            input.parse().map(Item::Trait)
+        } else if lookahead.peek(Token![impl])
+            || lookahead.peek(Token![default]) && !ahead.peek2(Token![!])
+        {
+            let allow_verbatim_impl = true;
+            if let Some(item) = parse_impl(input, allow_verbatim_impl)? {
+                Ok(Item::Impl(item))
+            } else {
+                Ok(Item::Verbatim(verbatim::between(&begin, input)))
+            }
+        } else if lookahead.peek(Token![macro]) {
+            input.advance_to(&ahead);
+            parse_macro2(begin, vis, input)
+        } else if vis.is_inherited()
+            && (lookahead.peek(Ident)
+                || lookahead.peek(Token![self])
+                || lookahead.peek(Token![super])
+                || lookahead.peek(Token![crate])
+                || lookahead.peek(Token![::]))
+        {
+            input.parse().map(Item::Macro)
+        } else {
+            Err(lookahead.error())
+        }?;
+
+        attrs.extend(item.replace_attrs(Vec::new()));
+        item.replace_attrs(attrs);
+        Ok(item)
+    }
+
+    struct FlexibleItemType {
+        vis: Visibility,
+        defaultness: Option<Token![default]>,
+        type_token: Token![type],
+        ident: Ident,
+        generics: Generics,
+        colon_token: Option<Token![:]>,
+        bounds: Punctuated<TypeParamBound, Token![+]>,
+        ty: Option<(Token![=], Type)>,
+        semi_token: Token![;],
+    }
+
+    enum TypeDefaultness {
+        Optional,
+        Disallowed,
+    }
+
+    enum WhereClauseLocation {
+        // type Ty<T> where T: 'static = T;
+        BeforeEq,
+        // type Ty<T> = T where T: 'static;
+        AfterEq,
+        // TODO: goes away once the migration period on rust-lang/rust#89122 is over
+        Both,
+    }
+
+    impl FlexibleItemType {
+        fn parse(
+            input: ParseStream,
+            allow_defaultness: TypeDefaultness,
+            where_clause_location: WhereClauseLocation,
+        ) -> Result<Self> {
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = match allow_defaultness {
+                TypeDefaultness::Optional => input.parse()?,
+                TypeDefaultness::Disallowed => None,
+            };
+            let type_token: Token![type] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut generics: Generics = input.parse()?;
+            let (colon_token, bounds) = Self::parse_optional_bounds(input)?;
+
+            match where_clause_location {
+                WhereClauseLocation::BeforeEq | WhereClauseLocation::Both => {
+                    generics.where_clause = input.parse()?;
+                }
+                WhereClauseLocation::AfterEq => {}
+            }
+
+            let ty = Self::parse_optional_definition(input)?;
+
+            match where_clause_location {
+                WhereClauseLocation::AfterEq | WhereClauseLocation::Both
+                    if generics.where_clause.is_none() =>
+                {
+                    generics.where_clause = input.parse()?;
+                }
+                _ => {}
+            }
+
+            let semi_token: Token![;] = input.parse()?;
+
+            Ok(FlexibleItemType {
+                vis,
+                defaultness,
+                type_token,
+                ident,
+                generics,
+                colon_token,
+                bounds,
+                ty,
+                semi_token,
+            })
+        }
+
+        fn parse_optional_bounds(
+            input: ParseStream,
+        ) -> Result<(Option<Token![:]>, Punctuated<TypeParamBound, Token![+]>)> {
+            let colon_token: Option<Token![:]> = input.parse()?;
+
+            let mut bounds = Punctuated::new();
+            if colon_token.is_some() {
+                loop {
+                    if input.peek(Token![where]) || input.peek(Token![=]) || input.peek(Token![;]) {
+                        break;
+                    }
+                    bounds.push_value(input.parse::<TypeParamBound>()?);
+                    if input.peek(Token![where]) || input.peek(Token![=]) || input.peek(Token![;]) {
+                        break;
+                    }
+                    bounds.push_punct(input.parse::<Token![+]>()?);
+                }
+            }
+
+            Ok((colon_token, bounds))
+        }
+
+        fn parse_optional_definition(input: ParseStream) -> Result<Option<(Token![=], Type)>> {
+            let eq_token: Option<Token![=]> = input.parse()?;
+            if let Some(eq_token) = eq_token {
+                let definition: Type = input.parse()?;
+                Ok(Some((eq_token, definition)))
+            } else {
+                Ok(None)
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let path = input.call(Path::parse_mod_style)?;
+            let bang_token: Token![!] = input.parse()?;
+            let ident: Option<Ident> = if input.peek(Token![try]) {
+                input.call(Ident::parse_any).map(Some)
+            } else {
+                input.parse()
+            }?;
+            let (delimiter, tokens) = input.call(mac::parse_delimiter)?;
+            let semi_token: Option<Token![;]> = if !delimiter.is_brace() {
+                Some(input.parse()?)
+            } else {
+                None
+            };
+            Ok(ItemMacro {
+                attrs,
+                ident,
+                mac: Macro {
+                    path,
+                    bang_token,
+                    delimiter,
+                    tokens,
+                },
+                semi_token,
+            })
+        }
+    }
+
+    fn parse_macro2(begin: ParseBuffer, _vis: Visibility, input: ParseStream) -> Result<Item> {
+        input.parse::<Token![macro]>()?;
+        input.parse::<Ident>()?;
+
+        let mut lookahead = input.lookahead1();
+        if lookahead.peek(token::Paren) {
+            let paren_content;
+            parenthesized!(paren_content in input);
+            paren_content.parse::<TokenStream>()?;
+            lookahead = input.lookahead1();
+        }
+
+        if lookahead.peek(token::Brace) {
+            let brace_content;
+            braced!(brace_content in input);
+            brace_content.parse::<TokenStream>()?;
+        } else {
+            return Err(lookahead.error());
+        }
+
+        Ok(Item::Verbatim(verbatim::between(&begin, input)))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemExternCrate {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ItemExternCrate {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                extern_token: input.parse()?,
+                crate_token: input.parse()?,
+                ident: {
+                    if input.peek(Token![self]) {
+                        input.call(Ident::parse_any)?
+                    } else {
+                        input.parse()?
+                    }
+                },
+                rename: {
+                    if input.peek(Token![as]) {
+                        let as_token: Token![as] = input.parse()?;
+                        let rename: Ident = if input.peek(Token![_]) {
+                            Ident::from(input.parse::<Token![_]>()?)
+                        } else {
+                            input.parse()?
+                        };
+                        Some((as_token, rename))
+                    } else {
+                        None
+                    }
+                },
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemUse {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_crate_root_in_path = false;
+            parse_item_use(input, allow_crate_root_in_path).map(Option::unwrap)
+        }
+    }
+
+    fn parse_item_use(
+        input: ParseStream,
+        allow_crate_root_in_path: bool,
+    ) -> Result<Option<ItemUse>> {
+        let attrs = input.call(Attribute::parse_outer)?;
+        let vis: Visibility = input.parse()?;
+        let use_token: Token![use] = input.parse()?;
+        let leading_colon: Option<Token![::]> = input.parse()?;
+        let tree = parse_use_tree(input, allow_crate_root_in_path && leading_colon.is_none())?;
+        let semi_token: Token![;] = input.parse()?;
+
+        let tree = match tree {
+            Some(tree) => tree,
+            None => return Ok(None),
+        };
+
+        Ok(Some(ItemUse {
+            attrs,
+            vis,
+            use_token,
+            leading_colon,
+            tree,
+            semi_token,
+        }))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for UseTree {
+        fn parse(input: ParseStream) -> Result<UseTree> {
+            let allow_crate_root_in_path = false;
+            parse_use_tree(input, allow_crate_root_in_path).map(Option::unwrap)
+        }
+    }
+
+    fn parse_use_tree(
+        input: ParseStream,
+        allow_crate_root_in_path: bool,
+    ) -> Result<Option<UseTree>> {
+        let lookahead = input.lookahead1();
+        if lookahead.peek(Ident)
+            || lookahead.peek(Token![self])
+            || lookahead.peek(Token![super])
+            || lookahead.peek(Token![crate])
+            || lookahead.peek(Token![try])
+        {
+            let ident = input.call(Ident::parse_any)?;
+            if input.peek(Token![::]) {
+                Ok(Some(UseTree::Path(UsePath {
+                    ident,
+                    colon2_token: input.parse()?,
+                    tree: Box::new(input.parse()?),
+                })))
+            } else if input.peek(Token![as]) {
+                Ok(Some(UseTree::Rename(UseRename {
+                    ident,
+                    as_token: input.parse()?,
+                    rename: {
+                        if input.peek(Ident) {
+                            input.parse()?
+                        } else if input.peek(Token![_]) {
+                            Ident::from(input.parse::<Token![_]>()?)
+                        } else {
+                            return Err(input.error("expected identifier or underscore"));
+                        }
+                    },
+                })))
+            } else {
+                Ok(Some(UseTree::Name(UseName { ident })))
+            }
+        } else if lookahead.peek(Token![*]) {
+            Ok(Some(UseTree::Glob(UseGlob {
+                star_token: input.parse()?,
+            })))
+        } else if lookahead.peek(token::Brace) {
+            let content;
+            let brace_token = braced!(content in input);
+            let mut items = Punctuated::new();
+            let mut has_any_crate_root_in_path = false;
+            loop {
+                if content.is_empty() {
+                    break;
+                }
+                let this_tree_starts_with_crate_root =
+                    allow_crate_root_in_path && content.parse::<Option<Token![::]>>()?.is_some();
+                has_any_crate_root_in_path |= this_tree_starts_with_crate_root;
+                match parse_use_tree(
+                    &content,
+                    allow_crate_root_in_path && !this_tree_starts_with_crate_root,
+                )? {
+                    Some(tree) => items.push_value(tree),
+                    None => has_any_crate_root_in_path = true,
+                }
+                if content.is_empty() {
+                    break;
+                }
+                let comma: Token![,] = content.parse()?;
+                items.push_punct(comma);
+            }
+            if has_any_crate_root_in_path {
+                Ok(None)
+            } else {
+                Ok(Some(UseTree::Group(UseGroup { brace_token, items })))
+            }
+        } else {
+            Err(lookahead.error())
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemStatic {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ItemStatic {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                static_token: input.parse()?,
+                mutability: input.parse()?,
+                ident: input.parse()?,
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+                eq_token: input.parse()?,
+                expr: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemConst {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let const_token: Token![const] = input.parse()?;
+
+            let lookahead = input.lookahead1();
+            let ident = if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                input.call(Ident::parse_any)?
+            } else {
+                return Err(lookahead.error());
+            };
+
+            let colon_token: Token![:] = input.parse()?;
+            let ty: Type = input.parse()?;
+            let eq_token: Token![=] = input.parse()?;
+            let expr: Expr = input.parse()?;
+            let semi_token: Token![;] = input.parse()?;
+
+            Ok(ItemConst {
+                attrs,
+                vis,
+                const_token,
+                ident,
+                generics: Generics::default(),
+                colon_token,
+                ty: Box::new(ty),
+                eq_token,
+                expr: Box::new(expr),
+                semi_token,
+            })
+        }
+    }
+
+    fn peek_signature(input: ParseStream) -> bool {
+        let fork = input.fork();
+        fork.parse::<Option<Token![const]>>().is_ok()
+            && fork.parse::<Option<Token![async]>>().is_ok()
+            && fork.parse::<Option<Token![unsafe]>>().is_ok()
+            && fork.parse::<Option<Abi>>().is_ok()
+            && fork.peek(Token![fn])
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Signature {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let constness: Option<Token![const]> = input.parse()?;
+            let asyncness: Option<Token![async]> = input.parse()?;
+            let unsafety: Option<Token![unsafe]> = input.parse()?;
+            let abi: Option<Abi> = input.parse()?;
+            let fn_token: Token![fn] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut generics: Generics = input.parse()?;
+
+            let content;
+            let paren_token = parenthesized!(content in input);
+            let (inputs, variadic) = parse_fn_args(&content)?;
+
+            let output: ReturnType = input.parse()?;
+            generics.where_clause = input.parse()?;
+
+            Ok(Signature {
+                constness,
+                asyncness,
+                unsafety,
+                abi,
+                fn_token,
+                ident,
+                generics,
+                paren_token,
+                inputs,
+                variadic,
+                output,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemFn {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let outer_attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let sig: Signature = input.parse()?;
+            parse_rest_of_fn(input, outer_attrs, vis, sig)
+        }
+    }
+
+    fn parse_rest_of_fn(
+        input: ParseStream,
+        mut attrs: Vec<Attribute>,
+        vis: Visibility,
+        sig: Signature,
+    ) -> Result<ItemFn> {
+        let content;
+        let brace_token = braced!(content in input);
+        attr::parsing::parse_inner(&content, &mut attrs)?;
+        let stmts = content.call(Block::parse_within)?;
+
+        Ok(ItemFn {
+            attrs,
+            vis,
+            sig,
+            block: Box::new(Block { brace_token, stmts }),
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for FnArg {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_variadic = false;
+            let attrs = input.call(Attribute::parse_outer)?;
+            match parse_fn_arg_or_variadic(input, attrs, allow_variadic)? {
+                FnArgOrVariadic::FnArg(arg) => Ok(arg),
+                FnArgOrVariadic::Variadic(_) => unreachable!(),
+            }
+        }
+    }
+
+    enum FnArgOrVariadic {
+        FnArg(FnArg),
+        Variadic(Variadic),
+    }
+
+    fn parse_fn_arg_or_variadic(
+        input: ParseStream,
+        attrs: Vec<Attribute>,
+        allow_variadic: bool,
+    ) -> Result<FnArgOrVariadic> {
+        let ahead = input.fork();
+        if let Ok(mut receiver) = ahead.parse::<Receiver>() {
+            input.advance_to(&ahead);
+            receiver.attrs = attrs;
+            return Ok(FnArgOrVariadic::FnArg(FnArg::Receiver(receiver)));
+        }
+
+        // Hack to parse pre-2018 syntax in
+        // test/ui/rfc-2565-param-attrs/param-attrs-pretty.rs
+        // because the rest of the test case is valuable.
+        if input.peek(Ident) && input.peek2(Token![<]) {
+            let span = input.fork().parse::<Ident>()?.span();
+            return Ok(FnArgOrVariadic::FnArg(FnArg::Typed(PatType {
+                attrs,
+                pat: Box::new(Pat::Wild(PatWild {
+                    attrs: Vec::new(),
+                    underscore_token: Token![_](span),
+                })),
+                colon_token: Token![:](span),
+                ty: input.parse()?,
+            })));
+        }
+
+        let pat = Box::new(Pat::parse_single(input)?);
+        let colon_token: Token![:] = input.parse()?;
+
+        if allow_variadic {
+            if let Some(dots) = input.parse::<Option<Token![...]>>()? {
+                return Ok(FnArgOrVariadic::Variadic(Variadic {
+                    attrs,
+                    pat: Some((pat, colon_token)),
+                    dots,
+                    comma: None,
+                }));
+            }
+        }
+
+        Ok(FnArgOrVariadic::FnArg(FnArg::Typed(PatType {
+            attrs,
+            pat,
+            colon_token,
+            ty: input.parse()?,
+        })))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Receiver {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let reference = if input.peek(Token![&]) {
+                let ampersand: Token![&] = input.parse()?;
+                let lifetime: Option<Lifetime> = input.parse()?;
+                Some((ampersand, lifetime))
+            } else {
+                None
+            };
+            let mutability: Option<Token![mut]> = input.parse()?;
+            let self_token: Token![self] = input.parse()?;
+            let colon_token: Option<Token![:]> = if reference.is_some() {
+                None
+            } else {
+                input.parse()?
+            };
+            let ty: Type = if colon_token.is_some() {
+                input.parse()?
+            } else {
+                let mut ty = Type::Path(TypePath {
+                    qself: None,
+                    path: Path::from(Ident::new("Self", self_token.span)),
+                });
+                if let Some((ampersand, lifetime)) = reference.as_ref() {
+                    ty = Type::Reference(TypeReference {
+                        and_token: Token![&](ampersand.span),
+                        lifetime: lifetime.clone(),
+                        mutability: mutability.as_ref().map(|m| Token![mut](m.span)),
+                        elem: Box::new(ty),
+                    });
+                }
+                ty
+            };
+            Ok(Receiver {
+                attrs: Vec::new(),
+                reference,
+                mutability,
+                self_token,
+                colon_token,
+                ty: Box::new(ty),
+            })
+        }
+    }
+
+    fn parse_fn_args(
+        input: ParseStream,
+    ) -> Result<(Punctuated<FnArg, Token![,]>, Option<Variadic>)> {
+        let mut args = Punctuated::new();
+        let mut variadic = None;
+        let mut has_receiver = false;
+
+        while !input.is_empty() {
+            let attrs = input.call(Attribute::parse_outer)?;
+
+            if let Some(dots) = input.parse::<Option<Token![...]>>()? {
+                variadic = Some(Variadic {
+                    attrs,
+                    pat: None,
+                    dots,
+                    comma: if input.is_empty() {
+                        None
+                    } else {
+                        Some(input.parse()?)
+                    },
+                });
+                break;
+            }
+
+            let allow_variadic = true;
+            let arg = match parse_fn_arg_or_variadic(input, attrs, allow_variadic)? {
+                FnArgOrVariadic::FnArg(arg) => arg,
+                FnArgOrVariadic::Variadic(arg) => {
+                    variadic = Some(Variadic {
+                        comma: if input.is_empty() {
+                            None
+                        } else {
+                            Some(input.parse()?)
+                        },
+                        ..arg
+                    });
+                    break;
+                }
+            };
+
+            match &arg {
+                FnArg::Receiver(receiver) if has_receiver => {
+                    return Err(Error::new(
+                        receiver.self_token.span,
+                        "unexpected second method receiver",
+                    ));
+                }
+                FnArg::Receiver(receiver) if !args.is_empty() => {
+                    return Err(Error::new(
+                        receiver.self_token.span,
+                        "unexpected method receiver",
+                    ));
+                }
+                FnArg::Receiver(_) => has_receiver = true,
+                FnArg::Typed(_) => {}
+            }
+            args.push_value(arg);
+
+            if input.is_empty() {
+                break;
+            }
+
+            let comma: Token![,] = input.parse()?;
+            args.push_punct(comma);
+        }
+
+        Ok((args, variadic))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemMod {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let unsafety: Option<Token![unsafe]> = input.parse()?;
+            let mod_token: Token![mod] = input.parse()?;
+            let ident: Ident = if input.peek(Token![try]) {
+                input.call(Ident::parse_any)
+            } else {
+                input.parse()
+            }?;
+
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Token![;]) {
+                Ok(ItemMod {
+                    attrs,
+                    vis,
+                    unsafety,
+                    mod_token,
+                    ident,
+                    content: None,
+                    semi: Some(input.parse()?),
+                })
+            } else if lookahead.peek(token::Brace) {
+                let content;
+                let brace_token = braced!(content in input);
+                attr::parsing::parse_inner(&content, &mut attrs)?;
+
+                let mut items = Vec::new();
+                while !content.is_empty() {
+                    items.push(content.parse()?);
+                }
+
+                Ok(ItemMod {
+                    attrs,
+                    vis,
+                    unsafety,
+                    mod_token,
+                    ident,
+                    content: Some((brace_token, items)),
+                    semi: None,
+                })
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemForeignMod {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let unsafety: Option<Token![unsafe]> = input.parse()?;
+            let abi: Abi = input.parse()?;
+
+            let content;
+            let brace_token = braced!(content in input);
+            attr::parsing::parse_inner(&content, &mut attrs)?;
+            let mut items = Vec::new();
+            while !content.is_empty() {
+                items.push(content.parse()?);
+            }
+
+            Ok(ItemForeignMod {
+                attrs,
+                unsafety,
+                abi,
+                brace_token,
+                items,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItem {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let ahead = input.fork();
+            let vis: Visibility = ahead.parse()?;
+
+            let lookahead = ahead.lookahead1();
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                let vis: Visibility = input.parse()?;
+                let sig: Signature = input.parse()?;
+                if input.peek(token::Brace) {
+                    let content;
+                    braced!(content in input);
+                    content.call(Attribute::parse_inner)?;
+                    content.call(Block::parse_within)?;
+
+                    Ok(ForeignItem::Verbatim(verbatim::between(&begin, input)))
+                } else {
+                    Ok(ForeignItem::Fn(ForeignItemFn {
+                        attrs: Vec::new(),
+                        vis,
+                        sig,
+                        semi_token: input.parse()?,
+                    }))
+                }
+            } else if lookahead.peek(Token![static]) {
+                let vis = input.parse()?;
+                let static_token = input.parse()?;
+                let mutability = input.parse()?;
+                let ident = input.parse()?;
+                let colon_token = input.parse()?;
+                let ty = input.parse()?;
+                if input.peek(Token![=]) {
+                    input.parse::<Token![=]>()?;
+                    input.parse::<Expr>()?;
+                    input.parse::<Token![;]>()?;
+                    Ok(ForeignItem::Verbatim(verbatim::between(&begin, input)))
+                } else {
+                    Ok(ForeignItem::Static(ForeignItemStatic {
+                        attrs: Vec::new(),
+                        vis,
+                        static_token,
+                        mutability,
+                        ident,
+                        colon_token,
+                        ty,
+                        semi_token: input.parse()?,
+                    }))
+                }
+            } else if lookahead.peek(Token![type]) {
+                parse_foreign_item_type(begin, input)
+            } else if vis.is_inherited()
+                && (lookahead.peek(Ident)
+                    || lookahead.peek(Token![self])
+                    || lookahead.peek(Token![super])
+                    || lookahead.peek(Token![crate])
+                    || lookahead.peek(Token![::]))
+            {
+                input.parse().map(ForeignItem::Macro)
+            } else {
+                Err(lookahead.error())
+            }?;
+
+            let item_attrs = match &mut item {
+                ForeignItem::Fn(item) => &mut item.attrs,
+                ForeignItem::Static(item) => &mut item.attrs,
+                ForeignItem::Type(item) => &mut item.attrs,
+                ForeignItem::Macro(item) => &mut item.attrs,
+                ForeignItem::Verbatim(_) => return Ok(item),
+            };
+            attrs.append(item_attrs);
+            *item_attrs = attrs;
+
+            Ok(item)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItemFn {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let sig: Signature = input.parse()?;
+            let semi_token: Token![;] = input.parse()?;
+            Ok(ForeignItemFn {
+                attrs,
+                vis,
+                sig,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItemStatic {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ForeignItemStatic {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                static_token: input.parse()?,
+                mutability: input.parse()?,
+                ident: input.parse()?,
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItemType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ForeignItemType {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                type_token: input.parse()?,
+                ident: input.parse()?,
+                generics: {
+                    let mut generics: Generics = input.parse()?;
+                    generics.where_clause = input.parse()?;
+                    generics
+                },
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    fn parse_foreign_item_type(begin: ParseBuffer, input: ParseStream) -> Result<ForeignItem> {
+        let FlexibleItemType {
+            vis,
+            defaultness: _,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds: _,
+            ty,
+            semi_token,
+        } = FlexibleItemType::parse(
+            input,
+            TypeDefaultness::Disallowed,
+            WhereClauseLocation::Both,
+        )?;
+
+        if colon_token.is_some() || ty.is_some() {
+            Ok(ForeignItem::Verbatim(verbatim::between(&begin, input)))
+        } else {
+            Ok(ForeignItem::Type(ForeignItemType {
+                attrs: Vec::new(),
+                vis,
+                type_token,
+                ident,
+                generics,
+                semi_token,
+            }))
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ForeignItemMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let mac: Macro = input.parse()?;
+            let semi_token: Option<Token![;]> = if mac.delimiter.is_brace() {
+                None
+            } else {
+                Some(input.parse()?)
+            };
+            Ok(ForeignItemMacro {
+                attrs,
+                mac,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(ItemType {
+                attrs: input.call(Attribute::parse_outer)?,
+                vis: input.parse()?,
+                type_token: input.parse()?,
+                ident: input.parse()?,
+                generics: {
+                    let mut generics: Generics = input.parse()?;
+                    generics.where_clause = input.parse()?;
+                    generics
+                },
+                eq_token: input.parse()?,
+                ty: input.parse()?,
+                semi_token: input.parse()?,
+            })
+        }
+    }
+
+    fn parse_item_type(begin: ParseBuffer, input: ParseStream) -> Result<Item> {
+        let FlexibleItemType {
+            vis,
+            defaultness: _,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds: _,
+            ty,
+            semi_token,
+        } = FlexibleItemType::parse(
+            input,
+            TypeDefaultness::Disallowed,
+            WhereClauseLocation::BeforeEq,
+        )?;
+
+        let (eq_token, ty) = match ty {
+            Some(ty) if colon_token.is_none() => ty,
+            _ => return Ok(Item::Verbatim(verbatim::between(&begin, input))),
+        };
+
+        Ok(Item::Type(ItemType {
+            attrs: Vec::new(),
+            vis,
+            type_token,
+            ident,
+            generics,
+            eq_token,
+            ty: Box::new(ty),
+            semi_token,
+        }))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemStruct {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis = input.parse::<Visibility>()?;
+            let struct_token = input.parse::<Token![struct]>()?;
+            let ident = input.parse::<Ident>()?;
+            let generics = input.parse::<Generics>()?;
+            let (where_clause, fields, semi_token) = derive::parsing::data_struct(input)?;
+            Ok(ItemStruct {
+                attrs,
+                vis,
+                struct_token,
+                ident,
+                generics: Generics {
+                    where_clause,
+                    ..generics
+                },
+                fields,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemEnum {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis = input.parse::<Visibility>()?;
+            let enum_token = input.parse::<Token![enum]>()?;
+            let ident = input.parse::<Ident>()?;
+            let generics = input.parse::<Generics>()?;
+            let (where_clause, brace_token, variants) = derive::parsing::data_enum(input)?;
+            Ok(ItemEnum {
+                attrs,
+                vis,
+                enum_token,
+                ident,
+                generics: Generics {
+                    where_clause,
+                    ..generics
+                },
+                brace_token,
+                variants,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemUnion {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis = input.parse::<Visibility>()?;
+            let union_token = input.parse::<Token![union]>()?;
+            let ident = input.parse::<Ident>()?;
+            let generics = input.parse::<Generics>()?;
+            let (where_clause, fields) = derive::parsing::data_union(input)?;
+            Ok(ItemUnion {
+                attrs,
+                vis,
+                union_token,
+                ident,
+                generics: Generics {
+                    where_clause,
+                    ..generics
+                },
+                fields,
+            })
+        }
+    }
+
+    fn parse_trait_or_trait_alias(input: ParseStream) -> Result<Item> {
+        let (attrs, vis, trait_token, ident, generics) = parse_start_of_trait_alias(input)?;
+        let lookahead = input.lookahead1();
+        if lookahead.peek(token::Brace)
+            || lookahead.peek(Token![:])
+            || lookahead.peek(Token![where])
+        {
+            let unsafety = None;
+            let auto_token = None;
+            parse_rest_of_trait(
+                input,
+                attrs,
+                vis,
+                unsafety,
+                auto_token,
+                trait_token,
+                ident,
+                generics,
+            )
+            .map(Item::Trait)
+        } else if lookahead.peek(Token![=]) {
+            parse_rest_of_trait_alias(input, attrs, vis, trait_token, ident, generics)
+                .map(Item::TraitAlias)
+        } else {
+            Err(lookahead.error())
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemTrait {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let outer_attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let unsafety: Option<Token![unsafe]> = input.parse()?;
+            let auto_token: Option<Token![auto]> = input.parse()?;
+            let trait_token: Token![trait] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let generics: Generics = input.parse()?;
+            parse_rest_of_trait(
+                input,
+                outer_attrs,
+                vis,
+                unsafety,
+                auto_token,
+                trait_token,
+                ident,
+                generics,
+            )
+        }
+    }
+
+    fn parse_rest_of_trait(
+        input: ParseStream,
+        mut attrs: Vec<Attribute>,
+        vis: Visibility,
+        unsafety: Option<Token![unsafe]>,
+        auto_token: Option<Token![auto]>,
+        trait_token: Token![trait],
+        ident: Ident,
+        mut generics: Generics,
+    ) -> Result<ItemTrait> {
+        let colon_token: Option<Token![:]> = input.parse()?;
+
+        let mut supertraits = Punctuated::new();
+        if colon_token.is_some() {
+            loop {
+                if input.peek(Token![where]) || input.peek(token::Brace) {
+                    break;
+                }
+                supertraits.push_value(input.parse()?);
+                if input.peek(Token![where]) || input.peek(token::Brace) {
+                    break;
+                }
+                supertraits.push_punct(input.parse()?);
+            }
+        }
+
+        generics.where_clause = input.parse()?;
+
+        let content;
+        let brace_token = braced!(content in input);
+        attr::parsing::parse_inner(&content, &mut attrs)?;
+        let mut items = Vec::new();
+        while !content.is_empty() {
+            items.push(content.parse()?);
+        }
+
+        Ok(ItemTrait {
+            attrs,
+            vis,
+            unsafety,
+            auto_token,
+            restriction: None,
+            trait_token,
+            ident,
+            generics,
+            colon_token,
+            supertraits,
+            brace_token,
+            items,
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemTraitAlias {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let (attrs, vis, trait_token, ident, generics) = parse_start_of_trait_alias(input)?;
+            parse_rest_of_trait_alias(input, attrs, vis, trait_token, ident, generics)
+        }
+    }
+
+    fn parse_start_of_trait_alias(
+        input: ParseStream,
+    ) -> Result<(Vec<Attribute>, Visibility, Token![trait], Ident, Generics)> {
+        let attrs = input.call(Attribute::parse_outer)?;
+        let vis: Visibility = input.parse()?;
+        let trait_token: Token![trait] = input.parse()?;
+        let ident: Ident = input.parse()?;
+        let generics: Generics = input.parse()?;
+        Ok((attrs, vis, trait_token, ident, generics))
+    }
+
+    fn parse_rest_of_trait_alias(
+        input: ParseStream,
+        attrs: Vec<Attribute>,
+        vis: Visibility,
+        trait_token: Token![trait],
+        ident: Ident,
+        mut generics: Generics,
+    ) -> Result<ItemTraitAlias> {
+        let eq_token: Token![=] = input.parse()?;
+
+        let mut bounds = Punctuated::new();
+        loop {
+            if input.peek(Token![where]) || input.peek(Token![;]) {
+                break;
+            }
+            bounds.push_value(input.parse()?);
+            if input.peek(Token![where]) || input.peek(Token![;]) {
+                break;
+            }
+            bounds.push_punct(input.parse()?);
+        }
+
+        generics.where_clause = input.parse()?;
+        let semi_token: Token![;] = input.parse()?;
+
+        Ok(ItemTraitAlias {
+            attrs,
+            vis,
+            trait_token,
+            ident,
+            generics,
+            eq_token,
+            bounds,
+            semi_token,
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItem {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = input.parse()?;
+            let ahead = input.fork();
+
+            let lookahead = ahead.lookahead1();
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                input.parse().map(TraitItem::Fn)
+            } else if lookahead.peek(Token![const]) {
+                let const_token: Token![const] = ahead.parse()?;
+                let lookahead = ahead.lookahead1();
+                if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                    input.advance_to(&ahead);
+                    let ident = input.call(Ident::parse_any)?;
+                    let mut generics: Generics = input.parse()?;
+                    let colon_token: Token![:] = input.parse()?;
+                    let ty: Type = input.parse()?;
+                    let default = if let Some(eq_token) = input.parse::<Option<Token![=]>>()? {
+                        let expr: Expr = input.parse()?;
+                        Some((eq_token, expr))
+                    } else {
+                        None
+                    };
+                    generics.where_clause = input.parse()?;
+                    let semi_token: Token![;] = input.parse()?;
+                    if generics.lt_token.is_none() && generics.where_clause.is_none() {
+                        Ok(TraitItem::Const(TraitItemConst {
+                            attrs: Vec::new(),
+                            const_token,
+                            ident,
+                            generics,
+                            colon_token,
+                            ty,
+                            default,
+                            semi_token,
+                        }))
+                    } else {
+                        return Ok(TraitItem::Verbatim(verbatim::between(&begin, input)));
+                    }
+                } else if lookahead.peek(Token![async])
+                    || lookahead.peek(Token![unsafe])
+                    || lookahead.peek(Token![extern])
+                    || lookahead.peek(Token![fn])
+                {
+                    input.parse().map(TraitItem::Fn)
+                } else {
+                    Err(lookahead.error())
+                }
+            } else if lookahead.peek(Token![type]) {
+                parse_trait_item_type(begin.fork(), input)
+            } else if vis.is_inherited()
+                && defaultness.is_none()
+                && (lookahead.peek(Ident)
+                    || lookahead.peek(Token![self])
+                    || lookahead.peek(Token![super])
+                    || lookahead.peek(Token![crate])
+                    || lookahead.peek(Token![::]))
+            {
+                input.parse().map(TraitItem::Macro)
+            } else {
+                Err(lookahead.error())
+            }?;
+
+            match (vis, defaultness) {
+                (Visibility::Inherited, None) => {}
+                _ => return Ok(TraitItem::Verbatim(verbatim::between(&begin, input))),
+            }
+
+            let item_attrs = match &mut item {
+                TraitItem::Const(item) => &mut item.attrs,
+                TraitItem::Fn(item) => &mut item.attrs,
+                TraitItem::Type(item) => &mut item.attrs,
+                TraitItem::Macro(item) => &mut item.attrs,
+                TraitItem::Verbatim(_) => unreachable!(),
+            };
+            attrs.append(item_attrs);
+            *item_attrs = attrs;
+            Ok(item)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItemConst {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let const_token: Token![const] = input.parse()?;
+
+            let lookahead = input.lookahead1();
+            let ident = if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                input.call(Ident::parse_any)?
+            } else {
+                return Err(lookahead.error());
+            };
+
+            let colon_token: Token![:] = input.parse()?;
+            let ty: Type = input.parse()?;
+            let default = if input.peek(Token![=]) {
+                let eq_token: Token![=] = input.parse()?;
+                let default: Expr = input.parse()?;
+                Some((eq_token, default))
+            } else {
+                None
+            };
+            let semi_token: Token![;] = input.parse()?;
+
+            Ok(TraitItemConst {
+                attrs,
+                const_token,
+                ident,
+                generics: Generics::default(),
+                colon_token,
+                ty,
+                default,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItemFn {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let sig: Signature = input.parse()?;
+
+            let lookahead = input.lookahead1();
+            let (brace_token, stmts, semi_token) = if lookahead.peek(token::Brace) {
+                let content;
+                let brace_token = braced!(content in input);
+                attr::parsing::parse_inner(&content, &mut attrs)?;
+                let stmts = content.call(Block::parse_within)?;
+                (Some(brace_token), stmts, None)
+            } else if lookahead.peek(Token![;]) {
+                let semi_token: Token![;] = input.parse()?;
+                (None, Vec::new(), Some(semi_token))
+            } else {
+                return Err(lookahead.error());
+            };
+
+            Ok(TraitItemFn {
+                attrs,
+                sig,
+                default: brace_token.map(|brace_token| Block { brace_token, stmts }),
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItemType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let type_token: Token![type] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut generics: Generics = input.parse()?;
+            let (colon_token, bounds) = FlexibleItemType::parse_optional_bounds(input)?;
+            let default = FlexibleItemType::parse_optional_definition(input)?;
+            generics.where_clause = input.parse()?;
+            let semi_token: Token![;] = input.parse()?;
+            Ok(TraitItemType {
+                attrs,
+                type_token,
+                ident,
+                generics,
+                colon_token,
+                bounds,
+                default,
+                semi_token,
+            })
+        }
+    }
+
+    fn parse_trait_item_type(begin: ParseBuffer, input: ParseStream) -> Result<TraitItem> {
+        let FlexibleItemType {
+            vis,
+            defaultness: _,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds,
+            ty,
+            semi_token,
+        } = FlexibleItemType::parse(
+            input,
+            TypeDefaultness::Disallowed,
+            WhereClauseLocation::AfterEq,
+        )?;
+
+        if vis.is_some() {
+            Ok(TraitItem::Verbatim(verbatim::between(&begin, input)))
+        } else {
+            Ok(TraitItem::Type(TraitItemType {
+                attrs: Vec::new(),
+                type_token,
+                ident,
+                generics,
+                colon_token,
+                bounds,
+                default: ty,
+                semi_token,
+            }))
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TraitItemMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let mac: Macro = input.parse()?;
+            let semi_token: Option<Token![;]> = if mac.delimiter.is_brace() {
+                None
+            } else {
+                Some(input.parse()?)
+            };
+            Ok(TraitItemMacro {
+                attrs,
+                mac,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ItemImpl {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_verbatim_impl = false;
+            parse_impl(input, allow_verbatim_impl).map(Option::unwrap)
+        }
+    }
+
+    fn parse_impl(input: ParseStream, allow_verbatim_impl: bool) -> Result<Option<ItemImpl>> {
+        let mut attrs = input.call(Attribute::parse_outer)?;
+        let has_visibility = allow_verbatim_impl && input.parse::<Visibility>()?.is_some();
+        let defaultness: Option<Token![default]> = input.parse()?;
+        let unsafety: Option<Token![unsafe]> = input.parse()?;
+        let impl_token: Token![impl] = input.parse()?;
+
+        let has_generics = input.peek(Token![<])
+            && (input.peek2(Token![>])
+                || input.peek2(Token![#])
+                || (input.peek2(Ident) || input.peek2(Lifetime))
+                    && (input.peek3(Token![:])
+                        || input.peek3(Token![,])
+                        || input.peek3(Token![>])
+                        || input.peek3(Token![=]))
+                || input.peek2(Token![const]));
+        let mut generics: Generics = if has_generics {
+            input.parse()?
+        } else {
+            Generics::default()
+        };
+
+        let is_const_impl = allow_verbatim_impl
+            && (input.peek(Token![const]) || input.peek(Token![?]) && input.peek2(Token![const]));
+        if is_const_impl {
+            input.parse::<Option<Token![?]>>()?;
+            input.parse::<Token![const]>()?;
+        }
+
+        let begin = input.fork();
+        let polarity = if input.peek(Token![!]) && !input.peek2(token::Brace) {
+            Some(input.parse::<Token![!]>()?)
+        } else {
+            None
+        };
+
+        #[cfg(not(feature = "printing"))]
+        let first_ty_span = input.span();
+        let mut first_ty: Type = input.parse()?;
+        let self_ty: Type;
+        let trait_;
+
+        let is_impl_for = input.peek(Token![for]);
+        if is_impl_for {
+            let for_token: Token![for] = input.parse()?;
+            let mut first_ty_ref = &first_ty;
+            while let Type::Group(ty) = first_ty_ref {
+                first_ty_ref = &ty.elem;
+            }
+            if let Type::Path(TypePath { qself: None, .. }) = first_ty_ref {
+                while let Type::Group(ty) = first_ty {
+                    first_ty = *ty.elem;
+                }
+                if let Type::Path(TypePath { qself: None, path }) = first_ty {
+                    trait_ = Some((polarity, path, for_token));
+                } else {
+                    unreachable!();
+                }
+            } else if !allow_verbatim_impl {
+                #[cfg(feature = "printing")]
+                return Err(Error::new_spanned(first_ty_ref, "expected trait path"));
+                #[cfg(not(feature = "printing"))]
+                return Err(Error::new(first_ty_span, "expected trait path"));
+            } else {
+                trait_ = None;
+            }
+            self_ty = input.parse()?;
+        } else {
+            trait_ = None;
+            self_ty = if polarity.is_none() {
+                first_ty
+            } else {
+                Type::Verbatim(verbatim::between(&begin, input))
+            };
+        }
+
+        generics.where_clause = input.parse()?;
+
+        let content;
+        let brace_token = braced!(content in input);
+        attr::parsing::parse_inner(&content, &mut attrs)?;
+
+        let mut items = Vec::new();
+        while !content.is_empty() {
+            items.push(content.parse()?);
+        }
+
+        if has_visibility || is_const_impl || is_impl_for && trait_.is_none() {
+            Ok(None)
+        } else {
+            Ok(Some(ItemImpl {
+                attrs,
+                defaultness,
+                unsafety,
+                impl_token,
+                generics,
+                trait_,
+                self_ty: Box::new(self_ty),
+                brace_token,
+                items,
+            }))
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItem {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let mut attrs = input.call(Attribute::parse_outer)?;
+            let ahead = input.fork();
+            let vis: Visibility = ahead.parse()?;
+
+            let mut lookahead = ahead.lookahead1();
+            let defaultness = if lookahead.peek(Token![default]) && !ahead.peek2(Token![!]) {
+                let defaultness: Token![default] = ahead.parse()?;
+                lookahead = ahead.lookahead1();
+                Some(defaultness)
+            } else {
+                None
+            };
+
+            let mut item = if lookahead.peek(Token![fn]) || peek_signature(&ahead) {
+                let allow_omitted_body = true;
+                if let Some(item) = parse_impl_item_fn(input, allow_omitted_body)? {
+                    Ok(ImplItem::Fn(item))
+                } else {
+                    Ok(ImplItem::Verbatim(verbatim::between(&begin, input)))
+                }
+            } else if lookahead.peek(Token![const]) {
+                input.advance_to(&ahead);
+                let const_token: Token![const] = input.parse()?;
+                let lookahead = input.lookahead1();
+                let ident = if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                    input.call(Ident::parse_any)?
+                } else {
+                    return Err(lookahead.error());
+                };
+                let mut generics: Generics = input.parse()?;
+                let colon_token: Token![:] = input.parse()?;
+                let ty: Type = input.parse()?;
+                let value = if let Some(eq_token) = input.parse::<Option<Token![=]>>()? {
+                    let expr: Expr = input.parse()?;
+                    Some((eq_token, expr))
+                } else {
+                    None
+                };
+                generics.where_clause = input.parse()?;
+                let semi_token: Token![;] = input.parse()?;
+                return match value {
+                    Some((eq_token, expr))
+                        if generics.lt_token.is_none() && generics.where_clause.is_none() =>
+                    {
+                        Ok(ImplItem::Const(ImplItemConst {
+                            attrs,
+                            vis,
+                            defaultness,
+                            const_token,
+                            ident,
+                            generics,
+                            colon_token,
+                            ty,
+                            eq_token,
+                            expr,
+                            semi_token,
+                        }))
+                    }
+                    _ => Ok(ImplItem::Verbatim(verbatim::between(&begin, input))),
+                };
+            } else if lookahead.peek(Token![type]) {
+                parse_impl_item_type(begin, input)
+            } else if vis.is_inherited()
+                && defaultness.is_none()
+                && (lookahead.peek(Ident)
+                    || lookahead.peek(Token![self])
+                    || lookahead.peek(Token![super])
+                    || lookahead.peek(Token![crate])
+                    || lookahead.peek(Token![::]))
+            {
+                input.parse().map(ImplItem::Macro)
+            } else {
+                Err(lookahead.error())
+            }?;
+
+            {
+                let item_attrs = match &mut item {
+                    ImplItem::Const(item) => &mut item.attrs,
+                    ImplItem::Fn(item) => &mut item.attrs,
+                    ImplItem::Type(item) => &mut item.attrs,
+                    ImplItem::Macro(item) => &mut item.attrs,
+                    ImplItem::Verbatim(_) => return Ok(item),
+                };
+                attrs.append(item_attrs);
+                *item_attrs = attrs;
+            }
+
+            Ok(item)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItemConst {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = input.parse()?;
+            let const_token: Token![const] = input.parse()?;
+
+            let lookahead = input.lookahead1();
+            let ident = if lookahead.peek(Ident) || lookahead.peek(Token![_]) {
+                input.call(Ident::parse_any)?
+            } else {
+                return Err(lookahead.error());
+            };
+
+            let colon_token: Token![:] = input.parse()?;
+            let ty: Type = input.parse()?;
+            let eq_token: Token![=] = input.parse()?;
+            let expr: Expr = input.parse()?;
+            let semi_token: Token![;] = input.parse()?;
+
+            Ok(ImplItemConst {
+                attrs,
+                vis,
+                defaultness,
+                const_token,
+                ident,
+                generics: Generics::default(),
+                colon_token,
+                ty,
+                eq_token,
+                expr,
+                semi_token,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItemFn {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_omitted_body = false;
+            parse_impl_item_fn(input, allow_omitted_body).map(Option::unwrap)
+        }
+    }
+
+    fn parse_impl_item_fn(
+        input: ParseStream,
+        allow_omitted_body: bool,
+    ) -> Result<Option<ImplItemFn>> {
+        let mut attrs = input.call(Attribute::parse_outer)?;
+        let vis: Visibility = input.parse()?;
+        let defaultness: Option<Token![default]> = input.parse()?;
+        let sig: Signature = input.parse()?;
+
+        // Accept functions without a body in an impl block because rustc's
+        // *parser* does not reject them (the compilation error is emitted later
+        // than parsing) and it can be useful for macro DSLs.
+        if allow_omitted_body && input.parse::<Option<Token![;]>>()?.is_some() {
+            return Ok(None);
+        }
+
+        let content;
+        let brace_token = braced!(content in input);
+        attrs.extend(content.call(Attribute::parse_inner)?);
+        let block = Block {
+            brace_token,
+            stmts: content.call(Block::parse_within)?,
+        };
+
+        Ok(Some(ImplItemFn {
+            attrs,
+            vis,
+            defaultness,
+            sig,
+            block,
+        }))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItemType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let vis: Visibility = input.parse()?;
+            let defaultness: Option<Token![default]> = input.parse()?;
+            let type_token: Token![type] = input.parse()?;
+            let ident: Ident = input.parse()?;
+            let mut generics: Generics = input.parse()?;
+            let eq_token: Token![=] = input.parse()?;
+            let ty: Type = input.parse()?;
+            generics.where_clause = input.parse()?;
+            let semi_token: Token![;] = input.parse()?;
+            Ok(ImplItemType {
+                attrs,
+                vis,
+                defaultness,
+                type_token,
+                ident,
+                generics,
+                eq_token,
+                ty,
+                semi_token,
+            })
+        }
+    }
+
+    fn parse_impl_item_type(begin: ParseBuffer, input: ParseStream) -> Result<ImplItem> {
+        let FlexibleItemType {
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            colon_token,
+            bounds: _,
+            ty,
+            semi_token,
+        } = FlexibleItemType::parse(
+            input,
+            TypeDefaultness::Optional,
+            WhereClauseLocation::AfterEq,
+        )?;
+
+        let (eq_token, ty) = match ty {
+            Some(ty) if colon_token.is_none() => ty,
+            _ => return Ok(ImplItem::Verbatim(verbatim::between(&begin, input))),
+        };
+
+        Ok(ImplItem::Type(ImplItemType {
+            attrs: Vec::new(),
+            vis,
+            defaultness,
+            type_token,
+            ident,
+            generics,
+            eq_token,
+            ty,
+            semi_token,
+        }))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ImplItemMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let attrs = input.call(Attribute::parse_outer)?;
+            let mac: Macro = input.parse()?;
+            let semi_token: Option<Token![;]> = if mac.delimiter.is_brace() {
+                None
+            } else {
+                Some(input.parse()?)
+            };
+            Ok(ImplItemMacro {
+                attrs,
+                mac,
+                semi_token,
+            })
+        }
+    }
+
+    impl Visibility {
+        fn is_inherited(&self) -> bool {
+            match self {
+                Visibility::Inherited => true,
+                _ => false,
+            }
+        }
+    }
+
+    impl MacroDelimiter {
+        pub(crate) fn is_brace(&self) -> bool {
+            match self {
+                MacroDelimiter::Brace(_) => true,
+                MacroDelimiter::Paren(_) | MacroDelimiter::Bracket(_) => false,
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for StaticMutability {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let mut_token: Option<Token![mut]> = input.parse()?;
+            Ok(mut_token.map_or(StaticMutability::None, StaticMutability::Mut))
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::attr::FilterAttrs;
+    use crate::data::Fields;
+    use crate::item::{
+        ForeignItemFn, ForeignItemMacro, ForeignItemStatic, ForeignItemType, ImplItemConst,
+        ImplItemFn, ImplItemMacro, ImplItemType, ItemConst, ItemEnum, ItemExternCrate, ItemFn,
+        ItemForeignMod, ItemImpl, ItemMacro, ItemMod, ItemStatic, ItemStruct, ItemTrait,
+        ItemTraitAlias, ItemType, ItemUnion, ItemUse, Receiver, Signature, StaticMutability,
+        TraitItemConst, TraitItemFn, TraitItemMacro, TraitItemType, UseGlob, UseGroup, UseName,
+        UsePath, UseRename, Variadic,
+    };
+    use crate::mac::MacroDelimiter;
+    use crate::print::TokensOrDefault;
+    use crate::ty::Type;
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemExternCrate {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.extern_token.to_tokens(tokens);
+            self.crate_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            if let Some((as_token, rename)) = &self.rename {
+                as_token.to_tokens(tokens);
+                rename.to_tokens(tokens);
+            }
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemUse {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.use_token.to_tokens(tokens);
+            self.leading_colon.to_tokens(tokens);
+            self.tree.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemStatic {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.static_token.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemConst {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.const_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemFn {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.sig.to_tokens(tokens);
+            self.block.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.block.stmts);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemMod {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.unsafety.to_tokens(tokens);
+            self.mod_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            if let Some((brace, items)) = &self.content {
+                brace.surround(tokens, |tokens| {
+                    tokens.append_all(self.attrs.inner());
+                    tokens.append_all(items);
+                });
+            } else {
+                TokensOrDefault(&self.semi).to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemForeignMod {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.unsafety.to_tokens(tokens);
+            self.abi.to_tokens(tokens);
+            self.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.items);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.type_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemEnum {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.enum_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.brace_token.surround(tokens, |tokens| {
+                self.variants.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemStruct {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.struct_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            match &self.fields {
+                Fields::Named(fields) => {
+                    self.generics.where_clause.to_tokens(tokens);
+                    fields.to_tokens(tokens);
+                }
+                Fields::Unnamed(fields) => {
+                    fields.to_tokens(tokens);
+                    self.generics.where_clause.to_tokens(tokens);
+                    TokensOrDefault(&self.semi_token).to_tokens(tokens);
+                }
+                Fields::Unit => {
+                    self.generics.where_clause.to_tokens(tokens);
+                    TokensOrDefault(&self.semi_token).to_tokens(tokens);
+                }
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemUnion {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.union_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.fields.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemTrait {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.unsafety.to_tokens(tokens);
+            self.auto_token.to_tokens(tokens);
+            self.trait_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            if !self.supertraits.is_empty() {
+                TokensOrDefault(&self.colon_token).to_tokens(tokens);
+                self.supertraits.to_tokens(tokens);
+            }
+            self.generics.where_clause.to_tokens(tokens);
+            self.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.items);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemTraitAlias {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.trait_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.bounds.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemImpl {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.defaultness.to_tokens(tokens);
+            self.unsafety.to_tokens(tokens);
+            self.impl_token.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            if let Some((polarity, path, for_token)) = &self.trait_ {
+                polarity.to_tokens(tokens);
+                path.to_tokens(tokens);
+                for_token.to_tokens(tokens);
+            }
+            self.self_ty.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.items);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ItemMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.mac.path.to_tokens(tokens);
+            self.mac.bang_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            match &self.mac.delimiter {
+                MacroDelimiter::Paren(paren) => {
+                    paren.surround(tokens, |tokens| self.mac.tokens.to_tokens(tokens));
+                }
+                MacroDelimiter::Brace(brace) => {
+                    brace.surround(tokens, |tokens| self.mac.tokens.to_tokens(tokens));
+                }
+                MacroDelimiter::Bracket(bracket) => {
+                    bracket.surround(tokens, |tokens| self.mac.tokens.to_tokens(tokens));
+                }
+            }
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UsePath {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+            self.colon2_token.to_tokens(tokens);
+            self.tree.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UseName {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UseRename {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+            self.as_token.to_tokens(tokens);
+            self.rename.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UseGlob {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.star_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UseGroup {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.brace_token.surround(tokens, |tokens| {
+                self.items.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitItemConst {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.const_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            if let Some((eq_token, default)) = &self.default {
+                eq_token.to_tokens(tokens);
+                default.to_tokens(tokens);
+            }
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitItemFn {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.sig.to_tokens(tokens);
+            match &self.default {
+                Some(block) => {
+                    block.brace_token.surround(tokens, |tokens| {
+                        tokens.append_all(self.attrs.inner());
+                        tokens.append_all(&block.stmts);
+                    });
+                }
+                None => {
+                    TokensOrDefault(&self.semi_token).to_tokens(tokens);
+                }
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitItemType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.type_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            if !self.bounds.is_empty() {
+                TokensOrDefault(&self.colon_token).to_tokens(tokens);
+                self.bounds.to_tokens(tokens);
+            }
+            if let Some((eq_token, default)) = &self.default {
+                eq_token.to_tokens(tokens);
+                default.to_tokens(tokens);
+            }
+            self.generics.where_clause.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TraitItemMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.mac.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ImplItemConst {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.defaultness.to_tokens(tokens);
+            self.const_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.expr.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ImplItemFn {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.defaultness.to_tokens(tokens);
+            self.sig.to_tokens(tokens);
+            self.block.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(self.attrs.inner());
+                tokens.append_all(&self.block.stmts);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ImplItemType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.defaultness.to_tokens(tokens);
+            self.type_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ImplItemMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.mac.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ForeignItemFn {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.sig.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ForeignItemStatic {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.static_token.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ForeignItemType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.vis.to_tokens(tokens);
+            self.type_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ForeignItemMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.mac.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Signature {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.constness.to_tokens(tokens);
+            self.asyncness.to_tokens(tokens);
+            self.unsafety.to_tokens(tokens);
+            self.abi.to_tokens(tokens);
+            self.fn_token.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.paren_token.surround(tokens, |tokens| {
+                self.inputs.to_tokens(tokens);
+                if let Some(variadic) = &self.variadic {
+                    if !self.inputs.empty_or_trailing() {
+                        <Token![,]>::default().to_tokens(tokens);
+                    }
+                    variadic.to_tokens(tokens);
+                }
+            });
+            self.output.to_tokens(tokens);
+            self.generics.where_clause.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Receiver {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            if let Some((ampersand, lifetime)) = &self.reference {
+                ampersand.to_tokens(tokens);
+                lifetime.to_tokens(tokens);
+            }
+            self.mutability.to_tokens(tokens);
+            self.self_token.to_tokens(tokens);
+            if let Some(colon_token) = &self.colon_token {
+                colon_token.to_tokens(tokens);
+                self.ty.to_tokens(tokens);
+            } else {
+                let consistent = match (&self.reference, &self.mutability, &*self.ty) {
+                    (Some(_), mutability, Type::Reference(ty)) => {
+                        mutability.is_some() == ty.mutability.is_some()
+                            && match &*ty.elem {
+                                Type::Path(ty) => ty.qself.is_none() && ty.path.is_ident("Self"),
+                                _ => false,
+                            }
+                    }
+                    (None, _, Type::Path(ty)) => ty.qself.is_none() && ty.path.is_ident("Self"),
+                    _ => false,
+                };
+                if !consistent {
+                    <Token![:]>::default().to_tokens(tokens);
+                    self.ty.to_tokens(tokens);
+                }
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Variadic {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            if let Some((pat, colon)) = &self.pat {
+                pat.to_tokens(tokens);
+                colon.to_tokens(tokens);
+            }
+            self.dots.to_tokens(tokens);
+            self.comma.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for StaticMutability {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                StaticMutability::None => {}
+                StaticMutability::Mut(mut_token) => mut_token.to_tokens(tokens),
+            }
+        }
+    }
+}
diff --git a/rust/syn/lib.rs b/rust/syn/lib.rs
new file mode 100644
index 0000000000000000000000000000000000000000..df741b33d3f392bdb4bc877ab8dfb71a827a18b4
--- /dev/null
+++ b/rust/syn/lib.rs
@@ -0,0 +1,1007 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! [![github]](https://github.com/dtolnay/syn)&ensp;[![crates-io]](https://crates.io/crates/syn)&ensp;[![docs-rs]](crate)
+//!
+//! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github
+//! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust
+//! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logo=docs.rs
+//!
+//! <br>
+//!
+//! Syn is a parsing library for parsing a stream of Rust tokens into a syntax
+//! tree of Rust source code.
+//!
+//! Currently this library is geared toward use in Rust procedural macros, but
+//! contains some APIs that may be useful more generally.
+//!
+//! - **Data structures** — Syn provides a complete syntax tree that can
+//!   represent any valid Rust source code. The syntax tree is rooted at
+//!   [`syn::File`] which represents a full source file, but there are other
+//!   entry points that may be useful to procedural macros including
+//!   [`syn::Item`], [`syn::Expr`] and [`syn::Type`].
+//!
+//! - **Derives** — Of particular interest to derive macros is
+//!   [`syn::DeriveInput`] which is any of the three legal input items to a
+//!   derive macro. An example below shows using this type in a library that can
+//!   derive implementations of a user-defined trait.
+//!
+//! - **Parsing** — Parsing in Syn is built around [parser functions] with the
+//!   signature `fn(ParseStream) -> Result<T>`. Every syntax tree node defined
+//!   by Syn is individually parsable and may be used as a building block for
+//!   custom syntaxes, or you may dream up your own brand new syntax without
+//!   involving any of our syntax tree types.
+//!
+//! - **Location information** — Every token parsed by Syn is associated with a
+//!   `Span` that tracks line and column information back to the source of that
+//!   token. These spans allow a procedural macro to display detailed error
+//!   messages pointing to all the right places in the user's code. There is an
+//!   example of this below.
+//!
+//! - **Feature flags** — Functionality is aggressively feature gated so your
+//!   procedural macros enable only what they need, and do not pay in compile
+//!   time for all the rest.
+//!
+//! [`syn::File`]: File
+//! [`syn::Item`]: Item
+//! [`syn::Expr`]: Expr
+//! [`syn::Type`]: Type
+//! [`syn::DeriveInput`]: DeriveInput
+//! [parser functions]: mod@parse
+//!
+//! <br>
+//!
+//! # Example of a derive macro
+//!
+//! The canonical derive macro using Syn looks like this. We write an ordinary
+//! Rust function tagged with a `proc_macro_derive` attribute and the name of
+//! the trait we are deriving. Any time that derive appears in the user's code,
+//! the Rust compiler passes their data structure as tokens into our macro. We
+//! get to execute arbitrary Rust code to figure out what to do with those
+//! tokens, then hand some tokens back to the compiler to compile into the
+//! user's crate.
+//!
+//! [`TokenStream`]: proc_macro::TokenStream
+//!
+//! ```toml
+//! [dependencies]
+//! syn = "2.0"
+//! quote = "1.0"
+//!
+//! [lib]
+//! proc-macro = true
+//! ```
+//!
+//! ```
+//! # extern crate proc_macro;
+//! #
+//! use proc_macro::TokenStream;
+//! use quote::quote;
+//! use syn::{parse_macro_input, DeriveInput};
+//!
+//! # const IGNORE_TOKENS: &str = stringify! {
+//! #[proc_macro_derive(MyMacro)]
+//! # };
+//! pub fn my_macro(input: TokenStream) -> TokenStream {
+//!     // Parse the input tokens into a syntax tree
+//!     let input = parse_macro_input!(input as DeriveInput);
+//!
+//!     // Build the output, possibly using quasi-quotation
+//!     let expanded = quote! {
+//!         // ...
+//!     };
+//!
+//!     // Hand the output tokens back to the compiler
+//!     TokenStream::from(expanded)
+//! }
+//! ```
+//!
+//! The [`heapsize`] example directory shows a complete working implementation
+//! of a derive macro. The example derives a `HeapSize` trait which computes an
+//! estimate of the amount of heap memory owned by a value.
+//!
+//! [`heapsize`]: https://github.com/dtolnay/syn/tree/master/examples/heapsize
+//!
+//! ```
+//! pub trait HeapSize {
+//!     /// Total number of bytes of heap memory owned by `self`.
+//!     fn heap_size_of_children(&self) -> usize;
+//! }
+//! ```
+//!
+//! The derive macro allows users to write `#[derive(HeapSize)]` on data
+//! structures in their program.
+//!
+//! ```
+//! # const IGNORE_TOKENS: &str = stringify! {
+//! #[derive(HeapSize)]
+//! # };
+//! struct Demo<'a, T: ?Sized> {
+//!     a: Box<T>,
+//!     b: u8,
+//!     c: &'a str,
+//!     d: String,
+//! }
+//! ```
+//!
+//! <p><br></p>
+//!
+//! # Spans and error reporting
+//!
+//! The token-based procedural macro API provides great control over where the
+//! compiler's error messages are displayed in user code. Consider the error the
+//! user sees if one of their field types does not implement `HeapSize`.
+//!
+//! ```
+//! # const IGNORE_TOKENS: &str = stringify! {
+//! #[derive(HeapSize)]
+//! # };
+//! struct Broken {
+//!     ok: String,
+//!     bad: std::thread::Thread,
+//! }
+//! ```
+//!
+//! By tracking span information all the way through the expansion of a
+//! procedural macro as shown in the `heapsize` example, token-based macros in
+//! Syn are able to trigger errors that directly pinpoint the source of the
+//! problem.
+//!
+//! ```text
+//! error[E0277]: the trait bound `std::thread::Thread: HeapSize` is not satisfied
+//!  --> src/main.rs:7:5
+//!   |
+//! 7 |     bad: std::thread::Thread,
+//!   |     ^^^^^^^^^^^^^^^^^^^^^^^^ the trait `HeapSize` is not implemented for `Thread`
+//! ```
+//!
+//! <br>
+//!
+//! # Parsing a custom syntax
+//!
+//! The [`lazy-static`] example directory shows the implementation of a
+//! `functionlike!(...)` procedural macro in which the input tokens are parsed
+//! using Syn's parsing API.
+//!
+//! [`lazy-static`]: https://github.com/dtolnay/syn/tree/master/examples/lazy-static
+//!
+//! The example reimplements the popular `lazy_static` crate from crates.io as a
+//! procedural macro.
+//!
+//! ```
+//! # macro_rules! lazy_static {
+//! #     ($($tt:tt)*) => {}
+//! # }
+//! #
+//! lazy_static! {
+//!     static ref USERNAME: Regex = Regex::new("^[a-z0-9_-]{3,16}$").unwrap();
+//! }
+//! ```
+//!
+//! The implementation shows how to trigger custom warnings and error messages
+//! on the macro input.
+//!
+//! ```text
+//! warning: come on, pick a more creative name
+//!   --> src/main.rs:10:16
+//!    |
+//! 10 |     static ref FOO: String = "lazy_static".to_owned();
+//!    |                ^^^
+//! ```
+//!
+//! <br>
+//!
+//! # Testing
+//!
+//! When testing macros, we often care not just that the macro can be used
+//! successfully but also that when the macro is provided with invalid input it
+//! produces maximally helpful error messages. Consider using the [`trybuild`]
+//! crate to write tests for errors that are emitted by your macro or errors
+//! detected by the Rust compiler in the expanded code following misuse of the
+//! macro. Such tests help avoid regressions from later refactors that
+//! mistakenly make an error no longer trigger or be less helpful than it used
+//! to be.
+//!
+//! [`trybuild`]: https://github.com/dtolnay/trybuild
+//!
+//! <br>
+//!
+//! # Debugging
+//!
+//! When developing a procedural macro it can be helpful to look at what the
+//! generated code looks like. Use `cargo rustc -- -Zunstable-options
+//! --pretty=expanded` or the [`cargo expand`] subcommand.
+//!
+//! [`cargo expand`]: https://github.com/dtolnay/cargo-expand
+//!
+//! To show the expanded code for some crate that uses your procedural macro,
+//! run `cargo expand` from that crate. To show the expanded code for one of
+//! your own test cases, run `cargo expand --test the_test_case` where the last
+//! argument is the name of the test file without the `.rs` extension.
+//!
+//! This write-up by Brandon W Maister discusses debugging in more detail:
+//! [Debugging Rust's new Custom Derive system][debugging].
+//!
+//! [debugging]: https://quodlibetor.github.io/posts/debugging-rusts-new-custom-derive-system/
+//!
+//! <br>
+//!
+//! # Optional features
+//!
+//! Syn puts a lot of functionality behind optional features in order to
+//! optimize compile time for the most common use cases. The following features
+//! are available.
+//!
+//! - **`derive`** *(enabled by default)* — Data structures for representing the
+//!   possible input to a derive macro, including structs and enums and types.
+//! - **`full`** — Data structures for representing the syntax tree of all valid
+//!   Rust source code, including items and expressions.
+//! - **`parsing`** *(enabled by default)* — Ability to parse input tokens into
+//!   a syntax tree node of a chosen type.
+//! - **`printing`** *(enabled by default)* — Ability to print a syntax tree
+//!   node as tokens of Rust source code.
+//! - **`visit`** — Trait for traversing a syntax tree.
+//! - **`visit-mut`** — Trait for traversing and mutating in place a syntax
+//!   tree.
+//! - **`fold`** — Trait for transforming an owned syntax tree.
+//! - **`clone-impls`** *(enabled by default)* — Clone impls for all syntax tree
+//!   types.
+//! - **`extra-traits`** — Debug, Eq, PartialEq, Hash impls for all syntax tree
+//!   types.
+//! - **`proc-macro`** *(enabled by default)* — Runtime dependency on the
+//!   dynamic library libproc_macro from rustc toolchain.
+
+// Syn types in rustdoc of other crates get linked to here.
+#![doc(html_root_url = "https://docs.rs/syn/2.0.58")]
+#![cfg_attr(doc_cfg, feature(doc_cfg))]
+#![deny(unsafe_op_in_unsafe_fn)]
+#![allow(non_camel_case_types)]
+#![allow(
+    clippy::bool_to_int_with_if,
+    clippy::cast_lossless,
+    clippy::cast_possible_truncation,
+    clippy::cast_possible_wrap,
+    clippy::cast_ptr_alignment,
+    clippy::default_trait_access,
+    clippy::derivable_impls,
+    clippy::diverging_sub_expression,
+    clippy::doc_markdown,
+    clippy::expl_impl_clone_on_copy,
+    clippy::explicit_auto_deref,
+    clippy::if_not_else,
+    clippy::inherent_to_string,
+    clippy::into_iter_without_iter,
+    clippy::items_after_statements,
+    clippy::large_enum_variant,
+    clippy::let_underscore_untyped, // https://github.com/rust-lang/rust-clippy/issues/10410
+    clippy::manual_assert,
+    clippy::manual_let_else,
+    clippy::match_like_matches_macro,
+    clippy::match_on_vec_items,
+    clippy::match_same_arms,
+    clippy::match_wildcard_for_single_variants, // clippy bug: https://github.com/rust-lang/rust-clippy/issues/6984
+    clippy::missing_errors_doc,
+    clippy::missing_panics_doc,
+    clippy::module_name_repetitions,
+    clippy::must_use_candidate,
+    clippy::needless_doctest_main,
+    clippy::needless_pass_by_value,
+    clippy::never_loop,
+    clippy::range_plus_one,
+    clippy::redundant_else,
+    clippy::return_self_not_must_use,
+    clippy::similar_names,
+    clippy::single_match_else,
+    clippy::too_many_arguments,
+    clippy::too_many_lines,
+    clippy::trivially_copy_pass_by_ref,
+    clippy::unconditional_recursion, // https://github.com/rust-lang/rust-clippy/issues/12133
+    clippy::uninhabited_references,
+    clippy::uninlined_format_args,
+    clippy::unnecessary_box_returns,
+    clippy::unnecessary_unwrap,
+    clippy::used_underscore_binding,
+    clippy::wildcard_imports,
+)]
+
+#[cfg(feature = "proc-macro")]
+extern crate proc_macro;
+
+#[macro_use]
+mod macros;
+
+#[cfg(feature = "parsing")]
+#[macro_use]
+mod group;
+
+#[macro_use]
+pub mod token;
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod attr;
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+pub use crate::attr::{AttrStyle, Attribute, Meta, MetaList, MetaNameValue};
+
+mod bigint;
+
+#[cfg(feature = "parsing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+pub mod buffer;
+
+mod custom_keyword;
+
+mod custom_punctuation;
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod data;
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+pub use crate::data::{Field, Fields, FieldsNamed, FieldsUnnamed, Variant};
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod derive;
+#[cfg(feature = "derive")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "derive")))]
+pub use crate::derive::{Data, DataEnum, DataStruct, DataUnion, DeriveInput};
+
+mod drops;
+
+mod error;
+pub use crate::error::{Error, Result};
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod expr;
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub use crate::expr::{Arm, Label, RangeLimits};
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+pub use crate::expr::{
+    Expr, ExprBinary, ExprCall, ExprCast, ExprField, ExprIndex, ExprLit, ExprMacro, ExprMethodCall,
+    ExprParen, ExprPath, ExprReference, ExprStruct, ExprUnary, FieldValue, Index, Member,
+};
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub use crate::expr::{
+    ExprArray, ExprAssign, ExprAsync, ExprAwait, ExprBlock, ExprBreak, ExprClosure, ExprConst,
+    ExprContinue, ExprForLoop, ExprGroup, ExprIf, ExprInfer, ExprLet, ExprLoop, ExprMatch,
+    ExprRange, ExprRepeat, ExprReturn, ExprTry, ExprTryBlock, ExprTuple, ExprUnsafe, ExprWhile,
+    ExprYield,
+};
+
+#[cfg(feature = "parsing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+pub mod ext;
+
+#[cfg(feature = "full")]
+mod file;
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub use crate::file::File;
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod generics;
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+pub use crate::generics::{
+    BoundLifetimes, ConstParam, GenericParam, Generics, LifetimeParam, PredicateLifetime,
+    PredicateType, TraitBound, TraitBoundModifier, TypeParam, TypeParamBound, WhereClause,
+    WherePredicate,
+};
+#[cfg(all(any(feature = "full", feature = "derive"), feature = "printing"))]
+#[cfg_attr(
+    doc_cfg,
+    doc(cfg(all(any(feature = "full", feature = "derive"), feature = "printing")))
+)]
+pub use crate::generics::{ImplGenerics, Turbofish, TypeGenerics};
+
+mod ident;
+#[doc(inline)]
+pub use crate::ident::Ident;
+
+#[cfg(feature = "full")]
+mod item;
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub use crate::item::{
+    FnArg, ForeignItem, ForeignItemFn, ForeignItemMacro, ForeignItemStatic, ForeignItemType,
+    ImplItem, ImplItemConst, ImplItemFn, ImplItemMacro, ImplItemType, ImplRestriction, Item,
+    ItemConst, ItemEnum, ItemExternCrate, ItemFn, ItemForeignMod, ItemImpl, ItemMacro, ItemMod,
+    ItemStatic, ItemStruct, ItemTrait, ItemTraitAlias, ItemType, ItemUnion, ItemUse, Receiver,
+    Signature, StaticMutability, TraitItem, TraitItemConst, TraitItemFn, TraitItemMacro,
+    TraitItemType, UseGlob, UseGroup, UseName, UsePath, UseRename, UseTree, Variadic,
+};
+
+mod lifetime;
+#[doc(inline)]
+pub use crate::lifetime::Lifetime;
+
+mod lit;
+#[doc(hidden)] // https://github.com/dtolnay/syn/issues/1566
+pub use crate::lit::StrStyle;
+#[doc(inline)]
+pub use crate::lit::{Lit, LitBool, LitByte, LitByteStr, LitChar, LitFloat, LitInt, LitStr};
+
+#[cfg(feature = "parsing")]
+mod lookahead;
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod mac;
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+pub use crate::mac::{Macro, MacroDelimiter};
+
+#[cfg(all(feature = "parsing", any(feature = "full", feature = "derive")))]
+#[cfg_attr(
+    doc_cfg,
+    doc(cfg(all(feature = "parsing", any(feature = "full", feature = "derive"))))
+)]
+pub mod meta;
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod op;
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+pub use crate::op::{BinOp, UnOp};
+
+#[cfg(feature = "parsing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+pub mod parse;
+
+#[cfg(all(feature = "parsing", feature = "proc-macro"))]
+mod parse_macro_input;
+
+#[cfg(all(feature = "parsing", feature = "printing"))]
+mod parse_quote;
+
+#[cfg(feature = "full")]
+mod pat;
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub use crate::pat::{
+    FieldPat, Pat, PatConst, PatIdent, PatLit, PatMacro, PatOr, PatParen, PatPath, PatRange,
+    PatReference, PatRest, PatSlice, PatStruct, PatTuple, PatTupleStruct, PatType, PatWild,
+};
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod path;
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+pub use crate::path::{
+    AngleBracketedGenericArguments, AssocConst, AssocType, Constraint, GenericArgument,
+    ParenthesizedGenericArguments, Path, PathArguments, PathSegment, QSelf,
+};
+
+#[cfg(all(any(feature = "full", feature = "derive"), feature = "printing"))]
+mod print;
+
+pub mod punctuated;
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod restriction;
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+pub use crate::restriction::{FieldMutability, VisRestricted, Visibility};
+
+mod sealed;
+
+mod span;
+
+#[cfg(all(feature = "parsing", feature = "printing"))]
+#[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "printing"))))]
+pub mod spanned;
+
+#[cfg(feature = "full")]
+mod stmt;
+#[cfg(feature = "full")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+pub use crate::stmt::{Block, Local, LocalInit, Stmt, StmtMacro};
+
+mod thread;
+
+#[cfg(all(any(feature = "full", feature = "derive"), feature = "extra-traits"))]
+mod tt;
+
+#[cfg(any(feature = "full", feature = "derive"))]
+mod ty;
+#[cfg(any(feature = "full", feature = "derive"))]
+#[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+pub use crate::ty::{
+    Abi, BareFnArg, BareVariadic, ReturnType, Type, TypeArray, TypeBareFn, TypeGroup,
+    TypeImplTrait, TypeInfer, TypeMacro, TypeNever, TypeParen, TypePath, TypePtr, TypeReference,
+    TypeSlice, TypeTraitObject, TypeTuple,
+};
+
+#[cfg(all(any(feature = "full", feature = "derive"), feature = "parsing"))]
+mod verbatim;
+
+#[cfg(all(feature = "parsing", feature = "full"))]
+mod whitespace;
+
+mod gen {
+    /// Syntax tree traversal to transform the nodes of an owned syntax tree.
+    ///
+    /// Each method of the [`Fold`] trait is a hook that can be overridden to
+    /// customize the behavior when transforming the corresponding type of node.
+    /// By default, every method recursively visits the substructure of the
+    /// input by invoking the right visitor method of each of its fields.
+    ///
+    /// [`Fold`]: fold::Fold
+    ///
+    /// ```
+    /// # use syn::{Attribute, BinOp, Expr, ExprBinary};
+    /// #
+    /// pub trait Fold {
+    ///     /* ... */
+    ///
+    ///     fn fold_expr_binary(&mut self, node: ExprBinary) -> ExprBinary {
+    ///         fold_expr_binary(self, node)
+    ///     }
+    ///
+    ///     /* ... */
+    ///     # fn fold_attribute(&mut self, node: Attribute) -> Attribute;
+    ///     # fn fold_expr(&mut self, node: Expr) -> Expr;
+    ///     # fn fold_bin_op(&mut self, node: BinOp) -> BinOp;
+    /// }
+    ///
+    /// pub fn fold_expr_binary<V>(v: &mut V, node: ExprBinary) -> ExprBinary
+    /// where
+    ///     V: Fold + ?Sized,
+    /// {
+    ///     ExprBinary {
+    ///         attrs: node
+    ///             .attrs
+    ///             .into_iter()
+    ///             .map(|attr| v.fold_attribute(attr))
+    ///             .collect(),
+    ///         left: Box::new(v.fold_expr(*node.left)),
+    ///         op: v.fold_bin_op(node.op),
+    ///         right: Box::new(v.fold_expr(*node.right)),
+    ///     }
+    /// }
+    ///
+    /// /* ... */
+    /// ```
+    ///
+    /// <br>
+    ///
+    /// # Example
+    ///
+    /// This fold inserts parentheses to fully parenthesizes any expression.
+    ///
+    /// ```
+    /// // [dependencies]
+    /// // quote = "1.0"
+    /// // syn = { version = "2.0", features = ["fold", "full"] }
+    ///
+    /// use quote::quote;
+    /// use syn::fold::{fold_expr, Fold};
+    /// use syn::{token, Expr, ExprParen};
+    ///
+    /// struct ParenthesizeEveryExpr;
+    ///
+    /// impl Fold for ParenthesizeEveryExpr {
+    ///     fn fold_expr(&mut self, expr: Expr) -> Expr {
+    ///         Expr::Paren(ExprParen {
+    ///             attrs: Vec::new(),
+    ///             expr: Box::new(fold_expr(self, expr)),
+    ///             paren_token: token::Paren::default(),
+    ///         })
+    ///     }
+    /// }
+    ///
+    /// fn main() {
+    ///     let code = quote! { a() + b(1) * c.d };
+    ///     let expr: Expr = syn::parse2(code).unwrap();
+    ///     let parenthesized = ParenthesizeEveryExpr.fold_expr(expr);
+    ///     println!("{}", quote!(#parenthesized));
+    ///
+    ///     // Output: (((a)()) + (((b)((1))) * ((c).d)))
+    /// }
+    /// ```
+    #[cfg(feature = "fold")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "fold")))]
+    #[rustfmt::skip]
+    pub mod fold;
+
+    /// Syntax tree traversal to walk a shared borrow of a syntax tree.
+    ///
+    /// Each method of the [`Visit`] trait is a hook that can be overridden to
+    /// customize the behavior when visiting the corresponding type of node. By
+    /// default, every method recursively visits the substructure of the input
+    /// by invoking the right visitor method of each of its fields.
+    ///
+    /// [`Visit`]: visit::Visit
+    ///
+    /// ```
+    /// # use syn::{Attribute, BinOp, Expr, ExprBinary};
+    /// #
+    /// pub trait Visit<'ast> {
+    ///     /* ... */
+    ///
+    ///     fn visit_expr_binary(&mut self, node: &'ast ExprBinary) {
+    ///         visit_expr_binary(self, node);
+    ///     }
+    ///
+    ///     /* ... */
+    ///     # fn visit_attribute(&mut self, node: &'ast Attribute);
+    ///     # fn visit_expr(&mut self, node: &'ast Expr);
+    ///     # fn visit_bin_op(&mut self, node: &'ast BinOp);
+    /// }
+    ///
+    /// pub fn visit_expr_binary<'ast, V>(v: &mut V, node: &'ast ExprBinary)
+    /// where
+    ///     V: Visit<'ast> + ?Sized,
+    /// {
+    ///     for attr in &node.attrs {
+    ///         v.visit_attribute(attr);
+    ///     }
+    ///     v.visit_expr(&*node.left);
+    ///     v.visit_bin_op(&node.op);
+    ///     v.visit_expr(&*node.right);
+    /// }
+    ///
+    /// /* ... */
+    /// ```
+    ///
+    /// <br>
+    ///
+    /// # Example
+    ///
+    /// This visitor will print the name of every freestanding function in the
+    /// syntax tree, including nested functions.
+    ///
+    /// ```
+    /// // [dependencies]
+    /// // quote = "1.0"
+    /// // syn = { version = "2.0", features = ["full", "visit"] }
+    ///
+    /// use quote::quote;
+    /// use syn::visit::{self, Visit};
+    /// use syn::{File, ItemFn};
+    ///
+    /// struct FnVisitor;
+    ///
+    /// impl<'ast> Visit<'ast> for FnVisitor {
+    ///     fn visit_item_fn(&mut self, node: &'ast ItemFn) {
+    ///         println!("Function with name={}", node.sig.ident);
+    ///
+    ///         // Delegate to the default impl to visit any nested functions.
+    ///         visit::visit_item_fn(self, node);
+    ///     }
+    /// }
+    ///
+    /// fn main() {
+    ///     let code = quote! {
+    ///         pub fn f() {
+    ///             fn g() {}
+    ///         }
+    ///     };
+    ///
+    ///     let syntax_tree: File = syn::parse2(code).unwrap();
+    ///     FnVisitor.visit_file(&syntax_tree);
+    /// }
+    /// ```
+    ///
+    /// The `'ast` lifetime on the input references means that the syntax tree
+    /// outlives the complete recursive visit call, so the visitor is allowed to
+    /// hold on to references into the syntax tree.
+    ///
+    /// ```
+    /// use quote::quote;
+    /// use syn::visit::{self, Visit};
+    /// use syn::{File, ItemFn};
+    ///
+    /// struct FnVisitor<'ast> {
+    ///     functions: Vec<&'ast ItemFn>,
+    /// }
+    ///
+    /// impl<'ast> Visit<'ast> for FnVisitor<'ast> {
+    ///     fn visit_item_fn(&mut self, node: &'ast ItemFn) {
+    ///         self.functions.push(node);
+    ///         visit::visit_item_fn(self, node);
+    ///     }
+    /// }
+    ///
+    /// fn main() {
+    ///     let code = quote! {
+    ///         pub fn f() {
+    ///             fn g() {}
+    ///         }
+    ///     };
+    ///
+    ///     let syntax_tree: File = syn::parse2(code).unwrap();
+    ///     let mut visitor = FnVisitor { functions: Vec::new() };
+    ///     visitor.visit_file(&syntax_tree);
+    ///     for f in visitor.functions {
+    ///         println!("Function with name={}", f.sig.ident);
+    ///     }
+    /// }
+    /// ```
+    #[cfg(feature = "visit")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "visit")))]
+    #[rustfmt::skip]
+    pub mod visit;
+
+    /// Syntax tree traversal to mutate an exclusive borrow of a syntax tree in
+    /// place.
+    ///
+    /// Each method of the [`VisitMut`] trait is a hook that can be overridden
+    /// to customize the behavior when mutating the corresponding type of node.
+    /// By default, every method recursively visits the substructure of the
+    /// input by invoking the right visitor method of each of its fields.
+    ///
+    /// [`VisitMut`]: visit_mut::VisitMut
+    ///
+    /// ```
+    /// # use syn::{Attribute, BinOp, Expr, ExprBinary};
+    /// #
+    /// pub trait VisitMut {
+    ///     /* ... */
+    ///
+    ///     fn visit_expr_binary_mut(&mut self, node: &mut ExprBinary) {
+    ///         visit_expr_binary_mut(self, node);
+    ///     }
+    ///
+    ///     /* ... */
+    ///     # fn visit_attribute_mut(&mut self, node: &mut Attribute);
+    ///     # fn visit_expr_mut(&mut self, node: &mut Expr);
+    ///     # fn visit_bin_op_mut(&mut self, node: &mut BinOp);
+    /// }
+    ///
+    /// pub fn visit_expr_binary_mut<V>(v: &mut V, node: &mut ExprBinary)
+    /// where
+    ///     V: VisitMut + ?Sized,
+    /// {
+    ///     for attr in &mut node.attrs {
+    ///         v.visit_attribute_mut(attr);
+    ///     }
+    ///     v.visit_expr_mut(&mut *node.left);
+    ///     v.visit_bin_op_mut(&mut node.op);
+    ///     v.visit_expr_mut(&mut *node.right);
+    /// }
+    ///
+    /// /* ... */
+    /// ```
+    ///
+    /// <br>
+    ///
+    /// # Example
+    ///
+    /// This mut visitor replace occurrences of u256 suffixed integer literals
+    /// like `999u256` with a macro invocation `bigint::u256!(999)`.
+    ///
+    /// ```
+    /// // [dependencies]
+    /// // quote = "1.0"
+    /// // syn = { version = "2.0", features = ["full", "visit-mut"] }
+    ///
+    /// use quote::quote;
+    /// use syn::visit_mut::{self, VisitMut};
+    /// use syn::{parse_quote, Expr, File, Lit, LitInt};
+    ///
+    /// struct BigintReplace;
+    ///
+    /// impl VisitMut for BigintReplace {
+    ///     fn visit_expr_mut(&mut self, node: &mut Expr) {
+    ///         if let Expr::Lit(expr) = &node {
+    ///             if let Lit::Int(int) = &expr.lit {
+    ///                 if int.suffix() == "u256" {
+    ///                     let digits = int.base10_digits();
+    ///                     let unsuffixed: LitInt = syn::parse_str(digits).unwrap();
+    ///                     *node = parse_quote!(bigint::u256!(#unsuffixed));
+    ///                     return;
+    ///                 }
+    ///             }
+    ///         }
+    ///
+    ///         // Delegate to the default impl to visit nested expressions.
+    ///         visit_mut::visit_expr_mut(self, node);
+    ///     }
+    /// }
+    ///
+    /// fn main() {
+    ///     let code = quote! {
+    ///         fn main() {
+    ///             let _ = 999u256;
+    ///         }
+    ///     };
+    ///
+    ///     let mut syntax_tree: File = syn::parse2(code).unwrap();
+    ///     BigintReplace.visit_file_mut(&mut syntax_tree);
+    ///     println!("{}", quote!(#syntax_tree));
+    /// }
+    /// ```
+    #[cfg(feature = "visit-mut")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "visit-mut")))]
+    #[rustfmt::skip]
+    pub mod visit_mut;
+
+    #[cfg(feature = "clone-impls")]
+    #[rustfmt::skip]
+    mod clone;
+
+    #[cfg(feature = "extra-traits")]
+    #[rustfmt::skip]
+    mod debug;
+
+    #[cfg(feature = "extra-traits")]
+    #[rustfmt::skip]
+    mod eq;
+
+    #[cfg(feature = "extra-traits")]
+    #[rustfmt::skip]
+    mod hash;
+
+    #[cfg(any(feature = "full", feature = "derive"))]
+    #[path = "../gen_helper.rs"]
+    mod helper;
+}
+
+#[cfg(feature = "fold")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "fold")))]
+pub use crate::gen::fold;
+
+#[cfg(feature = "visit")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "visit")))]
+pub use crate::gen::visit;
+
+#[cfg(feature = "visit-mut")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "visit-mut")))]
+pub use crate::gen::visit_mut;
+
+// Not public API.
+#[doc(hidden)]
+#[path = "export.rs"]
+pub mod __private;
+
+/// Parse tokens of source code into the chosen syntax tree node.
+///
+/// This is preferred over parsing a string because tokens are able to preserve
+/// information about where in the user's code they were originally written (the
+/// "span" of the token), possibly allowing the compiler to produce better error
+/// messages.
+///
+/// This function parses a `proc_macro::TokenStream` which is the type used for
+/// interop with the compiler in a procedural macro. To parse a
+/// `proc_macro2::TokenStream`, use [`syn::parse2`] instead.
+///
+/// [`syn::parse2`]: parse2
+///
+/// # Examples
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// use proc_macro::TokenStream;
+/// use quote::quote;
+/// use syn::DeriveInput;
+///
+/// # const IGNORE_TOKENS: &str = stringify! {
+/// #[proc_macro_derive(MyMacro)]
+/// # };
+/// pub fn my_macro(input: TokenStream) -> TokenStream {
+///     // Parse the tokens into a syntax tree
+///     let ast: DeriveInput = syn::parse(input).unwrap();
+///
+///     // Build the output, possibly using quasi-quotation
+///     let expanded = quote! {
+///         /* ... */
+///     };
+///
+///     // Convert into a token stream and return it
+///     expanded.into()
+/// }
+/// ```
+#[cfg(all(feature = "parsing", feature = "proc-macro"))]
+#[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "proc-macro"))))]
+pub fn parse<T: parse::Parse>(tokens: proc_macro::TokenStream) -> Result<T> {
+    parse::Parser::parse(T::parse, tokens)
+}
+
+/// Parse a proc-macro2 token stream into the chosen syntax tree node.
+///
+/// This function will check that the input is fully parsed. If there are
+/// any unparsed tokens at the end of the stream, an error is returned.
+///
+/// This function parses a `proc_macro2::TokenStream` which is commonly useful
+/// when the input comes from a node of the Syn syntax tree, for example the
+/// body tokens of a [`Macro`] node. When in a procedural macro parsing the
+/// `proc_macro::TokenStream` provided by the compiler, use [`syn::parse`]
+/// instead.
+///
+/// [`syn::parse`]: parse()
+#[cfg(feature = "parsing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+pub fn parse2<T: parse::Parse>(tokens: proc_macro2::TokenStream) -> Result<T> {
+    parse::Parser::parse2(T::parse, tokens)
+}
+
+/// Parse a string of Rust code into the chosen syntax tree node.
+///
+/// # Hygiene
+///
+/// Every span in the resulting syntax tree will be set to resolve at the macro
+/// call site.
+///
+/// # Examples
+///
+/// ```
+/// use syn::{Expr, Result};
+///
+/// fn run() -> Result<()> {
+///     let code = "assert_eq!(u8::max_value(), 255)";
+///     let expr = syn::parse_str::<Expr>(code)?;
+///     println!("{:#?}", expr);
+///     Ok(())
+/// }
+/// #
+/// # run().unwrap();
+/// ```
+#[cfg(feature = "parsing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+pub fn parse_str<T: parse::Parse>(s: &str) -> Result<T> {
+    parse::Parser::parse_str(T::parse, s)
+}
+
+// FIXME the name parse_file makes it sound like you might pass in a path to a
+// file, rather than the content.
+/// Parse the content of a file of Rust code.
+///
+/// This is different from `syn::parse_str::<File>(content)` in two ways:
+///
+/// - It discards a leading byte order mark `\u{FEFF}` if the file has one.
+/// - It preserves the shebang line of the file, such as `#!/usr/bin/env rustx`.
+///
+/// If present, either of these would be an error using `from_str`.
+///
+/// # Examples
+///
+/// ```no_run
+/// use std::error::Error;
+/// use std::fs::File;
+/// use std::io::Read;
+///
+/// fn run() -> Result<(), Box<dyn Error>> {
+///     let mut file = File::open("path/to/code.rs")?;
+///     let mut content = String::new();
+///     file.read_to_string(&mut content)?;
+///
+///     let ast = syn::parse_file(&content)?;
+///     if let Some(shebang) = ast.shebang {
+///         println!("{}", shebang);
+///     }
+///     println!("{} items", ast.items.len());
+///
+///     Ok(())
+/// }
+/// #
+/// # run().unwrap();
+/// ```
+#[cfg(all(feature = "parsing", feature = "full"))]
+#[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "full"))))]
+pub fn parse_file(mut content: &str) -> Result<File> {
+    // Strip the BOM if it is present
+    const BOM: &str = "\u{feff}";
+    if content.starts_with(BOM) {
+        content = &content[BOM.len()..];
+    }
+
+    let mut shebang = None;
+    if content.starts_with("#!") {
+        let rest = whitespace::skip(&content[2..]);
+        if !rest.starts_with('[') {
+            if let Some(idx) = content.find('\n') {
+                shebang = Some(content[..idx].to_string());
+                content = &content[idx..];
+            } else {
+                shebang = Some(content.to_string());
+                content = "";
+            }
+        }
+    }
+
+    let mut file: File = parse_str(content)?;
+    file.shebang = shebang;
+    Ok(file)
+}
diff --git a/rust/syn/lifetime.rs b/rust/syn/lifetime.rs
new file mode 100644
index 0000000000000000000000000000000000000000..8d42fe9552eb78251aea3c0fa532f5404094c77f
--- /dev/null
+++ b/rust/syn/lifetime.rs
@@ -0,0 +1,158 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "parsing")]
+use crate::lookahead;
+use proc_macro2::{Ident, Span};
+use std::cmp::Ordering;
+use std::fmt::{self, Display};
+use std::hash::{Hash, Hasher};
+
+/// A Rust lifetime: `'a`.
+///
+/// Lifetime names must conform to the following rules:
+///
+/// - Must start with an apostrophe.
+/// - Must not consist of just an apostrophe: `'`.
+/// - Character after the apostrophe must be `_` or a Unicode code point with
+///   the XID_Start property.
+/// - All following characters must be Unicode code points with the XID_Continue
+///   property.
+pub struct Lifetime {
+    pub apostrophe: Span,
+    pub ident: Ident,
+}
+
+impl Lifetime {
+    /// # Panics
+    ///
+    /// Panics if the lifetime does not conform to the bulleted rules above.
+    ///
+    /// # Invocation
+    ///
+    /// ```
+    /// # use proc_macro2::Span;
+    /// # use syn::Lifetime;
+    /// #
+    /// # fn f() -> Lifetime {
+    /// Lifetime::new("'a", Span::call_site())
+    /// # }
+    /// ```
+    pub fn new(symbol: &str, span: Span) -> Self {
+        if !symbol.starts_with('\'') {
+            panic!(
+                "lifetime name must start with apostrophe as in \"'a\", got {:?}",
+                symbol
+            );
+        }
+
+        if symbol == "'" {
+            panic!("lifetime name must not be empty");
+        }
+
+        if !crate::ident::xid_ok(&symbol[1..]) {
+            panic!("{:?} is not a valid lifetime name", symbol);
+        }
+
+        Lifetime {
+            apostrophe: span,
+            ident: Ident::new(&symbol[1..], span),
+        }
+    }
+
+    pub fn span(&self) -> Span {
+        self.apostrophe
+            .join(self.ident.span())
+            .unwrap_or(self.apostrophe)
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.apostrophe = span;
+        self.ident.set_span(span);
+    }
+}
+
+impl Display for Lifetime {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        "'".fmt(formatter)?;
+        self.ident.fmt(formatter)
+    }
+}
+
+impl Clone for Lifetime {
+    fn clone(&self) -> Self {
+        Lifetime {
+            apostrophe: self.apostrophe,
+            ident: self.ident.clone(),
+        }
+    }
+}
+
+impl PartialEq for Lifetime {
+    fn eq(&self, other: &Lifetime) -> bool {
+        self.ident.eq(&other.ident)
+    }
+}
+
+impl Eq for Lifetime {}
+
+impl PartialOrd for Lifetime {
+    fn partial_cmp(&self, other: &Lifetime) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Lifetime {
+    fn cmp(&self, other: &Lifetime) -> Ordering {
+        self.ident.cmp(&other.ident)
+    }
+}
+
+impl Hash for Lifetime {
+    fn hash<H: Hasher>(&self, h: &mut H) {
+        self.ident.hash(h);
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub_if_not_doc! {
+    #[doc(hidden)]
+    #[allow(non_snake_case)]
+    pub fn Lifetime(marker: lookahead::TokenMarker) -> Lifetime {
+        match marker {}
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::error::Result;
+    use crate::lifetime::Lifetime;
+    use crate::parse::{Parse, ParseStream};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Lifetime {
+        fn parse(input: ParseStream) -> Result<Self> {
+            input.step(|cursor| {
+                cursor
+                    .lifetime()
+                    .ok_or_else(|| cursor.error("expected lifetime"))
+            })
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::lifetime::Lifetime;
+    use proc_macro2::{Punct, Spacing, TokenStream};
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Lifetime {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            let mut apostrophe = Punct::new('\'', Spacing::Joint);
+            apostrophe.set_span(self.apostrophe);
+            tokens.append(apostrophe);
+            self.ident.to_tokens(tokens);
+        }
+    }
+}
diff --git a/rust/syn/lit.rs b/rust/syn/lit.rs
new file mode 100644
index 0000000000000000000000000000000000000000..29228e888dd3b8cebe364d1f540352ef2565c59d
--- /dev/null
+++ b/rust/syn/lit.rs
@@ -0,0 +1,1641 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "parsing")]
+use crate::lookahead;
+#[cfg(feature = "parsing")]
+use crate::parse::{Parse, Parser};
+use crate::{Error, Result};
+use proc_macro2::{Ident, Literal, Span};
+#[cfg(feature = "parsing")]
+use proc_macro2::{TokenStream, TokenTree};
+use std::fmt::{self, Display};
+#[cfg(feature = "extra-traits")]
+use std::hash::{Hash, Hasher};
+use std::str::{self, FromStr};
+
+ast_enum_of_structs! {
+    /// A Rust literal such as a string or integer or boolean.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[non_exhaustive]
+    pub enum Lit {
+        /// A UTF-8 string literal: `"foo"`.
+        Str(LitStr),
+
+        /// A byte string literal: `b"foo"`.
+        ByteStr(LitByteStr),
+
+        /// A byte literal: `b'f'`.
+        Byte(LitByte),
+
+        /// A character literal: `'a'`.
+        Char(LitChar),
+
+        /// An integer literal: `1` or `1u16`.
+        Int(LitInt),
+
+        /// A floating point literal: `1f64` or `1.0e10f64`.
+        ///
+        /// Must be finite. May not be infinite or NaN.
+        Float(LitFloat),
+
+        /// A boolean literal: `true` or `false`.
+        Bool(LitBool),
+
+        /// A raw token literal not interpreted by Syn.
+        Verbatim(Literal),
+    }
+}
+
+ast_struct! {
+    /// A UTF-8 string literal: `"foo"`.
+    pub struct LitStr {
+        repr: Box<LitRepr>,
+    }
+}
+
+ast_struct! {
+    /// A byte string literal: `b"foo"`.
+    pub struct LitByteStr {
+        repr: Box<LitRepr>,
+    }
+}
+
+ast_struct! {
+    /// A byte literal: `b'f'`.
+    pub struct LitByte {
+        repr: Box<LitRepr>,
+    }
+}
+
+ast_struct! {
+    /// A character literal: `'a'`.
+    pub struct LitChar {
+        repr: Box<LitRepr>,
+    }
+}
+
+struct LitRepr {
+    token: Literal,
+    suffix: Box<str>,
+}
+
+ast_struct! {
+    /// An integer literal: `1` or `1u16`.
+    pub struct LitInt {
+        repr: Box<LitIntRepr>,
+    }
+}
+
+struct LitIntRepr {
+    token: Literal,
+    digits: Box<str>,
+    suffix: Box<str>,
+}
+
+ast_struct! {
+    /// A floating point literal: `1f64` or `1.0e10f64`.
+    ///
+    /// Must be finite. May not be infinite or NaN.
+    pub struct LitFloat {
+        repr: Box<LitFloatRepr>,
+    }
+}
+
+struct LitFloatRepr {
+    token: Literal,
+    digits: Box<str>,
+    suffix: Box<str>,
+}
+
+ast_struct! {
+    /// A boolean literal: `true` or `false`.
+    pub struct LitBool {
+        pub value: bool,
+        pub span: Span,
+    }
+}
+
+impl LitStr {
+    pub fn new(value: &str, span: Span) -> Self {
+        let mut token = Literal::string(value);
+        token.set_span(span);
+        LitStr {
+            repr: Box::new(LitRepr {
+                token,
+                suffix: Box::<str>::default(),
+            }),
+        }
+    }
+
+    pub fn value(&self) -> String {
+        let repr = self.repr.token.to_string();
+        let (value, _suffix) = value::parse_lit_str(&repr);
+        String::from(value)
+    }
+
+    /// Parse a syntax tree node from the content of this string literal.
+    ///
+    /// All spans in the syntax tree will point to the span of this `LitStr`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{Attribute, Error, Expr, Lit, Meta, Path, Result};
+    ///
+    /// // Parses the path from an attribute that looks like:
+    /// //
+    /// //     #[path = "a::b::c"]
+    /// //
+    /// // or returns `None` if the input is some other attribute.
+    /// fn get_path(attr: &Attribute) -> Result<Option<Path>> {
+    ///     if !attr.path().is_ident("path") {
+    ///         return Ok(None);
+    ///     }
+    ///
+    ///     if let Meta::NameValue(meta) = &attr.meta {
+    ///         if let Expr::Lit(expr) = &meta.value {
+    ///             if let Lit::Str(lit_str) = &expr.lit {
+    ///                 return lit_str.parse().map(Some);
+    ///             }
+    ///         }
+    ///     }
+    ///
+    ///     let message = "expected #[path = \"...\"]";
+    ///     Err(Error::new_spanned(attr, message))
+    /// }
+    /// ```
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse<T: Parse>(&self) -> Result<T> {
+        self.parse_with(T::parse)
+    }
+
+    /// Invoke parser on the content of this string literal.
+    ///
+    /// All spans in the syntax tree will point to the span of this `LitStr`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use proc_macro2::Span;
+    /// # use syn::{LitStr, Result};
+    /// #
+    /// # fn main() -> Result<()> {
+    /// #     let lit_str = LitStr::new("a::b::c", Span::call_site());
+    /// #
+    /// #     const IGNORE: &str = stringify! {
+    /// let lit_str: LitStr = /* ... */;
+    /// #     };
+    ///
+    /// // Parse a string literal like "a::b::c" into a Path, not allowing
+    /// // generic arguments on any of the path segments.
+    /// let basic_path = lit_str.parse_with(syn::Path::parse_mod_style)?;
+    /// #
+    /// #     Ok(())
+    /// # }
+    /// ```
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_with<F: Parser>(&self, parser: F) -> Result<F::Output> {
+        use proc_macro2::Group;
+
+        // Token stream with every span replaced by the given one.
+        fn respan_token_stream(stream: TokenStream, span: Span) -> TokenStream {
+            stream
+                .into_iter()
+                .map(|token| respan_token_tree(token, span))
+                .collect()
+        }
+
+        // Token tree with every span replaced by the given one.
+        fn respan_token_tree(mut token: TokenTree, span: Span) -> TokenTree {
+            match &mut token {
+                TokenTree::Group(g) => {
+                    let stream = respan_token_stream(g.stream(), span);
+                    *g = Group::new(g.delimiter(), stream);
+                    g.set_span(span);
+                }
+                other => other.set_span(span),
+            }
+            token
+        }
+
+        // Parse string literal into a token stream with every span equal to the
+        // original literal's span.
+        let span = self.span();
+        let mut tokens = TokenStream::from_str(&self.value())?;
+        tokens = respan_token_stream(tokens, span);
+
+        let result = crate::parse::parse_scoped(parser, span, tokens)?;
+
+        let suffix = self.suffix();
+        if !suffix.is_empty() {
+            return Err(Error::new(
+                self.span(),
+                format!("unexpected suffix `{}` on string literal", suffix),
+            ));
+        }
+
+        Ok(result)
+    }
+
+    pub fn span(&self) -> Span {
+        self.repr.token.span()
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.repr.token.set_span(span);
+    }
+
+    pub fn suffix(&self) -> &str {
+        &self.repr.suffix
+    }
+
+    pub fn token(&self) -> Literal {
+        self.repr.token.clone()
+    }
+}
+
+impl LitByteStr {
+    pub fn new(value: &[u8], span: Span) -> Self {
+        let mut token = Literal::byte_string(value);
+        token.set_span(span);
+        LitByteStr {
+            repr: Box::new(LitRepr {
+                token,
+                suffix: Box::<str>::default(),
+            }),
+        }
+    }
+
+    pub fn value(&self) -> Vec<u8> {
+        let repr = self.repr.token.to_string();
+        let (value, _suffix) = value::parse_lit_byte_str(&repr);
+        value
+    }
+
+    pub fn span(&self) -> Span {
+        self.repr.token.span()
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.repr.token.set_span(span);
+    }
+
+    pub fn suffix(&self) -> &str {
+        &self.repr.suffix
+    }
+
+    pub fn token(&self) -> Literal {
+        self.repr.token.clone()
+    }
+}
+
+impl LitByte {
+    pub fn new(value: u8, span: Span) -> Self {
+        let mut token = Literal::u8_suffixed(value);
+        token.set_span(span);
+        LitByte {
+            repr: Box::new(LitRepr {
+                token,
+                suffix: Box::<str>::default(),
+            }),
+        }
+    }
+
+    pub fn value(&self) -> u8 {
+        let repr = self.repr.token.to_string();
+        let (value, _suffix) = value::parse_lit_byte(&repr);
+        value
+    }
+
+    pub fn span(&self) -> Span {
+        self.repr.token.span()
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.repr.token.set_span(span);
+    }
+
+    pub fn suffix(&self) -> &str {
+        &self.repr.suffix
+    }
+
+    pub fn token(&self) -> Literal {
+        self.repr.token.clone()
+    }
+}
+
+impl LitChar {
+    pub fn new(value: char, span: Span) -> Self {
+        let mut token = Literal::character(value);
+        token.set_span(span);
+        LitChar {
+            repr: Box::new(LitRepr {
+                token,
+                suffix: Box::<str>::default(),
+            }),
+        }
+    }
+
+    pub fn value(&self) -> char {
+        let repr = self.repr.token.to_string();
+        let (value, _suffix) = value::parse_lit_char(&repr);
+        value
+    }
+
+    pub fn span(&self) -> Span {
+        self.repr.token.span()
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.repr.token.set_span(span);
+    }
+
+    pub fn suffix(&self) -> &str {
+        &self.repr.suffix
+    }
+
+    pub fn token(&self) -> Literal {
+        self.repr.token.clone()
+    }
+}
+
+impl LitInt {
+    pub fn new(repr: &str, span: Span) -> Self {
+        let (digits, suffix) = match value::parse_lit_int(repr) {
+            Some(parse) => parse,
+            None => panic!("Not an integer literal: `{}`", repr),
+        };
+
+        let mut token: Literal = repr.parse().unwrap();
+        token.set_span(span);
+        LitInt {
+            repr: Box::new(LitIntRepr {
+                token,
+                digits,
+                suffix,
+            }),
+        }
+    }
+
+    pub fn base10_digits(&self) -> &str {
+        &self.repr.digits
+    }
+
+    /// Parses the literal into a selected number type.
+    ///
+    /// This is equivalent to `lit.base10_digits().parse()` except that the
+    /// resulting errors will be correctly spanned to point to the literal token
+    /// in the macro input.
+    ///
+    /// ```
+    /// use syn::LitInt;
+    /// use syn::parse::{Parse, ParseStream, Result};
+    ///
+    /// struct Port {
+    ///     value: u16,
+    /// }
+    ///
+    /// impl Parse for Port {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         let lit: LitInt = input.parse()?;
+    ///         let value = lit.base10_parse::<u16>()?;
+    ///         Ok(Port { value })
+    ///     }
+    /// }
+    /// ```
+    pub fn base10_parse<N>(&self) -> Result<N>
+    where
+        N: FromStr,
+        N::Err: Display,
+    {
+        self.base10_digits()
+            .parse()
+            .map_err(|err| Error::new(self.span(), err))
+    }
+
+    pub fn suffix(&self) -> &str {
+        &self.repr.suffix
+    }
+
+    pub fn span(&self) -> Span {
+        self.repr.token.span()
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.repr.token.set_span(span);
+    }
+
+    pub fn token(&self) -> Literal {
+        self.repr.token.clone()
+    }
+}
+
+impl From<Literal> for LitInt {
+    fn from(token: Literal) -> Self {
+        let repr = token.to_string();
+        if let Some((digits, suffix)) = value::parse_lit_int(&repr) {
+            LitInt {
+                repr: Box::new(LitIntRepr {
+                    token,
+                    digits,
+                    suffix,
+                }),
+            }
+        } else {
+            panic!("Not an integer literal: `{}`", repr);
+        }
+    }
+}
+
+impl Display for LitInt {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.repr.token.fmt(formatter)
+    }
+}
+
+impl LitFloat {
+    pub fn new(repr: &str, span: Span) -> Self {
+        let (digits, suffix) = match value::parse_lit_float(repr) {
+            Some(parse) => parse,
+            None => panic!("Not a float literal: `{}`", repr),
+        };
+
+        let mut token: Literal = repr.parse().unwrap();
+        token.set_span(span);
+        LitFloat {
+            repr: Box::new(LitFloatRepr {
+                token,
+                digits,
+                suffix,
+            }),
+        }
+    }
+
+    pub fn base10_digits(&self) -> &str {
+        &self.repr.digits
+    }
+
+    pub fn base10_parse<N>(&self) -> Result<N>
+    where
+        N: FromStr,
+        N::Err: Display,
+    {
+        self.base10_digits()
+            .parse()
+            .map_err(|err| Error::new(self.span(), err))
+    }
+
+    pub fn suffix(&self) -> &str {
+        &self.repr.suffix
+    }
+
+    pub fn span(&self) -> Span {
+        self.repr.token.span()
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.repr.token.set_span(span);
+    }
+
+    pub fn token(&self) -> Literal {
+        self.repr.token.clone()
+    }
+}
+
+impl From<Literal> for LitFloat {
+    fn from(token: Literal) -> Self {
+        let repr = token.to_string();
+        if let Some((digits, suffix)) = value::parse_lit_float(&repr) {
+            LitFloat {
+                repr: Box::new(LitFloatRepr {
+                    token,
+                    digits,
+                    suffix,
+                }),
+            }
+        } else {
+            panic!("Not a float literal: `{}`", repr);
+        }
+    }
+}
+
+impl Display for LitFloat {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        self.repr.token.fmt(formatter)
+    }
+}
+
+impl LitBool {
+    pub fn new(value: bool, span: Span) -> Self {
+        LitBool { value, span }
+    }
+
+    pub fn value(&self) -> bool {
+        self.value
+    }
+
+    pub fn span(&self) -> Span {
+        self.span
+    }
+
+    pub fn set_span(&mut self, span: Span) {
+        self.span = span;
+    }
+
+    pub fn token(&self) -> Ident {
+        let s = if self.value { "true" } else { "false" };
+        Ident::new(s, self.span)
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+mod debug_impls {
+    use crate::lit::{LitBool, LitByte, LitByteStr, LitChar, LitFloat, LitInt, LitStr};
+    use std::fmt::{self, Debug};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+    impl Debug for LitStr {
+        fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            self.debug(formatter, "LitStr")
+        }
+    }
+
+    impl LitStr {
+        pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+            formatter
+                .debug_struct(name)
+                .field("token", &format_args!("{}", self.repr.token))
+                .finish()
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+    impl Debug for LitByteStr {
+        fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            self.debug(formatter, "LitByteStr")
+        }
+    }
+
+    impl LitByteStr {
+        pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+            formatter
+                .debug_struct(name)
+                .field("token", &format_args!("{}", self.repr.token))
+                .finish()
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+    impl Debug for LitByte {
+        fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            self.debug(formatter, "LitByte")
+        }
+    }
+
+    impl LitByte {
+        pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+            formatter
+                .debug_struct(name)
+                .field("token", &format_args!("{}", self.repr.token))
+                .finish()
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+    impl Debug for LitChar {
+        fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            self.debug(formatter, "LitChar")
+        }
+    }
+
+    impl LitChar {
+        pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+            formatter
+                .debug_struct(name)
+                .field("token", &format_args!("{}", self.repr.token))
+                .finish()
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+    impl Debug for LitInt {
+        fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            self.debug(formatter, "LitInt")
+        }
+    }
+
+    impl LitInt {
+        pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+            formatter
+                .debug_struct(name)
+                .field("token", &format_args!("{}", self.repr.token))
+                .finish()
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+    impl Debug for LitFloat {
+        fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            self.debug(formatter, "LitFloat")
+        }
+    }
+
+    impl LitFloat {
+        pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+            formatter
+                .debug_struct(name)
+                .field("token", &format_args!("{}", self.repr.token))
+                .finish()
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+    impl Debug for LitBool {
+        fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+            self.debug(formatter, "LitBool")
+        }
+    }
+
+    impl LitBool {
+        pub(crate) fn debug(&self, formatter: &mut fmt::Formatter, name: &str) -> fmt::Result {
+            formatter
+                .debug_struct(name)
+                .field("value", &self.value)
+                .finish()
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for LitRepr {
+    fn clone(&self) -> Self {
+        LitRepr {
+            token: self.token.clone(),
+            suffix: self.suffix.clone(),
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for LitIntRepr {
+    fn clone(&self) -> Self {
+        LitIntRepr {
+            token: self.token.clone(),
+            digits: self.digits.clone(),
+            suffix: self.suffix.clone(),
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for LitFloatRepr {
+    fn clone(&self) -> Self {
+        LitFloatRepr {
+            token: self.token.clone(),
+            digits: self.digits.clone(),
+            suffix: self.suffix.clone(),
+        }
+    }
+}
+
+macro_rules! lit_extra_traits {
+    ($ty:ident) => {
+        #[cfg(feature = "clone-impls")]
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+        impl Clone for $ty {
+            fn clone(&self) -> Self {
+                $ty {
+                    repr: self.repr.clone(),
+                }
+            }
+        }
+
+        #[cfg(feature = "extra-traits")]
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+        impl PartialEq for $ty {
+            fn eq(&self, other: &Self) -> bool {
+                self.repr.token.to_string() == other.repr.token.to_string()
+            }
+        }
+
+        #[cfg(feature = "extra-traits")]
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+        impl Hash for $ty {
+            fn hash<H>(&self, state: &mut H)
+            where
+                H: Hasher,
+            {
+                self.repr.token.to_string().hash(state);
+            }
+        }
+
+        #[cfg(feature = "parsing")]
+        pub_if_not_doc! {
+            #[doc(hidden)]
+            #[allow(non_snake_case)]
+            pub fn $ty(marker: lookahead::TokenMarker) -> $ty {
+                match marker {}
+            }
+        }
+    };
+}
+
+lit_extra_traits!(LitStr);
+lit_extra_traits!(LitByteStr);
+lit_extra_traits!(LitByte);
+lit_extra_traits!(LitChar);
+lit_extra_traits!(LitInt);
+lit_extra_traits!(LitFloat);
+
+#[cfg(feature = "parsing")]
+pub_if_not_doc! {
+    #[doc(hidden)]
+    #[allow(non_snake_case)]
+    pub fn LitBool(marker: lookahead::TokenMarker) -> LitBool {
+        match marker {}
+    }
+}
+
+/// The style of a string literal, either plain quoted or a raw string like
+/// `r##"data"##`.
+#[doc(hidden)] // https://github.com/dtolnay/syn/issues/1566
+pub enum StrStyle {
+    /// An ordinary string like `"data"`.
+    Cooked,
+    /// A raw string like `r##"data"##`.
+    ///
+    /// The unsigned integer is the number of `#` symbols used.
+    Raw(usize),
+}
+
+#[cfg(feature = "parsing")]
+pub_if_not_doc! {
+    #[doc(hidden)]
+    #[allow(non_snake_case)]
+    pub fn Lit(marker: lookahead::TokenMarker) -> Lit {
+        match marker {}
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::buffer::Cursor;
+    use crate::error::Result;
+    use crate::lit::{
+        value, Lit, LitBool, LitByte, LitByteStr, LitChar, LitFloat, LitFloatRepr, LitInt,
+        LitIntRepr, LitStr,
+    };
+    use crate::parse::{Parse, ParseStream};
+    use proc_macro2::{Literal, Punct};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Lit {
+        fn parse(input: ParseStream) -> Result<Self> {
+            input.step(|cursor| {
+                if let Some((lit, rest)) = cursor.literal() {
+                    return Ok((Lit::new(lit), rest));
+                }
+
+                if let Some((ident, rest)) = cursor.ident() {
+                    let value = ident == "true";
+                    if value || ident == "false" {
+                        let lit_bool = LitBool {
+                            value,
+                            span: ident.span(),
+                        };
+                        return Ok((Lit::Bool(lit_bool), rest));
+                    }
+                }
+
+                if let Some((punct, rest)) = cursor.punct() {
+                    if punct.as_char() == '-' {
+                        if let Some((lit, rest)) = parse_negative_lit(punct, rest) {
+                            return Ok((lit, rest));
+                        }
+                    }
+                }
+
+                Err(cursor.error("expected literal"))
+            })
+        }
+    }
+
+    fn parse_negative_lit(neg: Punct, cursor: Cursor) -> Option<(Lit, Cursor)> {
+        let (lit, rest) = cursor.literal()?;
+
+        let mut span = neg.span();
+        span = span.join(lit.span()).unwrap_or(span);
+
+        let mut repr = lit.to_string();
+        repr.insert(0, '-');
+
+        if let Some((digits, suffix)) = value::parse_lit_int(&repr) {
+            let mut token: Literal = repr.parse().unwrap();
+            token.set_span(span);
+            return Some((
+                Lit::Int(LitInt {
+                    repr: Box::new(LitIntRepr {
+                        token,
+                        digits,
+                        suffix,
+                    }),
+                }),
+                rest,
+            ));
+        }
+
+        let (digits, suffix) = value::parse_lit_float(&repr)?;
+        let mut token: Literal = repr.parse().unwrap();
+        token.set_span(span);
+        Some((
+            Lit::Float(LitFloat {
+                repr: Box::new(LitFloatRepr {
+                    token,
+                    digits,
+                    suffix,
+                }),
+            }),
+            rest,
+        ))
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for LitStr {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let head = input.fork();
+            match input.parse() {
+                Ok(Lit::Str(lit)) => Ok(lit),
+                _ => Err(head.error("expected string literal")),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for LitByteStr {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let head = input.fork();
+            match input.parse() {
+                Ok(Lit::ByteStr(lit)) => Ok(lit),
+                _ => Err(head.error("expected byte string literal")),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for LitByte {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let head = input.fork();
+            match input.parse() {
+                Ok(Lit::Byte(lit)) => Ok(lit),
+                _ => Err(head.error("expected byte literal")),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for LitChar {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let head = input.fork();
+            match input.parse() {
+                Ok(Lit::Char(lit)) => Ok(lit),
+                _ => Err(head.error("expected character literal")),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for LitInt {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let head = input.fork();
+            match input.parse() {
+                Ok(Lit::Int(lit)) => Ok(lit),
+                _ => Err(head.error("expected integer literal")),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for LitFloat {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let head = input.fork();
+            match input.parse() {
+                Ok(Lit::Float(lit)) => Ok(lit),
+                _ => Err(head.error("expected floating point literal")),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for LitBool {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let head = input.fork();
+            match input.parse() {
+                Ok(Lit::Bool(lit)) => Ok(lit),
+                _ => Err(head.error("expected boolean literal")),
+            }
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::lit::{LitBool, LitByte, LitByteStr, LitChar, LitFloat, LitInt, LitStr};
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for LitStr {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.repr.token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for LitByteStr {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.repr.token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for LitByte {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.repr.token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for LitChar {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.repr.token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for LitInt {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.repr.token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for LitFloat {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.repr.token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for LitBool {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append(self.token());
+        }
+    }
+}
+
+mod value {
+    use crate::bigint::BigInt;
+    use crate::lit::{
+        Lit, LitBool, LitByte, LitByteStr, LitChar, LitFloat, LitFloatRepr, LitInt, LitIntRepr,
+        LitRepr, LitStr,
+    };
+    use proc_macro2::{Literal, Span};
+    use std::char;
+    use std::ops::{Index, RangeFrom};
+
+    impl Lit {
+        /// Interpret a Syn literal from a proc-macro2 literal.
+        pub fn new(token: Literal) -> Self {
+            let repr = token.to_string();
+
+            match byte(&repr, 0) {
+                // "...", r"...", r#"..."#
+                b'"' | b'r' => {
+                    let (_, suffix) = parse_lit_str(&repr);
+                    return Lit::Str(LitStr {
+                        repr: Box::new(LitRepr { token, suffix }),
+                    });
+                }
+                b'b' => match byte(&repr, 1) {
+                    // b"...", br"...", br#"...#"
+                    b'"' | b'r' => {
+                        let (_, suffix) = parse_lit_byte_str(&repr);
+                        return Lit::ByteStr(LitByteStr {
+                            repr: Box::new(LitRepr { token, suffix }),
+                        });
+                    }
+                    // b'...'
+                    b'\'' => {
+                        let (_, suffix) = parse_lit_byte(&repr);
+                        return Lit::Byte(LitByte {
+                            repr: Box::new(LitRepr { token, suffix }),
+                        });
+                    }
+                    _ => {}
+                },
+                // '...'
+                b'\'' => {
+                    let (_, suffix) = parse_lit_char(&repr);
+                    return Lit::Char(LitChar {
+                        repr: Box::new(LitRepr { token, suffix }),
+                    });
+                }
+                b'0'..=b'9' | b'-' => {
+                    // 0, 123, 0xFF, 0o77, 0b11
+                    if let Some((digits, suffix)) = parse_lit_int(&repr) {
+                        return Lit::Int(LitInt {
+                            repr: Box::new(LitIntRepr {
+                                token,
+                                digits,
+                                suffix,
+                            }),
+                        });
+                    }
+                    // 1.0, 1e-1, 1e+1
+                    if let Some((digits, suffix)) = parse_lit_float(&repr) {
+                        return Lit::Float(LitFloat {
+                            repr: Box::new(LitFloatRepr {
+                                token,
+                                digits,
+                                suffix,
+                            }),
+                        });
+                    }
+                }
+                // true, false
+                b't' | b'f' => {
+                    if repr == "true" || repr == "false" {
+                        return Lit::Bool(LitBool {
+                            value: repr == "true",
+                            span: token.span(),
+                        });
+                    }
+                }
+                // c"...", cr"...", cr#"..."#
+                // TODO: add a Lit::CStr variant?
+                b'c' => return Lit::Verbatim(token),
+                b'(' if repr == "(/*ERROR*/)" => return Lit::Verbatim(token),
+                _ => {}
+            }
+
+            panic!("Unrecognized literal: `{}`", repr);
+        }
+
+        pub fn suffix(&self) -> &str {
+            match self {
+                Lit::Str(lit) => lit.suffix(),
+                Lit::ByteStr(lit) => lit.suffix(),
+                Lit::Byte(lit) => lit.suffix(),
+                Lit::Char(lit) => lit.suffix(),
+                Lit::Int(lit) => lit.suffix(),
+                Lit::Float(lit) => lit.suffix(),
+                Lit::Bool(_) | Lit::Verbatim(_) => "",
+            }
+        }
+
+        pub fn span(&self) -> Span {
+            match self {
+                Lit::Str(lit) => lit.span(),
+                Lit::ByteStr(lit) => lit.span(),
+                Lit::Byte(lit) => lit.span(),
+                Lit::Char(lit) => lit.span(),
+                Lit::Int(lit) => lit.span(),
+                Lit::Float(lit) => lit.span(),
+                Lit::Bool(lit) => lit.span,
+                Lit::Verbatim(lit) => lit.span(),
+            }
+        }
+
+        pub fn set_span(&mut self, span: Span) {
+            match self {
+                Lit::Str(lit) => lit.set_span(span),
+                Lit::ByteStr(lit) => lit.set_span(span),
+                Lit::Byte(lit) => lit.set_span(span),
+                Lit::Char(lit) => lit.set_span(span),
+                Lit::Int(lit) => lit.set_span(span),
+                Lit::Float(lit) => lit.set_span(span),
+                Lit::Bool(lit) => lit.span = span,
+                Lit::Verbatim(lit) => lit.set_span(span),
+            }
+        }
+    }
+
+    /// Get the byte at offset idx, or a default of `b'\0'` if we're looking
+    /// past the end of the input buffer.
+    pub(crate) fn byte<S: AsRef<[u8]> + ?Sized>(s: &S, idx: usize) -> u8 {
+        let s = s.as_ref();
+        if idx < s.len() {
+            s[idx]
+        } else {
+            0
+        }
+    }
+
+    fn next_chr(s: &str) -> char {
+        s.chars().next().unwrap_or('\0')
+    }
+
+    // Returns (content, suffix).
+    pub(crate) fn parse_lit_str(s: &str) -> (Box<str>, Box<str>) {
+        match byte(s, 0) {
+            b'"' => parse_lit_str_cooked(s),
+            b'r' => parse_lit_str_raw(s),
+            _ => unreachable!(),
+        }
+    }
+
+    // Clippy false positive
+    // https://github.com/rust-lang-nursery/rust-clippy/issues/2329
+    #[allow(clippy::needless_continue)]
+    fn parse_lit_str_cooked(mut s: &str) -> (Box<str>, Box<str>) {
+        assert_eq!(byte(s, 0), b'"');
+        s = &s[1..];
+
+        let mut content = String::new();
+        'outer: loop {
+            let ch = match byte(s, 0) {
+                b'"' => break,
+                b'\\' => {
+                    let b = byte(s, 1);
+                    s = &s[2..];
+                    match b {
+                        b'x' => {
+                            let (byte, rest) = backslash_x(s);
+                            s = rest;
+                            assert!(byte <= 0x7F, "Invalid \\x byte in string literal");
+                            char::from_u32(u32::from(byte)).unwrap()
+                        }
+                        b'u' => {
+                            let (chr, rest) = backslash_u(s);
+                            s = rest;
+                            chr
+                        }
+                        b'n' => '\n',
+                        b'r' => '\r',
+                        b't' => '\t',
+                        b'\\' => '\\',
+                        b'0' => '\0',
+                        b'\'' => '\'',
+                        b'"' => '"',
+                        b'\r' | b'\n' => loop {
+                            let b = byte(s, 0);
+                            match b {
+                                b' ' | b'\t' | b'\n' | b'\r' => s = &s[1..],
+                                _ => continue 'outer,
+                            }
+                        },
+                        b => panic!("unexpected byte {:?} after \\ character in byte literal", b),
+                    }
+                }
+                b'\r' => {
+                    assert_eq!(byte(s, 1), b'\n', "Bare CR not allowed in string");
+                    s = &s[2..];
+                    '\n'
+                }
+                _ => {
+                    let ch = next_chr(s);
+                    s = &s[ch.len_utf8()..];
+                    ch
+                }
+            };
+            content.push(ch);
+        }
+
+        assert!(s.starts_with('"'));
+        let content = content.into_boxed_str();
+        let suffix = s[1..].to_owned().into_boxed_str();
+        (content, suffix)
+    }
+
+    fn parse_lit_str_raw(mut s: &str) -> (Box<str>, Box<str>) {
+        assert_eq!(byte(s, 0), b'r');
+        s = &s[1..];
+
+        let mut pounds = 0;
+        while byte(s, pounds) == b'#' {
+            pounds += 1;
+        }
+        assert_eq!(byte(s, pounds), b'"');
+        let close = s.rfind('"').unwrap();
+        for end in s[close + 1..close + 1 + pounds].bytes() {
+            assert_eq!(end, b'#');
+        }
+
+        let content = s[pounds + 1..close].to_owned().into_boxed_str();
+        let suffix = s[close + 1 + pounds..].to_owned().into_boxed_str();
+        (content, suffix)
+    }
+
+    // Returns (content, suffix).
+    pub(crate) fn parse_lit_byte_str(s: &str) -> (Vec<u8>, Box<str>) {
+        assert_eq!(byte(s, 0), b'b');
+        match byte(s, 1) {
+            b'"' => parse_lit_byte_str_cooked(s),
+            b'r' => parse_lit_byte_str_raw(s),
+            _ => unreachable!(),
+        }
+    }
+
+    // Clippy false positive
+    // https://github.com/rust-lang-nursery/rust-clippy/issues/2329
+    #[allow(clippy::needless_continue)]
+    fn parse_lit_byte_str_cooked(mut s: &str) -> (Vec<u8>, Box<str>) {
+        assert_eq!(byte(s, 0), b'b');
+        assert_eq!(byte(s, 1), b'"');
+        s = &s[2..];
+
+        // We're going to want to have slices which don't respect codepoint boundaries.
+        let mut v = s.as_bytes();
+
+        let mut out = Vec::new();
+        'outer: loop {
+            let byte = match byte(v, 0) {
+                b'"' => break,
+                b'\\' => {
+                    let b = byte(v, 1);
+                    v = &v[2..];
+                    match b {
+                        b'x' => {
+                            let (b, rest) = backslash_x(v);
+                            v = rest;
+                            b
+                        }
+                        b'n' => b'\n',
+                        b'r' => b'\r',
+                        b't' => b'\t',
+                        b'\\' => b'\\',
+                        b'0' => b'\0',
+                        b'\'' => b'\'',
+                        b'"' => b'"',
+                        b'\r' | b'\n' => loop {
+                            let byte = byte(v, 0);
+                            if matches!(byte, b' ' | b'\t' | b'\n' | b'\r') {
+                                v = &v[1..];
+                            } else {
+                                continue 'outer;
+                            }
+                        },
+                        b => panic!("unexpected byte {:?} after \\ character in byte literal", b),
+                    }
+                }
+                b'\r' => {
+                    assert_eq!(byte(v, 1), b'\n', "Bare CR not allowed in string");
+                    v = &v[2..];
+                    b'\n'
+                }
+                b => {
+                    v = &v[1..];
+                    b
+                }
+            };
+            out.push(byte);
+        }
+
+        assert_eq!(byte(v, 0), b'"');
+        let suffix = s[s.len() - v.len() + 1..].to_owned().into_boxed_str();
+        (out, suffix)
+    }
+
+    fn parse_lit_byte_str_raw(s: &str) -> (Vec<u8>, Box<str>) {
+        assert_eq!(byte(s, 0), b'b');
+        let (value, suffix) = parse_lit_str_raw(&s[1..]);
+        (String::from(value).into_bytes(), suffix)
+    }
+
+    // Returns (value, suffix).
+    pub(crate) fn parse_lit_byte(s: &str) -> (u8, Box<str>) {
+        assert_eq!(byte(s, 0), b'b');
+        assert_eq!(byte(s, 1), b'\'');
+
+        // We're going to want to have slices which don't respect codepoint boundaries.
+        let mut v = s[2..].as_bytes();
+
+        let b = match byte(v, 0) {
+            b'\\' => {
+                let b = byte(v, 1);
+                v = &v[2..];
+                match b {
+                    b'x' => {
+                        let (b, rest) = backslash_x(v);
+                        v = rest;
+                        b
+                    }
+                    b'n' => b'\n',
+                    b'r' => b'\r',
+                    b't' => b'\t',
+                    b'\\' => b'\\',
+                    b'0' => b'\0',
+                    b'\'' => b'\'',
+                    b'"' => b'"',
+                    b => panic!("unexpected byte {:?} after \\ character in byte literal", b),
+                }
+            }
+            b => {
+                v = &v[1..];
+                b
+            }
+        };
+
+        assert_eq!(byte(v, 0), b'\'');
+        let suffix = s[s.len() - v.len() + 1..].to_owned().into_boxed_str();
+        (b, suffix)
+    }
+
+    // Returns (value, suffix).
+    pub(crate) fn parse_lit_char(mut s: &str) -> (char, Box<str>) {
+        assert_eq!(byte(s, 0), b'\'');
+        s = &s[1..];
+
+        let ch = match byte(s, 0) {
+            b'\\' => {
+                let b = byte(s, 1);
+                s = &s[2..];
+                match b {
+                    b'x' => {
+                        let (byte, rest) = backslash_x(s);
+                        s = rest;
+                        assert!(byte <= 0x80, "Invalid \\x byte in string literal");
+                        char::from_u32(u32::from(byte)).unwrap()
+                    }
+                    b'u' => {
+                        let (chr, rest) = backslash_u(s);
+                        s = rest;
+                        chr
+                    }
+                    b'n' => '\n',
+                    b'r' => '\r',
+                    b't' => '\t',
+                    b'\\' => '\\',
+                    b'0' => '\0',
+                    b'\'' => '\'',
+                    b'"' => '"',
+                    b => panic!("unexpected byte {:?} after \\ character in byte literal", b),
+                }
+            }
+            _ => {
+                let ch = next_chr(s);
+                s = &s[ch.len_utf8()..];
+                ch
+            }
+        };
+        assert_eq!(byte(s, 0), b'\'');
+        let suffix = s[1..].to_owned().into_boxed_str();
+        (ch, suffix)
+    }
+
+    fn backslash_x<S>(s: &S) -> (u8, &S)
+    where
+        S: Index<RangeFrom<usize>, Output = S> + AsRef<[u8]> + ?Sized,
+    {
+        let mut ch = 0;
+        let b0 = byte(s, 0);
+        let b1 = byte(s, 1);
+        ch += 0x10
+            * match b0 {
+                b'0'..=b'9' => b0 - b'0',
+                b'a'..=b'f' => 10 + (b0 - b'a'),
+                b'A'..=b'F' => 10 + (b0 - b'A'),
+                _ => panic!("unexpected non-hex character after \\x"),
+            };
+        ch += match b1 {
+            b'0'..=b'9' => b1 - b'0',
+            b'a'..=b'f' => 10 + (b1 - b'a'),
+            b'A'..=b'F' => 10 + (b1 - b'A'),
+            _ => panic!("unexpected non-hex character after \\x"),
+        };
+        (ch, &s[2..])
+    }
+
+    fn backslash_u(mut s: &str) -> (char, &str) {
+        if byte(s, 0) != b'{' {
+            panic!("{}", "expected { after \\u");
+        }
+        s = &s[1..];
+
+        let mut ch = 0;
+        let mut digits = 0;
+        loop {
+            let b = byte(s, 0);
+            let digit = match b {
+                b'0'..=b'9' => b - b'0',
+                b'a'..=b'f' => 10 + b - b'a',
+                b'A'..=b'F' => 10 + b - b'A',
+                b'_' if digits > 0 => {
+                    s = &s[1..];
+                    continue;
+                }
+                b'}' if digits == 0 => panic!("invalid empty unicode escape"),
+                b'}' => break,
+                _ => panic!("unexpected non-hex character after \\u"),
+            };
+            if digits == 6 {
+                panic!("overlong unicode escape (must have at most 6 hex digits)");
+            }
+            ch *= 0x10;
+            ch += u32::from(digit);
+            digits += 1;
+            s = &s[1..];
+        }
+        assert!(byte(s, 0) == b'}');
+        s = &s[1..];
+
+        if let Some(ch) = char::from_u32(ch) {
+            (ch, s)
+        } else {
+            panic!("character code {:x} is not a valid unicode character", ch);
+        }
+    }
+
+    // Returns base 10 digits and suffix.
+    pub(crate) fn parse_lit_int(mut s: &str) -> Option<(Box<str>, Box<str>)> {
+        let negative = byte(s, 0) == b'-';
+        if negative {
+            s = &s[1..];
+        }
+
+        let base = match (byte(s, 0), byte(s, 1)) {
+            (b'0', b'x') => {
+                s = &s[2..];
+                16
+            }
+            (b'0', b'o') => {
+                s = &s[2..];
+                8
+            }
+            (b'0', b'b') => {
+                s = &s[2..];
+                2
+            }
+            (b'0'..=b'9', _) => 10,
+            _ => return None,
+        };
+
+        let mut value = BigInt::new();
+        let mut has_digit = false;
+        'outer: loop {
+            let b = byte(s, 0);
+            let digit = match b {
+                b'0'..=b'9' => b - b'0',
+                b'a'..=b'f' if base > 10 => b - b'a' + 10,
+                b'A'..=b'F' if base > 10 => b - b'A' + 10,
+                b'_' => {
+                    s = &s[1..];
+                    continue;
+                }
+                // If looking at a floating point literal, we don't want to
+                // consider it an integer.
+                b'.' if base == 10 => return None,
+                b'e' | b'E' if base == 10 => {
+                    let mut has_exp = false;
+                    for (i, b) in s[1..].bytes().enumerate() {
+                        match b {
+                            b'_' => {}
+                            b'-' | b'+' => return None,
+                            b'0'..=b'9' => has_exp = true,
+                            _ => {
+                                let suffix = &s[1 + i..];
+                                if has_exp && crate::ident::xid_ok(suffix) {
+                                    return None;
+                                } else {
+                                    break 'outer;
+                                }
+                            }
+                        }
+                    }
+                    if has_exp {
+                        return None;
+                    } else {
+                        break;
+                    }
+                }
+                _ => break,
+            };
+
+            if digit >= base {
+                return None;
+            }
+
+            has_digit = true;
+            value *= base;
+            value += digit;
+            s = &s[1..];
+        }
+
+        if !has_digit {
+            return None;
+        }
+
+        let suffix = s;
+        if suffix.is_empty() || crate::ident::xid_ok(suffix) {
+            let mut repr = value.to_string();
+            if negative {
+                repr.insert(0, '-');
+            }
+            Some((repr.into_boxed_str(), suffix.to_owned().into_boxed_str()))
+        } else {
+            None
+        }
+    }
+
+    // Returns base 10 digits and suffix.
+    pub(crate) fn parse_lit_float(input: &str) -> Option<(Box<str>, Box<str>)> {
+        // Rust's floating point literals are very similar to the ones parsed by
+        // the standard library, except that rust's literals can contain
+        // ignorable underscores. Let's remove those underscores.
+
+        let mut bytes = input.to_owned().into_bytes();
+
+        let start = (*bytes.first()? == b'-') as usize;
+        match bytes.get(start)? {
+            b'0'..=b'9' => {}
+            _ => return None,
+        }
+
+        let mut read = start;
+        let mut write = start;
+        let mut has_dot = false;
+        let mut has_e = false;
+        let mut has_sign = false;
+        let mut has_exponent = false;
+        while read < bytes.len() {
+            match bytes[read] {
+                b'_' => {
+                    // Don't increase write
+                    read += 1;
+                    continue;
+                }
+                b'0'..=b'9' => {
+                    if has_e {
+                        has_exponent = true;
+                    }
+                    bytes[write] = bytes[read];
+                }
+                b'.' => {
+                    if has_e || has_dot {
+                        return None;
+                    }
+                    has_dot = true;
+                    bytes[write] = b'.';
+                }
+                b'e' | b'E' => {
+                    match bytes[read + 1..]
+                        .iter()
+                        .find(|b| **b != b'_')
+                        .unwrap_or(&b'\0')
+                    {
+                        b'-' | b'+' | b'0'..=b'9' => {}
+                        _ => break,
+                    }
+                    if has_e {
+                        if has_exponent {
+                            break;
+                        } else {
+                            return None;
+                        }
+                    }
+                    has_e = true;
+                    bytes[write] = b'e';
+                }
+                b'-' | b'+' => {
+                    if has_sign || has_exponent || !has_e {
+                        return None;
+                    }
+                    has_sign = true;
+                    if bytes[read] == b'-' {
+                        bytes[write] = bytes[read];
+                    } else {
+                        // Omit '+'
+                        read += 1;
+                        continue;
+                    }
+                }
+                _ => break,
+            }
+            read += 1;
+            write += 1;
+        }
+
+        if has_e && !has_exponent {
+            return None;
+        }
+
+        let mut digits = String::from_utf8(bytes).unwrap();
+        let suffix = digits.split_off(read);
+        digits.truncate(write);
+        if suffix.is_empty() || crate::ident::xid_ok(&suffix) {
+            Some((digits.into_boxed_str(), suffix.into_boxed_str()))
+        } else {
+            None
+        }
+    }
+}
diff --git a/rust/syn/lookahead.rs b/rust/syn/lookahead.rs
new file mode 100644
index 0000000000000000000000000000000000000000..d86d4cd565bd6504ef38f59e5a336f27c7ccdfc9
--- /dev/null
+++ b/rust/syn/lookahead.rs
@@ -0,0 +1,171 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::buffer::Cursor;
+use crate::error::{self, Error};
+use crate::sealed::lookahead::Sealed;
+use crate::span::IntoSpans;
+use crate::token::Token;
+use proc_macro2::{Delimiter, Span};
+use std::cell::RefCell;
+
+/// Support for checking the next token in a stream to decide how to parse.
+///
+/// An important advantage over [`ParseStream::peek`] is that here we
+/// automatically construct an appropriate error message based on the token
+/// alternatives that get peeked. If you are producing your own error message,
+/// go ahead and use `ParseStream::peek` instead.
+///
+/// Use [`ParseStream::lookahead1`] to construct this object.
+///
+/// [`ParseStream::peek`]: crate::parse::ParseBuffer::peek
+/// [`ParseStream::lookahead1`]: crate::parse::ParseBuffer::lookahead1
+///
+/// Consuming tokens from the source stream after constructing a lookahead
+/// object does not also advance the lookahead object.
+///
+/// # Example
+///
+/// ```
+/// use syn::{ConstParam, Ident, Lifetime, LifetimeParam, Result, Token, TypeParam};
+/// use syn::parse::{Parse, ParseStream};
+///
+/// // A generic parameter, a single one of the comma-separated elements inside
+/// // angle brackets in:
+/// //
+/// //     fn f<T: Clone, 'a, 'b: 'a, const N: usize>() { ... }
+/// //
+/// // On invalid input, lookahead gives us a reasonable error message.
+/// //
+/// //     error: expected one of: identifier, lifetime, `const`
+/// //       |
+/// //     5 |     fn f<!Sized>() {}
+/// //       |          ^
+/// enum GenericParam {
+///     Type(TypeParam),
+///     Lifetime(LifetimeParam),
+///     Const(ConstParam),
+/// }
+///
+/// impl Parse for GenericParam {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         let lookahead = input.lookahead1();
+///         if lookahead.peek(Ident) {
+///             input.parse().map(GenericParam::Type)
+///         } else if lookahead.peek(Lifetime) {
+///             input.parse().map(GenericParam::Lifetime)
+///         } else if lookahead.peek(Token![const]) {
+///             input.parse().map(GenericParam::Const)
+///         } else {
+///             Err(lookahead.error())
+///         }
+///     }
+/// }
+/// ```
+pub struct Lookahead1<'a> {
+    scope: Span,
+    cursor: Cursor<'a>,
+    comparisons: RefCell<Vec<&'static str>>,
+}
+
+pub(crate) fn new(scope: Span, cursor: Cursor) -> Lookahead1 {
+    Lookahead1 {
+        scope,
+        cursor,
+        comparisons: RefCell::new(Vec::new()),
+    }
+}
+
+fn peek_impl(
+    lookahead: &Lookahead1,
+    peek: fn(Cursor) -> bool,
+    display: fn() -> &'static str,
+) -> bool {
+    if peek(lookahead.cursor) {
+        return true;
+    }
+    lookahead.comparisons.borrow_mut().push(display());
+    false
+}
+
+impl<'a> Lookahead1<'a> {
+    /// Looks at the next token in the parse stream to determine whether it
+    /// matches the requested type of token.
+    ///
+    /// # Syntax
+    ///
+    /// Note that this method does not use turbofish syntax. Pass the peek type
+    /// inside of parentheses.
+    ///
+    /// - `input.peek(Token![struct])`
+    /// - `input.peek(Token![==])`
+    /// - `input.peek(Ident)`&emsp;*(does not accept keywords)*
+    /// - `input.peek(Ident::peek_any)`
+    /// - `input.peek(Lifetime)`
+    /// - `input.peek(token::Brace)`
+    pub fn peek<T: Peek>(&self, token: T) -> bool {
+        let _ = token;
+        peek_impl(self, T::Token::peek, T::Token::display)
+    }
+
+    /// Triggers an error at the current position of the parse stream.
+    ///
+    /// The error message will identify all of the expected token types that
+    /// have been peeked against this lookahead instance.
+    pub fn error(self) -> Error {
+        let comparisons = self.comparisons.borrow();
+        match comparisons.len() {
+            0 => {
+                if self.cursor.eof() {
+                    Error::new(self.scope, "unexpected end of input")
+                } else {
+                    Error::new(self.cursor.span(), "unexpected token")
+                }
+            }
+            1 => {
+                let message = format!("expected {}", comparisons[0]);
+                error::new_at(self.scope, self.cursor, message)
+            }
+            2 => {
+                let message = format!("expected {} or {}", comparisons[0], comparisons[1]);
+                error::new_at(self.scope, self.cursor, message)
+            }
+            _ => {
+                let join = comparisons.join(", ");
+                let message = format!("expected one of: {}", join);
+                error::new_at(self.scope, self.cursor, message)
+            }
+        }
+    }
+}
+
+/// Types that can be parsed by looking at just one token.
+///
+/// Use [`ParseStream::peek`] to peek one of these types in a parse stream
+/// without consuming it from the stream.
+///
+/// This trait is sealed and cannot be implemented for types outside of Syn.
+///
+/// [`ParseStream::peek`]: crate::parse::ParseBuffer::peek
+pub trait Peek: Sealed {
+    // Not public API.
+    #[doc(hidden)]
+    type Token: Token;
+}
+
+impl<F: Copy + FnOnce(TokenMarker) -> T, T: Token> Peek for F {
+    type Token = T;
+}
+
+pub enum TokenMarker {}
+
+impl<S> IntoSpans<S> for TokenMarker {
+    fn into_spans(self) -> S {
+        match self {}
+    }
+}
+
+pub(crate) fn is_delimiter(cursor: Cursor, delimiter: Delimiter) -> bool {
+    cursor.group(delimiter).is_some()
+}
+
+impl<F: Copy + FnOnce(TokenMarker) -> T, T: Token> Sealed for F {}
diff --git a/rust/syn/mac.rs b/rust/syn/mac.rs
new file mode 100644
index 0000000000000000000000000000000000000000..e617a059ce8dd1ae3ed9bd19d2978e884c035aa8
--- /dev/null
+++ b/rust/syn/mac.rs
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "parsing")]
+use crate::error::Result;
+#[cfg(feature = "parsing")]
+use crate::parse::{Parse, ParseStream, Parser};
+use crate::path::Path;
+use crate::token::{Brace, Bracket, Paren};
+use proc_macro2::extra::DelimSpan;
+#[cfg(feature = "parsing")]
+use proc_macro2::Delimiter;
+use proc_macro2::TokenStream;
+#[cfg(feature = "parsing")]
+use proc_macro2::TokenTree;
+
+ast_struct! {
+    /// A macro invocation: `println!("{}", mac)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct Macro {
+        pub path: Path,
+        pub bang_token: Token![!],
+        pub delimiter: MacroDelimiter,
+        pub tokens: TokenStream,
+    }
+}
+
+ast_enum! {
+    /// A grouping token that surrounds a macro body: `m!(...)` or `m!{...}` or `m![...]`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum MacroDelimiter {
+        Paren(Paren),
+        Brace(Brace),
+        Bracket(Bracket),
+    }
+}
+
+impl MacroDelimiter {
+    pub fn span(&self) -> &DelimSpan {
+        match self {
+            MacroDelimiter::Paren(token) => &token.span,
+            MacroDelimiter::Brace(token) => &token.span,
+            MacroDelimiter::Bracket(token) => &token.span,
+        }
+    }
+}
+
+impl Macro {
+    /// Parse the tokens within the macro invocation's delimiters into a syntax
+    /// tree.
+    ///
+    /// This is equivalent to `syn::parse2::<T>(mac.tokens)` except that it
+    /// produces a more useful span when `tokens` is empty.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{parse_quote, Expr, ExprLit, Ident, Lit, LitStr, Macro, Token};
+    /// use syn::ext::IdentExt;
+    /// use syn::parse::{Error, Parse, ParseStream, Result};
+    /// use syn::punctuated::Punctuated;
+    ///
+    /// // The arguments expected by libcore's format_args macro, and as a
+    /// // result most other formatting and printing macros like println.
+    /// //
+    /// //     println!("{} is {number:.prec$}", "x", prec=5, number=0.01)
+    /// struct FormatArgs {
+    ///     format_string: Expr,
+    ///     positional_args: Vec<Expr>,
+    ///     named_args: Vec<(Ident, Expr)>,
+    /// }
+    ///
+    /// impl Parse for FormatArgs {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         let format_string: Expr;
+    ///         let mut positional_args = Vec::new();
+    ///         let mut named_args = Vec::new();
+    ///
+    ///         format_string = input.parse()?;
+    ///         while !input.is_empty() {
+    ///             input.parse::<Token![,]>()?;
+    ///             if input.is_empty() {
+    ///                 break;
+    ///             }
+    ///             if input.peek(Ident::peek_any) && input.peek2(Token![=]) {
+    ///                 while !input.is_empty() {
+    ///                     let name: Ident = input.call(Ident::parse_any)?;
+    ///                     input.parse::<Token![=]>()?;
+    ///                     let value: Expr = input.parse()?;
+    ///                     named_args.push((name, value));
+    ///                     if input.is_empty() {
+    ///                         break;
+    ///                     }
+    ///                     input.parse::<Token![,]>()?;
+    ///                 }
+    ///                 break;
+    ///             }
+    ///             positional_args.push(input.parse()?);
+    ///         }
+    ///
+    ///         Ok(FormatArgs {
+    ///             format_string,
+    ///             positional_args,
+    ///             named_args,
+    ///         })
+    ///     }
+    /// }
+    ///
+    /// // Extract the first argument, the format string literal, from an
+    /// // invocation of a formatting or printing macro.
+    /// fn get_format_string(m: &Macro) -> Result<LitStr> {
+    ///     let args: FormatArgs = m.parse_body()?;
+    ///     match args.format_string {
+    ///         Expr::Lit(ExprLit { lit: Lit::Str(lit), .. }) => Ok(lit),
+    ///         other => {
+    ///             // First argument was not a string literal expression.
+    ///             // Maybe something like: println!(concat!(...), ...)
+    ///             Err(Error::new_spanned(other, "format string must be a string literal"))
+    ///         }
+    ///     }
+    /// }
+    ///
+    /// fn main() {
+    ///     let invocation = parse_quote! {
+    ///         println!("{:?}", Instant::now())
+    ///     };
+    ///     let lit = get_format_string(&invocation).unwrap();
+    ///     assert_eq!(lit.value(), "{:?}");
+    /// }
+    /// ```
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_body<T: Parse>(&self) -> Result<T> {
+        self.parse_body_with(T::parse)
+    }
+
+    /// Parse the tokens within the macro invocation's delimiters using the
+    /// given parser.
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_body_with<F: Parser>(&self, parser: F) -> Result<F::Output> {
+        let scope = self.delimiter.span().close();
+        crate::parse::parse_scoped(parser, scope, self.tokens.clone())
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) fn parse_delimiter(input: ParseStream) -> Result<(MacroDelimiter, TokenStream)> {
+    input.step(|cursor| {
+        if let Some((TokenTree::Group(g), rest)) = cursor.token_tree() {
+            let span = g.delim_span();
+            let delimiter = match g.delimiter() {
+                Delimiter::Parenthesis => MacroDelimiter::Paren(Paren(span)),
+                Delimiter::Brace => MacroDelimiter::Brace(Brace(span)),
+                Delimiter::Bracket => MacroDelimiter::Bracket(Bracket(span)),
+                Delimiter::None => {
+                    return Err(cursor.error("expected delimiter"));
+                }
+            };
+            Ok(((delimiter, g.stream()), rest))
+        } else {
+            Err(cursor.error("expected delimiter"))
+        }
+    })
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::error::Result;
+    use crate::mac::{parse_delimiter, Macro};
+    use crate::parse::{Parse, ParseStream};
+    use crate::path::Path;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Macro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let tokens;
+            Ok(Macro {
+                path: input.call(Path::parse_mod_style)?,
+                bang_token: input.parse()?,
+                delimiter: {
+                    let (delimiter, content) = parse_delimiter(input)?;
+                    tokens = content;
+                    delimiter
+                },
+                tokens,
+            })
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::mac::{Macro, MacroDelimiter};
+    use crate::token;
+    use proc_macro2::{Delimiter, TokenStream};
+    use quote::ToTokens;
+
+    impl MacroDelimiter {
+        pub(crate) fn surround(&self, tokens: &mut TokenStream, inner: TokenStream) {
+            let (delim, span) = match self {
+                MacroDelimiter::Paren(paren) => (Delimiter::Parenthesis, paren.span),
+                MacroDelimiter::Brace(brace) => (Delimiter::Brace, brace.span),
+                MacroDelimiter::Bracket(bracket) => (Delimiter::Bracket, bracket.span),
+            };
+            token::printing::delim(delim, span.join(), tokens, inner);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Macro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.path.to_tokens(tokens);
+            self.bang_token.to_tokens(tokens);
+            self.delimiter.surround(tokens, self.tokens.clone());
+        }
+    }
+}
diff --git a/rust/syn/macros.rs b/rust/syn/macros.rs
new file mode 100644
index 0000000000000000000000000000000000000000..3511bac971e101e451204587776ce12573fad419
--- /dev/null
+++ b/rust/syn/macros.rs
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg_attr(
+    not(any(feature = "full", feature = "derive")),
+    allow(unknown_lints, unused_macro_rules)
+)]
+macro_rules! ast_struct {
+    (
+        $(#[$attr:meta])*
+        $pub:ident $struct:ident $name:ident #full $body:tt
+    ) => {
+        check_keyword_matches!(pub $pub);
+        check_keyword_matches!(struct $struct);
+
+        #[cfg(feature = "full")]
+        $(#[$attr])* $pub $struct $name $body
+
+        #[cfg(not(feature = "full"))]
+        $(#[$attr])* $pub $struct $name {
+            _noconstruct: ::std::marker::PhantomData<::proc_macro2::Span>,
+        }
+
+        #[cfg(all(not(feature = "full"), feature = "printing"))]
+        impl ::quote::ToTokens for $name {
+            fn to_tokens(&self, _: &mut ::proc_macro2::TokenStream) {
+                unreachable!()
+            }
+        }
+    };
+
+    (
+        $(#[$attr:meta])*
+        $pub:ident $struct:ident $name:ident $body:tt
+    ) => {
+        check_keyword_matches!(pub $pub);
+        check_keyword_matches!(struct $struct);
+
+        $(#[$attr])* $pub $struct $name $body
+    };
+}
+
+#[cfg(any(feature = "full", feature = "derive"))]
+macro_rules! ast_enum {
+    (
+        $(#[$enum_attr:meta])*
+        $pub:ident $enum:ident $name:ident $body:tt
+    ) => {
+        check_keyword_matches!(pub $pub);
+        check_keyword_matches!(enum $enum);
+
+        $(#[$enum_attr])* $pub $enum $name $body
+    };
+}
+
+macro_rules! ast_enum_of_structs {
+    (
+        $(#[$enum_attr:meta])*
+        $pub:ident $enum:ident $name:ident $body:tt
+    ) => {
+        check_keyword_matches!(pub $pub);
+        check_keyword_matches!(enum $enum);
+
+        $(#[$enum_attr])* $pub $enum $name $body
+
+        ast_enum_of_structs_impl!($name $body);
+    };
+}
+
+macro_rules! ast_enum_of_structs_impl {
+    (
+        $name:ident {
+            $(
+                $(#[cfg $cfg_attr:tt])*
+                $(#[doc $($doc_attr:tt)*])*
+                $variant:ident $( ($($member:ident)::+) )*,
+            )*
+        }
+    ) => {
+        $($(
+            ast_enum_from_struct!($name::$variant, $($member)::+);
+        )*)*
+
+        #[cfg(feature = "printing")]
+        generate_to_tokens! {
+            ()
+            tokens
+            $name {
+                $(
+                    $(#[cfg $cfg_attr])*
+                    $(#[doc $($doc_attr)*])*
+                    $variant $($($member)::+)*,
+                )*
+            }
+        }
+    };
+}
+
+macro_rules! ast_enum_from_struct {
+    // No From<TokenStream> for verbatim variants.
+    ($name:ident::Verbatim, $member:ident) => {};
+
+    ($name:ident::$variant:ident, $member:ident) => {
+        impl From<$member> for $name {
+            fn from(e: $member) -> $name {
+                $name::$variant(e)
+            }
+        }
+    };
+}
+
+#[cfg(feature = "printing")]
+macro_rules! generate_to_tokens {
+    (
+        ($($arms:tt)*) $tokens:ident $name:ident {
+            $(#[cfg $cfg_attr:tt])*
+            $(#[doc $($doc_attr:tt)*])*
+            $variant:ident,
+            $($next:tt)*
+        }
+    ) => {
+        generate_to_tokens!(
+            ($($arms)* $(#[cfg $cfg_attr])* $name::$variant => {})
+            $tokens $name { $($next)* }
+        );
+    };
+
+    (
+        ($($arms:tt)*) $tokens:ident $name:ident {
+            $(#[cfg $cfg_attr:tt])*
+            $(#[doc $($doc_attr:tt)*])*
+            $variant:ident $member:ident,
+            $($next:tt)*
+        }
+    ) => {
+        generate_to_tokens!(
+            ($($arms)* $(#[cfg $cfg_attr])* $name::$variant(_e) => _e.to_tokens($tokens),)
+            $tokens $name { $($next)* }
+        );
+    };
+
+    (($($arms:tt)*) $tokens:ident $name:ident {}) => {
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+        impl ::quote::ToTokens for $name {
+            fn to_tokens(&self, $tokens: &mut ::proc_macro2::TokenStream) {
+                match self {
+                    $($arms)*
+                }
+            }
+        }
+    };
+}
+
+// Rustdoc bug: does not respect the doc(hidden) on some items.
+#[cfg(all(doc, feature = "parsing"))]
+macro_rules! pub_if_not_doc {
+    ($(#[$m:meta])* $pub:ident $($item:tt)*) => {
+        check_keyword_matches!(pub $pub);
+
+        $(#[$m])*
+        $pub(crate) $($item)*
+    };
+}
+
+#[cfg(all(not(doc), feature = "parsing"))]
+macro_rules! pub_if_not_doc {
+    ($(#[$m:meta])* $pub:ident $($item:tt)*) => {
+        check_keyword_matches!(pub $pub);
+
+        $(#[$m])*
+        $pub $($item)*
+    };
+}
+
+macro_rules! check_keyword_matches {
+    (enum enum) => {};
+    (pub pub) => {};
+    (struct struct) => {};
+}
diff --git a/rust/syn/meta.rs b/rust/syn/meta.rs
new file mode 100644
index 0000000000000000000000000000000000000000..2dd138e6dd55604648d17c7dc384766178a4ef4c
--- /dev/null
+++ b/rust/syn/meta.rs
@@ -0,0 +1,429 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! Facility for interpreting structured content inside of an `Attribute`.
+
+use crate::error::{Error, Result};
+use crate::ext::IdentExt as _;
+use crate::lit::Lit;
+use crate::parse::{ParseStream, Parser};
+use crate::path::{Path, PathSegment};
+use crate::punctuated::Punctuated;
+use proc_macro2::Ident;
+use std::fmt::Display;
+
+/// Make a parser that is usable with `parse_macro_input!` in a
+/// `#[proc_macro_attribute]` macro.
+///
+/// *Warning:* When parsing attribute args **other than** the
+/// `proc_macro::TokenStream` input of a `proc_macro_attribute`, you do **not**
+/// need this function. In several cases your callers will get worse error
+/// messages if you use this function, because the surrounding delimiter's span
+/// is concealed from attribute macros by rustc. Use
+/// [`Attribute::parse_nested_meta`] instead.
+///
+/// [`Attribute::parse_nested_meta`]: crate::Attribute::parse_nested_meta
+///
+/// # Example
+///
+/// This example implements an attribute macro whose invocations look like this:
+///
+/// ```
+/// # const IGNORE: &str = stringify! {
+/// #[tea(kind = "EarlGrey", hot)]
+/// struct Picard {...}
+/// # };
+/// ```
+///
+/// The "parameters" supported by the attribute are:
+///
+/// - `kind = "..."`
+/// - `hot`
+/// - `with(sugar, milk, ...)`, a comma-separated list of ingredients
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// use proc_macro::TokenStream;
+/// use syn::{parse_macro_input, LitStr, Path};
+///
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro_attribute]
+/// # };
+/// pub fn tea(args: TokenStream, input: TokenStream) -> TokenStream {
+///     let mut kind: Option<LitStr> = None;
+///     let mut hot: bool = false;
+///     let mut with: Vec<Path> = Vec::new();
+///     let tea_parser = syn::meta::parser(|meta| {
+///         if meta.path.is_ident("kind") {
+///             kind = Some(meta.value()?.parse()?);
+///             Ok(())
+///         } else if meta.path.is_ident("hot") {
+///             hot = true;
+///             Ok(())
+///         } else if meta.path.is_ident("with") {
+///             meta.parse_nested_meta(|meta| {
+///                 with.push(meta.path);
+///                 Ok(())
+///             })
+///         } else {
+///             Err(meta.error("unsupported tea property"))
+///         }
+///     });
+///
+///     parse_macro_input!(args with tea_parser);
+///     eprintln!("kind={kind:?} hot={hot} with={with:?}");
+///
+///     /* ... */
+/// #   TokenStream::new()
+/// }
+/// ```
+///
+/// The `syn::meta` library will take care of dealing with the commas including
+/// trailing commas, and producing sensible error messages on unexpected input.
+///
+/// ```console
+/// error: expected `,`
+///  --> src/main.rs:3:37
+///   |
+/// 3 | #[tea(kind = "EarlGrey", with(sugar = "lol", milk))]
+///   |                                     ^
+/// ```
+///
+/// # Example
+///
+/// Same as above but we factor out most of the logic into a separate function.
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// use proc_macro::TokenStream;
+/// use syn::meta::ParseNestedMeta;
+/// use syn::parse::{Parser, Result};
+/// use syn::{parse_macro_input, LitStr, Path};
+///
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro_attribute]
+/// # };
+/// pub fn tea(args: TokenStream, input: TokenStream) -> TokenStream {
+///     let mut attrs = TeaAttributes::default();
+///     let tea_parser = syn::meta::parser(|meta| attrs.parse(meta));
+///     parse_macro_input!(args with tea_parser);
+///
+///     /* ... */
+/// #   TokenStream::new()
+/// }
+///
+/// #[derive(Default)]
+/// struct TeaAttributes {
+///     kind: Option<LitStr>,
+///     hot: bool,
+///     with: Vec<Path>,
+/// }
+///
+/// impl TeaAttributes {
+///     fn parse(&mut self, meta: ParseNestedMeta) -> Result<()> {
+///         if meta.path.is_ident("kind") {
+///             self.kind = Some(meta.value()?.parse()?);
+///             Ok(())
+///         } else /* just like in last example */
+/// #           { unimplemented!() }
+///
+///     }
+/// }
+/// ```
+pub fn parser(logic: impl FnMut(ParseNestedMeta) -> Result<()>) -> impl Parser<Output = ()> {
+    |input: ParseStream| {
+        if input.is_empty() {
+            Ok(())
+        } else {
+            parse_nested_meta(input, logic)
+        }
+    }
+}
+
+/// Context for parsing a single property in the conventional syntax for
+/// structured attributes.
+///
+/// # Examples
+///
+/// Refer to usage examples on the following two entry-points:
+///
+/// - [`Attribute::parse_nested_meta`] if you have an entire `Attribute` to
+///   parse. Always use this if possible. Generally this is able to produce
+///   better error messages because `Attribute` holds span information for all
+///   of the delimiters therein.
+///
+/// - [`syn::meta::parser`] if you are implementing a `proc_macro_attribute`
+///   macro and parsing the arguments to the attribute macro, i.e. the ones
+///   written in the same attribute that dispatched the macro invocation. Rustc
+///   does not pass span information for the surrounding delimiters into the
+///   attribute macro invocation in this situation, so error messages might be
+///   less precise.
+///
+/// [`Attribute::parse_nested_meta`]: crate::Attribute::parse_nested_meta
+/// [`syn::meta::parser`]: crate::meta::parser
+#[non_exhaustive]
+pub struct ParseNestedMeta<'a> {
+    pub path: Path,
+    pub input: ParseStream<'a>,
+}
+
+impl<'a> ParseNestedMeta<'a> {
+    /// Used when parsing `key = "value"` syntax.
+    ///
+    /// All it does is advance `meta.input` past the `=` sign in the input. You
+    /// could accomplish the same effect by writing
+    /// `meta.parse::<Token![=]>()?`, so at most it is a minor convenience to
+    /// use `meta.value()?`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{parse_quote, Attribute, LitStr};
+    ///
+    /// let attr: Attribute = parse_quote! {
+    ///     #[tea(kind = "EarlGrey")]
+    /// };
+    ///                                          // conceptually:
+    /// if attr.path().is_ident("tea") {         // this parses the `tea`
+    ///     attr.parse_nested_meta(|meta| {      // this parses the `(`
+    ///         if meta.path.is_ident("kind") {  // this parses the `kind`
+    ///             let value = meta.value()?;   // this parses the `=`
+    ///             let s: LitStr = value.parse()?;  // this parses `"EarlGrey"`
+    ///             if s.value() == "EarlGrey" {
+    ///                 // ...
+    ///             }
+    ///             Ok(())
+    ///         } else {
+    ///             Err(meta.error("unsupported attribute"))
+    ///         }
+    ///     })?;
+    /// }
+    /// # anyhow::Ok(())
+    /// ```
+    pub fn value(&self) -> Result<ParseStream<'a>> {
+        self.input.parse::<Token![=]>()?;
+        Ok(self.input)
+    }
+
+    /// Used when parsing `list(...)` syntax **if** the content inside the
+    /// nested parentheses is also expected to conform to Rust's structured
+    /// attribute convention.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{parse_quote, Attribute};
+    ///
+    /// let attr: Attribute = parse_quote! {
+    ///     #[tea(with(sugar, milk))]
+    /// };
+    ///
+    /// if attr.path().is_ident("tea") {
+    ///     attr.parse_nested_meta(|meta| {
+    ///         if meta.path.is_ident("with") {
+    ///             meta.parse_nested_meta(|meta| {  // <---
+    ///                 if meta.path.is_ident("sugar") {
+    ///                     // Here we can go even deeper if needed.
+    ///                     Ok(())
+    ///                 } else if meta.path.is_ident("milk") {
+    ///                     Ok(())
+    ///                 } else {
+    ///                     Err(meta.error("unsupported ingredient"))
+    ///                 }
+    ///             })
+    ///         } else {
+    ///             Err(meta.error("unsupported tea property"))
+    ///         }
+    ///     })?;
+    /// }
+    /// # anyhow::Ok(())
+    /// ```
+    ///
+    /// # Counterexample
+    ///
+    /// If you don't need `parse_nested_meta`'s help in parsing the content
+    /// written within the nested parentheses, keep in mind that you can always
+    /// just parse it yourself from the exposed ParseStream. Rust syntax permits
+    /// arbitrary tokens within those parentheses so for the crazier stuff,
+    /// `parse_nested_meta` is not what you want.
+    ///
+    /// ```
+    /// use syn::{parenthesized, parse_quote, Attribute, LitInt};
+    ///
+    /// let attr: Attribute = parse_quote! {
+    ///     #[repr(align(32))]
+    /// };
+    ///
+    /// let mut align: Option<LitInt> = None;
+    /// if attr.path().is_ident("repr") {
+    ///     attr.parse_nested_meta(|meta| {
+    ///         if meta.path.is_ident("align") {
+    ///             let content;
+    ///             parenthesized!(content in meta.input);
+    ///             align = Some(content.parse()?);
+    ///             Ok(())
+    ///         } else {
+    ///             Err(meta.error("unsupported repr"))
+    ///         }
+    ///     })?;
+    /// }
+    /// # anyhow::Ok(())
+    /// ```
+    pub fn parse_nested_meta(
+        &self,
+        logic: impl FnMut(ParseNestedMeta) -> Result<()>,
+    ) -> Result<()> {
+        let content;
+        parenthesized!(content in self.input);
+        parse_nested_meta(&content, logic)
+    }
+
+    /// Report that the attribute's content did not conform to expectations.
+    ///
+    /// The span of the resulting error will cover `meta.path` *and* everything
+    /// that has been parsed so far since it.
+    ///
+    /// There are 2 ways you might call this. First, if `meta.path` is not
+    /// something you recognize:
+    ///
+    /// ```
+    /// # use syn::Attribute;
+    /// #
+    /// # fn example(attr: &Attribute) -> syn::Result<()> {
+    /// attr.parse_nested_meta(|meta| {
+    ///     if meta.path.is_ident("kind") {
+    ///         // ...
+    ///         Ok(())
+    ///     } else {
+    ///         Err(meta.error("unsupported tea property"))
+    ///     }
+    /// })?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    ///
+    /// In this case, it behaves exactly like
+    /// `syn::Error::new_spanned(&meta.path, "message...")`.
+    ///
+    /// ```console
+    /// error: unsupported tea property
+    ///  --> src/main.rs:3:26
+    ///   |
+    /// 3 | #[tea(kind = "EarlGrey", wat = "foo")]
+    ///   |                          ^^^
+    /// ```
+    ///
+    /// More usefully, the second place is if you've already parsed a value but
+    /// have decided not to accept the value:
+    ///
+    /// ```
+    /// # use syn::Attribute;
+    /// #
+    /// # fn example(attr: &Attribute) -> syn::Result<()> {
+    /// use syn::Expr;
+    ///
+    /// attr.parse_nested_meta(|meta| {
+    ///     if meta.path.is_ident("kind") {
+    ///         let expr: Expr = meta.value()?.parse()?;
+    ///         match expr {
+    ///             Expr::Lit(expr) => /* ... */
+    /// #               unimplemented!(),
+    ///             Expr::Path(expr) => /* ... */
+    /// #               unimplemented!(),
+    ///             Expr::Macro(expr) => /* ... */
+    /// #               unimplemented!(),
+    ///             _ => Err(meta.error("tea kind must be a string literal, path, or macro")),
+    ///         }
+    ///     } else /* as above */
+    /// #       { unimplemented!() }
+    ///
+    /// })?;
+    /// # Ok(())
+    /// # }
+    /// ```
+    ///
+    /// ```console
+    /// error: tea kind must be a string literal, path, or macro
+    ///  --> src/main.rs:3:7
+    ///   |
+    /// 3 | #[tea(kind = async { replicator.await })]
+    ///   |       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+    /// ```
+    ///
+    /// Often you may want to use `syn::Error::new_spanned` even in this
+    /// situation. In the above code, that would be:
+    ///
+    /// ```
+    /// # use syn::{Error, Expr};
+    /// #
+    /// # fn example(expr: Expr) -> syn::Result<()> {
+    ///     match expr {
+    ///         Expr::Lit(expr) => /* ... */
+    /// #           unimplemented!(),
+    ///         Expr::Path(expr) => /* ... */
+    /// #           unimplemented!(),
+    ///         Expr::Macro(expr) => /* ... */
+    /// #           unimplemented!(),
+    ///         _ => Err(Error::new_spanned(expr, "unsupported expression type for `kind`")),
+    ///     }
+    /// # }
+    /// ```
+    ///
+    /// ```console
+    /// error: unsupported expression type for `kind`
+    ///  --> src/main.rs:3:14
+    ///   |
+    /// 3 | #[tea(kind = async { replicator.await })]
+    ///   |              ^^^^^^^^^^^^^^^^^^^^^^^^^^
+    /// ```
+    pub fn error(&self, msg: impl Display) -> Error {
+        let start_span = self.path.segments[0].ident.span();
+        let end_span = self.input.cursor().prev_span();
+        crate::error::new2(start_span, end_span, msg)
+    }
+}
+
+pub(crate) fn parse_nested_meta(
+    input: ParseStream,
+    mut logic: impl FnMut(ParseNestedMeta) -> Result<()>,
+) -> Result<()> {
+    loop {
+        let path = input.call(parse_meta_path)?;
+        logic(ParseNestedMeta { path, input })?;
+        if input.is_empty() {
+            return Ok(());
+        }
+        input.parse::<Token![,]>()?;
+        if input.is_empty() {
+            return Ok(());
+        }
+    }
+}
+
+// Like Path::parse_mod_style, but accepts keywords in the path.
+fn parse_meta_path(input: ParseStream) -> Result<Path> {
+    Ok(Path {
+        leading_colon: input.parse()?,
+        segments: {
+            let mut segments = Punctuated::new();
+            if input.peek(Ident::peek_any) {
+                let ident = Ident::parse_any(input)?;
+                segments.push_value(PathSegment::from(ident));
+            } else if input.is_empty() {
+                return Err(input.error("expected nested attribute"));
+            } else if input.peek(Lit) {
+                return Err(input.error("unexpected literal in nested attribute, expected ident"));
+            } else {
+                return Err(input.error("unexpected token in nested attribute, expected ident"));
+            }
+            while input.peek(Token![::]) {
+                let punct = input.parse()?;
+                segments.push_punct(punct);
+                let ident = Ident::parse_any(input)?;
+                segments.push_value(PathSegment::from(ident));
+            }
+            segments
+        },
+    })
+}
diff --git a/rust/syn/op.rs b/rust/syn/op.rs
new file mode 100644
index 0000000000000000000000000000000000000000..c2b2e1e1ca1d703e30386a8a8486438887f9e44f
--- /dev/null
+++ b/rust/syn/op.rs
@@ -0,0 +1,221 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+ast_enum! {
+    /// A binary operator: `+`, `+=`, `&`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum BinOp {
+        /// The `+` operator (addition)
+        Add(Token![+]),
+        /// The `-` operator (subtraction)
+        Sub(Token![-]),
+        /// The `*` operator (multiplication)
+        Mul(Token![*]),
+        /// The `/` operator (division)
+        Div(Token![/]),
+        /// The `%` operator (modulus)
+        Rem(Token![%]),
+        /// The `&&` operator (logical and)
+        And(Token![&&]),
+        /// The `||` operator (logical or)
+        Or(Token![||]),
+        /// The `^` operator (bitwise xor)
+        BitXor(Token![^]),
+        /// The `&` operator (bitwise and)
+        BitAnd(Token![&]),
+        /// The `|` operator (bitwise or)
+        BitOr(Token![|]),
+        /// The `<<` operator (shift left)
+        Shl(Token![<<]),
+        /// The `>>` operator (shift right)
+        Shr(Token![>>]),
+        /// The `==` operator (equality)
+        Eq(Token![==]),
+        /// The `<` operator (less than)
+        Lt(Token![<]),
+        /// The `<=` operator (less than or equal to)
+        Le(Token![<=]),
+        /// The `!=` operator (not equal to)
+        Ne(Token![!=]),
+        /// The `>=` operator (greater than or equal to)
+        Ge(Token![>=]),
+        /// The `>` operator (greater than)
+        Gt(Token![>]),
+        /// The `+=` operator
+        AddAssign(Token![+=]),
+        /// The `-=` operator
+        SubAssign(Token![-=]),
+        /// The `*=` operator
+        MulAssign(Token![*=]),
+        /// The `/=` operator
+        DivAssign(Token![/=]),
+        /// The `%=` operator
+        RemAssign(Token![%=]),
+        /// The `^=` operator
+        BitXorAssign(Token![^=]),
+        /// The `&=` operator
+        BitAndAssign(Token![&=]),
+        /// The `|=` operator
+        BitOrAssign(Token![|=]),
+        /// The `<<=` operator
+        ShlAssign(Token![<<=]),
+        /// The `>>=` operator
+        ShrAssign(Token![>>=]),
+    }
+}
+
+ast_enum! {
+    /// A unary operator: `*`, `!`, `-`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum UnOp {
+        /// The `*` operator for dereferencing
+        Deref(Token![*]),
+        /// The `!` operator for logical inversion
+        Not(Token![!]),
+        /// The `-` operator for negation
+        Neg(Token![-]),
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::error::Result;
+    use crate::op::{BinOp, UnOp};
+    use crate::parse::{Parse, ParseStream};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for BinOp {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Token![+=]) {
+                input.parse().map(BinOp::AddAssign)
+            } else if input.peek(Token![-=]) {
+                input.parse().map(BinOp::SubAssign)
+            } else if input.peek(Token![*=]) {
+                input.parse().map(BinOp::MulAssign)
+            } else if input.peek(Token![/=]) {
+                input.parse().map(BinOp::DivAssign)
+            } else if input.peek(Token![%=]) {
+                input.parse().map(BinOp::RemAssign)
+            } else if input.peek(Token![^=]) {
+                input.parse().map(BinOp::BitXorAssign)
+            } else if input.peek(Token![&=]) {
+                input.parse().map(BinOp::BitAndAssign)
+            } else if input.peek(Token![|=]) {
+                input.parse().map(BinOp::BitOrAssign)
+            } else if input.peek(Token![<<=]) {
+                input.parse().map(BinOp::ShlAssign)
+            } else if input.peek(Token![>>=]) {
+                input.parse().map(BinOp::ShrAssign)
+            } else if input.peek(Token![&&]) {
+                input.parse().map(BinOp::And)
+            } else if input.peek(Token![||]) {
+                input.parse().map(BinOp::Or)
+            } else if input.peek(Token![<<]) {
+                input.parse().map(BinOp::Shl)
+            } else if input.peek(Token![>>]) {
+                input.parse().map(BinOp::Shr)
+            } else if input.peek(Token![==]) {
+                input.parse().map(BinOp::Eq)
+            } else if input.peek(Token![<=]) {
+                input.parse().map(BinOp::Le)
+            } else if input.peek(Token![!=]) {
+                input.parse().map(BinOp::Ne)
+            } else if input.peek(Token![>=]) {
+                input.parse().map(BinOp::Ge)
+            } else if input.peek(Token![+]) {
+                input.parse().map(BinOp::Add)
+            } else if input.peek(Token![-]) {
+                input.parse().map(BinOp::Sub)
+            } else if input.peek(Token![*]) {
+                input.parse().map(BinOp::Mul)
+            } else if input.peek(Token![/]) {
+                input.parse().map(BinOp::Div)
+            } else if input.peek(Token![%]) {
+                input.parse().map(BinOp::Rem)
+            } else if input.peek(Token![^]) {
+                input.parse().map(BinOp::BitXor)
+            } else if input.peek(Token![&]) {
+                input.parse().map(BinOp::BitAnd)
+            } else if input.peek(Token![|]) {
+                input.parse().map(BinOp::BitOr)
+            } else if input.peek(Token![<]) {
+                input.parse().map(BinOp::Lt)
+            } else if input.peek(Token![>]) {
+                input.parse().map(BinOp::Gt)
+            } else {
+                Err(input.error("expected binary operator"))
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for UnOp {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Token![*]) {
+                input.parse().map(UnOp::Deref)
+            } else if lookahead.peek(Token![!]) {
+                input.parse().map(UnOp::Not)
+            } else if lookahead.peek(Token![-]) {
+                input.parse().map(UnOp::Neg)
+            } else {
+                Err(lookahead.error())
+            }
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::op::{BinOp, UnOp};
+    use proc_macro2::TokenStream;
+    use quote::ToTokens;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for BinOp {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                BinOp::Add(t) => t.to_tokens(tokens),
+                BinOp::Sub(t) => t.to_tokens(tokens),
+                BinOp::Mul(t) => t.to_tokens(tokens),
+                BinOp::Div(t) => t.to_tokens(tokens),
+                BinOp::Rem(t) => t.to_tokens(tokens),
+                BinOp::And(t) => t.to_tokens(tokens),
+                BinOp::Or(t) => t.to_tokens(tokens),
+                BinOp::BitXor(t) => t.to_tokens(tokens),
+                BinOp::BitAnd(t) => t.to_tokens(tokens),
+                BinOp::BitOr(t) => t.to_tokens(tokens),
+                BinOp::Shl(t) => t.to_tokens(tokens),
+                BinOp::Shr(t) => t.to_tokens(tokens),
+                BinOp::Eq(t) => t.to_tokens(tokens),
+                BinOp::Lt(t) => t.to_tokens(tokens),
+                BinOp::Le(t) => t.to_tokens(tokens),
+                BinOp::Ne(t) => t.to_tokens(tokens),
+                BinOp::Ge(t) => t.to_tokens(tokens),
+                BinOp::Gt(t) => t.to_tokens(tokens),
+                BinOp::AddAssign(t) => t.to_tokens(tokens),
+                BinOp::SubAssign(t) => t.to_tokens(tokens),
+                BinOp::MulAssign(t) => t.to_tokens(tokens),
+                BinOp::DivAssign(t) => t.to_tokens(tokens),
+                BinOp::RemAssign(t) => t.to_tokens(tokens),
+                BinOp::BitXorAssign(t) => t.to_tokens(tokens),
+                BinOp::BitAndAssign(t) => t.to_tokens(tokens),
+                BinOp::BitOrAssign(t) => t.to_tokens(tokens),
+                BinOp::ShlAssign(t) => t.to_tokens(tokens),
+                BinOp::ShrAssign(t) => t.to_tokens(tokens),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for UnOp {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                UnOp::Deref(t) => t.to_tokens(tokens),
+                UnOp::Not(t) => t.to_tokens(tokens),
+                UnOp::Neg(t) => t.to_tokens(tokens),
+            }
+        }
+    }
+}
diff --git a/rust/syn/parse.rs b/rust/syn/parse.rs
new file mode 100644
index 0000000000000000000000000000000000000000..68d4b418a29fa975c3b5ea16b8c42a78ab43f76e
--- /dev/null
+++ b/rust/syn/parse.rs
@@ -0,0 +1,1405 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! Parsing interface for parsing a token stream into a syntax tree node.
+//!
+//! Parsing in Syn is built on parser functions that take in a [`ParseStream`]
+//! and produce a [`Result<T>`] where `T` is some syntax tree node. Underlying
+//! these parser functions is a lower level mechanism built around the
+//! [`Cursor`] type. `Cursor` is a cheaply copyable cursor over a range of
+//! tokens in a token stream.
+//!
+//! [`Result<T>`]: Result
+//! [`Cursor`]: crate::buffer::Cursor
+//!
+//! # Example
+//!
+//! Here is a snippet of parsing code to get a feel for the style of the
+//! library. We define data structures for a subset of Rust syntax including
+//! enums (not shown) and structs, then provide implementations of the [`Parse`]
+//! trait to parse these syntax tree data structures from a token stream.
+//!
+//! Once `Parse` impls have been defined, they can be called conveniently from a
+//! procedural macro through [`parse_macro_input!`] as shown at the bottom of
+//! the snippet. If the caller provides syntactically invalid input to the
+//! procedural macro, they will receive a helpful compiler error message
+//! pointing out the exact token that triggered the failure to parse.
+//!
+//! [`parse_macro_input!`]: crate::parse_macro_input!
+//!
+//! ```
+//! # extern crate proc_macro;
+//! #
+//! use proc_macro::TokenStream;
+//! use syn::{braced, parse_macro_input, token, Field, Ident, Result, Token};
+//! use syn::parse::{Parse, ParseStream};
+//! use syn::punctuated::Punctuated;
+//!
+//! enum Item {
+//!     Struct(ItemStruct),
+//!     Enum(ItemEnum),
+//! }
+//!
+//! struct ItemStruct {
+//!     struct_token: Token![struct],
+//!     ident: Ident,
+//!     brace_token: token::Brace,
+//!     fields: Punctuated<Field, Token![,]>,
+//! }
+//! #
+//! # enum ItemEnum {}
+//!
+//! impl Parse for Item {
+//!     fn parse(input: ParseStream) -> Result<Self> {
+//!         let lookahead = input.lookahead1();
+//!         if lookahead.peek(Token![struct]) {
+//!             input.parse().map(Item::Struct)
+//!         } else if lookahead.peek(Token![enum]) {
+//!             input.parse().map(Item::Enum)
+//!         } else {
+//!             Err(lookahead.error())
+//!         }
+//!     }
+//! }
+//!
+//! impl Parse for ItemStruct {
+//!     fn parse(input: ParseStream) -> Result<Self> {
+//!         let content;
+//!         Ok(ItemStruct {
+//!             struct_token: input.parse()?,
+//!             ident: input.parse()?,
+//!             brace_token: braced!(content in input),
+//!             fields: content.parse_terminated(Field::parse_named, Token![,])?,
+//!         })
+//!     }
+//! }
+//! #
+//! # impl Parse for ItemEnum {
+//! #     fn parse(input: ParseStream) -> Result<Self> {
+//! #         unimplemented!()
+//! #     }
+//! # }
+//!
+//! # const IGNORE: &str = stringify! {
+//! #[proc_macro]
+//! # };
+//! pub fn my_macro(tokens: TokenStream) -> TokenStream {
+//!     let input = parse_macro_input!(tokens as Item);
+//!
+//!     /* ... */
+//! #   TokenStream::new()
+//! }
+//! ```
+//!
+//! # The `syn::parse*` functions
+//!
+//! The [`syn::parse`], [`syn::parse2`], and [`syn::parse_str`] functions serve
+//! as an entry point for parsing syntax tree nodes that can be parsed in an
+//! obvious default way. These functions can return any syntax tree node that
+//! implements the [`Parse`] trait, which includes most types in Syn.
+//!
+//! [`syn::parse`]: crate::parse()
+//! [`syn::parse2`]: crate::parse2()
+//! [`syn::parse_str`]: crate::parse_str()
+//!
+//! ```
+//! use syn::Type;
+//!
+//! # fn run_parser() -> syn::Result<()> {
+//! let t: Type = syn::parse_str("std::collections::HashMap<String, Value>")?;
+//! #     Ok(())
+//! # }
+//! #
+//! # run_parser().unwrap();
+//! ```
+//!
+//! The [`parse_quote!`] macro also uses this approach.
+//!
+//! [`parse_quote!`]: crate::parse_quote!
+//!
+//! # The `Parser` trait
+//!
+//! Some types can be parsed in several ways depending on context. For example
+//! an [`Attribute`] can be either "outer" like `#[...]` or "inner" like
+//! `#![...]` and parsing the wrong one would be a bug. Similarly [`Punctuated`]
+//! may or may not allow trailing punctuation, and parsing it the wrong way
+//! would either reject valid input or accept invalid input.
+//!
+//! [`Attribute`]: crate::Attribute
+//! [`Punctuated`]: crate::punctuated
+//!
+//! The `Parse` trait is not implemented in these cases because there is no good
+//! behavior to consider the default.
+//!
+//! ```compile_fail
+//! # extern crate proc_macro;
+//! #
+//! # use syn::punctuated::Punctuated;
+//! # use syn::{PathSegment, Result, Token};
+//! #
+//! # fn f(tokens: proc_macro::TokenStream) -> Result<()> {
+//! #
+//! // Can't parse `Punctuated` without knowing whether trailing punctuation
+//! // should be allowed in this context.
+//! let path: Punctuated<PathSegment, Token![::]> = syn::parse(tokens)?;
+//! #
+//! #     Ok(())
+//! # }
+//! ```
+//!
+//! In these cases the types provide a choice of parser functions rather than a
+//! single `Parse` implementation, and those parser functions can be invoked
+//! through the [`Parser`] trait.
+//!
+//!
+//! ```
+//! # extern crate proc_macro;
+//! #
+//! use proc_macro::TokenStream;
+//! use syn::parse::Parser;
+//! use syn::punctuated::Punctuated;
+//! use syn::{Attribute, Expr, PathSegment, Result, Token};
+//!
+//! fn call_some_parser_methods(input: TokenStream) -> Result<()> {
+//!     // Parse a nonempty sequence of path segments separated by `::` punctuation
+//!     // with no trailing punctuation.
+//!     let tokens = input.clone();
+//!     let parser = Punctuated::<PathSegment, Token![::]>::parse_separated_nonempty;
+//!     let _path = parser.parse(tokens)?;
+//!
+//!     // Parse a possibly empty sequence of expressions terminated by commas with
+//!     // an optional trailing punctuation.
+//!     let tokens = input.clone();
+//!     let parser = Punctuated::<Expr, Token![,]>::parse_terminated;
+//!     let _args = parser.parse(tokens)?;
+//!
+//!     // Parse zero or more outer attributes but not inner attributes.
+//!     let tokens = input.clone();
+//!     let parser = Attribute::parse_outer;
+//!     let _attrs = parser.parse(tokens)?;
+//!
+//!     Ok(())
+//! }
+//! ```
+
+#[path = "discouraged.rs"]
+pub mod discouraged;
+
+use crate::buffer::{Cursor, TokenBuffer};
+use crate::error;
+use crate::lookahead;
+use crate::punctuated::Punctuated;
+use crate::token::Token;
+use proc_macro2::{Delimiter, Group, Literal, Punct, Span, TokenStream, TokenTree};
+#[cfg(feature = "printing")]
+use quote::ToTokens;
+use std::cell::Cell;
+use std::fmt::{self, Debug, Display};
+#[cfg(feature = "extra-traits")]
+use std::hash::{Hash, Hasher};
+use std::marker::PhantomData;
+use std::mem;
+use std::ops::Deref;
+use std::rc::Rc;
+use std::str::FromStr;
+
+pub use crate::error::{Error, Result};
+pub use crate::lookahead::{Lookahead1, Peek};
+
+/// Parsing interface implemented by all types that can be parsed in a default
+/// way from a token stream.
+///
+/// Refer to the [module documentation] for details about implementing and using
+/// the `Parse` trait.
+///
+/// [module documentation]: self
+pub trait Parse: Sized {
+    fn parse(input: ParseStream) -> Result<Self>;
+}
+
+/// Input to a Syn parser function.
+///
+/// See the methods of this type under the documentation of [`ParseBuffer`]. For
+/// an overview of parsing in Syn, refer to the [module documentation].
+///
+/// [module documentation]: self
+pub type ParseStream<'a> = &'a ParseBuffer<'a>;
+
+/// Cursor position within a buffered token stream.
+///
+/// This type is more commonly used through the type alias [`ParseStream`] which
+/// is an alias for `&ParseBuffer`.
+///
+/// `ParseStream` is the input type for all parser functions in Syn. They have
+/// the signature `fn(ParseStream) -> Result<T>`.
+///
+/// ## Calling a parser function
+///
+/// There is no public way to construct a `ParseBuffer`. Instead, if you are
+/// looking to invoke a parser function that requires `ParseStream` as input,
+/// you will need to go through one of the public parsing entry points.
+///
+/// - The [`parse_macro_input!`] macro if parsing input of a procedural macro;
+/// - One of [the `syn::parse*` functions][syn-parse]; or
+/// - A method of the [`Parser`] trait.
+///
+/// [`parse_macro_input!`]: crate::parse_macro_input!
+/// [syn-parse]: self#the-synparse-functions
+pub struct ParseBuffer<'a> {
+    scope: Span,
+    // Instead of Cell<Cursor<'a>> so that ParseBuffer<'a> is covariant in 'a.
+    // The rest of the code in this module needs to be careful that only a
+    // cursor derived from this `cell` is ever assigned to this `cell`.
+    //
+    // Cell<Cursor<'a>> cannot be covariant in 'a because then we could take a
+    // ParseBuffer<'a>, upcast to ParseBuffer<'short> for some lifetime shorter
+    // than 'a, and then assign a Cursor<'short> into the Cell.
+    //
+    // By extension, it would not be safe to expose an API that accepts a
+    // Cursor<'a> and trusts that it lives as long as the cursor currently in
+    // the cell.
+    cell: Cell<Cursor<'static>>,
+    marker: PhantomData<Cursor<'a>>,
+    unexpected: Cell<Option<Rc<Cell<Unexpected>>>>,
+}
+
+impl<'a> Drop for ParseBuffer<'a> {
+    fn drop(&mut self) {
+        if let Some(unexpected_span) = span_of_unexpected_ignoring_nones(self.cursor()) {
+            let (inner, old_span) = inner_unexpected(self);
+            if old_span.is_none() {
+                inner.set(Unexpected::Some(unexpected_span));
+            }
+        }
+    }
+}
+
+impl<'a> Display for ParseBuffer<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Display::fmt(&self.cursor().token_stream(), f)
+    }
+}
+
+impl<'a> Debug for ParseBuffer<'a> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        Debug::fmt(&self.cursor().token_stream(), f)
+    }
+}
+
+/// Cursor state associated with speculative parsing.
+///
+/// This type is the input of the closure provided to [`ParseStream::step`].
+///
+/// [`ParseStream::step`]: ParseBuffer::step
+///
+/// # Example
+///
+/// ```
+/// use proc_macro2::TokenTree;
+/// use syn::Result;
+/// use syn::parse::ParseStream;
+///
+/// // This function advances the stream past the next occurrence of `@`. If
+/// // no `@` is present in the stream, the stream position is unchanged and
+/// // an error is returned.
+/// fn skip_past_next_at(input: ParseStream) -> Result<()> {
+///     input.step(|cursor| {
+///         let mut rest = *cursor;
+///         while let Some((tt, next)) = rest.token_tree() {
+///             match &tt {
+///                 TokenTree::Punct(punct) if punct.as_char() == '@' => {
+///                     return Ok(((), next));
+///                 }
+///                 _ => rest = next,
+///             }
+///         }
+///         Err(cursor.error("no `@` was found after this point"))
+///     })
+/// }
+/// #
+/// # fn remainder_after_skipping_past_next_at(
+/// #     input: ParseStream,
+/// # ) -> Result<proc_macro2::TokenStream> {
+/// #     skip_past_next_at(input)?;
+/// #     input.parse()
+/// # }
+/// #
+/// # use syn::parse::Parser;
+/// # let remainder = remainder_after_skipping_past_next_at
+/// #     .parse_str("a @ b c")
+/// #     .unwrap();
+/// # assert_eq!(remainder.to_string(), "b c");
+/// ```
+pub struct StepCursor<'c, 'a> {
+    scope: Span,
+    // This field is covariant in 'c.
+    cursor: Cursor<'c>,
+    // This field is contravariant in 'c. Together these make StepCursor
+    // invariant in 'c. Also covariant in 'a. The user cannot cast 'c to a
+    // different lifetime but can upcast into a StepCursor with a shorter
+    // lifetime 'a.
+    //
+    // As long as we only ever construct a StepCursor for which 'c outlives 'a,
+    // this means if ever a StepCursor<'c, 'a> exists we are guaranteed that 'c
+    // outlives 'a.
+    marker: PhantomData<fn(Cursor<'c>) -> Cursor<'a>>,
+}
+
+impl<'c, 'a> Deref for StepCursor<'c, 'a> {
+    type Target = Cursor<'c>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.cursor
+    }
+}
+
+impl<'c, 'a> Copy for StepCursor<'c, 'a> {}
+
+impl<'c, 'a> Clone for StepCursor<'c, 'a> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+impl<'c, 'a> StepCursor<'c, 'a> {
+    /// Triggers an error at the current position of the parse stream.
+    ///
+    /// The `ParseStream::step` invocation will return this same error without
+    /// advancing the stream state.
+    pub fn error<T: Display>(self, message: T) -> Error {
+        error::new_at(self.scope, self.cursor, message)
+    }
+}
+
+pub(crate) fn advance_step_cursor<'c, 'a>(proof: StepCursor<'c, 'a>, to: Cursor<'c>) -> Cursor<'a> {
+    // Refer to the comments within the StepCursor definition. We use the
+    // fact that a StepCursor<'c, 'a> exists as proof that 'c outlives 'a.
+    // Cursor is covariant in its lifetime parameter so we can cast a
+    // Cursor<'c> to one with the shorter lifetime Cursor<'a>.
+    let _ = proof;
+    unsafe { mem::transmute::<Cursor<'c>, Cursor<'a>>(to) }
+}
+
+pub(crate) fn new_parse_buffer(
+    scope: Span,
+    cursor: Cursor,
+    unexpected: Rc<Cell<Unexpected>>,
+) -> ParseBuffer {
+    ParseBuffer {
+        scope,
+        // See comment on `cell` in the struct definition.
+        cell: Cell::new(unsafe { mem::transmute::<Cursor, Cursor<'static>>(cursor) }),
+        marker: PhantomData,
+        unexpected: Cell::new(Some(unexpected)),
+    }
+}
+
+pub(crate) enum Unexpected {
+    None,
+    Some(Span),
+    Chain(Rc<Cell<Unexpected>>),
+}
+
+impl Default for Unexpected {
+    fn default() -> Self {
+        Unexpected::None
+    }
+}
+
+impl Clone for Unexpected {
+    fn clone(&self) -> Self {
+        match self {
+            Unexpected::None => Unexpected::None,
+            Unexpected::Some(span) => Unexpected::Some(*span),
+            Unexpected::Chain(next) => Unexpected::Chain(next.clone()),
+        }
+    }
+}
+
+// We call this on Cell<Unexpected> and Cell<Option<T>> where temporarily
+// swapping in a None is cheap.
+fn cell_clone<T: Default + Clone>(cell: &Cell<T>) -> T {
+    let prev = cell.take();
+    let ret = prev.clone();
+    cell.set(prev);
+    ret
+}
+
+fn inner_unexpected(buffer: &ParseBuffer) -> (Rc<Cell<Unexpected>>, Option<Span>) {
+    let mut unexpected = get_unexpected(buffer);
+    loop {
+        match cell_clone(&unexpected) {
+            Unexpected::None => return (unexpected, None),
+            Unexpected::Some(span) => return (unexpected, Some(span)),
+            Unexpected::Chain(next) => unexpected = next,
+        }
+    }
+}
+
+pub(crate) fn get_unexpected(buffer: &ParseBuffer) -> Rc<Cell<Unexpected>> {
+    cell_clone(&buffer.unexpected).unwrap()
+}
+
+fn span_of_unexpected_ignoring_nones(mut cursor: Cursor) -> Option<Span> {
+    if cursor.eof() {
+        return None;
+    }
+    while let Some((inner, _span, rest)) = cursor.group(Delimiter::None) {
+        if let Some(unexpected) = span_of_unexpected_ignoring_nones(inner) {
+            return Some(unexpected);
+        }
+        cursor = rest;
+    }
+    if cursor.eof() {
+        None
+    } else {
+        Some(cursor.span())
+    }
+}
+
+impl<'a> ParseBuffer<'a> {
+    /// Parses a syntax tree node of type `T`, advancing the position of our
+    /// parse stream past it.
+    pub fn parse<T: Parse>(&self) -> Result<T> {
+        T::parse(self)
+    }
+
+    /// Calls the given parser function to parse a syntax tree node of type `T`
+    /// from this stream.
+    ///
+    /// # Example
+    ///
+    /// The parser below invokes [`Attribute::parse_outer`] to parse a vector of
+    /// zero or more outer attributes.
+    ///
+    /// [`Attribute::parse_outer`]: crate::Attribute::parse_outer
+    ///
+    /// ```
+    /// use syn::{Attribute, Ident, Result, Token};
+    /// use syn::parse::{Parse, ParseStream};
+    ///
+    /// // Parses a unit struct with attributes.
+    /// //
+    /// //     #[path = "s.tmpl"]
+    /// //     struct S;
+    /// struct UnitStruct {
+    ///     attrs: Vec<Attribute>,
+    ///     struct_token: Token![struct],
+    ///     name: Ident,
+    ///     semi_token: Token![;],
+    /// }
+    ///
+    /// impl Parse for UnitStruct {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         Ok(UnitStruct {
+    ///             attrs: input.call(Attribute::parse_outer)?,
+    ///             struct_token: input.parse()?,
+    ///             name: input.parse()?,
+    ///             semi_token: input.parse()?,
+    ///         })
+    ///     }
+    /// }
+    /// ```
+    pub fn call<T>(&self, function: fn(ParseStream) -> Result<T>) -> Result<T> {
+        function(self)
+    }
+
+    /// Looks at the next token in the parse stream to determine whether it
+    /// matches the requested type of token.
+    ///
+    /// Does not advance the position of the parse stream.
+    ///
+    /// # Syntax
+    ///
+    /// Note that this method does not use turbofish syntax. Pass the peek type
+    /// inside of parentheses.
+    ///
+    /// - `input.peek(Token![struct])`
+    /// - `input.peek(Token![==])`
+    /// - `input.peek(syn::Ident)`&emsp;*(does not accept keywords)*
+    /// - `input.peek(syn::Ident::peek_any)`
+    /// - `input.peek(Lifetime)`
+    /// - `input.peek(token::Brace)`
+    ///
+    /// # Example
+    ///
+    /// In this example we finish parsing the list of supertraits when the next
+    /// token in the input is either `where` or an opening curly brace.
+    ///
+    /// ```
+    /// use syn::{braced, token, Generics, Ident, Result, Token, TypeParamBound};
+    /// use syn::parse::{Parse, ParseStream};
+    /// use syn::punctuated::Punctuated;
+    ///
+    /// // Parses a trait definition containing no associated items.
+    /// //
+    /// //     trait Marker<'de, T>: A + B<'de> where Box<T>: Clone {}
+    /// struct MarkerTrait {
+    ///     trait_token: Token![trait],
+    ///     ident: Ident,
+    ///     generics: Generics,
+    ///     colon_token: Option<Token![:]>,
+    ///     supertraits: Punctuated<TypeParamBound, Token![+]>,
+    ///     brace_token: token::Brace,
+    /// }
+    ///
+    /// impl Parse for MarkerTrait {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         let trait_token: Token![trait] = input.parse()?;
+    ///         let ident: Ident = input.parse()?;
+    ///         let mut generics: Generics = input.parse()?;
+    ///         let colon_token: Option<Token![:]> = input.parse()?;
+    ///
+    ///         let mut supertraits = Punctuated::new();
+    ///         if colon_token.is_some() {
+    ///             loop {
+    ///                 supertraits.push_value(input.parse()?);
+    ///                 if input.peek(Token![where]) || input.peek(token::Brace) {
+    ///                     break;
+    ///                 }
+    ///                 supertraits.push_punct(input.parse()?);
+    ///             }
+    ///         }
+    ///
+    ///         generics.where_clause = input.parse()?;
+    ///         let content;
+    ///         let empty_brace_token = braced!(content in input);
+    ///
+    ///         Ok(MarkerTrait {
+    ///             trait_token,
+    ///             ident,
+    ///             generics,
+    ///             colon_token,
+    ///             supertraits,
+    ///             brace_token: empty_brace_token,
+    ///         })
+    ///     }
+    /// }
+    /// ```
+    pub fn peek<T: Peek>(&self, token: T) -> bool {
+        let _ = token;
+        T::Token::peek(self.cursor())
+    }
+
+    /// Looks at the second-next token in the parse stream.
+    ///
+    /// This is commonly useful as a way to implement contextual keywords.
+    ///
+    /// # Example
+    ///
+    /// This example needs to use `peek2` because the symbol `union` is not a
+    /// keyword in Rust. We can't use just `peek` and decide to parse a union if
+    /// the very next token is `union`, because someone is free to write a `mod
+    /// union` and a macro invocation that looks like `union::some_macro! { ...
+    /// }`. In other words `union` is a contextual keyword.
+    ///
+    /// ```
+    /// use syn::{Ident, ItemUnion, Macro, Result, Token};
+    /// use syn::parse::{Parse, ParseStream};
+    ///
+    /// // Parses either a union or a macro invocation.
+    /// enum UnionOrMacro {
+    ///     // union MaybeUninit<T> { uninit: (), value: T }
+    ///     Union(ItemUnion),
+    ///     // lazy_static! { ... }
+    ///     Macro(Macro),
+    /// }
+    ///
+    /// impl Parse for UnionOrMacro {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         if input.peek(Token![union]) && input.peek2(Ident) {
+    ///             input.parse().map(UnionOrMacro::Union)
+    ///         } else {
+    ///             input.parse().map(UnionOrMacro::Macro)
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    pub fn peek2<T: Peek>(&self, token: T) -> bool {
+        fn peek2(buffer: &ParseBuffer, peek: fn(Cursor) -> bool) -> bool {
+            if let Some(group) = buffer.cursor().group(Delimiter::None) {
+                if group.0.skip().map_or(false, peek) {
+                    return true;
+                }
+            }
+            buffer.cursor().skip().map_or(false, peek)
+        }
+
+        let _ = token;
+        peek2(self, T::Token::peek)
+    }
+
+    /// Looks at the third-next token in the parse stream.
+    pub fn peek3<T: Peek>(&self, token: T) -> bool {
+        fn peek3(buffer: &ParseBuffer, peek: fn(Cursor) -> bool) -> bool {
+            if let Some(group) = buffer.cursor().group(Delimiter::None) {
+                if group.0.skip().and_then(Cursor::skip).map_or(false, peek) {
+                    return true;
+                }
+            }
+            buffer
+                .cursor()
+                .skip()
+                .and_then(Cursor::skip)
+                .map_or(false, peek)
+        }
+
+        let _ = token;
+        peek3(self, T::Token::peek)
+    }
+
+    /// Parses zero or more occurrences of `T` separated by punctuation of type
+    /// `P`, with optional trailing punctuation.
+    ///
+    /// Parsing continues until the end of this parse stream. The entire content
+    /// of this parse stream must consist of `T` and `P`.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use quote::quote;
+    /// #
+    /// use syn::{parenthesized, token, Ident, Result, Token, Type};
+    /// use syn::parse::{Parse, ParseStream};
+    /// use syn::punctuated::Punctuated;
+    ///
+    /// // Parse a simplified tuple struct syntax like:
+    /// //
+    /// //     struct S(A, B);
+    /// struct TupleStruct {
+    ///     struct_token: Token![struct],
+    ///     ident: Ident,
+    ///     paren_token: token::Paren,
+    ///     fields: Punctuated<Type, Token![,]>,
+    ///     semi_token: Token![;],
+    /// }
+    ///
+    /// impl Parse for TupleStruct {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         let content;
+    ///         Ok(TupleStruct {
+    ///             struct_token: input.parse()?,
+    ///             ident: input.parse()?,
+    ///             paren_token: parenthesized!(content in input),
+    ///             fields: content.parse_terminated(Type::parse, Token![,])?,
+    ///             semi_token: input.parse()?,
+    ///         })
+    ///     }
+    /// }
+    /// #
+    /// # let input = quote! {
+    /// #     struct S(A, B);
+    /// # };
+    /// # syn::parse2::<TupleStruct>(input).unwrap();
+    /// ```
+    ///
+    /// # See also
+    ///
+    /// If your separator is anything more complicated than an invocation of the
+    /// `Token!` macro, this method won't be applicable and you can instead
+    /// directly use `Punctuated`'s parser functions: [`parse_terminated`],
+    /// [`parse_separated_nonempty`] etc.
+    ///
+    /// [`parse_terminated`]: Punctuated::parse_terminated
+    /// [`parse_separated_nonempty`]: Punctuated::parse_separated_nonempty
+    ///
+    /// ```
+    /// use syn::{custom_keyword, Expr, Result, Token};
+    /// use syn::parse::{Parse, ParseStream};
+    /// use syn::punctuated::Punctuated;
+    ///
+    /// mod kw {
+    ///     syn::custom_keyword!(fin);
+    /// }
+    ///
+    /// struct Fin(kw::fin, Token![;]);
+    ///
+    /// impl Parse for Fin {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         Ok(Self(input.parse()?, input.parse()?))
+    ///     }
+    /// }
+    ///
+    /// struct Thing {
+    ///     steps: Punctuated<Expr, Fin>,
+    /// }
+    ///
+    /// impl Parse for Thing {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    /// # if true {
+    ///         Ok(Thing {
+    ///             steps: Punctuated::parse_terminated(input)?,
+    ///         })
+    /// # } else {
+    ///         // or equivalently, this means the same thing:
+    /// #       Ok(Thing {
+    ///             steps: input.call(Punctuated::parse_terminated)?,
+    /// #       })
+    /// # }
+    ///     }
+    /// }
+    /// ```
+    pub fn parse_terminated<T, P>(
+        &self,
+        parser: fn(ParseStream) -> Result<T>,
+        separator: P,
+    ) -> Result<Punctuated<T, P::Token>>
+    where
+        P: Peek,
+        P::Token: Parse,
+    {
+        let _ = separator;
+        Punctuated::parse_terminated_with(self, parser)
+    }
+
+    /// Returns whether there are tokens remaining in this stream.
+    ///
+    /// This method returns true at the end of the content of a set of
+    /// delimiters, as well as at the very end of the complete macro input.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{braced, token, Ident, Item, Result, Token};
+    /// use syn::parse::{Parse, ParseStream};
+    ///
+    /// // Parses a Rust `mod m { ... }` containing zero or more items.
+    /// struct Mod {
+    ///     mod_token: Token![mod],
+    ///     name: Ident,
+    ///     brace_token: token::Brace,
+    ///     items: Vec<Item>,
+    /// }
+    ///
+    /// impl Parse for Mod {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         let content;
+    ///         Ok(Mod {
+    ///             mod_token: input.parse()?,
+    ///             name: input.parse()?,
+    ///             brace_token: braced!(content in input),
+    ///             items: {
+    ///                 let mut items = Vec::new();
+    ///                 while !content.is_empty() {
+    ///                     items.push(content.parse()?);
+    ///                 }
+    ///                 items
+    ///             },
+    ///         })
+    ///     }
+    /// }
+    /// ```
+    pub fn is_empty(&self) -> bool {
+        self.cursor().eof()
+    }
+
+    /// Constructs a helper for peeking at the next token in this stream and
+    /// building an error message if it is not one of a set of expected tokens.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{ConstParam, Ident, Lifetime, LifetimeParam, Result, Token, TypeParam};
+    /// use syn::parse::{Parse, ParseStream};
+    ///
+    /// // A generic parameter, a single one of the comma-separated elements inside
+    /// // angle brackets in:
+    /// //
+    /// //     fn f<T: Clone, 'a, 'b: 'a, const N: usize>() { ... }
+    /// //
+    /// // On invalid input, lookahead gives us a reasonable error message.
+    /// //
+    /// //     error: expected one of: identifier, lifetime, `const`
+    /// //       |
+    /// //     5 |     fn f<!Sized>() {}
+    /// //       |          ^
+    /// enum GenericParam {
+    ///     Type(TypeParam),
+    ///     Lifetime(LifetimeParam),
+    ///     Const(ConstParam),
+    /// }
+    ///
+    /// impl Parse for GenericParam {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         let lookahead = input.lookahead1();
+    ///         if lookahead.peek(Ident) {
+    ///             input.parse().map(GenericParam::Type)
+    ///         } else if lookahead.peek(Lifetime) {
+    ///             input.parse().map(GenericParam::Lifetime)
+    ///         } else if lookahead.peek(Token![const]) {
+    ///             input.parse().map(GenericParam::Const)
+    ///         } else {
+    ///             Err(lookahead.error())
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    pub fn lookahead1(&self) -> Lookahead1<'a> {
+        lookahead::new(self.scope, self.cursor())
+    }
+
+    /// Forks a parse stream so that parsing tokens out of either the original
+    /// or the fork does not advance the position of the other.
+    ///
+    /// # Performance
+    ///
+    /// Forking a parse stream is a cheap fixed amount of work and does not
+    /// involve copying token buffers. Where you might hit performance problems
+    /// is if your macro ends up parsing a large amount of content more than
+    /// once.
+    ///
+    /// ```
+    /// # use syn::{Expr, Result};
+    /// # use syn::parse::ParseStream;
+    /// #
+    /// # fn bad(input: ParseStream) -> Result<Expr> {
+    /// // Do not do this.
+    /// if input.fork().parse::<Expr>().is_ok() {
+    ///     return input.parse::<Expr>();
+    /// }
+    /// # unimplemented!()
+    /// # }
+    /// ```
+    ///
+    /// As a rule, avoid parsing an unbounded amount of tokens out of a forked
+    /// parse stream. Only use a fork when the amount of work performed against
+    /// the fork is small and bounded.
+    ///
+    /// When complex speculative parsing against the forked stream is
+    /// unavoidable, use [`parse::discouraged::Speculative`] to advance the
+    /// original stream once the fork's parse is determined to have been
+    /// successful.
+    ///
+    /// For a lower level way to perform speculative parsing at the token level,
+    /// consider using [`ParseStream::step`] instead.
+    ///
+    /// [`parse::discouraged::Speculative`]: discouraged::Speculative
+    /// [`ParseStream::step`]: ParseBuffer::step
+    ///
+    /// # Example
+    ///
+    /// The parse implementation shown here parses possibly restricted `pub`
+    /// visibilities.
+    ///
+    /// - `pub`
+    /// - `pub(crate)`
+    /// - `pub(self)`
+    /// - `pub(super)`
+    /// - `pub(in some::path)`
+    ///
+    /// To handle the case of visibilities inside of tuple structs, the parser
+    /// needs to distinguish parentheses that specify visibility restrictions
+    /// from parentheses that form part of a tuple type.
+    ///
+    /// ```
+    /// # struct A;
+    /// # struct B;
+    /// # struct C;
+    /// #
+    /// struct S(pub(crate) A, pub (B, C));
+    /// ```
+    ///
+    /// In this example input the first tuple struct element of `S` has
+    /// `pub(crate)` visibility while the second tuple struct element has `pub`
+    /// visibility; the parentheses around `(B, C)` are part of the type rather
+    /// than part of a visibility restriction.
+    ///
+    /// The parser uses a forked parse stream to check the first token inside of
+    /// parentheses after the `pub` keyword. This is a small bounded amount of
+    /// work performed against the forked parse stream.
+    ///
+    /// ```
+    /// use syn::{parenthesized, token, Ident, Path, Result, Token};
+    /// use syn::ext::IdentExt;
+    /// use syn::parse::{Parse, ParseStream};
+    ///
+    /// struct PubVisibility {
+    ///     pub_token: Token![pub],
+    ///     restricted: Option<Restricted>,
+    /// }
+    ///
+    /// struct Restricted {
+    ///     paren_token: token::Paren,
+    ///     in_token: Option<Token![in]>,
+    ///     path: Path,
+    /// }
+    ///
+    /// impl Parse for PubVisibility {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         let pub_token: Token![pub] = input.parse()?;
+    ///
+    ///         if input.peek(token::Paren) {
+    ///             let ahead = input.fork();
+    ///             let mut content;
+    ///             parenthesized!(content in ahead);
+    ///
+    ///             if content.peek(Token![crate])
+    ///                 || content.peek(Token![self])
+    ///                 || content.peek(Token![super])
+    ///             {
+    ///                 return Ok(PubVisibility {
+    ///                     pub_token,
+    ///                     restricted: Some(Restricted {
+    ///                         paren_token: parenthesized!(content in input),
+    ///                         in_token: None,
+    ///                         path: Path::from(content.call(Ident::parse_any)?),
+    ///                     }),
+    ///                 });
+    ///             } else if content.peek(Token![in]) {
+    ///                 return Ok(PubVisibility {
+    ///                     pub_token,
+    ///                     restricted: Some(Restricted {
+    ///                         paren_token: parenthesized!(content in input),
+    ///                         in_token: Some(content.parse()?),
+    ///                         path: content.call(Path::parse_mod_style)?,
+    ///                     }),
+    ///                 });
+    ///             }
+    ///         }
+    ///
+    ///         Ok(PubVisibility {
+    ///             pub_token,
+    ///             restricted: None,
+    ///         })
+    ///     }
+    /// }
+    /// ```
+    pub fn fork(&self) -> Self {
+        ParseBuffer {
+            scope: self.scope,
+            cell: self.cell.clone(),
+            marker: PhantomData,
+            // Not the parent's unexpected. Nothing cares whether the clone
+            // parses all the way unless we `advance_to`.
+            unexpected: Cell::new(Some(Rc::new(Cell::new(Unexpected::None)))),
+        }
+    }
+
+    /// Triggers an error at the current position of the parse stream.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use syn::{Expr, Result, Token};
+    /// use syn::parse::{Parse, ParseStream};
+    ///
+    /// // Some kind of loop: `while` or `for` or `loop`.
+    /// struct Loop {
+    ///     expr: Expr,
+    /// }
+    ///
+    /// impl Parse for Loop {
+    ///     fn parse(input: ParseStream) -> Result<Self> {
+    ///         if input.peek(Token![while])
+    ///             || input.peek(Token![for])
+    ///             || input.peek(Token![loop])
+    ///         {
+    ///             Ok(Loop {
+    ///                 expr: input.parse()?,
+    ///             })
+    ///         } else {
+    ///             Err(input.error("expected some kind of loop"))
+    ///         }
+    ///     }
+    /// }
+    /// ```
+    pub fn error<T: Display>(&self, message: T) -> Error {
+        error::new_at(self.scope, self.cursor(), message)
+    }
+
+    /// Speculatively parses tokens from this parse stream, advancing the
+    /// position of this stream only if parsing succeeds.
+    ///
+    /// This is a powerful low-level API used for defining the `Parse` impls of
+    /// the basic built-in token types. It is not something that will be used
+    /// widely outside of the Syn codebase.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use proc_macro2::TokenTree;
+    /// use syn::Result;
+    /// use syn::parse::ParseStream;
+    ///
+    /// // This function advances the stream past the next occurrence of `@`. If
+    /// // no `@` is present in the stream, the stream position is unchanged and
+    /// // an error is returned.
+    /// fn skip_past_next_at(input: ParseStream) -> Result<()> {
+    ///     input.step(|cursor| {
+    ///         let mut rest = *cursor;
+    ///         while let Some((tt, next)) = rest.token_tree() {
+    ///             match &tt {
+    ///                 TokenTree::Punct(punct) if punct.as_char() == '@' => {
+    ///                     return Ok(((), next));
+    ///                 }
+    ///                 _ => rest = next,
+    ///             }
+    ///         }
+    ///         Err(cursor.error("no `@` was found after this point"))
+    ///     })
+    /// }
+    /// #
+    /// # fn remainder_after_skipping_past_next_at(
+    /// #     input: ParseStream,
+    /// # ) -> Result<proc_macro2::TokenStream> {
+    /// #     skip_past_next_at(input)?;
+    /// #     input.parse()
+    /// # }
+    /// #
+    /// # use syn::parse::Parser;
+    /// # let remainder = remainder_after_skipping_past_next_at
+    /// #     .parse_str("a @ b c")
+    /// #     .unwrap();
+    /// # assert_eq!(remainder.to_string(), "b c");
+    /// ```
+    pub fn step<F, R>(&self, function: F) -> Result<R>
+    where
+        F: for<'c> FnOnce(StepCursor<'c, 'a>) -> Result<(R, Cursor<'c>)>,
+    {
+        // Since the user's function is required to work for any 'c, we know
+        // that the Cursor<'c> they return is either derived from the input
+        // StepCursor<'c, 'a> or from a Cursor<'static>.
+        //
+        // It would not be legal to write this function without the invariant
+        // lifetime 'c in StepCursor<'c, 'a>. If this function were written only
+        // in terms of 'a, the user could take our ParseBuffer<'a>, upcast it to
+        // a ParseBuffer<'short> which some shorter lifetime than 'a, invoke
+        // `step` on their ParseBuffer<'short> with a closure that returns
+        // Cursor<'short>, and we would wrongly write that Cursor<'short> into
+        // the Cell intended to hold Cursor<'a>.
+        //
+        // In some cases it may be necessary for R to contain a Cursor<'a>.
+        // Within Syn we solve this using `advance_step_cursor` which uses the
+        // existence of a StepCursor<'c, 'a> as proof that it is safe to cast
+        // from Cursor<'c> to Cursor<'a>. If needed outside of Syn, it would be
+        // safe to expose that API as a method on StepCursor.
+        let (node, rest) = function(StepCursor {
+            scope: self.scope,
+            cursor: self.cell.get(),
+            marker: PhantomData,
+        })?;
+        self.cell.set(rest);
+        Ok(node)
+    }
+
+    /// Returns the `Span` of the next token in the parse stream, or
+    /// `Span::call_site()` if this parse stream has completely exhausted its
+    /// input `TokenStream`.
+    pub fn span(&self) -> Span {
+        let cursor = self.cursor();
+        if cursor.eof() {
+            self.scope
+        } else {
+            crate::buffer::open_span_of_group(cursor)
+        }
+    }
+
+    /// Provides low-level access to the token representation underlying this
+    /// parse stream.
+    ///
+    /// Cursors are immutable so no operations you perform against the cursor
+    /// will affect the state of this parse stream.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use proc_macro2::TokenStream;
+    /// use syn::buffer::Cursor;
+    /// use syn::parse::{ParseStream, Result};
+    ///
+    /// // Run a parser that returns T, but get its output as TokenStream instead of T.
+    /// // This works without T needing to implement ToTokens.
+    /// fn recognize_token_stream<T>(
+    ///     recognizer: fn(ParseStream) -> Result<T>,
+    /// ) -> impl Fn(ParseStream) -> Result<TokenStream> {
+    ///     move |input| {
+    ///         let begin = input.cursor();
+    ///         recognizer(input)?;
+    ///         let end = input.cursor();
+    ///         Ok(tokens_between(begin, end))
+    ///     }
+    /// }
+    ///
+    /// // Collect tokens between two cursors as a TokenStream.
+    /// fn tokens_between(begin: Cursor, end: Cursor) -> TokenStream {
+    ///     assert!(begin <= end);
+    ///
+    ///     let mut cursor = begin;
+    ///     let mut tokens = TokenStream::new();
+    ///     while cursor < end {
+    ///         let (token, next) = cursor.token_tree().unwrap();
+    ///         tokens.extend(std::iter::once(token));
+    ///         cursor = next;
+    ///     }
+    ///     tokens
+    /// }
+    ///
+    /// fn main() {
+    ///     use quote::quote;
+    ///     use syn::parse::{Parse, Parser};
+    ///     use syn::Token;
+    ///
+    ///     // Parse syn::Type as a TokenStream, surrounded by angle brackets.
+    ///     fn example(input: ParseStream) -> Result<TokenStream> {
+    ///         let _langle: Token![<] = input.parse()?;
+    ///         let ty = recognize_token_stream(syn::Type::parse)(input)?;
+    ///         let _rangle: Token![>] = input.parse()?;
+    ///         Ok(ty)
+    ///     }
+    ///
+    ///     let tokens = quote! { <fn() -> u8> };
+    ///     println!("{}", example.parse2(tokens).unwrap());
+    /// }
+    /// ```
+    pub fn cursor(&self) -> Cursor<'a> {
+        self.cell.get()
+    }
+
+    fn check_unexpected(&self) -> Result<()> {
+        match inner_unexpected(self).1 {
+            Some(span) => Err(Error::new(span, "unexpected token")),
+            None => Ok(()),
+        }
+    }
+}
+
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+impl<T: Parse> Parse for Box<T> {
+    fn parse(input: ParseStream) -> Result<Self> {
+        input.parse().map(Box::new)
+    }
+}
+
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+impl<T: Parse + Token> Parse for Option<T> {
+    fn parse(input: ParseStream) -> Result<Self> {
+        if T::peek(input.cursor()) {
+            Ok(Some(input.parse()?))
+        } else {
+            Ok(None)
+        }
+    }
+}
+
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+impl Parse for TokenStream {
+    fn parse(input: ParseStream) -> Result<Self> {
+        input.step(|cursor| Ok((cursor.token_stream(), Cursor::empty())))
+    }
+}
+
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+impl Parse for TokenTree {
+    fn parse(input: ParseStream) -> Result<Self> {
+        input.step(|cursor| match cursor.token_tree() {
+            Some((tt, rest)) => Ok((tt, rest)),
+            None => Err(cursor.error("expected token tree")),
+        })
+    }
+}
+
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+impl Parse for Group {
+    fn parse(input: ParseStream) -> Result<Self> {
+        input.step(|cursor| {
+            if let Some((group, rest)) = cursor.any_group_token() {
+                if group.delimiter() != Delimiter::None {
+                    return Ok((group, rest));
+                }
+            }
+            Err(cursor.error("expected group token"))
+        })
+    }
+}
+
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+impl Parse for Punct {
+    fn parse(input: ParseStream) -> Result<Self> {
+        input.step(|cursor| match cursor.punct() {
+            Some((punct, rest)) => Ok((punct, rest)),
+            None => Err(cursor.error("expected punctuation token")),
+        })
+    }
+}
+
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+impl Parse for Literal {
+    fn parse(input: ParseStream) -> Result<Self> {
+        input.step(|cursor| match cursor.literal() {
+            Some((literal, rest)) => Ok((literal, rest)),
+            None => Err(cursor.error("expected literal token")),
+        })
+    }
+}
+
+/// Parser that can parse Rust tokens into a particular syntax tree node.
+///
+/// Refer to the [module documentation] for details about parsing in Syn.
+///
+/// [module documentation]: self
+pub trait Parser: Sized {
+    type Output;
+
+    /// Parse a proc-macro2 token stream into the chosen syntax tree node.
+    ///
+    /// This function will check that the input is fully parsed. If there are
+    /// any unparsed tokens at the end of the stream, an error is returned.
+    fn parse2(self, tokens: TokenStream) -> Result<Self::Output>;
+
+    /// Parse tokens of source code into the chosen syntax tree node.
+    ///
+    /// This function will check that the input is fully parsed. If there are
+    /// any unparsed tokens at the end of the stream, an error is returned.
+    #[cfg(feature = "proc-macro")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "proc-macro")))]
+    fn parse(self, tokens: proc_macro::TokenStream) -> Result<Self::Output> {
+        self.parse2(proc_macro2::TokenStream::from(tokens))
+    }
+
+    /// Parse a string of Rust code into the chosen syntax tree node.
+    ///
+    /// This function will check that the input is fully parsed. If there are
+    /// any unparsed tokens at the end of the string, an error is returned.
+    ///
+    /// # Hygiene
+    ///
+    /// Every span in the resulting syntax tree will be set to resolve at the
+    /// macro call site.
+    fn parse_str(self, s: &str) -> Result<Self::Output> {
+        self.parse2(proc_macro2::TokenStream::from_str(s)?)
+    }
+
+    // Not public API.
+    #[doc(hidden)]
+    fn __parse_scoped(self, scope: Span, tokens: TokenStream) -> Result<Self::Output> {
+        let _ = scope;
+        self.parse2(tokens)
+    }
+}
+
+fn tokens_to_parse_buffer(tokens: &TokenBuffer) -> ParseBuffer {
+    let scope = Span::call_site();
+    let cursor = tokens.begin();
+    let unexpected = Rc::new(Cell::new(Unexpected::None));
+    new_parse_buffer(scope, cursor, unexpected)
+}
+
+impl<F, T> Parser for F
+where
+    F: FnOnce(ParseStream) -> Result<T>,
+{
+    type Output = T;
+
+    fn parse2(self, tokens: TokenStream) -> Result<T> {
+        let buf = TokenBuffer::new2(tokens);
+        let state = tokens_to_parse_buffer(&buf);
+        let node = self(&state)?;
+        state.check_unexpected()?;
+        if let Some(unexpected_span) = span_of_unexpected_ignoring_nones(state.cursor()) {
+            Err(Error::new(unexpected_span, "unexpected token"))
+        } else {
+            Ok(node)
+        }
+    }
+
+    fn __parse_scoped(self, scope: Span, tokens: TokenStream) -> Result<Self::Output> {
+        let buf = TokenBuffer::new2(tokens);
+        let cursor = buf.begin();
+        let unexpected = Rc::new(Cell::new(Unexpected::None));
+        let state = new_parse_buffer(scope, cursor, unexpected);
+        let node = self(&state)?;
+        state.check_unexpected()?;
+        if let Some(unexpected_span) = span_of_unexpected_ignoring_nones(state.cursor()) {
+            Err(Error::new(unexpected_span, "unexpected token"))
+        } else {
+            Ok(node)
+        }
+    }
+}
+
+pub(crate) fn parse_scoped<F: Parser>(f: F, scope: Span, tokens: TokenStream) -> Result<F::Output> {
+    f.__parse_scoped(scope, tokens)
+}
+
+/// An empty syntax tree node that consumes no tokens when parsed.
+///
+/// This is useful for attribute macros that want to ensure they are not
+/// provided any attribute args.
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// use proc_macro::TokenStream;
+/// use syn::parse_macro_input;
+/// use syn::parse::Nothing;
+///
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro_attribute]
+/// # };
+/// pub fn my_attr(args: TokenStream, input: TokenStream) -> TokenStream {
+///     parse_macro_input!(args as Nothing);
+///
+///     /* ... */
+/// #   TokenStream::new()
+/// }
+/// ```
+///
+/// ```text
+/// error: unexpected token
+///  --> src/main.rs:3:19
+///   |
+/// 3 | #[my_attr(asdf)]
+///   |           ^^^^
+/// ```
+pub struct Nothing;
+
+impl Parse for Nothing {
+    fn parse(_input: ParseStream) -> Result<Self> {
+        Ok(Nothing)
+    }
+}
+
+#[cfg(feature = "printing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+impl ToTokens for Nothing {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        let _ = tokens;
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for Nothing {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Copy for Nothing {}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for Nothing {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("Nothing")
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Eq for Nothing {}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for Nothing {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for Nothing {
+    fn hash<H: Hasher>(&self, _state: &mut H) {}
+}
diff --git a/rust/syn/parse_macro_input.rs b/rust/syn/parse_macro_input.rs
new file mode 100644
index 0000000000000000000000000000000000000000..6e3e71ecd6f229222c5c81e4eb1e93e6a198ec24
--- /dev/null
+++ b/rust/syn/parse_macro_input.rs
@@ -0,0 +1,130 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+/// Parse the input TokenStream of a macro, triggering a compile error if the
+/// tokens fail to parse.
+///
+/// Refer to the [`parse` module] documentation for more details about parsing
+/// in Syn.
+///
+/// [`parse` module]: mod@crate::parse
+///
+/// <br>
+///
+/// # Intended usage
+///
+/// This macro must be called from a function that returns
+/// `proc_macro::TokenStream`. Usually this will be your proc macro entry point,
+/// the function that has the #\[proc_macro\] / #\[proc_macro_derive\] /
+/// #\[proc_macro_attribute\] attribute.
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// use proc_macro::TokenStream;
+/// use syn::{parse_macro_input, Result};
+/// use syn::parse::{Parse, ParseStream};
+///
+/// struct MyMacroInput {
+///     /* ... */
+/// }
+///
+/// impl Parse for MyMacroInput {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         /* ... */
+/// #       Ok(MyMacroInput {})
+///     }
+/// }
+///
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro]
+/// # };
+/// pub fn my_macro(tokens: TokenStream) -> TokenStream {
+///     let input = parse_macro_input!(tokens as MyMacroInput);
+///
+///     /* ... */
+/// #   TokenStream::new()
+/// }
+/// ```
+///
+/// <br>
+///
+/// # Usage with Parser
+///
+/// This macro can also be used with the [`Parser` trait] for types that have
+/// multiple ways that they can be parsed.
+///
+/// [`Parser` trait]: crate::parse::Parser
+///
+/// ```
+/// # extern crate proc_macro;
+/// #
+/// # use proc_macro::TokenStream;
+/// # use syn::{parse_macro_input, Result};
+/// # use syn::parse::ParseStream;
+/// #
+/// # struct MyMacroInput {}
+/// #
+/// impl MyMacroInput {
+///     fn parse_alternate(input: ParseStream) -> Result<Self> {
+///         /* ... */
+/// #       Ok(MyMacroInput {})
+///     }
+/// }
+///
+/// # const IGNORE: &str = stringify! {
+/// #[proc_macro]
+/// # };
+/// pub fn my_macro(tokens: TokenStream) -> TokenStream {
+///     let input = parse_macro_input!(tokens with MyMacroInput::parse_alternate);
+///
+///     /* ... */
+/// #   TokenStream::new()
+/// }
+/// ```
+///
+/// <br>
+///
+/// # Expansion
+///
+/// `parse_macro_input!($variable as $Type)` expands to something like:
+///
+/// ```no_run
+/// # extern crate proc_macro;
+/// #
+/// # macro_rules! doc_test {
+/// #     ($variable:ident as $Type:ty) => {
+/// match syn::parse::<$Type>($variable) {
+///     Ok(syntax_tree) => syntax_tree,
+///     Err(err) => return proc_macro::TokenStream::from(err.to_compile_error()),
+/// }
+/// #     };
+/// # }
+/// #
+/// # fn test(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
+/// #     let _ = doc_test!(input as syn::Ident);
+/// #     proc_macro::TokenStream::new()
+/// # }
+/// ```
+#[macro_export]
+#[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "proc-macro"))))]
+macro_rules! parse_macro_input {
+    ($tokenstream:ident as $ty:ty) => {
+        match $crate::parse::<$ty>($tokenstream) {
+            $crate::__private::Ok(data) => data,
+            $crate::__private::Err(err) => {
+                return $crate::__private::TokenStream::from(err.to_compile_error());
+            }
+        }
+    };
+    ($tokenstream:ident with $parser:path) => {
+        match $crate::parse::Parser::parse($parser, $tokenstream) {
+            $crate::__private::Ok(data) => data,
+            $crate::__private::Err(err) => {
+                return $crate::__private::TokenStream::from(err.to_compile_error());
+            }
+        }
+    };
+    ($tokenstream:ident) => {
+        $crate::parse_macro_input!($tokenstream as _)
+    };
+}
diff --git a/rust/syn/parse_quote.rs b/rust/syn/parse_quote.rs
new file mode 100644
index 0000000000000000000000000000000000000000..7075108d0927ccc6b8f0cf737036a31bb76793ff
--- /dev/null
+++ b/rust/syn/parse_quote.rs
@@ -0,0 +1,212 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+/// Quasi-quotation macro that accepts input like the [`quote!`] macro but uses
+/// type inference to figure out a return type for those tokens.
+///
+/// [`quote!`]: https://docs.rs/quote/1.0/quote/index.html
+///
+/// The return type can be any syntax tree node that implements the [`Parse`]
+/// trait.
+///
+/// [`Parse`]: crate::parse::Parse
+///
+/// ```
+/// use quote::quote;
+/// use syn::{parse_quote, Stmt};
+///
+/// fn main() {
+///     let name = quote!(v);
+///     let ty = quote!(u8);
+///
+///     let stmt: Stmt = parse_quote! {
+///         let #name: #ty = Default::default();
+///     };
+///
+///     println!("{:#?}", stmt);
+/// }
+/// ```
+///
+/// *This macro is available only if Syn is built with both the `"parsing"` and
+/// `"printing"` features.*
+///
+/// # Example
+///
+/// The following helper function adds a bound `T: HeapSize` to every type
+/// parameter `T` in the input generics.
+///
+/// ```
+/// use syn::{parse_quote, Generics, GenericParam};
+///
+/// // Add a bound `T: HeapSize` to every type parameter T.
+/// fn add_trait_bounds(mut generics: Generics) -> Generics {
+///     for param in &mut generics.params {
+///         if let GenericParam::Type(type_param) = param {
+///             type_param.bounds.push(parse_quote!(HeapSize));
+///         }
+///     }
+///     generics
+/// }
+/// ```
+///
+/// # Special cases
+///
+/// This macro can parse the following additional types as a special case even
+/// though they do not implement the `Parse` trait.
+///
+/// - [`Attribute`] — parses one attribute, allowing either outer like `#[...]`
+///   or inner like `#![...]`
+/// - [`Punctuated<T, P>`] — parses zero or more `T` separated by punctuation
+///   `P` with optional trailing punctuation
+/// - [`Vec<Stmt>`] — parses the same as `Block::parse_within`
+///
+/// [`Vec<Stmt>`]: Block::parse_within
+///
+/// # Panics
+///
+/// Panics if the tokens fail to parse as the expected syntax tree type. The
+/// caller is responsible for ensuring that the input tokens are syntactically
+/// valid.
+#[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "printing"))))]
+#[macro_export]
+macro_rules! parse_quote {
+    ($($tt:tt)*) => {
+        $crate::__private::parse_quote($crate::__private::quote::quote!($($tt)*))
+    };
+}
+
+/// This macro is [`parse_quote!`] + [`quote_spanned!`][quote::quote_spanned].
+///
+/// Please refer to each of their documentation.
+///
+/// # Example
+///
+/// ```
+/// use quote::{quote, quote_spanned};
+/// use syn::spanned::Spanned;
+/// use syn::{parse_quote_spanned, ReturnType, Signature};
+///
+/// // Changes `fn()` to `fn() -> Pin<Box<dyn Future<Output = ()>>>`,
+/// // and `fn() -> T` to `fn() -> Pin<Box<dyn Future<Output = T>>>`,
+/// // without introducing any call_site() spans.
+/// fn make_ret_pinned_future(sig: &mut Signature) {
+///     let ret = match &sig.output {
+///         ReturnType::Default => quote_spanned!(sig.paren_token.span=> ()),
+///         ReturnType::Type(_, ret) => quote!(#ret),
+///     };
+///     sig.output = parse_quote_spanned! {ret.span()=>
+///         -> ::std::pin::Pin<::std::boxed::Box<dyn ::std::future::Future<Output = #ret>>>
+///     };
+/// }
+/// ```
+#[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "printing"))))]
+#[macro_export]
+macro_rules! parse_quote_spanned {
+    ($span:expr=> $($tt:tt)*) => {
+        $crate::__private::parse_quote($crate::__private::quote::quote_spanned!($span=> $($tt)*))
+    };
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Can parse any type that implements Parse.
+
+use crate::error::Result;
+use crate::parse::{Parse, ParseStream, Parser};
+use proc_macro2::TokenStream;
+
+// Not public API.
+#[doc(hidden)]
+pub fn parse<T: ParseQuote>(token_stream: TokenStream) -> T {
+    let parser = T::parse;
+    match parser.parse2(token_stream) {
+        Ok(t) => t,
+        Err(err) => panic!("{}", err),
+    }
+}
+
+#[doc(hidden)]
+pub trait ParseQuote: Sized {
+    fn parse(input: ParseStream) -> Result<Self>;
+}
+
+impl<T: Parse> ParseQuote for T {
+    fn parse(input: ParseStream) -> Result<Self> {
+        <T as Parse>::parse(input)
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// Any other types that we want `parse_quote!` to be able to parse.
+
+use crate::punctuated::Punctuated;
+#[cfg(any(feature = "full", feature = "derive"))]
+use crate::{attr, Attribute, Field, FieldMutability, Ident, Type, Visibility};
+#[cfg(feature = "full")]
+use crate::{Block, Pat, Stmt};
+
+#[cfg(any(feature = "full", feature = "derive"))]
+impl ParseQuote for Attribute {
+    fn parse(input: ParseStream) -> Result<Self> {
+        if input.peek(Token![#]) && input.peek2(Token![!]) {
+            attr::parsing::single_parse_inner(input)
+        } else {
+            attr::parsing::single_parse_outer(input)
+        }
+    }
+}
+
+#[cfg(any(feature = "full", feature = "derive"))]
+impl ParseQuote for Field {
+    fn parse(input: ParseStream) -> Result<Self> {
+        let attrs = input.call(Attribute::parse_outer)?;
+        let vis: Visibility = input.parse()?;
+
+        let ident: Option<Ident>;
+        let colon_token: Option<Token![:]>;
+        let is_named = input.peek(Ident) && input.peek2(Token![:]) && !input.peek2(Token![::]);
+        if is_named {
+            ident = Some(input.parse()?);
+            colon_token = Some(input.parse()?);
+        } else {
+            ident = None;
+            colon_token = None;
+        }
+
+        let ty: Type = input.parse()?;
+
+        Ok(Field {
+            attrs,
+            vis,
+            mutability: FieldMutability::None,
+            ident,
+            colon_token,
+            ty,
+        })
+    }
+}
+
+#[cfg(feature = "full")]
+impl ParseQuote for Pat {
+    fn parse(input: ParseStream) -> Result<Self> {
+        Pat::parse_multi_with_leading_vert(input)
+    }
+}
+
+#[cfg(feature = "full")]
+impl ParseQuote for Box<Pat> {
+    fn parse(input: ParseStream) -> Result<Self> {
+        <Pat as ParseQuote>::parse(input).map(Box::new)
+    }
+}
+
+impl<T: Parse, P: Parse> ParseQuote for Punctuated<T, P> {
+    fn parse(input: ParseStream) -> Result<Self> {
+        Self::parse_terminated(input)
+    }
+}
+
+#[cfg(feature = "full")]
+impl ParseQuote for Vec<Stmt> {
+    fn parse(input: ParseStream) -> Result<Self> {
+        Block::parse_within(input)
+    }
+}
diff --git a/rust/syn/pat.rs b/rust/syn/pat.rs
new file mode 100644
index 0000000000000000000000000000000000000000..68898a51a9b9083592dc3db1f4d8056f41f1b721
--- /dev/null
+++ b/rust/syn/pat.rs
@@ -0,0 +1,949 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+use crate::expr::Member;
+use crate::ident::Ident;
+use crate::path::{Path, QSelf};
+use crate::punctuated::Punctuated;
+use crate::token;
+use crate::ty::Type;
+use proc_macro2::TokenStream;
+
+pub use crate::expr::{
+    ExprConst as PatConst, ExprLit as PatLit, ExprMacro as PatMacro, ExprPath as PatPath,
+    ExprRange as PatRange,
+};
+
+ast_enum_of_structs! {
+    /// A pattern in a local binding, function signature, match expression, or
+    /// various other places.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    #[non_exhaustive]
+    pub enum Pat {
+        /// A const block: `const { ... }`.
+        Const(PatConst),
+
+        /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
+        Ident(PatIdent),
+
+        /// A literal pattern: `0`.
+        Lit(PatLit),
+
+        /// A macro in pattern position.
+        Macro(PatMacro),
+
+        /// A pattern that matches any one of a set of cases.
+        Or(PatOr),
+
+        /// A parenthesized pattern: `(A | B)`.
+        Paren(PatParen),
+
+        /// A path pattern like `Color::Red`, optionally qualified with a
+        /// self-type.
+        ///
+        /// Unqualified path patterns can legally refer to variants, structs,
+        /// constants or associated constants. Qualified path patterns like
+        /// `<A>::B::C` and `<A as Trait>::B::C` can only legally refer to
+        /// associated constants.
+        Path(PatPath),
+
+        /// A range pattern: `1..=2`.
+        Range(PatRange),
+
+        /// A reference pattern: `&mut var`.
+        Reference(PatReference),
+
+        /// The dots in a tuple or slice pattern: `[0, 1, ..]`.
+        Rest(PatRest),
+
+        /// A dynamically sized slice pattern: `[a, b, ref i @ .., y, z]`.
+        Slice(PatSlice),
+
+        /// A struct or struct variant pattern: `Variant { x, y, .. }`.
+        Struct(PatStruct),
+
+        /// A tuple pattern: `(a, b)`.
+        Tuple(PatTuple),
+
+        /// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
+        TupleStruct(PatTupleStruct),
+
+        /// A type ascription pattern: `foo: f64`.
+        Type(PatType),
+
+        /// Tokens in pattern position not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        /// A pattern that matches any value: `_`.
+        Wild(PatWild),
+
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match pat {
+        //         #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //
+        //         Pat::Box(pat) => {...}
+        //         Pat::Ident(pat) => {...}
+        //         ...
+        //         Pat::Wild(pat) => {...}
+        //
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+    }
+}
+
+ast_struct! {
+    /// A pattern that binds a new variable: `ref mut binding @ SUBPATTERN`.
+    ///
+    /// It may also be a unit struct or struct variant (e.g. `None`), or a
+    /// constant; these cannot be distinguished syntactically.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatIdent {
+        pub attrs: Vec<Attribute>,
+        pub by_ref: Option<Token![ref]>,
+        pub mutability: Option<Token![mut]>,
+        pub ident: Ident,
+        pub subpat: Option<(Token![@], Box<Pat>)>,
+    }
+}
+
+ast_struct! {
+    /// A pattern that matches any one of a set of cases.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatOr {
+        pub attrs: Vec<Attribute>,
+        pub leading_vert: Option<Token![|]>,
+        pub cases: Punctuated<Pat, Token![|]>,
+    }
+}
+
+ast_struct! {
+    /// A parenthesized pattern: `(A | B)`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatParen {
+        pub attrs: Vec<Attribute>,
+        pub paren_token: token::Paren,
+        pub pat: Box<Pat>,
+    }
+}
+
+ast_struct! {
+    /// A reference pattern: `&mut var`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatReference {
+        pub attrs: Vec<Attribute>,
+        pub and_token: Token![&],
+        pub mutability: Option<Token![mut]>,
+        pub pat: Box<Pat>,
+    }
+}
+
+ast_struct! {
+    /// The dots in a tuple or slice pattern: `[0, 1, ..]`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatRest {
+        pub attrs: Vec<Attribute>,
+        pub dot2_token: Token![..],
+    }
+}
+
+ast_struct! {
+    /// A dynamically sized slice pattern: `[a, b, ref i @ .., y, z]`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatSlice {
+        pub attrs: Vec<Attribute>,
+        pub bracket_token: token::Bracket,
+        pub elems: Punctuated<Pat, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A struct or struct variant pattern: `Variant { x, y, .. }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatStruct {
+        pub attrs: Vec<Attribute>,
+        pub qself: Option<QSelf>,
+        pub path: Path,
+        pub brace_token: token::Brace,
+        pub fields: Punctuated<FieldPat, Token![,]>,
+        pub rest: Option<PatRest>,
+    }
+}
+
+ast_struct! {
+    /// A tuple pattern: `(a, b)`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatTuple {
+        pub attrs: Vec<Attribute>,
+        pub paren_token: token::Paren,
+        pub elems: Punctuated<Pat, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatTupleStruct {
+        pub attrs: Vec<Attribute>,
+        pub qself: Option<QSelf>,
+        pub path: Path,
+        pub paren_token: token::Paren,
+        pub elems: Punctuated<Pat, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// A type ascription pattern: `foo: f64`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatType {
+        pub attrs: Vec<Attribute>,
+        pub pat: Box<Pat>,
+        pub colon_token: Token![:],
+        pub ty: Box<Type>,
+    }
+}
+
+ast_struct! {
+    /// A pattern that matches any value: `_`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct PatWild {
+        pub attrs: Vec<Attribute>,
+        pub underscore_token: Token![_],
+    }
+}
+
+ast_struct! {
+    /// A single field in a struct pattern.
+    ///
+    /// Patterns like the fields of Foo `{ x, ref y, ref mut z }` are treated
+    /// the same as `x: x, y: ref y, z: ref mut z` but there is no colon token.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct FieldPat {
+        pub attrs: Vec<Attribute>,
+        pub member: Member,
+        pub colon_token: Option<Token![:]>,
+        pub pat: Box<Pat>,
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::Attribute;
+    use crate::error::{self, Result};
+    use crate::expr::{
+        Expr, ExprConst, ExprLit, ExprMacro, ExprPath, ExprRange, Member, RangeLimits,
+    };
+    use crate::ext::IdentExt as _;
+    use crate::ident::Ident;
+    use crate::lit::Lit;
+    use crate::mac::{self, Macro};
+    use crate::parse::{Parse, ParseBuffer, ParseStream};
+    use crate::pat::{
+        FieldPat, Pat, PatIdent, PatOr, PatParen, PatReference, PatRest, PatSlice, PatStruct,
+        PatTuple, PatTupleStruct, PatType, PatWild,
+    };
+    use crate::path::{self, Path, QSelf};
+    use crate::punctuated::Punctuated;
+    use crate::stmt::Block;
+    use crate::token;
+    use crate::verbatim;
+    use proc_macro2::TokenStream;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Pat {
+        /// Parse a pattern that does _not_ involve `|` at the top level.
+        ///
+        /// This parser matches the behavior of the `$:pat_param` macro_rules
+        /// matcher, and on editions prior to Rust 2021, the behavior of
+        /// `$:pat`.
+        ///
+        /// In Rust syntax, some examples of where this syntax would occur are
+        /// in the argument pattern of functions and closures. Patterns using
+        /// `|` are not allowed to occur in these positions.
+        ///
+        /// ```compile_fail
+        /// fn f(Some(_) | None: Option<T>) {
+        ///     let _ = |Some(_) | None: Option<T>| {};
+        ///     //       ^^^^^^^^^^^^^^^^^^^^^^^^^??? :(
+        /// }
+        /// ```
+        ///
+        /// ```console
+        /// error: top-level or-patterns are not allowed in function parameters
+        ///  --> src/main.rs:1:6
+        ///   |
+        /// 1 | fn f(Some(_) | None: Option<T>) {
+        ///   |      ^^^^^^^^^^^^^^ help: wrap the pattern in parentheses: `(Some(_) | None)`
+        /// ```
+        pub fn parse_single(input: ParseStream) -> Result<Self> {
+            let begin = input.fork();
+            let lookahead = input.lookahead1();
+            if lookahead.peek(Ident)
+                && (input.peek2(Token![::])
+                    || input.peek2(Token![!])
+                    || input.peek2(token::Brace)
+                    || input.peek2(token::Paren)
+                    || input.peek2(Token![..]))
+                || input.peek(Token![self]) && input.peek2(Token![::])
+                || lookahead.peek(Token![::])
+                || lookahead.peek(Token![<])
+                || input.peek(Token![Self])
+                || input.peek(Token![super])
+                || input.peek(Token![crate])
+            {
+                pat_path_or_macro_or_struct_or_range(input)
+            } else if lookahead.peek(Token![_]) {
+                input.call(pat_wild).map(Pat::Wild)
+            } else if input.peek(Token![box]) {
+                pat_box(begin, input)
+            } else if input.peek(Token![-]) || lookahead.peek(Lit) || lookahead.peek(Token![const])
+            {
+                pat_lit_or_range(input)
+            } else if lookahead.peek(Token![ref])
+                || lookahead.peek(Token![mut])
+                || input.peek(Token![self])
+                || input.peek(Ident)
+            {
+                input.call(pat_ident).map(Pat::Ident)
+            } else if lookahead.peek(Token![&]) {
+                input.call(pat_reference).map(Pat::Reference)
+            } else if lookahead.peek(token::Paren) {
+                input.call(pat_paren_or_tuple)
+            } else if lookahead.peek(token::Bracket) {
+                input.call(pat_slice).map(Pat::Slice)
+            } else if lookahead.peek(Token![..]) && !input.peek(Token![...]) {
+                pat_range_half_open(input)
+            } else if lookahead.peek(Token![const]) {
+                input.call(pat_const).map(Pat::Verbatim)
+            } else {
+                Err(lookahead.error())
+            }
+        }
+
+        /// Parse a pattern, possibly involving `|`, but not a leading `|`.
+        pub fn parse_multi(input: ParseStream) -> Result<Self> {
+            multi_pat_impl(input, None)
+        }
+
+        /// Parse a pattern, possibly involving `|`, possibly including a
+        /// leading `|`.
+        ///
+        /// This parser matches the behavior of the Rust 2021 edition's `$:pat`
+        /// macro_rules matcher.
+        ///
+        /// In Rust syntax, an example of where this syntax would occur is in
+        /// the pattern of a `match` arm, where the language permits an optional
+        /// leading `|`, although it is not idiomatic to write one there in
+        /// handwritten code.
+        ///
+        /// ```
+        /// # let wat = None;
+        /// match wat {
+        ///     | None | Some(false) => {}
+        ///     | Some(true) => {}
+        /// }
+        /// ```
+        ///
+        /// The compiler accepts it only to facilitate some situations in
+        /// macro-generated code where a macro author might need to write:
+        ///
+        /// ```
+        /// # macro_rules! doc {
+        /// #     ($value:expr, ($($conditions1:pat),*), ($($conditions2:pat),*), $then:expr) => {
+        /// match $value {
+        ///     $(| $conditions1)* $(| $conditions2)* => $then
+        /// }
+        /// #     };
+        /// # }
+        /// #
+        /// # doc!(true, (true), (false), {});
+        /// # doc!(true, (), (true, false), {});
+        /// # doc!(true, (true, false), (), {});
+        /// ```
+        ///
+        /// Expressing the same thing correctly in the case that either one (but
+        /// not both) of `$conditions1` and `$conditions2` might be empty,
+        /// without leading `|`, is complex.
+        ///
+        /// Use [`Pat::parse_multi`] instead if you are not intending to support
+        /// macro-generated macro input.
+        pub fn parse_multi_with_leading_vert(input: ParseStream) -> Result<Self> {
+            let leading_vert: Option<Token![|]> = input.parse()?;
+            multi_pat_impl(input, leading_vert)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for PatType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(PatType {
+                attrs: Vec::new(),
+                pat: Box::new(Pat::parse_single(input)?),
+                colon_token: input.parse()?,
+                ty: input.parse()?,
+            })
+        }
+    }
+
+    fn multi_pat_impl(input: ParseStream, leading_vert: Option<Token![|]>) -> Result<Pat> {
+        let mut pat = Pat::parse_single(input)?;
+        if leading_vert.is_some()
+            || input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=])
+        {
+            let mut cases = Punctuated::new();
+            cases.push_value(pat);
+            while input.peek(Token![|]) && !input.peek(Token![||]) && !input.peek(Token![|=]) {
+                let punct = input.parse()?;
+                cases.push_punct(punct);
+                let pat = Pat::parse_single(input)?;
+                cases.push_value(pat);
+            }
+            pat = Pat::Or(PatOr {
+                attrs: Vec::new(),
+                leading_vert,
+                cases,
+            });
+        }
+        Ok(pat)
+    }
+
+    fn pat_path_or_macro_or_struct_or_range(input: ParseStream) -> Result<Pat> {
+        let (qself, path) = path::parsing::qpath(input, true)?;
+
+        if qself.is_none()
+            && input.peek(Token![!])
+            && !input.peek(Token![!=])
+            && path.is_mod_style()
+        {
+            let bang_token: Token![!] = input.parse()?;
+            let (delimiter, tokens) = mac::parse_delimiter(input)?;
+            return Ok(Pat::Macro(ExprMacro {
+                attrs: Vec::new(),
+                mac: Macro {
+                    path,
+                    bang_token,
+                    delimiter,
+                    tokens,
+                },
+            }));
+        }
+
+        if input.peek(token::Brace) {
+            pat_struct(input, qself, path).map(Pat::Struct)
+        } else if input.peek(token::Paren) {
+            pat_tuple_struct(input, qself, path).map(Pat::TupleStruct)
+        } else if input.peek(Token![..]) {
+            pat_range(input, qself, path)
+        } else {
+            Ok(Pat::Path(ExprPath {
+                attrs: Vec::new(),
+                qself,
+                path,
+            }))
+        }
+    }
+
+    fn pat_wild(input: ParseStream) -> Result<PatWild> {
+        Ok(PatWild {
+            attrs: Vec::new(),
+            underscore_token: input.parse()?,
+        })
+    }
+
+    fn pat_box(begin: ParseBuffer, input: ParseStream) -> Result<Pat> {
+        input.parse::<Token![box]>()?;
+        Pat::parse_single(input)?;
+        Ok(Pat::Verbatim(verbatim::between(&begin, input)))
+    }
+
+    fn pat_ident(input: ParseStream) -> Result<PatIdent> {
+        Ok(PatIdent {
+            attrs: Vec::new(),
+            by_ref: input.parse()?,
+            mutability: input.parse()?,
+            ident: input.call(Ident::parse_any)?,
+            subpat: {
+                if input.peek(Token![@]) {
+                    let at_token: Token![@] = input.parse()?;
+                    let subpat = Pat::parse_single(input)?;
+                    Some((at_token, Box::new(subpat)))
+                } else {
+                    None
+                }
+            },
+        })
+    }
+
+    fn pat_tuple_struct(
+        input: ParseStream,
+        qself: Option<QSelf>,
+        path: Path,
+    ) -> Result<PatTupleStruct> {
+        let content;
+        let paren_token = parenthesized!(content in input);
+
+        let mut elems = Punctuated::new();
+        while !content.is_empty() {
+            let value = Pat::parse_multi_with_leading_vert(&content)?;
+            elems.push_value(value);
+            if content.is_empty() {
+                break;
+            }
+            let punct = content.parse()?;
+            elems.push_punct(punct);
+        }
+
+        Ok(PatTupleStruct {
+            attrs: Vec::new(),
+            qself,
+            path,
+            paren_token,
+            elems,
+        })
+    }
+
+    fn pat_struct(input: ParseStream, qself: Option<QSelf>, path: Path) -> Result<PatStruct> {
+        let content;
+        let brace_token = braced!(content in input);
+
+        let mut fields = Punctuated::new();
+        let mut rest = None;
+        while !content.is_empty() {
+            let attrs = content.call(Attribute::parse_outer)?;
+            if content.peek(Token![..]) {
+                rest = Some(PatRest {
+                    attrs,
+                    dot2_token: content.parse()?,
+                });
+                break;
+            }
+            let mut value = content.call(field_pat)?;
+            value.attrs = attrs;
+            fields.push_value(value);
+            if content.is_empty() {
+                break;
+            }
+            let punct: Token![,] = content.parse()?;
+            fields.push_punct(punct);
+        }
+
+        Ok(PatStruct {
+            attrs: Vec::new(),
+            qself,
+            path,
+            brace_token,
+            fields,
+            rest,
+        })
+    }
+
+    fn field_pat(input: ParseStream) -> Result<FieldPat> {
+        let begin = input.fork();
+        let boxed: Option<Token![box]> = input.parse()?;
+        let by_ref: Option<Token![ref]> = input.parse()?;
+        let mutability: Option<Token![mut]> = input.parse()?;
+
+        let member = if boxed.is_some() || by_ref.is_some() || mutability.is_some() {
+            input.parse().map(Member::Named)
+        } else {
+            input.parse()
+        }?;
+
+        if boxed.is_none() && by_ref.is_none() && mutability.is_none() && input.peek(Token![:])
+            || !member.is_named()
+        {
+            return Ok(FieldPat {
+                attrs: Vec::new(),
+                member,
+                colon_token: Some(input.parse()?),
+                pat: Box::new(Pat::parse_multi_with_leading_vert(input)?),
+            });
+        }
+
+        let ident = match member {
+            Member::Named(ident) => ident,
+            Member::Unnamed(_) => unreachable!(),
+        };
+
+        let pat = if boxed.is_some() {
+            Pat::Verbatim(verbatim::between(&begin, input))
+        } else {
+            Pat::Ident(PatIdent {
+                attrs: Vec::new(),
+                by_ref,
+                mutability,
+                ident: ident.clone(),
+                subpat: None,
+            })
+        };
+
+        Ok(FieldPat {
+            attrs: Vec::new(),
+            member: Member::Named(ident),
+            colon_token: None,
+            pat: Box::new(pat),
+        })
+    }
+
+    fn pat_range(input: ParseStream, qself: Option<QSelf>, path: Path) -> Result<Pat> {
+        let limits = RangeLimits::parse_obsolete(input)?;
+        let end = input.call(pat_range_bound)?;
+        if let (RangeLimits::Closed(_), None) = (&limits, &end) {
+            return Err(input.error("expected range upper bound"));
+        }
+        Ok(Pat::Range(ExprRange {
+            attrs: Vec::new(),
+            start: Some(Box::new(Expr::Path(ExprPath {
+                attrs: Vec::new(),
+                qself,
+                path,
+            }))),
+            limits,
+            end: end.map(PatRangeBound::into_expr),
+        }))
+    }
+
+    fn pat_range_half_open(input: ParseStream) -> Result<Pat> {
+        let limits: RangeLimits = input.parse()?;
+        let end = input.call(pat_range_bound)?;
+        if end.is_some() {
+            Ok(Pat::Range(ExprRange {
+                attrs: Vec::new(),
+                start: None,
+                limits,
+                end: end.map(PatRangeBound::into_expr),
+            }))
+        } else {
+            match limits {
+                RangeLimits::HalfOpen(dot2_token) => Ok(Pat::Rest(PatRest {
+                    attrs: Vec::new(),
+                    dot2_token,
+                })),
+                RangeLimits::Closed(_) => Err(input.error("expected range upper bound")),
+            }
+        }
+    }
+
+    fn pat_paren_or_tuple(input: ParseStream) -> Result<Pat> {
+        let content;
+        let paren_token = parenthesized!(content in input);
+
+        let mut elems = Punctuated::new();
+        while !content.is_empty() {
+            let value = Pat::parse_multi_with_leading_vert(&content)?;
+            if content.is_empty() {
+                if elems.is_empty() && !matches!(value, Pat::Rest(_)) {
+                    return Ok(Pat::Paren(PatParen {
+                        attrs: Vec::new(),
+                        paren_token,
+                        pat: Box::new(value),
+                    }));
+                }
+                elems.push_value(value);
+                break;
+            }
+            elems.push_value(value);
+            let punct = content.parse()?;
+            elems.push_punct(punct);
+        }
+
+        Ok(Pat::Tuple(PatTuple {
+            attrs: Vec::new(),
+            paren_token,
+            elems,
+        }))
+    }
+
+    fn pat_reference(input: ParseStream) -> Result<PatReference> {
+        Ok(PatReference {
+            attrs: Vec::new(),
+            and_token: input.parse()?,
+            mutability: input.parse()?,
+            pat: Box::new(Pat::parse_single(input)?),
+        })
+    }
+
+    fn pat_lit_or_range(input: ParseStream) -> Result<Pat> {
+        let start = input.call(pat_range_bound)?.unwrap();
+        if input.peek(Token![..]) {
+            let limits = RangeLimits::parse_obsolete(input)?;
+            let end = input.call(pat_range_bound)?;
+            if let (RangeLimits::Closed(_), None) = (&limits, &end) {
+                return Err(input.error("expected range upper bound"));
+            }
+            Ok(Pat::Range(ExprRange {
+                attrs: Vec::new(),
+                start: Some(start.into_expr()),
+                limits,
+                end: end.map(PatRangeBound::into_expr),
+            }))
+        } else {
+            Ok(start.into_pat())
+        }
+    }
+
+    // Patterns that can appear on either side of a range pattern.
+    enum PatRangeBound {
+        Const(ExprConst),
+        Lit(ExprLit),
+        Path(ExprPath),
+    }
+
+    impl PatRangeBound {
+        fn into_expr(self) -> Box<Expr> {
+            Box::new(match self {
+                PatRangeBound::Const(pat) => Expr::Const(pat),
+                PatRangeBound::Lit(pat) => Expr::Lit(pat),
+                PatRangeBound::Path(pat) => Expr::Path(pat),
+            })
+        }
+
+        fn into_pat(self) -> Pat {
+            match self {
+                PatRangeBound::Const(pat) => Pat::Const(pat),
+                PatRangeBound::Lit(pat) => Pat::Lit(pat),
+                PatRangeBound::Path(pat) => Pat::Path(pat),
+            }
+        }
+    }
+
+    fn pat_range_bound(input: ParseStream) -> Result<Option<PatRangeBound>> {
+        if input.is_empty()
+            || input.peek(Token![|])
+            || input.peek(Token![=])
+            || input.peek(Token![:]) && !input.peek(Token![::])
+            || input.peek(Token![,])
+            || input.peek(Token![;])
+            || input.peek(Token![if])
+        {
+            return Ok(None);
+        }
+
+        let lookahead = input.lookahead1();
+        let expr = if lookahead.peek(Lit) {
+            PatRangeBound::Lit(input.parse()?)
+        } else if lookahead.peek(Ident)
+            || lookahead.peek(Token![::])
+            || lookahead.peek(Token![<])
+            || lookahead.peek(Token![self])
+            || lookahead.peek(Token![Self])
+            || lookahead.peek(Token![super])
+            || lookahead.peek(Token![crate])
+        {
+            PatRangeBound::Path(input.parse()?)
+        } else if lookahead.peek(Token![const]) {
+            PatRangeBound::Const(input.parse()?)
+        } else {
+            return Err(lookahead.error());
+        };
+
+        Ok(Some(expr))
+    }
+
+    fn pat_slice(input: ParseStream) -> Result<PatSlice> {
+        let content;
+        let bracket_token = bracketed!(content in input);
+
+        let mut elems = Punctuated::new();
+        while !content.is_empty() {
+            let value = Pat::parse_multi_with_leading_vert(&content)?;
+            match value {
+                Pat::Range(pat) if pat.start.is_none() || pat.end.is_none() => {
+                    let (start, end) = match pat.limits {
+                        RangeLimits::HalfOpen(dot_dot) => (dot_dot.spans[0], dot_dot.spans[1]),
+                        RangeLimits::Closed(dot_dot_eq) => {
+                            (dot_dot_eq.spans[0], dot_dot_eq.spans[2])
+                        }
+                    };
+                    let msg = "range pattern is not allowed unparenthesized inside slice pattern";
+                    return Err(error::new2(start, end, msg));
+                }
+                _ => {}
+            }
+            elems.push_value(value);
+            if content.is_empty() {
+                break;
+            }
+            let punct = content.parse()?;
+            elems.push_punct(punct);
+        }
+
+        Ok(PatSlice {
+            attrs: Vec::new(),
+            bracket_token,
+            elems,
+        })
+    }
+
+    fn pat_const(input: ParseStream) -> Result<TokenStream> {
+        let begin = input.fork();
+        input.parse::<Token![const]>()?;
+
+        let content;
+        braced!(content in input);
+        content.call(Attribute::parse_inner)?;
+        content.call(Block::parse_within)?;
+
+        Ok(verbatim::between(&begin, input))
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::attr::FilterAttrs;
+    use crate::pat::{
+        FieldPat, Pat, PatIdent, PatOr, PatParen, PatReference, PatRest, PatSlice, PatStruct,
+        PatTuple, PatTupleStruct, PatType, PatWild,
+    };
+    use crate::path;
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatIdent {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.by_ref.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.ident.to_tokens(tokens);
+            if let Some((at_token, subpat)) = &self.subpat {
+                at_token.to_tokens(tokens);
+                subpat.to_tokens(tokens);
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatOr {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.leading_vert.to_tokens(tokens);
+            self.cases.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatParen {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.paren_token.surround(tokens, |tokens| {
+                self.pat.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatReference {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.and_token.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.pat.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatRest {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.dot2_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatSlice {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.bracket_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatStruct {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            path::printing::print_path(tokens, &self.qself, &self.path);
+            self.brace_token.surround(tokens, |tokens| {
+                self.fields.to_tokens(tokens);
+                // NOTE: We need a comma before the dot2 token if it is present.
+                if !self.fields.empty_or_trailing() && self.rest.is_some() {
+                    <Token![,]>::default().to_tokens(tokens);
+                }
+                self.rest.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatTuple {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.paren_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+                // If there is only one element, a trailing comma is needed to
+                // distinguish PatTuple from PatParen, unless this is `(..)`
+                // which is a tuple pattern even without comma.
+                if self.elems.len() == 1
+                    && !self.elems.trailing_punct()
+                    && !matches!(self.elems[0], Pat::Rest { .. })
+                {
+                    <Token![,]>::default().to_tokens(tokens);
+                }
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatTupleStruct {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            path::printing::print_path(tokens, &self.qself, &self.path);
+            self.paren_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.pat.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PatWild {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            self.underscore_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for FieldPat {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            if let Some(colon_token) = &self.colon_token {
+                self.member.to_tokens(tokens);
+                colon_token.to_tokens(tokens);
+            }
+            self.pat.to_tokens(tokens);
+        }
+    }
+}
diff --git a/rust/syn/path.rs b/rust/syn/path.rs
new file mode 100644
index 0000000000000000000000000000000000000000..165fe82ef3b735de9e7b9c74793955b7fabfa3e2
--- /dev/null
+++ b/rust/syn/path.rs
@@ -0,0 +1,909 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "parsing")]
+use crate::error::Result;
+use crate::expr::Expr;
+use crate::generics::TypeParamBound;
+use crate::ident::Ident;
+use crate::lifetime::Lifetime;
+use crate::punctuated::Punctuated;
+use crate::token;
+use crate::ty::{ReturnType, Type};
+
+ast_struct! {
+    /// A path at which a named item is exported (e.g. `std::collections::HashMap`).
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct Path {
+        pub leading_colon: Option<Token![::]>,
+        pub segments: Punctuated<PathSegment, Token![::]>,
+    }
+}
+
+impl<T> From<T> for Path
+where
+    T: Into<PathSegment>,
+{
+    fn from(segment: T) -> Self {
+        let mut path = Path {
+            leading_colon: None,
+            segments: Punctuated::new(),
+        };
+        path.segments.push_value(segment.into());
+        path
+    }
+}
+
+impl Path {
+    /// Determines whether this is a path of length 1 equal to the given
+    /// ident.
+    ///
+    /// For them to compare equal, it must be the case that:
+    ///
+    /// - the path has no leading colon,
+    /// - the number of path segments is 1,
+    /// - the first path segment has no angle bracketed or parenthesized
+    ///   path arguments, and
+    /// - the ident of the first path segment is equal to the given one.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// use proc_macro2::TokenStream;
+    /// use syn::{Attribute, Error, Meta, Result};
+    ///
+    /// fn get_serde_meta_item(attr: &Attribute) -> Result<Option<&TokenStream>> {
+    ///     if attr.path().is_ident("serde") {
+    ///         match &attr.meta {
+    ///             Meta::List(meta) => Ok(Some(&meta.tokens)),
+    ///             bad => Err(Error::new_spanned(bad, "unrecognized attribute")),
+    ///         }
+    ///     } else {
+    ///         Ok(None)
+    ///     }
+    /// }
+    /// ```
+    pub fn is_ident<I>(&self, ident: &I) -> bool
+    where
+        I: ?Sized,
+        Ident: PartialEq<I>,
+    {
+        match self.get_ident() {
+            Some(id) => id == ident,
+            None => false,
+        }
+    }
+
+    /// If this path consists of a single ident, returns the ident.
+    ///
+    /// A path is considered an ident if:
+    ///
+    /// - the path has no leading colon,
+    /// - the number of path segments is 1, and
+    /// - the first path segment has no angle bracketed or parenthesized
+    ///   path arguments.
+    pub fn get_ident(&self) -> Option<&Ident> {
+        if self.leading_colon.is_none()
+            && self.segments.len() == 1
+            && self.segments[0].arguments.is_none()
+        {
+            Some(&self.segments[0].ident)
+        } else {
+            None
+        }
+    }
+
+    /// An error if this path is not a single ident, as defined in `get_ident`.
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn require_ident(&self) -> Result<&Ident> {
+        self.get_ident().ok_or_else(|| {
+            crate::error::new2(
+                self.segments.first().unwrap().ident.span(),
+                self.segments.last().unwrap().ident.span(),
+                "expected this path to be an identifier",
+            )
+        })
+    }
+}
+
+ast_struct! {
+    /// A segment of a path together with any path arguments on that segment.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct PathSegment {
+        pub ident: Ident,
+        pub arguments: PathArguments,
+    }
+}
+
+impl<T> From<T> for PathSegment
+where
+    T: Into<Ident>,
+{
+    fn from(ident: T) -> Self {
+        PathSegment {
+            ident: ident.into(),
+            arguments: PathArguments::None,
+        }
+    }
+}
+
+ast_enum! {
+    /// Angle bracketed or parenthesized arguments of a path segment.
+    ///
+    /// ## Angle bracketed
+    ///
+    /// The `<'a, T>` in `std::slice::iter<'a, T>`.
+    ///
+    /// ## Parenthesized
+    ///
+    /// The `(A, B) -> C` in `Fn(A, B) -> C`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum PathArguments {
+        None,
+        /// The `<'a, T>` in `std::slice::iter<'a, T>`.
+        AngleBracketed(AngleBracketedGenericArguments),
+        /// The `(A, B) -> C` in `Fn(A, B) -> C`.
+        Parenthesized(ParenthesizedGenericArguments),
+    }
+}
+
+impl Default for PathArguments {
+    fn default() -> Self {
+        PathArguments::None
+    }
+}
+
+impl PathArguments {
+    pub fn is_empty(&self) -> bool {
+        match self {
+            PathArguments::None => true,
+            PathArguments::AngleBracketed(bracketed) => bracketed.args.is_empty(),
+            PathArguments::Parenthesized(_) => false,
+        }
+    }
+
+    pub fn is_none(&self) -> bool {
+        match self {
+            PathArguments::None => true,
+            PathArguments::AngleBracketed(_) | PathArguments::Parenthesized(_) => false,
+        }
+    }
+}
+
+ast_enum! {
+    /// An individual generic argument, like `'a`, `T`, or `Item = T`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum GenericArgument {
+        /// A lifetime argument.
+        Lifetime(Lifetime),
+        /// A type argument.
+        Type(Type),
+        /// A const expression. Must be inside of a block.
+        ///
+        /// NOTE: Identity expressions are represented as Type arguments, as
+        /// they are indistinguishable syntactically.
+        Const(Expr),
+        /// A binding (equality constraint) on an associated type: the `Item =
+        /// u8` in `Iterator<Item = u8>`.
+        AssocType(AssocType),
+        /// An equality constraint on an associated constant: the `PANIC =
+        /// false` in `Trait<PANIC = false>`.
+        AssocConst(AssocConst),
+        /// An associated type bound: `Iterator<Item: Display>`.
+        Constraint(Constraint),
+    }
+}
+
+ast_struct! {
+    /// Angle bracketed arguments of a path segment: the `<K, V>` in `HashMap<K,
+    /// V>`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct AngleBracketedGenericArguments {
+        pub colon2_token: Option<Token![::]>,
+        pub lt_token: Token![<],
+        pub args: Punctuated<GenericArgument, Token![,]>,
+        pub gt_token: Token![>],
+    }
+}
+
+ast_struct! {
+    /// A binding (equality constraint) on an associated type: the `Item = u8`
+    /// in `Iterator<Item = u8>`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct AssocType {
+        pub ident: Ident,
+        pub generics: Option<AngleBracketedGenericArguments>,
+        pub eq_token: Token![=],
+        pub ty: Type,
+    }
+}
+
+ast_struct! {
+    /// An equality constraint on an associated constant: the `PANIC = false` in
+    /// `Trait<PANIC = false>`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct AssocConst {
+        pub ident: Ident,
+        pub generics: Option<AngleBracketedGenericArguments>,
+        pub eq_token: Token![=],
+        pub value: Expr,
+    }
+}
+
+ast_struct! {
+    /// An associated type bound: `Iterator<Item: Display>`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct Constraint {
+        pub ident: Ident,
+        pub generics: Option<AngleBracketedGenericArguments>,
+        pub colon_token: Token![:],
+        pub bounds: Punctuated<TypeParamBound, Token![+]>,
+    }
+}
+
+ast_struct! {
+    /// Arguments of a function path segment: the `(A, B) -> C` in `Fn(A,B) ->
+    /// C`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct ParenthesizedGenericArguments {
+        pub paren_token: token::Paren,
+        /// `(A, B)`
+        pub inputs: Punctuated<Type, Token![,]>,
+        /// `C`
+        pub output: ReturnType,
+    }
+}
+
+ast_struct! {
+    /// The explicit Self type in a qualified path: the `T` in `<T as
+    /// Display>::fmt`.
+    ///
+    /// The actual path, including the trait and the associated item, is stored
+    /// separately. The `position` field represents the index of the associated
+    /// item qualified with this Self type.
+    ///
+    /// ```text
+    /// <Vec<T> as a::b::Trait>::AssociatedItem
+    ///  ^~~~~~    ~~~~~~~~~~~~~~^
+    ///  ty        position = 3
+    ///
+    /// <Vec<T>>::AssociatedItem
+    ///  ^~~~~~   ^
+    ///  ty       position = 0
+    /// ```
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct QSelf {
+        pub lt_token: Token![<],
+        pub ty: Box<Type>,
+        pub position: usize,
+        pub as_token: Option<Token![as]>,
+        pub gt_token: Token![>],
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::error::Result;
+    #[cfg(feature = "full")]
+    use crate::expr::ExprBlock;
+    use crate::expr::{Expr, ExprPath};
+    use crate::ext::IdentExt as _;
+    #[cfg(feature = "full")]
+    use crate::generics::TypeParamBound;
+    use crate::ident::Ident;
+    use crate::lifetime::Lifetime;
+    use crate::lit::Lit;
+    use crate::parse::{Parse, ParseStream};
+    #[cfg(feature = "full")]
+    use crate::path::Constraint;
+    use crate::path::{
+        AngleBracketedGenericArguments, AssocConst, AssocType, GenericArgument,
+        ParenthesizedGenericArguments, Path, PathArguments, PathSegment, QSelf,
+    };
+    use crate::punctuated::Punctuated;
+    use crate::token;
+    use crate::ty::{ReturnType, Type};
+    #[cfg(not(feature = "full"))]
+    use crate::verbatim;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Path {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Self::parse_helper(input, false)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for GenericArgument {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Lifetime) && !input.peek2(Token![+]) {
+                return Ok(GenericArgument::Lifetime(input.parse()?));
+            }
+
+            if input.peek(Lit) || input.peek(token::Brace) {
+                return const_argument(input).map(GenericArgument::Const);
+            }
+
+            let mut argument: Type = input.parse()?;
+
+            match argument {
+                Type::Path(mut ty)
+                    if ty.qself.is_none()
+                        && ty.path.leading_colon.is_none()
+                        && ty.path.segments.len() == 1
+                        && match &ty.path.segments[0].arguments {
+                            PathArguments::None | PathArguments::AngleBracketed(_) => true,
+                            PathArguments::Parenthesized(_) => false,
+                        } =>
+                {
+                    if let Some(eq_token) = input.parse::<Option<Token![=]>>()? {
+                        let segment = ty.path.segments.pop().unwrap().into_value();
+                        let ident = segment.ident;
+                        let generics = match segment.arguments {
+                            PathArguments::None => None,
+                            PathArguments::AngleBracketed(arguments) => Some(arguments),
+                            PathArguments::Parenthesized(_) => unreachable!(),
+                        };
+                        return if input.peek(Lit) || input.peek(token::Brace) {
+                            Ok(GenericArgument::AssocConst(AssocConst {
+                                ident,
+                                generics,
+                                eq_token,
+                                value: const_argument(input)?,
+                            }))
+                        } else {
+                            Ok(GenericArgument::AssocType(AssocType {
+                                ident,
+                                generics,
+                                eq_token,
+                                ty: input.parse()?,
+                            }))
+                        };
+                    }
+
+                    #[cfg(feature = "full")]
+                    if let Some(colon_token) = input.parse::<Option<Token![:]>>()? {
+                        let segment = ty.path.segments.pop().unwrap().into_value();
+                        return Ok(GenericArgument::Constraint(Constraint {
+                            ident: segment.ident,
+                            generics: match segment.arguments {
+                                PathArguments::None => None,
+                                PathArguments::AngleBracketed(arguments) => Some(arguments),
+                                PathArguments::Parenthesized(_) => unreachable!(),
+                            },
+                            colon_token,
+                            bounds: {
+                                let mut bounds = Punctuated::new();
+                                loop {
+                                    if input.peek(Token![,]) || input.peek(Token![>]) {
+                                        break;
+                                    }
+                                    let value: TypeParamBound = input.parse()?;
+                                    bounds.push_value(value);
+                                    if !input.peek(Token![+]) {
+                                        break;
+                                    }
+                                    let punct: Token![+] = input.parse()?;
+                                    bounds.push_punct(punct);
+                                }
+                                bounds
+                            },
+                        }));
+                    }
+
+                    argument = Type::Path(ty);
+                }
+                _ => {}
+            }
+
+            Ok(GenericArgument::Type(argument))
+        }
+    }
+
+    pub(crate) fn const_argument(input: ParseStream) -> Result<Expr> {
+        let lookahead = input.lookahead1();
+
+        if input.peek(Lit) {
+            let lit = input.parse()?;
+            return Ok(Expr::Lit(lit));
+        }
+
+        if input.peek(Ident) {
+            let ident: Ident = input.parse()?;
+            return Ok(Expr::Path(ExprPath {
+                attrs: Vec::new(),
+                qself: None,
+                path: Path::from(ident),
+            }));
+        }
+
+        if input.peek(token::Brace) {
+            #[cfg(feature = "full")]
+            {
+                let block: ExprBlock = input.parse()?;
+                return Ok(Expr::Block(block));
+            }
+
+            #[cfg(not(feature = "full"))]
+            {
+                let begin = input.fork();
+                let content;
+                braced!(content in input);
+                content.parse::<Expr>()?;
+                let verbatim = verbatim::between(&begin, input);
+                return Ok(Expr::Verbatim(verbatim));
+            }
+        }
+
+        Err(lookahead.error())
+    }
+
+    impl AngleBracketedGenericArguments {
+        /// Parse `::<…>` with mandatory leading `::`.
+        ///
+        /// The ordinary [`Parse`] impl for `AngleBracketedGenericArguments`
+        /// parses optional leading `::`.
+        #[cfg(feature = "full")]
+        #[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "full"))))]
+        pub fn parse_turbofish(input: ParseStream) -> Result<Self> {
+            let colon2_token: Token![::] = input.parse()?;
+            Self::do_parse(Some(colon2_token), input)
+        }
+
+        pub(crate) fn do_parse(
+            colon2_token: Option<Token![::]>,
+            input: ParseStream,
+        ) -> Result<Self> {
+            Ok(AngleBracketedGenericArguments {
+                colon2_token,
+                lt_token: input.parse()?,
+                args: {
+                    let mut args = Punctuated::new();
+                    loop {
+                        if input.peek(Token![>]) {
+                            break;
+                        }
+                        let value: GenericArgument = input.parse()?;
+                        args.push_value(value);
+                        if input.peek(Token![>]) {
+                            break;
+                        }
+                        let punct: Token![,] = input.parse()?;
+                        args.push_punct(punct);
+                    }
+                    args
+                },
+                gt_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for AngleBracketedGenericArguments {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let colon2_token: Option<Token![::]> = input.parse()?;
+            Self::do_parse(colon2_token, input)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ParenthesizedGenericArguments {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let content;
+            Ok(ParenthesizedGenericArguments {
+                paren_token: parenthesized!(content in input),
+                inputs: content.parse_terminated(Type::parse, Token![,])?,
+                output: input.call(ReturnType::without_plus)?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for PathSegment {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Self::parse_helper(input, false)
+        }
+    }
+
+    impl PathSegment {
+        fn parse_helper(input: ParseStream, expr_style: bool) -> Result<Self> {
+            if input.peek(Token![super])
+                || input.peek(Token![self])
+                || input.peek(Token![crate])
+                || cfg!(feature = "full") && input.peek(Token![try])
+            {
+                let ident = input.call(Ident::parse_any)?;
+                return Ok(PathSegment::from(ident));
+            }
+
+            let ident = if input.peek(Token![Self]) {
+                input.call(Ident::parse_any)?
+            } else {
+                input.parse()?
+            };
+
+            if !expr_style && input.peek(Token![<]) && !input.peek(Token![<=])
+                || input.peek(Token![::]) && input.peek3(Token![<])
+            {
+                Ok(PathSegment {
+                    ident,
+                    arguments: PathArguments::AngleBracketed(input.parse()?),
+                })
+            } else {
+                Ok(PathSegment::from(ident))
+            }
+        }
+    }
+
+    impl Path {
+        /// Parse a `Path` containing no path arguments on any of its segments.
+        ///
+        /// # Example
+        ///
+        /// ```
+        /// use syn::{Path, Result, Token};
+        /// use syn::parse::{Parse, ParseStream};
+        ///
+        /// // A simplified single `use` statement like:
+        /// //
+        /// //     use std::collections::HashMap;
+        /// //
+        /// // Note that generic parameters are not allowed in a `use` statement
+        /// // so the following must not be accepted.
+        /// //
+        /// //     use a::<b>::c;
+        /// struct SingleUse {
+        ///     use_token: Token![use],
+        ///     path: Path,
+        /// }
+        ///
+        /// impl Parse for SingleUse {
+        ///     fn parse(input: ParseStream) -> Result<Self> {
+        ///         Ok(SingleUse {
+        ///             use_token: input.parse()?,
+        ///             path: input.call(Path::parse_mod_style)?,
+        ///         })
+        ///     }
+        /// }
+        /// ```
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+        pub fn parse_mod_style(input: ParseStream) -> Result<Self> {
+            Ok(Path {
+                leading_colon: input.parse()?,
+                segments: {
+                    let mut segments = Punctuated::new();
+                    loop {
+                        if !input.peek(Ident)
+                            && !input.peek(Token![super])
+                            && !input.peek(Token![self])
+                            && !input.peek(Token![Self])
+                            && !input.peek(Token![crate])
+                        {
+                            break;
+                        }
+                        let ident = Ident::parse_any(input)?;
+                        segments.push_value(PathSegment::from(ident));
+                        if !input.peek(Token![::]) {
+                            break;
+                        }
+                        let punct = input.parse()?;
+                        segments.push_punct(punct);
+                    }
+                    if segments.is_empty() {
+                        return Err(input.parse::<Ident>().unwrap_err());
+                    } else if segments.trailing_punct() {
+                        return Err(input.error("expected path segment after `::`"));
+                    }
+                    segments
+                },
+            })
+        }
+
+        pub(crate) fn parse_helper(input: ParseStream, expr_style: bool) -> Result<Self> {
+            let mut path = Path {
+                leading_colon: input.parse()?,
+                segments: {
+                    let mut segments = Punctuated::new();
+                    let value = PathSegment::parse_helper(input, expr_style)?;
+                    segments.push_value(value);
+                    segments
+                },
+            };
+            Path::parse_rest(input, &mut path, expr_style)?;
+            Ok(path)
+        }
+
+        pub(crate) fn parse_rest(
+            input: ParseStream,
+            path: &mut Self,
+            expr_style: bool,
+        ) -> Result<()> {
+            while input.peek(Token![::]) && !input.peek3(token::Paren) {
+                let punct: Token![::] = input.parse()?;
+                path.segments.push_punct(punct);
+                let value = PathSegment::parse_helper(input, expr_style)?;
+                path.segments.push_value(value);
+            }
+            Ok(())
+        }
+
+        pub(crate) fn is_mod_style(&self) -> bool {
+            self.segments
+                .iter()
+                .all(|segment| segment.arguments.is_none())
+        }
+    }
+
+    pub(crate) fn qpath(input: ParseStream, expr_style: bool) -> Result<(Option<QSelf>, Path)> {
+        if input.peek(Token![<]) {
+            let lt_token: Token![<] = input.parse()?;
+            let this: Type = input.parse()?;
+            let path = if input.peek(Token![as]) {
+                let as_token: Token![as] = input.parse()?;
+                let path: Path = input.parse()?;
+                Some((as_token, path))
+            } else {
+                None
+            };
+            let gt_token: Token![>] = input.parse()?;
+            let colon2_token: Token![::] = input.parse()?;
+            let mut rest = Punctuated::new();
+            loop {
+                let path = PathSegment::parse_helper(input, expr_style)?;
+                rest.push_value(path);
+                if !input.peek(Token![::]) {
+                    break;
+                }
+                let punct: Token![::] = input.parse()?;
+                rest.push_punct(punct);
+            }
+            let (position, as_token, path) = match path {
+                Some((as_token, mut path)) => {
+                    let pos = path.segments.len();
+                    path.segments.push_punct(colon2_token);
+                    path.segments.extend(rest.into_pairs());
+                    (pos, Some(as_token), path)
+                }
+                None => {
+                    let path = Path {
+                        leading_colon: Some(colon2_token),
+                        segments: rest,
+                    };
+                    (0, None, path)
+                }
+            };
+            let qself = QSelf {
+                lt_token,
+                ty: Box::new(this),
+                position,
+                as_token,
+                gt_token,
+            };
+            Ok((Some(qself), path))
+        } else {
+            let path = Path::parse_helper(input, expr_style)?;
+            Ok((None, path))
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+pub(crate) mod printing {
+    use crate::expr::Expr;
+    use crate::path::{
+        AngleBracketedGenericArguments, AssocConst, AssocType, Constraint, GenericArgument,
+        ParenthesizedGenericArguments, Path, PathArguments, PathSegment, QSelf,
+    };
+    use crate::print::TokensOrDefault;
+    #[cfg(feature = "parsing")]
+    use crate::spanned::Spanned;
+    use crate::token;
+    #[cfg(feature = "parsing")]
+    use proc_macro2::Span;
+    use proc_macro2::TokenStream;
+    use quote::ToTokens;
+    use std::cmp;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Path {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.leading_colon.to_tokens(tokens);
+            self.segments.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PathSegment {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+            self.arguments.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for PathArguments {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                PathArguments::None => {}
+                PathArguments::AngleBracketed(arguments) => {
+                    arguments.to_tokens(tokens);
+                }
+                PathArguments::Parenthesized(arguments) => {
+                    arguments.to_tokens(tokens);
+                }
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for GenericArgument {
+        #[allow(clippy::match_same_arms)]
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                GenericArgument::Lifetime(lt) => lt.to_tokens(tokens),
+                GenericArgument::Type(ty) => ty.to_tokens(tokens),
+                GenericArgument::Const(expr) => match expr {
+                    Expr::Lit(expr) => expr.to_tokens(tokens),
+
+                    Expr::Path(expr)
+                        if expr.attrs.is_empty()
+                            && expr.qself.is_none()
+                            && expr.path.get_ident().is_some() =>
+                    {
+                        expr.to_tokens(tokens);
+                    }
+
+                    #[cfg(feature = "full")]
+                    Expr::Block(expr) => expr.to_tokens(tokens),
+
+                    #[cfg(not(feature = "full"))]
+                    Expr::Verbatim(expr) => expr.to_tokens(tokens),
+
+                    // ERROR CORRECTION: Add braces to make sure that the
+                    // generated code is valid.
+                    _ => token::Brace::default().surround(tokens, |tokens| {
+                        expr.to_tokens(tokens);
+                    }),
+                },
+                GenericArgument::AssocType(assoc) => assoc.to_tokens(tokens),
+                GenericArgument::AssocConst(assoc) => assoc.to_tokens(tokens),
+                GenericArgument::Constraint(constraint) => constraint.to_tokens(tokens),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for AngleBracketedGenericArguments {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.colon2_token.to_tokens(tokens);
+            self.lt_token.to_tokens(tokens);
+
+            // Print lifetimes before types/consts/bindings, regardless of their
+            // order in self.args.
+            let mut trailing_or_empty = true;
+            for param in self.args.pairs() {
+                match param.value() {
+                    GenericArgument::Lifetime(_) => {
+                        param.to_tokens(tokens);
+                        trailing_or_empty = param.punct().is_some();
+                    }
+                    GenericArgument::Type(_)
+                    | GenericArgument::Const(_)
+                    | GenericArgument::AssocType(_)
+                    | GenericArgument::AssocConst(_)
+                    | GenericArgument::Constraint(_) => {}
+                }
+            }
+            for param in self.args.pairs() {
+                match param.value() {
+                    GenericArgument::Type(_)
+                    | GenericArgument::Const(_)
+                    | GenericArgument::AssocType(_)
+                    | GenericArgument::AssocConst(_)
+                    | GenericArgument::Constraint(_) => {
+                        if !trailing_or_empty {
+                            <Token![,]>::default().to_tokens(tokens);
+                        }
+                        param.to_tokens(tokens);
+                        trailing_or_empty = param.punct().is_some();
+                    }
+                    GenericArgument::Lifetime(_) => {}
+                }
+            }
+
+            self.gt_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for AssocType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.ty.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for AssocConst {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.eq_token.to_tokens(tokens);
+            self.value.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Constraint {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.ident.to_tokens(tokens);
+            self.generics.to_tokens(tokens);
+            self.colon_token.to_tokens(tokens);
+            self.bounds.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ParenthesizedGenericArguments {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.paren_token.surround(tokens, |tokens| {
+                self.inputs.to_tokens(tokens);
+            });
+            self.output.to_tokens(tokens);
+        }
+    }
+
+    pub(crate) fn print_path(tokens: &mut TokenStream, qself: &Option<QSelf>, path: &Path) {
+        let qself = match qself {
+            Some(qself) => qself,
+            None => {
+                path.to_tokens(tokens);
+                return;
+            }
+        };
+        qself.lt_token.to_tokens(tokens);
+        qself.ty.to_tokens(tokens);
+
+        let pos = cmp::min(qself.position, path.segments.len());
+        let mut segments = path.segments.pairs();
+        if pos > 0 {
+            TokensOrDefault(&qself.as_token).to_tokens(tokens);
+            path.leading_colon.to_tokens(tokens);
+            for (i, segment) in segments.by_ref().take(pos).enumerate() {
+                if i + 1 == pos {
+                    segment.value().to_tokens(tokens);
+                    qself.gt_token.to_tokens(tokens);
+                    segment.punct().to_tokens(tokens);
+                } else {
+                    segment.to_tokens(tokens);
+                }
+            }
+        } else {
+            qself.gt_token.to_tokens(tokens);
+            path.leading_colon.to_tokens(tokens);
+        }
+        for segment in segments {
+            segment.to_tokens(tokens);
+        }
+    }
+
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(all(feature = "parsing", feature = "printing"))))]
+    impl Spanned for QSelf {
+        fn span(&self) -> Span {
+            struct QSelfDelimiters<'a>(&'a QSelf);
+
+            impl<'a> ToTokens for QSelfDelimiters<'a> {
+                fn to_tokens(&self, tokens: &mut TokenStream) {
+                    self.0.lt_token.to_tokens(tokens);
+                    self.0.gt_token.to_tokens(tokens);
+                }
+            }
+
+            QSelfDelimiters(self).span()
+        }
+    }
+}
diff --git a/rust/syn/print.rs b/rust/syn/print.rs
new file mode 100644
index 0000000000000000000000000000000000000000..d73262cda0605267b2d798900e921edb836312a6
--- /dev/null
+++ b/rust/syn/print.rs
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use proc_macro2::TokenStream;
+use quote::ToTokens;
+
+pub(crate) struct TokensOrDefault<'a, T: 'a>(pub &'a Option<T>);
+
+impl<'a, T> ToTokens for TokensOrDefault<'a, T>
+where
+    T: ToTokens + Default,
+{
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        match self.0 {
+            Some(t) => t.to_tokens(tokens),
+            None => T::default().to_tokens(tokens),
+        }
+    }
+}
diff --git a/rust/syn/punctuated.rs b/rust/syn/punctuated.rs
new file mode 100644
index 0000000000000000000000000000000000000000..8bfec6c3fdcc42ad4b2e2773ec4414a6d35ff926
--- /dev/null
+++ b/rust/syn/punctuated.rs
@@ -0,0 +1,1111 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! A punctuated sequence of syntax tree nodes separated by punctuation.
+//!
+//! Lots of things in Rust are punctuated sequences.
+//!
+//! - The fields of a struct are `Punctuated<Field, Token![,]>`.
+//! - The segments of a path are `Punctuated<PathSegment, Token![::]>`.
+//! - The bounds on a generic parameter are `Punctuated<TypeParamBound,
+//!   Token![+]>`.
+//! - The arguments to a function call are `Punctuated<Expr, Token![,]>`.
+//!
+//! This module provides a common representation for these punctuated sequences
+//! in the form of the [`Punctuated<T, P>`] type. We store a vector of pairs of
+//! syntax tree node + punctuation, where every node in the sequence is followed
+//! by punctuation except for possibly the final one.
+//!
+//! [`Punctuated<T, P>`]: Punctuated
+//!
+//! ```text
+//! a_function_call(arg1, arg2, arg3);
+//!                 ~~~~^ ~~~~^ ~~~~
+//! ```
+
+use crate::drops::{NoDrop, TrivialDrop};
+#[cfg(feature = "parsing")]
+use crate::error::Result;
+#[cfg(feature = "parsing")]
+use crate::parse::{Parse, ParseStream};
+#[cfg(feature = "parsing")]
+use crate::token::Token;
+#[cfg(feature = "extra-traits")]
+use std::fmt::{self, Debug};
+#[cfg(feature = "extra-traits")]
+use std::hash::{Hash, Hasher};
+#[cfg(any(feature = "full", feature = "derive"))]
+use std::iter;
+use std::ops::{Index, IndexMut};
+use std::option;
+use std::slice;
+use std::vec;
+
+/// **A punctuated sequence of syntax tree nodes of type `T` separated by
+/// punctuation of type `P`.**
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct Punctuated<T, P> {
+    inner: Vec<(T, P)>,
+    last: Option<Box<T>>,
+}
+
+impl<T, P> Punctuated<T, P> {
+    /// Creates an empty punctuated sequence.
+    pub const fn new() -> Self {
+        Punctuated {
+            inner: Vec::new(),
+            last: None,
+        }
+    }
+
+    /// Determines whether this punctuated sequence is empty, meaning it
+    /// contains no syntax tree nodes or punctuation.
+    pub fn is_empty(&self) -> bool {
+        self.inner.len() == 0 && self.last.is_none()
+    }
+
+    /// Returns the number of syntax tree nodes in this punctuated sequence.
+    ///
+    /// This is the number of nodes of type `T`, not counting the punctuation of
+    /// type `P`.
+    pub fn len(&self) -> usize {
+        self.inner.len() + if self.last.is_some() { 1 } else { 0 }
+    }
+
+    /// Borrows the first element in this sequence.
+    pub fn first(&self) -> Option<&T> {
+        self.iter().next()
+    }
+
+    /// Mutably borrows the first element in this sequence.
+    pub fn first_mut(&mut self) -> Option<&mut T> {
+        self.iter_mut().next()
+    }
+
+    /// Borrows the last element in this sequence.
+    pub fn last(&self) -> Option<&T> {
+        self.iter().next_back()
+    }
+
+    /// Mutably borrows the last element in this sequence.
+    pub fn last_mut(&mut self) -> Option<&mut T> {
+        self.iter_mut().next_back()
+    }
+
+    /// Returns an iterator over borrowed syntax tree nodes of type `&T`.
+    pub fn iter(&self) -> Iter<T> {
+        Iter {
+            inner: Box::new(NoDrop::new(PrivateIter {
+                inner: self.inner.iter(),
+                last: self.last.as_ref().map(Box::as_ref).into_iter(),
+            })),
+        }
+    }
+
+    /// Returns an iterator over mutably borrowed syntax tree nodes of type
+    /// `&mut T`.
+    pub fn iter_mut(&mut self) -> IterMut<T> {
+        IterMut {
+            inner: Box::new(NoDrop::new(PrivateIterMut {
+                inner: self.inner.iter_mut(),
+                last: self.last.as_mut().map(Box::as_mut).into_iter(),
+            })),
+        }
+    }
+
+    /// Returns an iterator over the contents of this sequence as borrowed
+    /// punctuated pairs.
+    pub fn pairs(&self) -> Pairs<T, P> {
+        Pairs {
+            inner: self.inner.iter(),
+            last: self.last.as_ref().map(Box::as_ref).into_iter(),
+        }
+    }
+
+    /// Returns an iterator over the contents of this sequence as mutably
+    /// borrowed punctuated pairs.
+    pub fn pairs_mut(&mut self) -> PairsMut<T, P> {
+        PairsMut {
+            inner: self.inner.iter_mut(),
+            last: self.last.as_mut().map(Box::as_mut).into_iter(),
+        }
+    }
+
+    /// Returns an iterator over the contents of this sequence as owned
+    /// punctuated pairs.
+    pub fn into_pairs(self) -> IntoPairs<T, P> {
+        IntoPairs {
+            inner: self.inner.into_iter(),
+            last: self.last.map(|t| *t).into_iter(),
+        }
+    }
+
+    /// Appends a syntax tree node onto the end of this punctuated sequence. The
+    /// sequence must already have a trailing punctuation, or be empty.
+    ///
+    /// Use [`push`] instead if the punctuated sequence may or may not already
+    /// have trailing punctuation.
+    ///
+    /// [`push`]: Punctuated::push
+    ///
+    /// # Panics
+    ///
+    /// Panics if the sequence is nonempty and does not already have a trailing
+    /// punctuation.
+    pub fn push_value(&mut self, value: T) {
+        assert!(
+            self.empty_or_trailing(),
+            "Punctuated::push_value: cannot push value if Punctuated is missing trailing punctuation",
+        );
+
+        self.last = Some(Box::new(value));
+    }
+
+    /// Appends a trailing punctuation onto the end of this punctuated sequence.
+    /// The sequence must be non-empty and must not already have trailing
+    /// punctuation.
+    ///
+    /// # Panics
+    ///
+    /// Panics if the sequence is empty or already has a trailing punctuation.
+    pub fn push_punct(&mut self, punctuation: P) {
+        assert!(
+            self.last.is_some(),
+            "Punctuated::push_punct: cannot push punctuation if Punctuated is empty or already has trailing punctuation",
+        );
+
+        let last = self.last.take().unwrap();
+        self.inner.push((*last, punctuation));
+    }
+
+    /// Removes the last punctuated pair from this sequence, or `None` if the
+    /// sequence is empty.
+    pub fn pop(&mut self) -> Option<Pair<T, P>> {
+        if self.last.is_some() {
+            self.last.take().map(|t| Pair::End(*t))
+        } else {
+            self.inner.pop().map(|(t, p)| Pair::Punctuated(t, p))
+        }
+    }
+
+    /// Removes the trailing punctuation from this punctuated sequence, or
+    /// `None` if there isn't any.
+    pub fn pop_punct(&mut self) -> Option<P> {
+        if self.last.is_some() {
+            None
+        } else {
+            let (t, p) = self.inner.pop()?;
+            self.last = Some(Box::new(t));
+            Some(p)
+        }
+    }
+
+    /// Determines whether this punctuated sequence ends with a trailing
+    /// punctuation.
+    pub fn trailing_punct(&self) -> bool {
+        self.last.is_none() && !self.is_empty()
+    }
+
+    /// Returns true if either this `Punctuated` is empty, or it has a trailing
+    /// punctuation.
+    ///
+    /// Equivalent to `punctuated.is_empty() || punctuated.trailing_punct()`.
+    pub fn empty_or_trailing(&self) -> bool {
+        self.last.is_none()
+    }
+
+    /// Appends a syntax tree node onto the end of this punctuated sequence.
+    ///
+    /// If there is not a trailing punctuation in this sequence when this method
+    /// is called, the default value of punctuation type `P` is inserted before
+    /// the given value of type `T`.
+    pub fn push(&mut self, value: T)
+    where
+        P: Default,
+    {
+        if !self.empty_or_trailing() {
+            self.push_punct(Default::default());
+        }
+        self.push_value(value);
+    }
+
+    /// Inserts an element at position `index`.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `index` is greater than the number of elements previously in
+    /// this punctuated sequence.
+    pub fn insert(&mut self, index: usize, value: T)
+    where
+        P: Default,
+    {
+        assert!(
+            index <= self.len(),
+            "Punctuated::insert: index out of range",
+        );
+
+        if index == self.len() {
+            self.push(value);
+        } else {
+            self.inner.insert(index, (value, Default::default()));
+        }
+    }
+
+    /// Clears the sequence of all values and punctuation, making it empty.
+    pub fn clear(&mut self) {
+        self.inner.clear();
+        self.last = None;
+    }
+
+    /// Parses zero or more occurrences of `T` separated by punctuation of type
+    /// `P`, with optional trailing punctuation.
+    ///
+    /// Parsing continues until the end of this parse stream. The entire content
+    /// of this parse stream must consist of `T` and `P`.
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_terminated(input: ParseStream) -> Result<Self>
+    where
+        T: Parse,
+        P: Parse,
+    {
+        Self::parse_terminated_with(input, T::parse)
+    }
+
+    /// Parses zero or more occurrences of `T` using the given parse function,
+    /// separated by punctuation of type `P`, with optional trailing
+    /// punctuation.
+    ///
+    /// Like [`parse_terminated`], the entire content of this stream is expected
+    /// to be parsed.
+    ///
+    /// [`parse_terminated`]: Punctuated::parse_terminated
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_terminated_with(
+        input: ParseStream,
+        parser: fn(ParseStream) -> Result<T>,
+    ) -> Result<Self>
+    where
+        P: Parse,
+    {
+        let mut punctuated = Punctuated::new();
+
+        loop {
+            if input.is_empty() {
+                break;
+            }
+            let value = parser(input)?;
+            punctuated.push_value(value);
+            if input.is_empty() {
+                break;
+            }
+            let punct = input.parse()?;
+            punctuated.push_punct(punct);
+        }
+
+        Ok(punctuated)
+    }
+
+    /// Parses one or more occurrences of `T` separated by punctuation of type
+    /// `P`, not accepting trailing punctuation.
+    ///
+    /// Parsing continues as long as punctuation `P` is present at the head of
+    /// the stream. This method returns upon parsing a `T` and observing that it
+    /// is not followed by a `P`, even if there are remaining tokens in the
+    /// stream.
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_separated_nonempty(input: ParseStream) -> Result<Self>
+    where
+        T: Parse,
+        P: Token + Parse,
+    {
+        Self::parse_separated_nonempty_with(input, T::parse)
+    }
+
+    /// Parses one or more occurrences of `T` using the given parse function,
+    /// separated by punctuation of type `P`, not accepting trailing
+    /// punctuation.
+    ///
+    /// Like [`parse_separated_nonempty`], may complete early without parsing
+    /// the entire content of this stream.
+    ///
+    /// [`parse_separated_nonempty`]: Punctuated::parse_separated_nonempty
+    #[cfg(feature = "parsing")]
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    pub fn parse_separated_nonempty_with(
+        input: ParseStream,
+        parser: fn(ParseStream) -> Result<T>,
+    ) -> Result<Self>
+    where
+        P: Token + Parse,
+    {
+        let mut punctuated = Punctuated::new();
+
+        loop {
+            let value = parser(input)?;
+            punctuated.push_value(value);
+            if !P::peek(input.cursor()) {
+                break;
+            }
+            let punct = input.parse()?;
+            punctuated.push_punct(punct);
+        }
+
+        Ok(punctuated)
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl<T, P> Clone for Punctuated<T, P>
+where
+    T: Clone,
+    P: Clone,
+{
+    fn clone(&self) -> Self {
+        Punctuated {
+            inner: self.inner.clone(),
+            last: self.last.clone(),
+        }
+    }
+
+    fn clone_from(&mut self, other: &Self) {
+        self.inner.clone_from(&other.inner);
+        self.last.clone_from(&other.last);
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl<T, P> Eq for Punctuated<T, P>
+where
+    T: Eq,
+    P: Eq,
+{
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl<T, P> PartialEq for Punctuated<T, P>
+where
+    T: PartialEq,
+    P: PartialEq,
+{
+    fn eq(&self, other: &Self) -> bool {
+        let Punctuated { inner, last } = self;
+        *inner == other.inner && *last == other.last
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl<T, P> Hash for Punctuated<T, P>
+where
+    T: Hash,
+    P: Hash,
+{
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        let Punctuated { inner, last } = self;
+        inner.hash(state);
+        last.hash(state);
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl<T: Debug, P: Debug> Debug for Punctuated<T, P> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        let mut list = f.debug_list();
+        for (t, p) in &self.inner {
+            list.entry(t);
+            list.entry(p);
+        }
+        if let Some(last) = &self.last {
+            list.entry(last);
+        }
+        list.finish()
+    }
+}
+
+impl<T, P> FromIterator<T> for Punctuated<T, P>
+where
+    P: Default,
+{
+    fn from_iter<I: IntoIterator<Item = T>>(i: I) -> Self {
+        let mut ret = Punctuated::new();
+        ret.extend(i);
+        ret
+    }
+}
+
+impl<T, P> Extend<T> for Punctuated<T, P>
+where
+    P: Default,
+{
+    fn extend<I: IntoIterator<Item = T>>(&mut self, i: I) {
+        for value in i {
+            self.push(value);
+        }
+    }
+}
+
+impl<T, P> FromIterator<Pair<T, P>> for Punctuated<T, P> {
+    fn from_iter<I: IntoIterator<Item = Pair<T, P>>>(i: I) -> Self {
+        let mut ret = Punctuated::new();
+        do_extend(&mut ret, i.into_iter());
+        ret
+    }
+}
+
+impl<T, P> Extend<Pair<T, P>> for Punctuated<T, P>
+where
+    P: Default,
+{
+    fn extend<I: IntoIterator<Item = Pair<T, P>>>(&mut self, i: I) {
+        if !self.empty_or_trailing() {
+            self.push_punct(P::default());
+        }
+        do_extend(self, i.into_iter());
+    }
+}
+
+fn do_extend<T, P, I>(punctuated: &mut Punctuated<T, P>, i: I)
+where
+    I: Iterator<Item = Pair<T, P>>,
+{
+    let mut nomore = false;
+    for pair in i {
+        if nomore {
+            panic!("Punctuated extended with items after a Pair::End");
+        }
+        match pair {
+            Pair::Punctuated(a, b) => punctuated.inner.push((a, b)),
+            Pair::End(a) => {
+                punctuated.last = Some(Box::new(a));
+                nomore = true;
+            }
+        }
+    }
+}
+
+impl<T, P> IntoIterator for Punctuated<T, P> {
+    type Item = T;
+    type IntoIter = IntoIter<T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        let mut elements = Vec::with_capacity(self.len());
+        elements.extend(self.inner.into_iter().map(|pair| pair.0));
+        elements.extend(self.last.map(|t| *t));
+
+        IntoIter {
+            inner: elements.into_iter(),
+        }
+    }
+}
+
+impl<'a, T, P> IntoIterator for &'a Punctuated<T, P> {
+    type Item = &'a T;
+    type IntoIter = Iter<'a, T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        Punctuated::iter(self)
+    }
+}
+
+impl<'a, T, P> IntoIterator for &'a mut Punctuated<T, P> {
+    type Item = &'a mut T;
+    type IntoIter = IterMut<'a, T>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        Punctuated::iter_mut(self)
+    }
+}
+
+impl<T, P> Default for Punctuated<T, P> {
+    fn default() -> Self {
+        Punctuated::new()
+    }
+}
+
+/// An iterator over borrowed pairs of type `Pair<&T, &P>`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct Pairs<'a, T: 'a, P: 'a> {
+    inner: slice::Iter<'a, (T, P)>,
+    last: option::IntoIter<&'a T>,
+}
+
+impl<'a, T, P> Iterator for Pairs<'a, T, P> {
+    type Item = Pair<&'a T, &'a P>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner
+            .next()
+            .map(|(t, p)| Pair::Punctuated(t, p))
+            .or_else(|| self.last.next().map(Pair::End))
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len(), Some(self.len()))
+    }
+}
+
+impl<'a, T, P> DoubleEndedIterator for Pairs<'a, T, P> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.last
+            .next()
+            .map(Pair::End)
+            .or_else(|| self.inner.next_back().map(|(t, p)| Pair::Punctuated(t, p)))
+    }
+}
+
+impl<'a, T, P> ExactSizeIterator for Pairs<'a, T, P> {
+    fn len(&self) -> usize {
+        self.inner.len() + self.last.len()
+    }
+}
+
+// No Clone bound on T or P.
+impl<'a, T, P> Clone for Pairs<'a, T, P> {
+    fn clone(&self) -> Self {
+        Pairs {
+            inner: self.inner.clone(),
+            last: self.last.clone(),
+        }
+    }
+}
+
+/// An iterator over mutably borrowed pairs of type `Pair<&mut T, &mut P>`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct PairsMut<'a, T: 'a, P: 'a> {
+    inner: slice::IterMut<'a, (T, P)>,
+    last: option::IntoIter<&'a mut T>,
+}
+
+impl<'a, T, P> Iterator for PairsMut<'a, T, P> {
+    type Item = Pair<&'a mut T, &'a mut P>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner
+            .next()
+            .map(|(t, p)| Pair::Punctuated(t, p))
+            .or_else(|| self.last.next().map(Pair::End))
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len(), Some(self.len()))
+    }
+}
+
+impl<'a, T, P> DoubleEndedIterator for PairsMut<'a, T, P> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.last
+            .next()
+            .map(Pair::End)
+            .or_else(|| self.inner.next_back().map(|(t, p)| Pair::Punctuated(t, p)))
+    }
+}
+
+impl<'a, T, P> ExactSizeIterator for PairsMut<'a, T, P> {
+    fn len(&self) -> usize {
+        self.inner.len() + self.last.len()
+    }
+}
+
+/// An iterator over owned pairs of type `Pair<T, P>`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct IntoPairs<T, P> {
+    inner: vec::IntoIter<(T, P)>,
+    last: option::IntoIter<T>,
+}
+
+impl<T, P> Iterator for IntoPairs<T, P> {
+    type Item = Pair<T, P>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner
+            .next()
+            .map(|(t, p)| Pair::Punctuated(t, p))
+            .or_else(|| self.last.next().map(Pair::End))
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len(), Some(self.len()))
+    }
+}
+
+impl<T, P> DoubleEndedIterator for IntoPairs<T, P> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.last
+            .next()
+            .map(Pair::End)
+            .or_else(|| self.inner.next_back().map(|(t, p)| Pair::Punctuated(t, p)))
+    }
+}
+
+impl<T, P> ExactSizeIterator for IntoPairs<T, P> {
+    fn len(&self) -> usize {
+        self.inner.len() + self.last.len()
+    }
+}
+
+impl<T, P> Clone for IntoPairs<T, P>
+where
+    T: Clone,
+    P: Clone,
+{
+    fn clone(&self) -> Self {
+        IntoPairs {
+            inner: self.inner.clone(),
+            last: self.last.clone(),
+        }
+    }
+}
+
+/// An iterator over owned values of type `T`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct IntoIter<T> {
+    inner: vec::IntoIter<T>,
+}
+
+impl<T> Iterator for IntoIter<T> {
+    type Item = T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next()
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len(), Some(self.len()))
+    }
+}
+
+impl<T> DoubleEndedIterator for IntoIter<T> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.inner.next_back()
+    }
+}
+
+impl<T> ExactSizeIterator for IntoIter<T> {
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+
+impl<T> Clone for IntoIter<T>
+where
+    T: Clone,
+{
+    fn clone(&self) -> Self {
+        IntoIter {
+            inner: self.inner.clone(),
+        }
+    }
+}
+
+/// An iterator over borrowed values of type `&T`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct Iter<'a, T: 'a> {
+    inner: Box<NoDrop<dyn IterTrait<'a, T> + 'a>>,
+}
+
+trait IterTrait<'a, T: 'a>: Iterator<Item = &'a T> + DoubleEndedIterator + ExactSizeIterator {
+    fn clone_box(&self) -> Box<NoDrop<dyn IterTrait<'a, T> + 'a>>;
+}
+
+struct PrivateIter<'a, T: 'a, P: 'a> {
+    inner: slice::Iter<'a, (T, P)>,
+    last: option::IntoIter<&'a T>,
+}
+
+impl<'a, T, P> TrivialDrop for PrivateIter<'a, T, P>
+where
+    slice::Iter<'a, (T, P)>: TrivialDrop,
+    option::IntoIter<&'a T>: TrivialDrop,
+{
+}
+
+#[cfg(any(feature = "full", feature = "derive"))]
+pub(crate) fn empty_punctuated_iter<'a, T>() -> Iter<'a, T> {
+    Iter {
+        inner: Box::new(NoDrop::new(iter::empty())),
+    }
+}
+
+// No Clone bound on T.
+impl<'a, T> Clone for Iter<'a, T> {
+    fn clone(&self) -> Self {
+        Iter {
+            inner: self.inner.clone_box(),
+        }
+    }
+}
+
+impl<'a, T> Iterator for Iter<'a, T> {
+    type Item = &'a T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next()
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len(), Some(self.len()))
+    }
+}
+
+impl<'a, T> DoubleEndedIterator for Iter<'a, T> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.inner.next_back()
+    }
+}
+
+impl<'a, T> ExactSizeIterator for Iter<'a, T> {
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+
+impl<'a, T, P> Iterator for PrivateIter<'a, T, P> {
+    type Item = &'a T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner
+            .next()
+            .map(|pair| &pair.0)
+            .or_else(|| self.last.next())
+    }
+}
+
+impl<'a, T, P> DoubleEndedIterator for PrivateIter<'a, T, P> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.last
+            .next()
+            .or_else(|| self.inner.next_back().map(|pair| &pair.0))
+    }
+}
+
+impl<'a, T, P> ExactSizeIterator for PrivateIter<'a, T, P> {
+    fn len(&self) -> usize {
+        self.inner.len() + self.last.len()
+    }
+}
+
+// No Clone bound on T or P.
+impl<'a, T, P> Clone for PrivateIter<'a, T, P> {
+    fn clone(&self) -> Self {
+        PrivateIter {
+            inner: self.inner.clone(),
+            last: self.last.clone(),
+        }
+    }
+}
+
+impl<'a, T, I> IterTrait<'a, T> for I
+where
+    T: 'a,
+    I: DoubleEndedIterator<Item = &'a T>
+        + ExactSizeIterator<Item = &'a T>
+        + Clone
+        + TrivialDrop
+        + 'a,
+{
+    fn clone_box(&self) -> Box<NoDrop<dyn IterTrait<'a, T> + 'a>> {
+        Box::new(NoDrop::new(self.clone()))
+    }
+}
+
+/// An iterator over mutably borrowed values of type `&mut T`.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub struct IterMut<'a, T: 'a> {
+    inner: Box<NoDrop<dyn IterMutTrait<'a, T, Item = &'a mut T> + 'a>>,
+}
+
+trait IterMutTrait<'a, T: 'a>:
+    DoubleEndedIterator<Item = &'a mut T> + ExactSizeIterator<Item = &'a mut T>
+{
+}
+
+struct PrivateIterMut<'a, T: 'a, P: 'a> {
+    inner: slice::IterMut<'a, (T, P)>,
+    last: option::IntoIter<&'a mut T>,
+}
+
+impl<'a, T, P> TrivialDrop for PrivateIterMut<'a, T, P>
+where
+    slice::IterMut<'a, (T, P)>: TrivialDrop,
+    option::IntoIter<&'a mut T>: TrivialDrop,
+{
+}
+
+#[cfg(any(feature = "full", feature = "derive"))]
+pub(crate) fn empty_punctuated_iter_mut<'a, T>() -> IterMut<'a, T> {
+    IterMut {
+        inner: Box::new(NoDrop::new(iter::empty())),
+    }
+}
+
+impl<'a, T> Iterator for IterMut<'a, T> {
+    type Item = &'a mut T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner.next()
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len(), Some(self.len()))
+    }
+}
+
+impl<'a, T> DoubleEndedIterator for IterMut<'a, T> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.inner.next_back()
+    }
+}
+
+impl<'a, T> ExactSizeIterator for IterMut<'a, T> {
+    fn len(&self) -> usize {
+        self.inner.len()
+    }
+}
+
+impl<'a, T, P> Iterator for PrivateIterMut<'a, T, P> {
+    type Item = &'a mut T;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        self.inner
+            .next()
+            .map(|pair| &mut pair.0)
+            .or_else(|| self.last.next())
+    }
+}
+
+impl<'a, T, P> DoubleEndedIterator for PrivateIterMut<'a, T, P> {
+    fn next_back(&mut self) -> Option<Self::Item> {
+        self.last
+            .next()
+            .or_else(|| self.inner.next_back().map(|pair| &mut pair.0))
+    }
+}
+
+impl<'a, T, P> ExactSizeIterator for PrivateIterMut<'a, T, P> {
+    fn len(&self) -> usize {
+        self.inner.len() + self.last.len()
+    }
+}
+
+impl<'a, T, I> IterMutTrait<'a, T> for I
+where
+    T: 'a,
+    I: DoubleEndedIterator<Item = &'a mut T> + ExactSizeIterator<Item = &'a mut T> + 'a,
+{
+}
+
+/// A single syntax tree node of type `T` followed by its trailing punctuation
+/// of type `P` if any.
+///
+/// Refer to the [module documentation] for details about punctuated sequences.
+///
+/// [module documentation]: self
+pub enum Pair<T, P> {
+    Punctuated(T, P),
+    End(T),
+}
+
+impl<T, P> Pair<T, P> {
+    /// Extracts the syntax tree node from this punctuated pair, discarding the
+    /// following punctuation.
+    pub fn into_value(self) -> T {
+        match self {
+            Pair::Punctuated(t, _) | Pair::End(t) => t,
+        }
+    }
+
+    /// Borrows the syntax tree node from this punctuated pair.
+    pub fn value(&self) -> &T {
+        match self {
+            Pair::Punctuated(t, _) | Pair::End(t) => t,
+        }
+    }
+
+    /// Mutably borrows the syntax tree node from this punctuated pair.
+    pub fn value_mut(&mut self) -> &mut T {
+        match self {
+            Pair::Punctuated(t, _) | Pair::End(t) => t,
+        }
+    }
+
+    /// Borrows the punctuation from this punctuated pair, unless this pair is
+    /// the final one and there is no trailing punctuation.
+    pub fn punct(&self) -> Option<&P> {
+        match self {
+            Pair::Punctuated(_, p) => Some(p),
+            Pair::End(_) => None,
+        }
+    }
+
+    /// Mutably borrows the punctuation from this punctuated pair, unless the
+    /// pair is the final one and there is no trailing punctuation.
+    ///
+    /// # Example
+    ///
+    /// ```
+    /// # use proc_macro2::Span;
+    /// # use syn::punctuated::Punctuated;
+    /// # use syn::{parse_quote, Token, TypeParamBound};
+    /// #
+    /// # let mut punctuated = Punctuated::<TypeParamBound, Token![+]>::new();
+    /// # let span = Span::call_site();
+    /// #
+    /// punctuated.insert(0, parse_quote!('lifetime));
+    /// if let Some(punct) = punctuated.pairs_mut().next().unwrap().punct_mut() {
+    ///     punct.span = span;
+    /// }
+    /// ```
+    pub fn punct_mut(&mut self) -> Option<&mut P> {
+        match self {
+            Pair::Punctuated(_, p) => Some(p),
+            Pair::End(_) => None,
+        }
+    }
+
+    /// Creates a punctuated pair out of a syntax tree node and an optional
+    /// following punctuation.
+    pub fn new(t: T, p: Option<P>) -> Self {
+        match p {
+            Some(p) => Pair::Punctuated(t, p),
+            None => Pair::End(t),
+        }
+    }
+
+    /// Produces this punctuated pair as a tuple of syntax tree node and
+    /// optional following punctuation.
+    pub fn into_tuple(self) -> (T, Option<P>) {
+        match self {
+            Pair::Punctuated(t, p) => (t, Some(p)),
+            Pair::End(t) => (t, None),
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl<T, P> Pair<&T, &P> {
+    pub fn cloned(self) -> Pair<T, P>
+    where
+        T: Clone,
+        P: Clone,
+    {
+        match self {
+            Pair::Punctuated(t, p) => Pair::Punctuated(t.clone(), p.clone()),
+            Pair::End(t) => Pair::End(t.clone()),
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl<T, P> Clone for Pair<T, P>
+where
+    T: Clone,
+    P: Clone,
+{
+    fn clone(&self) -> Self {
+        match self {
+            Pair::Punctuated(t, p) => Pair::Punctuated(t.clone(), p.clone()),
+            Pair::End(t) => Pair::End(t.clone()),
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl<T, P> Copy for Pair<T, P>
+where
+    T: Copy,
+    P: Copy,
+{
+}
+
+impl<T, P> Index<usize> for Punctuated<T, P> {
+    type Output = T;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        if index == self.len() - 1 {
+            match &self.last {
+                Some(t) => t,
+                None => &self.inner[index].0,
+            }
+        } else {
+            &self.inner[index].0
+        }
+    }
+}
+
+impl<T, P> IndexMut<usize> for Punctuated<T, P> {
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        if index == self.len() - 1 {
+            match &mut self.last {
+                Some(t) => t,
+                None => &mut self.inner[index].0,
+            }
+        } else {
+            &mut self.inner[index].0
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::punctuated::{Pair, Punctuated};
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl<T, P> ToTokens for Punctuated<T, P>
+    where
+        T: ToTokens,
+        P: ToTokens,
+    {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.pairs());
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl<T, P> ToTokens for Pair<T, P>
+    where
+        T: ToTokens,
+        P: ToTokens,
+    {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                Pair::Punctuated(a, b) => {
+                    a.to_tokens(tokens);
+                    b.to_tokens(tokens);
+                }
+                Pair::End(a) => a.to_tokens(tokens),
+            }
+        }
+    }
+}
diff --git a/rust/syn/restriction.rs b/rust/syn/restriction.rs
new file mode 100644
index 0000000000000000000000000000000000000000..83e54d11d54871bcab40161d4c4125444ab97d8d
--- /dev/null
+++ b/rust/syn/restriction.rs
@@ -0,0 +1,178 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::path::Path;
+use crate::token;
+
+ast_enum! {
+    /// The visibility level of an item: inherited or `pub` or
+    /// `pub(restricted)`.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum Visibility {
+        /// A public visibility level: `pub`.
+        Public(Token![pub]),
+
+        /// A visibility level restricted to some path: `pub(self)` or
+        /// `pub(super)` or `pub(crate)` or `pub(in some::module)`.
+        Restricted(VisRestricted),
+
+        /// An inherited visibility, which usually means private.
+        Inherited,
+    }
+}
+
+ast_struct! {
+    /// A visibility level restricted to some path: `pub(self)` or
+    /// `pub(super)` or `pub(crate)` or `pub(in some::module)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct VisRestricted {
+        pub pub_token: Token![pub],
+        pub paren_token: token::Paren,
+        pub in_token: Option<Token![in]>,
+        pub path: Box<Path>,
+    }
+}
+
+ast_enum! {
+    /// Unused, but reserved for RFC 3323 restrictions.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum FieldMutability {
+        None,
+
+        // TODO: https://rust-lang.github.io/rfcs/3323-restrictions.html
+        //
+        // FieldMutability::Restricted(MutRestricted)
+        //
+        // pub struct MutRestricted {
+        //     pub mut_token: Token![mut],
+        //     pub paren_token: token::Paren,
+        //     pub in_token: Option<Token![in]>,
+        //     pub path: Box<Path>,
+        // }
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::error::Result;
+    use crate::ext::IdentExt as _;
+    use crate::ident::Ident;
+    use crate::parse::discouraged::Speculative as _;
+    use crate::parse::{Parse, ParseStream};
+    use crate::path::Path;
+    use crate::restriction::{VisRestricted, Visibility};
+    use crate::token;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Visibility {
+        fn parse(input: ParseStream) -> Result<Self> {
+            // Recognize an empty None-delimited group, as produced by a $:vis
+            // matcher that matched no tokens.
+            if input.peek(token::Group) {
+                let ahead = input.fork();
+                let group = crate::group::parse_group(&ahead)?;
+                if group.content.is_empty() {
+                    input.advance_to(&ahead);
+                    return Ok(Visibility::Inherited);
+                }
+            }
+
+            if input.peek(Token![pub]) {
+                Self::parse_pub(input)
+            } else {
+                Ok(Visibility::Inherited)
+            }
+        }
+    }
+
+    impl Visibility {
+        fn parse_pub(input: ParseStream) -> Result<Self> {
+            let pub_token = input.parse::<Token![pub]>()?;
+
+            if input.peek(token::Paren) {
+                let ahead = input.fork();
+
+                let content;
+                let paren_token = parenthesized!(content in ahead);
+                if content.peek(Token![crate])
+                    || content.peek(Token![self])
+                    || content.peek(Token![super])
+                {
+                    let path = content.call(Ident::parse_any)?;
+
+                    // Ensure there are no additional tokens within `content`.
+                    // Without explicitly checking, we may misinterpret a tuple
+                    // field as a restricted visibility, causing a parse error.
+                    // e.g. `pub (crate::A, crate::B)` (Issue #720).
+                    if content.is_empty() {
+                        input.advance_to(&ahead);
+                        return Ok(Visibility::Restricted(VisRestricted {
+                            pub_token,
+                            paren_token,
+                            in_token: None,
+                            path: Box::new(Path::from(path)),
+                        }));
+                    }
+                } else if content.peek(Token![in]) {
+                    let in_token: Token![in] = content.parse()?;
+                    let path = content.call(Path::parse_mod_style)?;
+
+                    input.advance_to(&ahead);
+                    return Ok(Visibility::Restricted(VisRestricted {
+                        pub_token,
+                        paren_token,
+                        in_token: Some(in_token),
+                        path: Box::new(path),
+                    }));
+                }
+            }
+
+            Ok(Visibility::Public(pub_token))
+        }
+
+        #[cfg(feature = "full")]
+        pub(crate) fn is_some(&self) -> bool {
+            match self {
+                Visibility::Inherited => false,
+                _ => true,
+            }
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::restriction::{VisRestricted, Visibility};
+    use proc_macro2::TokenStream;
+    use quote::ToTokens;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Visibility {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                Visibility::Public(pub_token) => pub_token.to_tokens(tokens),
+                Visibility::Restricted(vis_restricted) => vis_restricted.to_tokens(tokens),
+                Visibility::Inherited => {}
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for VisRestricted {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.pub_token.to_tokens(tokens);
+            self.paren_token.surround(tokens, |tokens| {
+                // TODO: If we have a path which is not "self" or "super" or
+                // "crate", automatically add the "in" token.
+                self.in_token.to_tokens(tokens);
+                self.path.to_tokens(tokens);
+            });
+        }
+    }
+}
diff --git a/rust/syn/sealed.rs b/rust/syn/sealed.rs
new file mode 100644
index 0000000000000000000000000000000000000000..541df962375562dcb31f59d8a369a129c93b7ad1
--- /dev/null
+++ b/rust/syn/sealed.rs
@@ -0,0 +1,6 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+#[cfg(feature = "parsing")]
+pub(crate) mod lookahead {
+    pub trait Sealed: Copy {}
+}
diff --git a/rust/syn/span.rs b/rust/syn/span.rs
new file mode 100644
index 0000000000000000000000000000000000000000..e6d55b3ccd039abbc363689d845a73c2048b3511
--- /dev/null
+++ b/rust/syn/span.rs
@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use proc_macro2::extra::DelimSpan;
+use proc_macro2::{Delimiter, Group, Span, TokenStream};
+
+#[doc(hidden)]
+pub trait IntoSpans<S> {
+    fn into_spans(self) -> S;
+}
+
+impl IntoSpans<Span> for Span {
+    fn into_spans(self) -> Span {
+        self
+    }
+}
+
+impl IntoSpans<[Span; 1]> for Span {
+    fn into_spans(self) -> [Span; 1] {
+        [self]
+    }
+}
+
+impl IntoSpans<[Span; 2]> for Span {
+    fn into_spans(self) -> [Span; 2] {
+        [self, self]
+    }
+}
+
+impl IntoSpans<[Span; 3]> for Span {
+    fn into_spans(self) -> [Span; 3] {
+        [self, self, self]
+    }
+}
+
+impl IntoSpans<[Span; 1]> for [Span; 1] {
+    fn into_spans(self) -> [Span; 1] {
+        self
+    }
+}
+
+impl IntoSpans<[Span; 2]> for [Span; 2] {
+    fn into_spans(self) -> [Span; 2] {
+        self
+    }
+}
+
+impl IntoSpans<[Span; 3]> for [Span; 3] {
+    fn into_spans(self) -> [Span; 3] {
+        self
+    }
+}
+
+impl IntoSpans<DelimSpan> for Span {
+    fn into_spans(self) -> DelimSpan {
+        let mut group = Group::new(Delimiter::None, TokenStream::new());
+        group.set_span(self);
+        group.delim_span()
+    }
+}
+
+impl IntoSpans<DelimSpan> for DelimSpan {
+    fn into_spans(self) -> DelimSpan {
+        self
+    }
+}
diff --git a/rust/syn/spanned.rs b/rust/syn/spanned.rs
new file mode 100644
index 0000000000000000000000000000000000000000..fcc93699f742252cdfcd8f8714aded304d59e48f
--- /dev/null
+++ b/rust/syn/spanned.rs
@@ -0,0 +1,120 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! A trait that can provide the `Span` of the complete contents of a syntax
+//! tree node.
+//!
+//! <br>
+//!
+//! # Example
+//!
+//! Suppose in a procedural macro we have a [`Type`] that we want to assert
+//! implements the [`Sync`] trait. Maybe this is the type of one of the fields
+//! of a struct for which we are deriving a trait implementation, and we need to
+//! be able to pass a reference to one of those fields across threads.
+//!
+//! [`Type`]: crate::Type
+//! [`Sync`]: std::marker::Sync
+//!
+//! If the field type does *not* implement `Sync` as required, we want the
+//! compiler to report an error pointing out exactly which type it was.
+//!
+//! The following macro code takes a variable `ty` of type `Type` and produces a
+//! static assertion that `Sync` is implemented for that type.
+//!
+//! ```
+//! # extern crate proc_macro;
+//! #
+//! use proc_macro::TokenStream;
+//! use proc_macro2::Span;
+//! use quote::quote_spanned;
+//! use syn::Type;
+//! use syn::spanned::Spanned;
+//!
+//! # const IGNORE_TOKENS: &str = stringify! {
+//! #[proc_macro_derive(MyMacro)]
+//! # };
+//! pub fn my_macro(input: TokenStream) -> TokenStream {
+//!     # let ty = get_a_type();
+//!     /* ... */
+//!
+//!     let assert_sync = quote_spanned! {ty.span()=>
+//!         struct _AssertSync where #ty: Sync;
+//!     };
+//!
+//!     /* ... */
+//!     # input
+//! }
+//! #
+//! # fn get_a_type() -> Type {
+//! #     unimplemented!()
+//! # }
+//! ```
+//!
+//! By inserting this `assert_sync` fragment into the output code generated by
+//! our macro, the user's code will fail to compile if `ty` does not implement
+//! `Sync`. The errors they would see look like the following.
+//!
+//! ```text
+//! error[E0277]: the trait bound `*const i32: std::marker::Sync` is not satisfied
+//!   --> src/main.rs:10:21
+//!    |
+//! 10 |     bad_field: *const i32,
+//!    |                ^^^^^^^^^^ `*const i32` cannot be shared between threads safely
+//! ```
+//!
+//! In this technique, using the `Type`'s span for the error message makes the
+//! error appear in the correct place underlining the right type.
+//!
+//! <br>
+//!
+//! # Limitations
+//!
+//! The underlying [`proc_macro::Span::join`] method is nightly-only. When
+//! called from within a procedural macro in a nightly compiler, `Spanned` will
+//! use `join` to produce the intended span. When not using a nightly compiler,
+//! only the span of the *first token* of the syntax tree node is returned.
+//!
+//! In the common case of wanting to use the joined span as the span of a
+//! `syn::Error`, consider instead using [`syn::Error::new_spanned`] which is
+//! able to span the error correctly under the complete syntax tree node without
+//! needing the unstable `join`.
+//!
+//! [`syn::Error::new_spanned`]: crate::Error::new_spanned
+
+use proc_macro2::Span;
+use quote::spanned::Spanned as ToTokens;
+
+/// A trait that can provide the `Span` of the complete contents of a syntax
+/// tree node.
+///
+/// This trait is automatically implemented for all types that implement
+/// [`ToTokens`] from the `quote` crate, as well as for `Span` itself.
+///
+/// [`ToTokens`]: quote::ToTokens
+///
+/// See the [module documentation] for an example.
+///
+/// [module documentation]: self
+pub trait Spanned: private::Sealed {
+    /// Returns a `Span` covering the complete contents of this syntax tree
+    /// node, or [`Span::call_site()`] if this node is empty.
+    ///
+    /// [`Span::call_site()`]: proc_macro2::Span::call_site
+    fn span(&self) -> Span;
+}
+
+impl<T: ?Sized + ToTokens> Spanned for T {
+    fn span(&self) -> Span {
+        self.__span()
+    }
+}
+
+mod private {
+    use crate::spanned::ToTokens;
+
+    pub trait Sealed {}
+    impl<T: ?Sized + ToTokens> Sealed for T {}
+
+    #[cfg(any(feature = "full", feature = "derive"))]
+    impl Sealed for crate::QSelf {}
+}
diff --git a/rust/syn/stmt.rs b/rust/syn/stmt.rs
new file mode 100644
index 0000000000000000000000000000000000000000..378a59af65c5bdd71e8831f93822dacc2ea987d7
--- /dev/null
+++ b/rust/syn/stmt.rs
@@ -0,0 +1,470 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+use crate::expr::Expr;
+use crate::item::Item;
+use crate::mac::Macro;
+use crate::pat::Pat;
+use crate::token;
+
+ast_struct! {
+    /// A braced block containing Rust statements.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct Block {
+        pub brace_token: token::Brace,
+        /// Statements in a block
+        pub stmts: Vec<Stmt>,
+    }
+}
+
+ast_enum! {
+    /// A statement, usually ending in a semicolon.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub enum Stmt {
+        /// A local (let) binding.
+        Local(Local),
+
+        /// An item definition.
+        Item(Item),
+
+        /// Expression, with or without trailing semicolon.
+        Expr(Expr, Option<Token![;]>),
+
+        /// A macro invocation in statement position.
+        ///
+        /// Syntactically it's ambiguous which other kind of statement this
+        /// macro would expand to. It can be any of local variable (`let`),
+        /// item, or expression.
+        Macro(StmtMacro),
+    }
+}
+
+ast_struct! {
+    /// A local `let` binding: `let x: u64 = s.parse()?`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct Local {
+        pub attrs: Vec<Attribute>,
+        pub let_token: Token![let],
+        pub pat: Pat,
+        pub init: Option<LocalInit>,
+        pub semi_token: Token![;],
+    }
+}
+
+ast_struct! {
+    /// The expression assigned in a local `let` binding, including optional
+    /// diverging `else` block.
+    ///
+    /// `LocalInit` represents `= s.parse()?` in `let x: u64 = s.parse()?` and
+    /// `= r else { return }` in `let Ok(x) = r else { return }`.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct LocalInit {
+        pub eq_token: Token![=],
+        pub expr: Box<Expr>,
+        pub diverge: Option<(Token![else], Box<Expr>)>,
+    }
+}
+
+ast_struct! {
+    /// A macro invocation in statement position.
+    ///
+    /// Syntactically it's ambiguous which other kind of statement this macro
+    /// would expand to. It can be any of local variable (`let`), item, or
+    /// expression.
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "full")))]
+    pub struct StmtMacro {
+        pub attrs: Vec<Attribute>,
+        pub mac: Macro,
+        pub semi_token: Option<Token![;]>,
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::Attribute;
+    use crate::error::Result;
+    use crate::expr::{self, Expr, ExprBlock, ExprMacro};
+    use crate::ident::Ident;
+    use crate::item;
+    use crate::mac::{self, Macro};
+    use crate::parse::discouraged::Speculative as _;
+    use crate::parse::{Parse, ParseStream};
+    use crate::pat::{Pat, PatType};
+    use crate::path::Path;
+    use crate::stmt::{Block, Local, LocalInit, Stmt, StmtMacro};
+    use crate::token;
+    use crate::ty::Type;
+    use proc_macro2::TokenStream;
+
+    struct AllowNoSemi(bool);
+
+    impl Block {
+        /// Parse the body of a block as zero or more statements, possibly
+        /// including one trailing expression.
+        ///
+        /// # Example
+        ///
+        /// ```
+        /// use syn::{braced, token, Attribute, Block, Ident, Result, Stmt, Token};
+        /// use syn::parse::{Parse, ParseStream};
+        ///
+        /// // Parse a function with no generics or parameter list.
+        /// //
+        /// //     fn playground {
+        /// //         let mut x = 1;
+        /// //         x += 1;
+        /// //         println!("{}", x);
+        /// //     }
+        /// struct MiniFunction {
+        ///     attrs: Vec<Attribute>,
+        ///     fn_token: Token![fn],
+        ///     name: Ident,
+        ///     brace_token: token::Brace,
+        ///     stmts: Vec<Stmt>,
+        /// }
+        ///
+        /// impl Parse for MiniFunction {
+        ///     fn parse(input: ParseStream) -> Result<Self> {
+        ///         let outer_attrs = input.call(Attribute::parse_outer)?;
+        ///         let fn_token: Token![fn] = input.parse()?;
+        ///         let name: Ident = input.parse()?;
+        ///
+        ///         let content;
+        ///         let brace_token = braced!(content in input);
+        ///         let inner_attrs = content.call(Attribute::parse_inner)?;
+        ///         let stmts = content.call(Block::parse_within)?;
+        ///
+        ///         Ok(MiniFunction {
+        ///             attrs: {
+        ///                 let mut attrs = outer_attrs;
+        ///                 attrs.extend(inner_attrs);
+        ///                 attrs
+        ///             },
+        ///             fn_token,
+        ///             name,
+        ///             brace_token,
+        ///             stmts,
+        ///         })
+        ///     }
+        /// }
+        /// ```
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+        pub fn parse_within(input: ParseStream) -> Result<Vec<Stmt>> {
+            let mut stmts = Vec::new();
+            loop {
+                while let semi @ Some(_) = input.parse()? {
+                    stmts.push(Stmt::Expr(Expr::Verbatim(TokenStream::new()), semi));
+                }
+                if input.is_empty() {
+                    break;
+                }
+                let stmt = parse_stmt(input, AllowNoSemi(true))?;
+                let requires_semicolon = match &stmt {
+                    Stmt::Expr(stmt, None) => expr::requires_terminator(stmt),
+                    Stmt::Macro(stmt) => {
+                        stmt.semi_token.is_none() && !stmt.mac.delimiter.is_brace()
+                    }
+                    Stmt::Local(_) | Stmt::Item(_) | Stmt::Expr(_, Some(_)) => false,
+                };
+                stmts.push(stmt);
+                if input.is_empty() {
+                    break;
+                } else if requires_semicolon {
+                    return Err(input.error("unexpected token, expected `;`"));
+                }
+            }
+            Ok(stmts)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Block {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let content;
+            Ok(Block {
+                brace_token: braced!(content in input),
+                stmts: content.call(Block::parse_within)?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Stmt {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_nosemi = AllowNoSemi(false);
+            parse_stmt(input, allow_nosemi)
+        }
+    }
+
+    fn parse_stmt(input: ParseStream, allow_nosemi: AllowNoSemi) -> Result<Stmt> {
+        let begin = input.fork();
+        let attrs = input.call(Attribute::parse_outer)?;
+
+        // brace-style macros; paren and bracket macros get parsed as
+        // expression statements.
+        let ahead = input.fork();
+        let mut is_item_macro = false;
+        if let Ok(path) = ahead.call(Path::parse_mod_style) {
+            if ahead.peek(Token![!]) {
+                if ahead.peek2(Ident) || ahead.peek2(Token![try]) {
+                    is_item_macro = true;
+                } else if ahead.peek2(token::Brace)
+                    && !(ahead.peek3(Token![.]) || ahead.peek3(Token![?]))
+                {
+                    input.advance_to(&ahead);
+                    return stmt_mac(input, attrs, path).map(Stmt::Macro);
+                }
+            }
+        }
+
+        if input.peek(Token![let]) && !input.peek(token::Group) {
+            stmt_local(input, attrs).map(Stmt::Local)
+        } else if input.peek(Token![pub])
+            || input.peek(Token![crate]) && !input.peek2(Token![::])
+            || input.peek(Token![extern])
+            || input.peek(Token![use])
+            || input.peek(Token![static])
+                && (input.peek2(Token![mut])
+                    || input.peek2(Ident)
+                        && !(input.peek2(Token![async])
+                            && (input.peek3(Token![move]) || input.peek3(Token![|]))))
+            || input.peek(Token![const])
+                && !(input.peek2(token::Brace)
+                    || input.peek2(Token![static])
+                    || input.peek2(Token![async])
+                        && !(input.peek3(Token![unsafe])
+                            || input.peek3(Token![extern])
+                            || input.peek3(Token![fn]))
+                    || input.peek2(Token![move])
+                    || input.peek2(Token![|]))
+            || input.peek(Token![unsafe]) && !input.peek2(token::Brace)
+            || input.peek(Token![async])
+                && (input.peek2(Token![unsafe])
+                    || input.peek2(Token![extern])
+                    || input.peek2(Token![fn]))
+            || input.peek(Token![fn])
+            || input.peek(Token![mod])
+            || input.peek(Token![type])
+            || input.peek(Token![struct])
+            || input.peek(Token![enum])
+            || input.peek(Token![union]) && input.peek2(Ident)
+            || input.peek(Token![auto]) && input.peek2(Token![trait])
+            || input.peek(Token![trait])
+            || input.peek(Token![default])
+                && (input.peek2(Token![unsafe]) || input.peek2(Token![impl]))
+            || input.peek(Token![impl])
+            || input.peek(Token![macro])
+            || is_item_macro
+        {
+            let item = item::parsing::parse_rest_of_item(begin, attrs, input)?;
+            Ok(Stmt::Item(item))
+        } else {
+            stmt_expr(input, allow_nosemi, attrs)
+        }
+    }
+
+    fn stmt_mac(input: ParseStream, attrs: Vec<Attribute>, path: Path) -> Result<StmtMacro> {
+        let bang_token: Token![!] = input.parse()?;
+        let (delimiter, tokens) = mac::parse_delimiter(input)?;
+        let semi_token: Option<Token![;]> = input.parse()?;
+
+        Ok(StmtMacro {
+            attrs,
+            mac: Macro {
+                path,
+                bang_token,
+                delimiter,
+                tokens,
+            },
+            semi_token,
+        })
+    }
+
+    fn stmt_local(input: ParseStream, attrs: Vec<Attribute>) -> Result<Local> {
+        let let_token: Token![let] = input.parse()?;
+
+        let mut pat = Pat::parse_single(input)?;
+        if input.peek(Token![:]) {
+            let colon_token: Token![:] = input.parse()?;
+            let ty: Type = input.parse()?;
+            pat = Pat::Type(PatType {
+                attrs: Vec::new(),
+                pat: Box::new(pat),
+                colon_token,
+                ty: Box::new(ty),
+            });
+        }
+
+        let init = if let Some(eq_token) = input.parse()? {
+            let eq_token: Token![=] = eq_token;
+            let expr: Expr = input.parse()?;
+
+            let diverge = if let Some(else_token) = input.parse()? {
+                let else_token: Token![else] = else_token;
+                let diverge = ExprBlock {
+                    attrs: Vec::new(),
+                    label: None,
+                    block: input.parse()?,
+                };
+                Some((else_token, Box::new(Expr::Block(diverge))))
+            } else {
+                None
+            };
+
+            Some(LocalInit {
+                eq_token,
+                expr: Box::new(expr),
+                diverge,
+            })
+        } else {
+            None
+        };
+
+        let semi_token: Token![;] = input.parse()?;
+
+        Ok(Local {
+            attrs,
+            let_token,
+            pat,
+            init,
+            semi_token,
+        })
+    }
+
+    fn stmt_expr(
+        input: ParseStream,
+        allow_nosemi: AllowNoSemi,
+        mut attrs: Vec<Attribute>,
+    ) -> Result<Stmt> {
+        let mut e = Expr::parse_with_earlier_boundary_rule(input)?;
+
+        let mut attr_target = &mut e;
+        loop {
+            attr_target = match attr_target {
+                Expr::Assign(e) => &mut e.left,
+                Expr::Binary(e) => &mut e.left,
+                Expr::Cast(e) => &mut e.expr,
+                Expr::Array(_)
+                | Expr::Async(_)
+                | Expr::Await(_)
+                | Expr::Block(_)
+                | Expr::Break(_)
+                | Expr::Call(_)
+                | Expr::Closure(_)
+                | Expr::Const(_)
+                | Expr::Continue(_)
+                | Expr::Field(_)
+                | Expr::ForLoop(_)
+                | Expr::Group(_)
+                | Expr::If(_)
+                | Expr::Index(_)
+                | Expr::Infer(_)
+                | Expr::Let(_)
+                | Expr::Lit(_)
+                | Expr::Loop(_)
+                | Expr::Macro(_)
+                | Expr::Match(_)
+                | Expr::MethodCall(_)
+                | Expr::Paren(_)
+                | Expr::Path(_)
+                | Expr::Range(_)
+                | Expr::Reference(_)
+                | Expr::Repeat(_)
+                | Expr::Return(_)
+                | Expr::Struct(_)
+                | Expr::Try(_)
+                | Expr::TryBlock(_)
+                | Expr::Tuple(_)
+                | Expr::Unary(_)
+                | Expr::Unsafe(_)
+                | Expr::While(_)
+                | Expr::Yield(_)
+                | Expr::Verbatim(_) => break,
+            };
+        }
+        attrs.extend(attr_target.replace_attrs(Vec::new()));
+        attr_target.replace_attrs(attrs);
+
+        let semi_token: Option<Token![;]> = input.parse()?;
+
+        match e {
+            Expr::Macro(ExprMacro { attrs, mac })
+                if semi_token.is_some() || mac.delimiter.is_brace() =>
+            {
+                return Ok(Stmt::Macro(StmtMacro {
+                    attrs,
+                    mac,
+                    semi_token,
+                }));
+            }
+            _ => {}
+        }
+
+        if semi_token.is_some() {
+            Ok(Stmt::Expr(e, semi_token))
+        } else if allow_nosemi.0 || !expr::requires_terminator(&e) {
+            Ok(Stmt::Expr(e, None))
+        } else {
+            Err(input.error("expected semicolon"))
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::expr;
+    use crate::stmt::{Block, Local, Stmt, StmtMacro};
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Block {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.brace_token.surround(tokens, |tokens| {
+                tokens.append_all(&self.stmts);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Stmt {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                Stmt::Local(local) => local.to_tokens(tokens),
+                Stmt::Item(item) => item.to_tokens(tokens),
+                Stmt::Expr(expr, semi) => {
+                    expr.to_tokens(tokens);
+                    semi.to_tokens(tokens);
+                }
+                Stmt::Macro(mac) => mac.to_tokens(tokens),
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Local {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            expr::printing::outer_attrs_to_tokens(&self.attrs, tokens);
+            self.let_token.to_tokens(tokens);
+            self.pat.to_tokens(tokens);
+            if let Some(init) = &self.init {
+                init.eq_token.to_tokens(tokens);
+                init.expr.to_tokens(tokens);
+                if let Some((else_token, diverge)) = &init.diverge {
+                    else_token.to_tokens(tokens);
+                    diverge.to_tokens(tokens);
+                }
+            }
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for StmtMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            expr::printing::outer_attrs_to_tokens(&self.attrs, tokens);
+            self.mac.to_tokens(tokens);
+            self.semi_token.to_tokens(tokens);
+        }
+    }
+}
diff --git a/rust/syn/thread.rs b/rust/syn/thread.rs
new file mode 100644
index 0000000000000000000000000000000000000000..4165a173d9e1a9870a3ff8599b09997cb4ea8e31
--- /dev/null
+++ b/rust/syn/thread.rs
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use std::fmt::{self, Debug};
+use std::thread::{self, ThreadId};
+
+/// ThreadBound is a Sync-maker and Send-maker that allows accessing a value
+/// of type T only from the original thread on which the ThreadBound was
+/// constructed.
+pub(crate) struct ThreadBound<T> {
+    value: T,
+    thread_id: ThreadId,
+}
+
+unsafe impl<T> Sync for ThreadBound<T> {}
+
+// Send bound requires Copy, as otherwise Drop could run in the wrong place.
+//
+// Today Copy and Drop are mutually exclusive so `T: Copy` implies `T: !Drop`.
+// This impl needs to be revisited if that restriction is relaxed in the future.
+unsafe impl<T: Copy> Send for ThreadBound<T> {}
+
+impl<T> ThreadBound<T> {
+    pub(crate) fn new(value: T) -> Self {
+        ThreadBound {
+            value,
+            thread_id: thread::current().id(),
+        }
+    }
+
+    pub(crate) fn get(&self) -> Option<&T> {
+        if thread::current().id() == self.thread_id {
+            Some(&self.value)
+        } else {
+            None
+        }
+    }
+}
+
+impl<T: Debug> Debug for ThreadBound<T> {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        match self.get() {
+            Some(value) => Debug::fmt(value, formatter),
+            None => formatter.write_str("unknown"),
+        }
+    }
+}
+
+// Copy the bytes of T, even if the currently running thread is the "wrong"
+// thread. This is fine as long as the original thread is not simultaneously
+// mutating this value via interior mutability, which would be a data race.
+//
+// Currently `T: Copy` is sufficient to guarantee that T contains no interior
+// mutability, because _all_ interior mutability in Rust is built on
+// std::cell::UnsafeCell, which has no Copy impl. This impl needs to be
+// revisited if that restriction is relaxed in the future.
+impl<T: Copy> Copy for ThreadBound<T> {}
+
+impl<T: Copy> Clone for ThreadBound<T> {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
diff --git a/rust/syn/token.rs b/rust/syn/token.rs
new file mode 100644
index 0000000000000000000000000000000000000000..4a8edc0e6b44f8931ec5ab32e9ddcd224abd3a8e
--- /dev/null
+++ b/rust/syn/token.rs
@@ -0,0 +1,1140 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+//! Tokens representing Rust punctuation, keywords, and delimiters.
+//!
+//! The type names in this module can be difficult to keep straight, so we
+//! prefer to use the [`Token!`] macro instead. This is a type-macro that
+//! expands to the token type of the given token.
+//!
+//! [`Token!`]: crate::Token
+//!
+//! # Example
+//!
+//! The [`ItemStatic`] syntax tree node is defined like this.
+//!
+//! [`ItemStatic`]: crate::ItemStatic
+//!
+//! ```
+//! # use syn::{Attribute, Expr, Ident, Token, Type, Visibility};
+//! #
+//! pub struct ItemStatic {
+//!     pub attrs: Vec<Attribute>,
+//!     pub vis: Visibility,
+//!     pub static_token: Token![static],
+//!     pub mutability: Option<Token![mut]>,
+//!     pub ident: Ident,
+//!     pub colon_token: Token![:],
+//!     pub ty: Box<Type>,
+//!     pub eq_token: Token![=],
+//!     pub expr: Box<Expr>,
+//!     pub semi_token: Token![;],
+//! }
+//! ```
+//!
+//! # Parsing
+//!
+//! Keywords and punctuation can be parsed through the [`ParseStream::parse`]
+//! method. Delimiter tokens are parsed using the [`parenthesized!`],
+//! [`bracketed!`] and [`braced!`] macros.
+//!
+//! [`ParseStream::parse`]: crate::parse::ParseBuffer::parse()
+//! [`parenthesized!`]: crate::parenthesized!
+//! [`bracketed!`]: crate::bracketed!
+//! [`braced!`]: crate::braced!
+//!
+//! ```
+//! use syn::{Attribute, Result};
+//! use syn::parse::{Parse, ParseStream};
+//! #
+//! # enum ItemStatic {}
+//!
+//! // Parse the ItemStatic struct shown above.
+//! impl Parse for ItemStatic {
+//!     fn parse(input: ParseStream) -> Result<Self> {
+//!         # use syn::ItemStatic;
+//!         # fn parse(input: ParseStream) -> Result<ItemStatic> {
+//!         Ok(ItemStatic {
+//!             attrs: input.call(Attribute::parse_outer)?,
+//!             vis: input.parse()?,
+//!             static_token: input.parse()?,
+//!             mutability: input.parse()?,
+//!             ident: input.parse()?,
+//!             colon_token: input.parse()?,
+//!             ty: input.parse()?,
+//!             eq_token: input.parse()?,
+//!             expr: input.parse()?,
+//!             semi_token: input.parse()?,
+//!         })
+//!         # }
+//!         # unimplemented!()
+//!     }
+//! }
+//! ```
+//!
+//! # Other operations
+//!
+//! Every keyword and punctuation token supports the following operations.
+//!
+//! - [Peeking] — `input.peek(Token![...])`
+//!
+//! - [Parsing] — `input.parse::<Token![...]>()?`
+//!
+//! - [Printing] — `quote!( ... #the_token ... )`
+//!
+//! - Construction from a [`Span`] — `let the_token = Token![...](sp)`
+//!
+//! - Field access to its span — `let sp = the_token.span`
+//!
+//! [Peeking]: crate::parse::ParseBuffer::peek()
+//! [Parsing]: crate::parse::ParseBuffer::parse()
+//! [Printing]: https://docs.rs/quote/1.0/quote/trait.ToTokens.html
+//! [`Span`]: https://docs.rs/proc-macro2/1.0/proc_macro2/struct.Span.html
+
+#[cfg(feature = "parsing")]
+pub(crate) use self::private::CustomToken;
+use self::private::WithSpan;
+#[cfg(feature = "parsing")]
+use crate::buffer::Cursor;
+#[cfg(feature = "parsing")]
+use crate::error::Result;
+#[cfg(feature = "parsing")]
+use crate::lifetime::Lifetime;
+#[cfg(feature = "parsing")]
+use crate::lit::{Lit, LitBool, LitByte, LitByteStr, LitChar, LitFloat, LitInt, LitStr};
+#[cfg(feature = "parsing")]
+use crate::lookahead;
+#[cfg(feature = "parsing")]
+use crate::parse::{Parse, ParseStream};
+use crate::span::IntoSpans;
+use proc_macro2::extra::DelimSpan;
+use proc_macro2::Span;
+#[cfg(feature = "printing")]
+use proc_macro2::TokenStream;
+#[cfg(any(feature = "parsing", feature = "printing"))]
+use proc_macro2::{Delimiter, Ident};
+#[cfg(feature = "parsing")]
+use proc_macro2::{Literal, Punct, TokenTree};
+#[cfg(feature = "printing")]
+use quote::{ToTokens, TokenStreamExt};
+#[cfg(feature = "extra-traits")]
+use std::cmp;
+#[cfg(feature = "extra-traits")]
+use std::fmt::{self, Debug};
+#[cfg(feature = "extra-traits")]
+use std::hash::{Hash, Hasher};
+use std::ops::{Deref, DerefMut};
+
+/// Marker trait for types that represent single tokens.
+///
+/// This trait is sealed and cannot be implemented for types outside of Syn.
+#[cfg(feature = "parsing")]
+pub trait Token: private::Sealed {
+    // Not public API.
+    #[doc(hidden)]
+    fn peek(cursor: Cursor) -> bool;
+
+    // Not public API.
+    #[doc(hidden)]
+    fn display() -> &'static str;
+}
+
+pub(crate) mod private {
+    #[cfg(feature = "parsing")]
+    use crate::buffer::Cursor;
+    use proc_macro2::Span;
+
+    #[cfg(feature = "parsing")]
+    pub trait Sealed {}
+
+    /// Support writing `token.span` rather than `token.spans[0]` on tokens that
+    /// hold a single span.
+    #[repr(transparent)]
+    #[allow(unknown_lints, repr_transparent_external_private_fields)] // False positive: https://github.com/rust-lang/rust/issues/78586#issuecomment-1722680482
+    pub struct WithSpan {
+        pub span: Span,
+    }
+
+    // Not public API.
+    #[doc(hidden)]
+    #[cfg(feature = "parsing")]
+    pub trait CustomToken {
+        fn peek(cursor: Cursor) -> bool;
+        fn display() -> &'static str;
+    }
+}
+
+#[cfg(feature = "parsing")]
+impl private::Sealed for Ident {}
+
+#[cfg(feature = "parsing")]
+fn peek_impl(cursor: Cursor, peek: fn(ParseStream) -> bool) -> bool {
+    use crate::parse::Unexpected;
+    use std::cell::Cell;
+    use std::rc::Rc;
+
+    let scope = Span::call_site();
+    let unexpected = Rc::new(Cell::new(Unexpected::None));
+    let buffer = crate::parse::new_parse_buffer(scope, cursor, unexpected);
+    peek(&buffer)
+}
+
+macro_rules! impl_token {
+    ($display:literal $name:ty) => {
+        #[cfg(feature = "parsing")]
+        impl Token for $name {
+            fn peek(cursor: Cursor) -> bool {
+                fn peek(input: ParseStream) -> bool {
+                    <$name as Parse>::parse(input).is_ok()
+                }
+                peek_impl(cursor, peek)
+            }
+
+            fn display() -> &'static str {
+                $display
+            }
+        }
+
+        #[cfg(feature = "parsing")]
+        impl private::Sealed for $name {}
+    };
+}
+
+impl_token!("lifetime" Lifetime);
+impl_token!("literal" Lit);
+impl_token!("string literal" LitStr);
+impl_token!("byte string literal" LitByteStr);
+impl_token!("byte literal" LitByte);
+impl_token!("character literal" LitChar);
+impl_token!("integer literal" LitInt);
+impl_token!("floating point literal" LitFloat);
+impl_token!("boolean literal" LitBool);
+impl_token!("group token" proc_macro2::Group);
+
+macro_rules! impl_low_level_token {
+    ($display:literal $ty:ident $get:ident) => {
+        #[cfg(feature = "parsing")]
+        impl Token for $ty {
+            fn peek(cursor: Cursor) -> bool {
+                cursor.$get().is_some()
+            }
+
+            fn display() -> &'static str {
+                $display
+            }
+        }
+
+        #[cfg(feature = "parsing")]
+        impl private::Sealed for $ty {}
+    };
+}
+
+impl_low_level_token!("punctuation token" Punct punct);
+impl_low_level_token!("literal" Literal literal);
+impl_low_level_token!("token" TokenTree token_tree);
+
+#[cfg(feature = "parsing")]
+impl<T: CustomToken> private::Sealed for T {}
+
+#[cfg(feature = "parsing")]
+impl<T: CustomToken> Token for T {
+    fn peek(cursor: Cursor) -> bool {
+        <Self as CustomToken>::peek(cursor)
+    }
+
+    fn display() -> &'static str {
+        <Self as CustomToken>::display()
+    }
+}
+
+macro_rules! define_keywords {
+    ($($token:literal pub struct $name:ident)*) => {
+        $(
+            #[doc = concat!('`', $token, '`')]
+            ///
+            /// Don't try to remember the name of this type &mdash; use the
+            /// [`Token!`] macro instead.
+            ///
+            /// [`Token!`]: crate::token
+            pub struct $name {
+                pub span: Span,
+            }
+
+            #[doc(hidden)]
+            #[allow(non_snake_case)]
+            pub fn $name<S: IntoSpans<Span>>(span: S) -> $name {
+                $name {
+                    span: span.into_spans(),
+                }
+            }
+
+            impl std::default::Default for $name {
+                fn default() -> Self {
+                    $name {
+                        span: Span::call_site(),
+                    }
+                }
+            }
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Copy for $name {}
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Clone for $name {
+                fn clone(&self) -> Self {
+                    *self
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl Debug for $name {
+                fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                    f.write_str(stringify!($name))
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl cmp::Eq for $name {}
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl PartialEq for $name {
+                fn eq(&self, _other: &$name) -> bool {
+                    true
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl Hash for $name {
+                fn hash<H: Hasher>(&self, _state: &mut H) {}
+            }
+
+            #[cfg(feature = "printing")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+            impl ToTokens for $name {
+                fn to_tokens(&self, tokens: &mut TokenStream) {
+                    printing::keyword($token, self.span, tokens);
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+            impl Parse for $name {
+                fn parse(input: ParseStream) -> Result<Self> {
+                    Ok($name {
+                        span: parsing::keyword(input, $token)?,
+                    })
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            impl Token for $name {
+                fn peek(cursor: Cursor) -> bool {
+                    parsing::peek_keyword(cursor, $token)
+                }
+
+                fn display() -> &'static str {
+                    concat!("`", $token, "`")
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            impl private::Sealed for $name {}
+        )*
+    };
+}
+
+macro_rules! impl_deref_if_len_is_1 {
+    ($name:ident/1) => {
+        impl Deref for $name {
+            type Target = WithSpan;
+
+            fn deref(&self) -> &Self::Target {
+                unsafe { &*(self as *const Self).cast::<WithSpan>() }
+            }
+        }
+
+        impl DerefMut for $name {
+            fn deref_mut(&mut self) -> &mut Self::Target {
+                unsafe { &mut *(self as *mut Self).cast::<WithSpan>() }
+            }
+        }
+    };
+
+    ($name:ident/$len:literal) => {};
+}
+
+macro_rules! define_punctuation_structs {
+    ($($token:literal pub struct $name:ident/$len:tt #[doc = $usage:literal])*) => {
+        $(
+            #[cfg_attr(not(doc), repr(transparent))]
+            #[allow(unknown_lints, repr_transparent_external_private_fields)] // False positive: https://github.com/rust-lang/rust/issues/78586#issuecomment-1722680482
+            #[doc = concat!('`', $token, '`')]
+            ///
+            /// Usage:
+            #[doc = concat!($usage, '.')]
+            ///
+            /// Don't try to remember the name of this type &mdash; use the
+            /// [`Token!`] macro instead.
+            ///
+            /// [`Token!`]: crate::token
+            pub struct $name {
+                pub spans: [Span; $len],
+            }
+
+            #[doc(hidden)]
+            #[allow(non_snake_case)]
+            pub fn $name<S: IntoSpans<[Span; $len]>>(spans: S) -> $name {
+                $name {
+                    spans: spans.into_spans(),
+                }
+            }
+
+            impl std::default::Default for $name {
+                fn default() -> Self {
+                    $name {
+                        spans: [Span::call_site(); $len],
+                    }
+                }
+            }
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Copy for $name {}
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Clone for $name {
+                fn clone(&self) -> Self {
+                    *self
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl Debug for $name {
+                fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                    f.write_str(stringify!($name))
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl cmp::Eq for $name {}
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl PartialEq for $name {
+                fn eq(&self, _other: &$name) -> bool {
+                    true
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl Hash for $name {
+                fn hash<H: Hasher>(&self, _state: &mut H) {}
+            }
+
+            impl_deref_if_len_is_1!($name/$len);
+        )*
+    };
+}
+
+macro_rules! define_punctuation {
+    ($($token:literal pub struct $name:ident/$len:tt #[doc = $usage:literal])*) => {
+        $(
+            define_punctuation_structs! {
+                $token pub struct $name/$len #[doc = $usage]
+            }
+
+            #[cfg(feature = "printing")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+            impl ToTokens for $name {
+                fn to_tokens(&self, tokens: &mut TokenStream) {
+                    printing::punct($token, &self.spans, tokens);
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+            impl Parse for $name {
+                fn parse(input: ParseStream) -> Result<Self> {
+                    Ok($name {
+                        spans: parsing::punct(input, $token)?,
+                    })
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            impl Token for $name {
+                fn peek(cursor: Cursor) -> bool {
+                    parsing::peek_punct(cursor, $token)
+                }
+
+                fn display() -> &'static str {
+                    concat!("`", $token, "`")
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            impl private::Sealed for $name {}
+        )*
+    };
+}
+
+macro_rules! define_delimiters {
+    ($($delim:ident pub struct $name:ident #[$doc:meta])*) => {
+        $(
+            #[$doc]
+            pub struct $name {
+                pub span: DelimSpan,
+            }
+
+            #[doc(hidden)]
+            #[allow(non_snake_case)]
+            pub fn $name<S: IntoSpans<DelimSpan>>(span: S) -> $name {
+                $name {
+                    span: span.into_spans(),
+                }
+            }
+
+            impl std::default::Default for $name {
+                fn default() -> Self {
+                    $name(Span::call_site())
+                }
+            }
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Copy for $name {}
+
+            #[cfg(feature = "clone-impls")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+            impl Clone for $name {
+                fn clone(&self) -> Self {
+                    *self
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl Debug for $name {
+                fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+                    f.write_str(stringify!($name))
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl cmp::Eq for $name {}
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl PartialEq for $name {
+                fn eq(&self, _other: &$name) -> bool {
+                    true
+                }
+            }
+
+            #[cfg(feature = "extra-traits")]
+            #[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+            impl Hash for $name {
+                fn hash<H: Hasher>(&self, _state: &mut H) {}
+            }
+
+            impl $name {
+                #[cfg(feature = "printing")]
+                pub fn surround<F>(&self, tokens: &mut TokenStream, f: F)
+                where
+                    F: FnOnce(&mut TokenStream),
+                {
+                    let mut inner = TokenStream::new();
+                    f(&mut inner);
+                    printing::delim(Delimiter::$delim, self.span.join(), tokens, inner);
+                }
+            }
+
+            #[cfg(feature = "parsing")]
+            impl private::Sealed for $name {}
+        )*
+    };
+}
+
+define_punctuation_structs! {
+    "_" pub struct Underscore/1 /// wildcard patterns, inferred types, unnamed items in constants, extern crates, use declarations, and destructuring assignment
+}
+
+#[cfg(feature = "printing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+impl ToTokens for Underscore {
+    fn to_tokens(&self, tokens: &mut TokenStream) {
+        tokens.append(Ident::new("_", self.span));
+    }
+}
+
+#[cfg(feature = "parsing")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+impl Parse for Underscore {
+    fn parse(input: ParseStream) -> Result<Self> {
+        input.step(|cursor| {
+            if let Some((ident, rest)) = cursor.ident() {
+                if ident == "_" {
+                    return Ok((Underscore(ident.span()), rest));
+                }
+            }
+            if let Some((punct, rest)) = cursor.punct() {
+                if punct.as_char() == '_' {
+                    return Ok((Underscore(punct.span()), rest));
+                }
+            }
+            Err(cursor.error("expected `_`"))
+        })
+    }
+}
+
+#[cfg(feature = "parsing")]
+impl Token for Underscore {
+    fn peek(cursor: Cursor) -> bool {
+        if let Some((ident, _rest)) = cursor.ident() {
+            return ident == "_";
+        }
+        if let Some((punct, _rest)) = cursor.punct() {
+            return punct.as_char() == '_';
+        }
+        false
+    }
+
+    fn display() -> &'static str {
+        "`_`"
+    }
+}
+
+#[cfg(feature = "parsing")]
+impl private::Sealed for Underscore {}
+
+/// None-delimited group
+pub struct Group {
+    pub span: Span,
+}
+
+#[doc(hidden)]
+#[allow(non_snake_case)]
+pub fn Group<S: IntoSpans<Span>>(span: S) -> Group {
+    Group {
+        span: span.into_spans(),
+    }
+}
+
+impl std::default::Default for Group {
+    fn default() -> Self {
+        Group {
+            span: Span::call_site(),
+        }
+    }
+}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Copy for Group {}
+
+#[cfg(feature = "clone-impls")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "clone-impls")))]
+impl Clone for Group {
+    fn clone(&self) -> Self {
+        *self
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Debug for Group {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.write_str("Group")
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl cmp::Eq for Group {}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl PartialEq for Group {
+    fn eq(&self, _other: &Group) -> bool {
+        true
+    }
+}
+
+#[cfg(feature = "extra-traits")]
+#[cfg_attr(doc_cfg, doc(cfg(feature = "extra-traits")))]
+impl Hash for Group {
+    fn hash<H: Hasher>(&self, _state: &mut H) {}
+}
+
+impl Group {
+    #[cfg(feature = "printing")]
+    pub fn surround<F>(&self, tokens: &mut TokenStream, f: F)
+    where
+        F: FnOnce(&mut TokenStream),
+    {
+        let mut inner = TokenStream::new();
+        f(&mut inner);
+        printing::delim(Delimiter::None, self.span, tokens, inner);
+    }
+}
+
+#[cfg(feature = "parsing")]
+impl private::Sealed for Group {}
+
+#[cfg(feature = "parsing")]
+impl Token for Paren {
+    fn peek(cursor: Cursor) -> bool {
+        lookahead::is_delimiter(cursor, Delimiter::Parenthesis)
+    }
+
+    fn display() -> &'static str {
+        "parentheses"
+    }
+}
+
+#[cfg(feature = "parsing")]
+impl Token for Brace {
+    fn peek(cursor: Cursor) -> bool {
+        lookahead::is_delimiter(cursor, Delimiter::Brace)
+    }
+
+    fn display() -> &'static str {
+        "curly braces"
+    }
+}
+
+#[cfg(feature = "parsing")]
+impl Token for Bracket {
+    fn peek(cursor: Cursor) -> bool {
+        lookahead::is_delimiter(cursor, Delimiter::Bracket)
+    }
+
+    fn display() -> &'static str {
+        "square brackets"
+    }
+}
+
+#[cfg(feature = "parsing")]
+impl Token for Group {
+    fn peek(cursor: Cursor) -> bool {
+        lookahead::is_delimiter(cursor, Delimiter::None)
+    }
+
+    fn display() -> &'static str {
+        "invisible group"
+    }
+}
+
+define_keywords! {
+    "abstract"    pub struct Abstract
+    "as"          pub struct As
+    "async"       pub struct Async
+    "auto"        pub struct Auto
+    "await"       pub struct Await
+    "become"      pub struct Become
+    "box"         pub struct Box
+    "break"       pub struct Break
+    "const"       pub struct Const
+    "continue"    pub struct Continue
+    "crate"       pub struct Crate
+    "default"     pub struct Default
+    "do"          pub struct Do
+    "dyn"         pub struct Dyn
+    "else"        pub struct Else
+    "enum"        pub struct Enum
+    "extern"      pub struct Extern
+    "final"       pub struct Final
+    "fn"          pub struct Fn
+    "for"         pub struct For
+    "if"          pub struct If
+    "impl"        pub struct Impl
+    "in"          pub struct In
+    "let"         pub struct Let
+    "loop"        pub struct Loop
+    "macro"       pub struct Macro
+    "match"       pub struct Match
+    "mod"         pub struct Mod
+    "move"        pub struct Move
+    "mut"         pub struct Mut
+    "override"    pub struct Override
+    "priv"        pub struct Priv
+    "pub"         pub struct Pub
+    "ref"         pub struct Ref
+    "return"      pub struct Return
+    "Self"        pub struct SelfType
+    "self"        pub struct SelfValue
+    "static"      pub struct Static
+    "struct"      pub struct Struct
+    "super"       pub struct Super
+    "trait"       pub struct Trait
+    "try"         pub struct Try
+    "type"        pub struct Type
+    "typeof"      pub struct Typeof
+    "union"       pub struct Union
+    "unsafe"      pub struct Unsafe
+    "unsized"     pub struct Unsized
+    "use"         pub struct Use
+    "virtual"     pub struct Virtual
+    "where"       pub struct Where
+    "while"       pub struct While
+    "yield"       pub struct Yield
+}
+
+define_punctuation! {
+    "&"           pub struct And/1        /// bitwise and logical AND, borrow, references, reference patterns
+    "&&"          pub struct AndAnd/2     /// lazy AND, borrow, references, reference patterns
+    "&="          pub struct AndEq/2      /// bitwise AND assignment
+    "@"           pub struct At/1         /// subpattern binding
+    "^"           pub struct Caret/1      /// bitwise and logical XOR
+    "^="          pub struct CaretEq/2    /// bitwise XOR assignment
+    ":"           pub struct Colon/1      /// various separators
+    ","           pub struct Comma/1      /// various separators
+    "$"           pub struct Dollar/1     /// macros
+    "."           pub struct Dot/1        /// field access, tuple index
+    ".."          pub struct DotDot/2     /// range, struct expressions, patterns, range patterns
+    "..."         pub struct DotDotDot/3  /// variadic functions, range patterns
+    "..="         pub struct DotDotEq/3   /// inclusive range, range patterns
+    "="           pub struct Eq/1         /// assignment, attributes, various type definitions
+    "=="          pub struct EqEq/2       /// equal
+    "=>"          pub struct FatArrow/2   /// match arms, macros
+    ">="          pub struct Ge/2         /// greater than or equal to, generics
+    ">"           pub struct Gt/1         /// greater than, generics, paths
+    "<-"          pub struct LArrow/2     /// unused
+    "<="          pub struct Le/2         /// less than or equal to
+    "<"           pub struct Lt/1         /// less than, generics, paths
+    "-"           pub struct Minus/1      /// subtraction, negation
+    "-="          pub struct MinusEq/2    /// subtraction assignment
+    "!="          pub struct Ne/2         /// not equal
+    "!"           pub struct Not/1        /// bitwise and logical NOT, macro calls, inner attributes, never type, negative impls
+    "|"           pub struct Or/1         /// bitwise and logical OR, closures, patterns in match, if let, and while let
+    "|="          pub struct OrEq/2       /// bitwise OR assignment
+    "||"          pub struct OrOr/2       /// lazy OR, closures
+    "::"          pub struct PathSep/2    /// path separator
+    "%"           pub struct Percent/1    /// remainder
+    "%="          pub struct PercentEq/2  /// remainder assignment
+    "+"           pub struct Plus/1       /// addition, trait bounds, macro Kleene matcher
+    "+="          pub struct PlusEq/2     /// addition assignment
+    "#"           pub struct Pound/1      /// attributes
+    "?"           pub struct Question/1   /// question mark operator, questionably sized, macro Kleene matcher
+    "->"          pub struct RArrow/2     /// function return type, closure return type, function pointer type
+    ";"           pub struct Semi/1       /// terminator for various items and statements, array types
+    "<<"          pub struct Shl/2        /// shift left, nested generics
+    "<<="         pub struct ShlEq/3      /// shift left assignment
+    ">>"          pub struct Shr/2        /// shift right, nested generics
+    ">>="         pub struct ShrEq/3      /// shift right assignment, nested generics
+    "/"           pub struct Slash/1      /// division
+    "/="          pub struct SlashEq/2    /// division assignment
+    "*"           pub struct Star/1       /// multiplication, dereference, raw pointers, macro Kleene matcher, use wildcards
+    "*="          pub struct StarEq/2     /// multiplication assignment
+    "~"           pub struct Tilde/1      /// unused since before Rust 1.0
+}
+
+define_delimiters! {
+    Brace         pub struct Brace        /// `{`&hellip;`}`
+    Bracket       pub struct Bracket      /// `[`&hellip;`]`
+    Parenthesis   pub struct Paren        /// `(`&hellip;`)`
+}
+
+/// A type-macro that expands to the name of the Rust type representation of a
+/// given token.
+///
+/// As a type, `Token!` is commonly used in the type of struct fields, the type
+/// of a `let` statement, or in turbofish for a `parse` function.
+///
+/// ```
+/// use syn::{Ident, Token};
+/// use syn::parse::{Parse, ParseStream, Result};
+///
+/// // `struct Foo;`
+/// pub struct UnitStruct {
+///     struct_token: Token![struct],
+///     ident: Ident,
+///     semi_token: Token![;],
+/// }
+///
+/// impl Parse for UnitStruct {
+///     fn parse(input: ParseStream) -> Result<Self> {
+///         let struct_token: Token![struct] = input.parse()?;
+///         let ident: Ident = input.parse()?;
+///         let semi_token = input.parse::<Token![;]>()?;
+///         Ok(UnitStruct { struct_token, ident, semi_token })
+///     }
+/// }
+/// ```
+///
+/// As an expression, `Token!` is used for peeking tokens or instantiating
+/// tokens from a span.
+///
+/// ```
+/// # use syn::{Ident, Token};
+/// # use syn::parse::{Parse, ParseStream, Result};
+/// #
+/// # struct UnitStruct {
+/// #     struct_token: Token![struct],
+/// #     ident: Ident,
+/// #     semi_token: Token![;],
+/// # }
+/// #
+/// # impl Parse for UnitStruct {
+/// #     fn parse(input: ParseStream) -> Result<Self> {
+/// #         unimplemented!()
+/// #     }
+/// # }
+/// #
+/// fn make_unit_struct(name: Ident) -> UnitStruct {
+///     let span = name.span();
+///     UnitStruct {
+///         struct_token: Token![struct](span),
+///         ident: name,
+///         semi_token: Token![;](span),
+///     }
+/// }
+///
+/// # fn parse(input: ParseStream) -> Result<()> {
+/// if input.peek(Token![struct]) {
+///     let unit_struct: UnitStruct = input.parse()?;
+///     /* ... */
+/// }
+/// # Ok(())
+/// # }
+/// ```
+///
+/// See the [token module] documentation for details and examples.
+///
+/// [token module]: crate::token
+#[macro_export]
+macro_rules! Token {
+    [abstract]    => { $crate::token::Abstract };
+    [as]          => { $crate::token::As };
+    [async]       => { $crate::token::Async };
+    [auto]        => { $crate::token::Auto };
+    [await]       => { $crate::token::Await };
+    [become]      => { $crate::token::Become };
+    [box]         => { $crate::token::Box };
+    [break]       => { $crate::token::Break };
+    [const]       => { $crate::token::Const };
+    [continue]    => { $crate::token::Continue };
+    [crate]       => { $crate::token::Crate };
+    [default]     => { $crate::token::Default };
+    [do]          => { $crate::token::Do };
+    [dyn]         => { $crate::token::Dyn };
+    [else]        => { $crate::token::Else };
+    [enum]        => { $crate::token::Enum };
+    [extern]      => { $crate::token::Extern };
+    [final]       => { $crate::token::Final };
+    [fn]          => { $crate::token::Fn };
+    [for]         => { $crate::token::For };
+    [if]          => { $crate::token::If };
+    [impl]        => { $crate::token::Impl };
+    [in]          => { $crate::token::In };
+    [let]         => { $crate::token::Let };
+    [loop]        => { $crate::token::Loop };
+    [macro]       => { $crate::token::Macro };
+    [match]       => { $crate::token::Match };
+    [mod]         => { $crate::token::Mod };
+    [move]        => { $crate::token::Move };
+    [mut]         => { $crate::token::Mut };
+    [override]    => { $crate::token::Override };
+    [priv]        => { $crate::token::Priv };
+    [pub]         => { $crate::token::Pub };
+    [ref]         => { $crate::token::Ref };
+    [return]      => { $crate::token::Return };
+    [Self]        => { $crate::token::SelfType };
+    [self]        => { $crate::token::SelfValue };
+    [static]      => { $crate::token::Static };
+    [struct]      => { $crate::token::Struct };
+    [super]       => { $crate::token::Super };
+    [trait]       => { $crate::token::Trait };
+    [try]         => { $crate::token::Try };
+    [type]        => { $crate::token::Type };
+    [typeof]      => { $crate::token::Typeof };
+    [union]       => { $crate::token::Union };
+    [unsafe]      => { $crate::token::Unsafe };
+    [unsized]     => { $crate::token::Unsized };
+    [use]         => { $crate::token::Use };
+    [virtual]     => { $crate::token::Virtual };
+    [where]       => { $crate::token::Where };
+    [while]       => { $crate::token::While };
+    [yield]       => { $crate::token::Yield };
+    [&]           => { $crate::token::And };
+    [&&]          => { $crate::token::AndAnd };
+    [&=]          => { $crate::token::AndEq };
+    [@]           => { $crate::token::At };
+    [^]           => { $crate::token::Caret };
+    [^=]          => { $crate::token::CaretEq };
+    [:]           => { $crate::token::Colon };
+    [,]           => { $crate::token::Comma };
+    [$]           => { $crate::token::Dollar };
+    [.]           => { $crate::token::Dot };
+    [..]          => { $crate::token::DotDot };
+    [...]         => { $crate::token::DotDotDot };
+    [..=]         => { $crate::token::DotDotEq };
+    [=]           => { $crate::token::Eq };
+    [==]          => { $crate::token::EqEq };
+    [=>]          => { $crate::token::FatArrow };
+    [>=]          => { $crate::token::Ge };
+    [>]           => { $crate::token::Gt };
+    [<-]          => { $crate::token::LArrow };
+    [<=]          => { $crate::token::Le };
+    [<]           => { $crate::token::Lt };
+    [-]           => { $crate::token::Minus };
+    [-=]          => { $crate::token::MinusEq };
+    [!=]          => { $crate::token::Ne };
+    [!]           => { $crate::token::Not };
+    [|]           => { $crate::token::Or };
+    [|=]          => { $crate::token::OrEq };
+    [||]          => { $crate::token::OrOr };
+    [::]          => { $crate::token::PathSep };
+    [%]           => { $crate::token::Percent };
+    [%=]          => { $crate::token::PercentEq };
+    [+]           => { $crate::token::Plus };
+    [+=]          => { $crate::token::PlusEq };
+    [#]           => { $crate::token::Pound };
+    [?]           => { $crate::token::Question };
+    [->]          => { $crate::token::RArrow };
+    [;]           => { $crate::token::Semi };
+    [<<]          => { $crate::token::Shl };
+    [<<=]         => { $crate::token::ShlEq };
+    [>>]          => { $crate::token::Shr };
+    [>>=]         => { $crate::token::ShrEq };
+    [/]           => { $crate::token::Slash };
+    [/=]          => { $crate::token::SlashEq };
+    [*]           => { $crate::token::Star };
+    [*=]          => { $crate::token::StarEq };
+    [~]           => { $crate::token::Tilde };
+    [_]           => { $crate::token::Underscore };
+}
+
+// Not public API.
+#[doc(hidden)]
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::buffer::Cursor;
+    use crate::error::{Error, Result};
+    use crate::parse::ParseStream;
+    use proc_macro2::{Spacing, Span};
+
+    pub(crate) fn keyword(input: ParseStream, token: &str) -> Result<Span> {
+        input.step(|cursor| {
+            if let Some((ident, rest)) = cursor.ident() {
+                if ident == token {
+                    return Ok((ident.span(), rest));
+                }
+            }
+            Err(cursor.error(format!("expected `{}`", token)))
+        })
+    }
+
+    pub(crate) fn peek_keyword(cursor: Cursor, token: &str) -> bool {
+        if let Some((ident, _rest)) = cursor.ident() {
+            ident == token
+        } else {
+            false
+        }
+    }
+
+    #[doc(hidden)]
+    pub fn punct<const N: usize>(input: ParseStream, token: &str) -> Result<[Span; N]> {
+        let mut spans = [input.span(); N];
+        punct_helper(input, token, &mut spans)?;
+        Ok(spans)
+    }
+
+    fn punct_helper(input: ParseStream, token: &str, spans: &mut [Span]) -> Result<()> {
+        input.step(|cursor| {
+            let mut cursor = *cursor;
+            assert_eq!(token.len(), spans.len());
+
+            for (i, ch) in token.chars().enumerate() {
+                match cursor.punct() {
+                    Some((punct, rest)) => {
+                        spans[i] = punct.span();
+                        if punct.as_char() != ch {
+                            break;
+                        } else if i == token.len() - 1 {
+                            return Ok(((), rest));
+                        } else if punct.spacing() != Spacing::Joint {
+                            break;
+                        }
+                        cursor = rest;
+                    }
+                    None => break,
+                }
+            }
+
+            Err(Error::new(spans[0], format!("expected `{}`", token)))
+        })
+    }
+
+    #[doc(hidden)]
+    pub fn peek_punct(mut cursor: Cursor, token: &str) -> bool {
+        for (i, ch) in token.chars().enumerate() {
+            match cursor.punct() {
+                Some((punct, rest)) => {
+                    if punct.as_char() != ch {
+                        break;
+                    } else if i == token.len() - 1 {
+                        return true;
+                    } else if punct.spacing() != Spacing::Joint {
+                        break;
+                    }
+                    cursor = rest;
+                }
+                None => break,
+            }
+        }
+        false
+    }
+}
+
+// Not public API.
+#[doc(hidden)]
+#[cfg(feature = "printing")]
+pub(crate) mod printing {
+    use proc_macro2::{Delimiter, Group, Ident, Punct, Spacing, Span, TokenStream};
+    use quote::TokenStreamExt;
+
+    #[doc(hidden)]
+    pub fn punct(s: &str, spans: &[Span], tokens: &mut TokenStream) {
+        assert_eq!(s.len(), spans.len());
+
+        let mut chars = s.chars();
+        let mut spans = spans.iter();
+        let ch = chars.next_back().unwrap();
+        let span = spans.next_back().unwrap();
+        for (ch, span) in chars.zip(spans) {
+            let mut op = Punct::new(ch, Spacing::Joint);
+            op.set_span(*span);
+            tokens.append(op);
+        }
+
+        let mut op = Punct::new(ch, Spacing::Alone);
+        op.set_span(*span);
+        tokens.append(op);
+    }
+
+    pub(crate) fn keyword(s: &str, span: Span, tokens: &mut TokenStream) {
+        tokens.append(Ident::new(s, span));
+    }
+
+    pub(crate) fn delim(
+        delim: Delimiter,
+        span: Span,
+        tokens: &mut TokenStream,
+        inner: TokenStream,
+    ) {
+        let mut g = Group::new(delim, inner);
+        g.set_span(span);
+        tokens.append(g);
+    }
+}
diff --git a/rust/syn/tt.rs b/rust/syn/tt.rs
new file mode 100644
index 0000000000000000000000000000000000000000..4fc8ad1e07fa1dd347e5f0dbb740d11b65e4f28b
--- /dev/null
+++ b/rust/syn/tt.rs
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use proc_macro2::{Delimiter, TokenStream, TokenTree};
+use std::hash::{Hash, Hasher};
+
+pub(crate) struct TokenTreeHelper<'a>(pub &'a TokenTree);
+
+impl<'a> PartialEq for TokenTreeHelper<'a> {
+    fn eq(&self, other: &Self) -> bool {
+        use proc_macro2::Spacing;
+
+        match (self.0, other.0) {
+            (TokenTree::Group(g1), TokenTree::Group(g2)) => {
+                match (g1.delimiter(), g2.delimiter()) {
+                    (Delimiter::Parenthesis, Delimiter::Parenthesis)
+                    | (Delimiter::Brace, Delimiter::Brace)
+                    | (Delimiter::Bracket, Delimiter::Bracket)
+                    | (Delimiter::None, Delimiter::None) => {}
+                    _ => return false,
+                }
+
+                let s1 = g1.stream().into_iter();
+                let mut s2 = g2.stream().into_iter();
+
+                for item1 in s1 {
+                    let item2 = match s2.next() {
+                        Some(item) => item,
+                        None => return false,
+                    };
+                    if TokenTreeHelper(&item1) != TokenTreeHelper(&item2) {
+                        return false;
+                    }
+                }
+                s2.next().is_none()
+            }
+            (TokenTree::Punct(o1), TokenTree::Punct(o2)) => {
+                o1.as_char() == o2.as_char()
+                    && match (o1.spacing(), o2.spacing()) {
+                        (Spacing::Alone, Spacing::Alone) | (Spacing::Joint, Spacing::Joint) => true,
+                        _ => false,
+                    }
+            }
+            (TokenTree::Literal(l1), TokenTree::Literal(l2)) => l1.to_string() == l2.to_string(),
+            (TokenTree::Ident(s1), TokenTree::Ident(s2)) => s1 == s2,
+            _ => false,
+        }
+    }
+}
+
+impl<'a> Hash for TokenTreeHelper<'a> {
+    fn hash<H: Hasher>(&self, h: &mut H) {
+        use proc_macro2::Spacing;
+
+        match self.0 {
+            TokenTree::Group(g) => {
+                0u8.hash(h);
+                match g.delimiter() {
+                    Delimiter::Parenthesis => 0u8.hash(h),
+                    Delimiter::Brace => 1u8.hash(h),
+                    Delimiter::Bracket => 2u8.hash(h),
+                    Delimiter::None => 3u8.hash(h),
+                }
+
+                for item in g.stream() {
+                    TokenTreeHelper(&item).hash(h);
+                }
+                0xffu8.hash(h); // terminator w/ a variant we don't normally hash
+            }
+            TokenTree::Punct(op) => {
+                1u8.hash(h);
+                op.as_char().hash(h);
+                match op.spacing() {
+                    Spacing::Alone => 0u8.hash(h),
+                    Spacing::Joint => 1u8.hash(h),
+                }
+            }
+            TokenTree::Literal(lit) => (2u8, lit.to_string()).hash(h),
+            TokenTree::Ident(word) => (3u8, word).hash(h),
+        }
+    }
+}
+
+pub(crate) struct TokenStreamHelper<'a>(pub &'a TokenStream);
+
+impl<'a> PartialEq for TokenStreamHelper<'a> {
+    fn eq(&self, other: &Self) -> bool {
+        let left = self.0.clone().into_iter().collect::<Vec<_>>();
+        let right = other.0.clone().into_iter().collect::<Vec<_>>();
+        if left.len() != right.len() {
+            return false;
+        }
+        for (a, b) in left.into_iter().zip(right) {
+            if TokenTreeHelper(&a) != TokenTreeHelper(&b) {
+                return false;
+            }
+        }
+        true
+    }
+}
+
+impl<'a> Hash for TokenStreamHelper<'a> {
+    fn hash<H: Hasher>(&self, state: &mut H) {
+        let tts = self.0.clone().into_iter().collect::<Vec<_>>();
+        tts.len().hash(state);
+        for tt in tts {
+            TokenTreeHelper(&tt).hash(state);
+        }
+    }
+}
diff --git a/rust/syn/ty.rs b/rust/syn/ty.rs
new file mode 100644
index 0000000000000000000000000000000000000000..033f31d66c8660edeb1b34c08670587b12f36ea3
--- /dev/null
+++ b/rust/syn/ty.rs
@@ -0,0 +1,1218 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::attr::Attribute;
+use crate::expr::Expr;
+use crate::generics::{BoundLifetimes, TypeParamBound};
+use crate::ident::Ident;
+use crate::lifetime::Lifetime;
+use crate::lit::LitStr;
+use crate::mac::Macro;
+use crate::path::{Path, QSelf};
+use crate::punctuated::Punctuated;
+use crate::token;
+use proc_macro2::TokenStream;
+
+ast_enum_of_structs! {
+    /// The possible types that a Rust value could have.
+    ///
+    /// # Syntax tree enum
+    ///
+    /// This type is a [syntax tree enum].
+    ///
+    /// [syntax tree enum]: crate::expr::Expr#syntax-tree-enums
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    #[non_exhaustive]
+    pub enum Type {
+        /// A fixed size array type: `[T; n]`.
+        Array(TypeArray),
+
+        /// A bare function type: `fn(usize) -> bool`.
+        BareFn(TypeBareFn),
+
+        /// A type contained within invisible delimiters.
+        Group(TypeGroup),
+
+        /// An `impl Bound1 + Bound2 + Bound3` type where `Bound` is a trait or
+        /// a lifetime.
+        ImplTrait(TypeImplTrait),
+
+        /// Indication that a type should be inferred by the compiler: `_`.
+        Infer(TypeInfer),
+
+        /// A macro in the type position.
+        Macro(TypeMacro),
+
+        /// The never type: `!`.
+        Never(TypeNever),
+
+        /// A parenthesized type equivalent to the inner type.
+        Paren(TypeParen),
+
+        /// A path like `std::slice::Iter`, optionally qualified with a
+        /// self-type as in `<Vec<T> as SomeTrait>::Associated`.
+        Path(TypePath),
+
+        /// A raw pointer type: `*const T` or `*mut T`.
+        Ptr(TypePtr),
+
+        /// A reference type: `&'a T` or `&'a mut T`.
+        Reference(TypeReference),
+
+        /// A dynamically sized slice type: `[T]`.
+        Slice(TypeSlice),
+
+        /// A trait object type `dyn Bound1 + Bound2 + Bound3` where `Bound` is a
+        /// trait or a lifetime.
+        TraitObject(TypeTraitObject),
+
+        /// A tuple type: `(A, B, C, String)`.
+        Tuple(TypeTuple),
+
+        /// Tokens in type position not interpreted by Syn.
+        Verbatim(TokenStream),
+
+        // For testing exhaustiveness in downstream code, use the following idiom:
+        //
+        //     match ty {
+        //         #![cfg_attr(test, deny(non_exhaustive_omitted_patterns))]
+        //
+        //         Type::Array(ty) => {...}
+        //         Type::BareFn(ty) => {...}
+        //         ...
+        //         Type::Verbatim(ty) => {...}
+        //
+        //         _ => { /* some sane fallback */ }
+        //     }
+        //
+        // This way we fail your tests but don't break your library when adding
+        // a variant. You will be notified by a test failure when a variant is
+        // added, so that you can add code to handle it, but your library will
+        // continue to compile and work for downstream users in the interim.
+    }
+}
+
+ast_struct! {
+    /// A fixed size array type: `[T; n]`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeArray {
+        pub bracket_token: token::Bracket,
+        pub elem: Box<Type>,
+        pub semi_token: Token![;],
+        pub len: Expr,
+    }
+}
+
+ast_struct! {
+    /// A bare function type: `fn(usize) -> bool`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeBareFn {
+        pub lifetimes: Option<BoundLifetimes>,
+        pub unsafety: Option<Token![unsafe]>,
+        pub abi: Option<Abi>,
+        pub fn_token: Token![fn],
+        pub paren_token: token::Paren,
+        pub inputs: Punctuated<BareFnArg, Token![,]>,
+        pub variadic: Option<BareVariadic>,
+        pub output: ReturnType,
+    }
+}
+
+ast_struct! {
+    /// A type contained within invisible delimiters.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeGroup {
+        pub group_token: token::Group,
+        pub elem: Box<Type>,
+    }
+}
+
+ast_struct! {
+    /// An `impl Bound1 + Bound2 + Bound3` type where `Bound` is a trait or
+    /// a lifetime.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeImplTrait {
+        pub impl_token: Token![impl],
+        pub bounds: Punctuated<TypeParamBound, Token![+]>,
+    }
+}
+
+ast_struct! {
+    /// Indication that a type should be inferred by the compiler: `_`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeInfer {
+        pub underscore_token: Token![_],
+    }
+}
+
+ast_struct! {
+    /// A macro in the type position.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeMacro {
+        pub mac: Macro,
+    }
+}
+
+ast_struct! {
+    /// The never type: `!`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeNever {
+        pub bang_token: Token![!],
+    }
+}
+
+ast_struct! {
+    /// A parenthesized type equivalent to the inner type.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeParen {
+        pub paren_token: token::Paren,
+        pub elem: Box<Type>,
+    }
+}
+
+ast_struct! {
+    /// A path like `std::slice::Iter`, optionally qualified with a
+    /// self-type as in `<Vec<T> as SomeTrait>::Associated`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypePath {
+        pub qself: Option<QSelf>,
+        pub path: Path,
+    }
+}
+
+ast_struct! {
+    /// A raw pointer type: `*const T` or `*mut T`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypePtr {
+        pub star_token: Token![*],
+        pub const_token: Option<Token![const]>,
+        pub mutability: Option<Token![mut]>,
+        pub elem: Box<Type>,
+    }
+}
+
+ast_struct! {
+    /// A reference type: `&'a T` or `&'a mut T`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeReference {
+        pub and_token: Token![&],
+        pub lifetime: Option<Lifetime>,
+        pub mutability: Option<Token![mut]>,
+        pub elem: Box<Type>,
+    }
+}
+
+ast_struct! {
+    /// A dynamically sized slice type: `[T]`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeSlice {
+        pub bracket_token: token::Bracket,
+        pub elem: Box<Type>,
+    }
+}
+
+ast_struct! {
+    /// A trait object type `dyn Bound1 + Bound2 + Bound3` where `Bound` is a
+    /// trait or a lifetime.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeTraitObject {
+        pub dyn_token: Option<Token![dyn]>,
+        pub bounds: Punctuated<TypeParamBound, Token![+]>,
+    }
+}
+
+ast_struct! {
+    /// A tuple type: `(A, B, C, String)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct TypeTuple {
+        pub paren_token: token::Paren,
+        pub elems: Punctuated<Type, Token![,]>,
+    }
+}
+
+ast_struct! {
+    /// The binary interface of a function: `extern "C"`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct Abi {
+        pub extern_token: Token![extern],
+        pub name: Option<LitStr>,
+    }
+}
+
+ast_struct! {
+    /// An argument in a function type: the `usize` in `fn(usize) -> bool`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct BareFnArg {
+        pub attrs: Vec<Attribute>,
+        pub name: Option<(Ident, Token![:])>,
+        pub ty: Type,
+    }
+}
+
+ast_struct! {
+    /// The variadic argument of a function pointer like `fn(usize, ...)`.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub struct BareVariadic {
+        pub attrs: Vec<Attribute>,
+        pub name: Option<(Ident, Token![:])>,
+        pub dots: Token![...],
+        pub comma: Option<Token![,]>,
+    }
+}
+
+ast_enum! {
+    /// Return type of a function signature.
+    #[cfg_attr(doc_cfg, doc(cfg(any(feature = "full", feature = "derive"))))]
+    pub enum ReturnType {
+        /// Return type is not specified.
+        ///
+        /// Functions default to `()` and closures default to type inference.
+        Default,
+        /// A particular type is returned.
+        Type(Token![->], Box<Type>),
+    }
+}
+
+#[cfg(feature = "parsing")]
+pub(crate) mod parsing {
+    use crate::attr::Attribute;
+    use crate::error::{self, Result};
+    use crate::ext::IdentExt as _;
+    use crate::generics::{BoundLifetimes, TraitBound, TraitBoundModifier, TypeParamBound};
+    use crate::ident::Ident;
+    use crate::lifetime::Lifetime;
+    use crate::mac::{self, Macro};
+    use crate::parse::{Parse, ParseStream};
+    use crate::path;
+    use crate::path::{Path, PathArguments, QSelf};
+    use crate::punctuated::Punctuated;
+    use crate::token;
+    use crate::ty::{
+        Abi, BareFnArg, BareVariadic, ReturnType, Type, TypeArray, TypeBareFn, TypeGroup,
+        TypeImplTrait, TypeInfer, TypeMacro, TypeNever, TypeParen, TypePath, TypePtr,
+        TypeReference, TypeSlice, TypeTraitObject, TypeTuple,
+    };
+    use crate::verbatim;
+    use proc_macro2::Span;
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Type {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_plus = true;
+            let allow_group_generic = true;
+            ambig_ty(input, allow_plus, allow_group_generic)
+        }
+    }
+
+    impl Type {
+        /// In some positions, types may not contain the `+` character, to
+        /// disambiguate them. For example in the expression `1 as T`, T may not
+        /// contain a `+` character.
+        ///
+        /// This parser does not allow a `+`, while the default parser does.
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+        pub fn without_plus(input: ParseStream) -> Result<Self> {
+            let allow_plus = false;
+            let allow_group_generic = true;
+            ambig_ty(input, allow_plus, allow_group_generic)
+        }
+    }
+
+    pub(crate) fn ambig_ty(
+        input: ParseStream,
+        allow_plus: bool,
+        allow_group_generic: bool,
+    ) -> Result<Type> {
+        let begin = input.fork();
+
+        if input.peek(token::Group) {
+            let mut group: TypeGroup = input.parse()?;
+            if input.peek(Token![::]) && input.peek3(Ident::peek_any) {
+                if let Type::Path(mut ty) = *group.elem {
+                    Path::parse_rest(input, &mut ty.path, false)?;
+                    return Ok(Type::Path(ty));
+                } else {
+                    return Ok(Type::Path(TypePath {
+                        qself: Some(QSelf {
+                            lt_token: Token![<](group.group_token.span),
+                            position: 0,
+                            as_token: None,
+                            gt_token: Token![>](group.group_token.span),
+                            ty: group.elem,
+                        }),
+                        path: Path::parse_helper(input, false)?,
+                    }));
+                }
+            } else if input.peek(Token![<]) && allow_group_generic
+                || input.peek(Token![::]) && input.peek3(Token![<])
+            {
+                if let Type::Path(mut ty) = *group.elem {
+                    let arguments = &mut ty.path.segments.last_mut().unwrap().arguments;
+                    if arguments.is_none() {
+                        *arguments = PathArguments::AngleBracketed(input.parse()?);
+                        Path::parse_rest(input, &mut ty.path, false)?;
+                        return Ok(Type::Path(ty));
+                    } else {
+                        group.elem = Box::new(Type::Path(ty));
+                    }
+                }
+            }
+            return Ok(Type::Group(group));
+        }
+
+        let mut lifetimes = None::<BoundLifetimes>;
+        let mut lookahead = input.lookahead1();
+        if lookahead.peek(Token![for]) {
+            lifetimes = input.parse()?;
+            lookahead = input.lookahead1();
+            if !lookahead.peek(Ident)
+                && !lookahead.peek(Token![fn])
+                && !lookahead.peek(Token![unsafe])
+                && !lookahead.peek(Token![extern])
+                && !lookahead.peek(Token![super])
+                && !lookahead.peek(Token![self])
+                && !lookahead.peek(Token![Self])
+                && !lookahead.peek(Token![crate])
+                || input.peek(Token![dyn])
+            {
+                return Err(lookahead.error());
+            }
+        }
+
+        if lookahead.peek(token::Paren) {
+            let content;
+            let paren_token = parenthesized!(content in input);
+            if content.is_empty() {
+                return Ok(Type::Tuple(TypeTuple {
+                    paren_token,
+                    elems: Punctuated::new(),
+                }));
+            }
+            if content.peek(Lifetime) {
+                return Ok(Type::Paren(TypeParen {
+                    paren_token,
+                    elem: Box::new(Type::TraitObject(content.parse()?)),
+                }));
+            }
+            if content.peek(Token![?]) {
+                return Ok(Type::TraitObject(TypeTraitObject {
+                    dyn_token: None,
+                    bounds: {
+                        let mut bounds = Punctuated::new();
+                        bounds.push_value(TypeParamBound::Trait(TraitBound {
+                            paren_token: Some(paren_token),
+                            ..content.parse()?
+                        }));
+                        while let Some(plus) = input.parse()? {
+                            bounds.push_punct(plus);
+                            bounds.push_value(input.parse()?);
+                        }
+                        bounds
+                    },
+                }));
+            }
+            let mut first: Type = content.parse()?;
+            if content.peek(Token![,]) {
+                return Ok(Type::Tuple(TypeTuple {
+                    paren_token,
+                    elems: {
+                        let mut elems = Punctuated::new();
+                        elems.push_value(first);
+                        elems.push_punct(content.parse()?);
+                        while !content.is_empty() {
+                            elems.push_value(content.parse()?);
+                            if content.is_empty() {
+                                break;
+                            }
+                            elems.push_punct(content.parse()?);
+                        }
+                        elems
+                    },
+                }));
+            }
+            if allow_plus && input.peek(Token![+]) {
+                loop {
+                    let first = match first {
+                        Type::Path(TypePath { qself: None, path }) => {
+                            TypeParamBound::Trait(TraitBound {
+                                paren_token: Some(paren_token),
+                                modifier: TraitBoundModifier::None,
+                                lifetimes: None,
+                                path,
+                            })
+                        }
+                        Type::TraitObject(TypeTraitObject {
+                            dyn_token: None,
+                            bounds,
+                        }) => {
+                            if bounds.len() > 1 || bounds.trailing_punct() {
+                                first = Type::TraitObject(TypeTraitObject {
+                                    dyn_token: None,
+                                    bounds,
+                                });
+                                break;
+                            }
+                            match bounds.into_iter().next().unwrap() {
+                                TypeParamBound::Trait(trait_bound) => {
+                                    TypeParamBound::Trait(TraitBound {
+                                        paren_token: Some(paren_token),
+                                        ..trait_bound
+                                    })
+                                }
+                                other @ (TypeParamBound::Lifetime(_)
+                                | TypeParamBound::Verbatim(_)) => other,
+                            }
+                        }
+                        _ => break,
+                    };
+                    return Ok(Type::TraitObject(TypeTraitObject {
+                        dyn_token: None,
+                        bounds: {
+                            let mut bounds = Punctuated::new();
+                            bounds.push_value(first);
+                            while let Some(plus) = input.parse()? {
+                                bounds.push_punct(plus);
+                                bounds.push_value(input.parse()?);
+                            }
+                            bounds
+                        },
+                    }));
+                }
+            }
+            Ok(Type::Paren(TypeParen {
+                paren_token,
+                elem: Box::new(first),
+            }))
+        } else if lookahead.peek(Token![fn])
+            || lookahead.peek(Token![unsafe])
+            || lookahead.peek(Token![extern])
+        {
+            let mut bare_fn: TypeBareFn = input.parse()?;
+            bare_fn.lifetimes = lifetimes;
+            Ok(Type::BareFn(bare_fn))
+        } else if lookahead.peek(Ident)
+            || input.peek(Token![super])
+            || input.peek(Token![self])
+            || input.peek(Token![Self])
+            || input.peek(Token![crate])
+            || lookahead.peek(Token![::])
+            || lookahead.peek(Token![<])
+        {
+            let ty: TypePath = input.parse()?;
+            if ty.qself.is_some() {
+                return Ok(Type::Path(ty));
+            }
+
+            if input.peek(Token![!]) && !input.peek(Token![!=]) && ty.path.is_mod_style() {
+                let bang_token: Token![!] = input.parse()?;
+                let (delimiter, tokens) = mac::parse_delimiter(input)?;
+                return Ok(Type::Macro(TypeMacro {
+                    mac: Macro {
+                        path: ty.path,
+                        bang_token,
+                        delimiter,
+                        tokens,
+                    },
+                }));
+            }
+
+            if lifetimes.is_some() || allow_plus && input.peek(Token![+]) {
+                let mut bounds = Punctuated::new();
+                bounds.push_value(TypeParamBound::Trait(TraitBound {
+                    paren_token: None,
+                    modifier: TraitBoundModifier::None,
+                    lifetimes,
+                    path: ty.path,
+                }));
+                if allow_plus {
+                    while input.peek(Token![+]) {
+                        bounds.push_punct(input.parse()?);
+                        if !(input.peek(Ident::peek_any)
+                            || input.peek(Token![::])
+                            || input.peek(Token![?])
+                            || input.peek(Lifetime)
+                            || input.peek(token::Paren))
+                        {
+                            break;
+                        }
+                        bounds.push_value(input.parse()?);
+                    }
+                }
+                return Ok(Type::TraitObject(TypeTraitObject {
+                    dyn_token: None,
+                    bounds,
+                }));
+            }
+
+            Ok(Type::Path(ty))
+        } else if lookahead.peek(Token![dyn]) {
+            let dyn_token: Token![dyn] = input.parse()?;
+            let dyn_span = dyn_token.span;
+            let star_token: Option<Token![*]> = input.parse()?;
+            let bounds = TypeTraitObject::parse_bounds(dyn_span, input, allow_plus)?;
+            return Ok(if star_token.is_some() {
+                Type::Verbatim(verbatim::between(&begin, input))
+            } else {
+                Type::TraitObject(TypeTraitObject {
+                    dyn_token: Some(dyn_token),
+                    bounds,
+                })
+            });
+        } else if lookahead.peek(token::Bracket) {
+            let content;
+            let bracket_token = bracketed!(content in input);
+            let elem: Type = content.parse()?;
+            if content.peek(Token![;]) {
+                Ok(Type::Array(TypeArray {
+                    bracket_token,
+                    elem: Box::new(elem),
+                    semi_token: content.parse()?,
+                    len: content.parse()?,
+                }))
+            } else {
+                Ok(Type::Slice(TypeSlice {
+                    bracket_token,
+                    elem: Box::new(elem),
+                }))
+            }
+        } else if lookahead.peek(Token![*]) {
+            input.parse().map(Type::Ptr)
+        } else if lookahead.peek(Token![&]) {
+            input.parse().map(Type::Reference)
+        } else if lookahead.peek(Token![!]) && !input.peek(Token![=]) {
+            input.parse().map(Type::Never)
+        } else if lookahead.peek(Token![impl]) {
+            TypeImplTrait::parse(input, allow_plus).map(Type::ImplTrait)
+        } else if lookahead.peek(Token![_]) {
+            input.parse().map(Type::Infer)
+        } else if lookahead.peek(Lifetime) {
+            input.parse().map(Type::TraitObject)
+        } else {
+            Err(lookahead.error())
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeSlice {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let content;
+            Ok(TypeSlice {
+                bracket_token: bracketed!(content in input),
+                elem: content.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeArray {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let content;
+            Ok(TypeArray {
+                bracket_token: bracketed!(content in input),
+                elem: content.parse()?,
+                semi_token: content.parse()?,
+                len: content.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypePtr {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let star_token: Token![*] = input.parse()?;
+
+            let lookahead = input.lookahead1();
+            let (const_token, mutability) = if lookahead.peek(Token![const]) {
+                (Some(input.parse()?), None)
+            } else if lookahead.peek(Token![mut]) {
+                (None, Some(input.parse()?))
+            } else {
+                return Err(lookahead.error());
+            };
+
+            Ok(TypePtr {
+                star_token,
+                const_token,
+                mutability,
+                elem: Box::new(input.call(Type::without_plus)?),
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeReference {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(TypeReference {
+                and_token: input.parse()?,
+                lifetime: input.parse()?,
+                mutability: input.parse()?,
+                // & binds tighter than +, so we don't allow + here.
+                elem: Box::new(input.call(Type::without_plus)?),
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeBareFn {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let args;
+            let mut variadic = None;
+
+            Ok(TypeBareFn {
+                lifetimes: input.parse()?,
+                unsafety: input.parse()?,
+                abi: input.parse()?,
+                fn_token: input.parse()?,
+                paren_token: parenthesized!(args in input),
+                inputs: {
+                    let mut inputs = Punctuated::new();
+
+                    while !args.is_empty() {
+                        let attrs = args.call(Attribute::parse_outer)?;
+
+                        if inputs.empty_or_trailing()
+                            && (args.peek(Token![...])
+                                || args.peek(Ident)
+                                    && args.peek2(Token![:])
+                                    && args.peek3(Token![...]))
+                        {
+                            variadic = Some(parse_bare_variadic(&args, attrs)?);
+                            break;
+                        }
+
+                        let allow_self = inputs.is_empty();
+                        let arg = parse_bare_fn_arg(&args, allow_self)?;
+                        inputs.push_value(BareFnArg { attrs, ..arg });
+                        if args.is_empty() {
+                            break;
+                        }
+
+                        let comma = args.parse()?;
+                        inputs.push_punct(comma);
+                    }
+
+                    inputs
+                },
+                variadic,
+                output: input.call(ReturnType::without_plus)?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeNever {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(TypeNever {
+                bang_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeInfer {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(TypeInfer {
+                underscore_token: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeTuple {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let content;
+            let paren_token = parenthesized!(content in input);
+
+            if content.is_empty() {
+                return Ok(TypeTuple {
+                    paren_token,
+                    elems: Punctuated::new(),
+                });
+            }
+
+            let first: Type = content.parse()?;
+            Ok(TypeTuple {
+                paren_token,
+                elems: {
+                    let mut elems = Punctuated::new();
+                    elems.push_value(first);
+                    elems.push_punct(content.parse()?);
+                    while !content.is_empty() {
+                        elems.push_value(content.parse()?);
+                        if content.is_empty() {
+                            break;
+                        }
+                        elems.push_punct(content.parse()?);
+                    }
+                    elems
+                },
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeMacro {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(TypeMacro {
+                mac: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypePath {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let expr_style = false;
+            let (qself, path) = path::parsing::qpath(input, expr_style)?;
+            Ok(TypePath { qself, path })
+        }
+    }
+
+    impl ReturnType {
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+        pub fn without_plus(input: ParseStream) -> Result<Self> {
+            let allow_plus = false;
+            Self::parse(input, allow_plus)
+        }
+
+        pub(crate) fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
+            if input.peek(Token![->]) {
+                let arrow = input.parse()?;
+                let allow_group_generic = true;
+                let ty = ambig_ty(input, allow_plus, allow_group_generic)?;
+                Ok(ReturnType::Type(arrow, Box::new(ty)))
+            } else {
+                Ok(ReturnType::Default)
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for ReturnType {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_plus = true;
+            Self::parse(input, allow_plus)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeTraitObject {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_plus = true;
+            Self::parse(input, allow_plus)
+        }
+    }
+
+    impl TypeTraitObject {
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+        pub fn without_plus(input: ParseStream) -> Result<Self> {
+            let allow_plus = false;
+            Self::parse(input, allow_plus)
+        }
+
+        // Only allow multiple trait references if allow_plus is true.
+        pub(crate) fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
+            let dyn_token: Option<Token![dyn]> = input.parse()?;
+            let dyn_span = match &dyn_token {
+                Some(token) => token.span,
+                None => input.span(),
+            };
+            let bounds = Self::parse_bounds(dyn_span, input, allow_plus)?;
+            Ok(TypeTraitObject { dyn_token, bounds })
+        }
+
+        fn parse_bounds(
+            dyn_span: Span,
+            input: ParseStream,
+            allow_plus: bool,
+        ) -> Result<Punctuated<TypeParamBound, Token![+]>> {
+            let bounds = TypeParamBound::parse_multiple(input, allow_plus)?;
+            let mut last_lifetime_span = None;
+            let mut at_least_one_trait = false;
+            for bound in &bounds {
+                match bound {
+                    TypeParamBound::Trait(_) | TypeParamBound::Verbatim(_) => {
+                        at_least_one_trait = true;
+                        break;
+                    }
+                    TypeParamBound::Lifetime(lifetime) => {
+                        last_lifetime_span = Some(lifetime.ident.span());
+                    }
+                }
+            }
+            // Just lifetimes like `'a + 'b` is not a TraitObject.
+            if !at_least_one_trait {
+                let msg = "at least one trait is required for an object type";
+                return Err(error::new2(dyn_span, last_lifetime_span.unwrap(), msg));
+            }
+            Ok(bounds)
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeImplTrait {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_plus = true;
+            Self::parse(input, allow_plus)
+        }
+    }
+
+    impl TypeImplTrait {
+        #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+        pub fn without_plus(input: ParseStream) -> Result<Self> {
+            let allow_plus = false;
+            Self::parse(input, allow_plus)
+        }
+
+        pub(crate) fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
+            let impl_token: Token![impl] = input.parse()?;
+            let bounds = TypeParamBound::parse_multiple(input, allow_plus)?;
+            let mut last_lifetime_span = None;
+            let mut at_least_one_trait = false;
+            for bound in &bounds {
+                match bound {
+                    TypeParamBound::Trait(_) | TypeParamBound::Verbatim(_) => {
+                        at_least_one_trait = true;
+                        break;
+                    }
+                    TypeParamBound::Lifetime(lifetime) => {
+                        last_lifetime_span = Some(lifetime.ident.span());
+                    }
+                }
+            }
+            if !at_least_one_trait {
+                let msg = "at least one trait must be specified";
+                return Err(error::new2(
+                    impl_token.span,
+                    last_lifetime_span.unwrap(),
+                    msg,
+                ));
+            }
+            Ok(TypeImplTrait { impl_token, bounds })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeGroup {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let group = crate::group::parse_group(input)?;
+            Ok(TypeGroup {
+                group_token: group.token,
+                elem: group.content.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for TypeParen {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_plus = false;
+            Self::parse(input, allow_plus)
+        }
+    }
+
+    impl TypeParen {
+        fn parse(input: ParseStream, allow_plus: bool) -> Result<Self> {
+            let content;
+            Ok(TypeParen {
+                paren_token: parenthesized!(content in input),
+                elem: Box::new({
+                    let allow_group_generic = true;
+                    ambig_ty(&content, allow_plus, allow_group_generic)?
+                }),
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for BareFnArg {
+        fn parse(input: ParseStream) -> Result<Self> {
+            let allow_self = false;
+            parse_bare_fn_arg(input, allow_self)
+        }
+    }
+
+    fn parse_bare_fn_arg(input: ParseStream, allow_self: bool) -> Result<BareFnArg> {
+        let attrs = input.call(Attribute::parse_outer)?;
+
+        let begin = input.fork();
+
+        let has_mut_self = allow_self && input.peek(Token![mut]) && input.peek2(Token![self]);
+        if has_mut_self {
+            input.parse::<Token![mut]>()?;
+        }
+
+        let mut has_self = false;
+        let mut name = if (input.peek(Ident) || input.peek(Token![_]) || {
+            has_self = allow_self && input.peek(Token![self]);
+            has_self
+        }) && input.peek2(Token![:])
+            && !input.peek2(Token![::])
+        {
+            let name = input.call(Ident::parse_any)?;
+            let colon: Token![:] = input.parse()?;
+            Some((name, colon))
+        } else {
+            has_self = false;
+            None
+        };
+
+        let ty = if allow_self && !has_self && input.peek(Token![mut]) && input.peek2(Token![self])
+        {
+            input.parse::<Token![mut]>()?;
+            input.parse::<Token![self]>()?;
+            None
+        } else if has_mut_self && name.is_none() {
+            input.parse::<Token![self]>()?;
+            None
+        } else {
+            Some(input.parse()?)
+        };
+
+        let ty = match ty {
+            Some(ty) if !has_mut_self => ty,
+            _ => {
+                name = None;
+                Type::Verbatim(verbatim::between(&begin, input))
+            }
+        };
+
+        Ok(BareFnArg { attrs, name, ty })
+    }
+
+    fn parse_bare_variadic(input: ParseStream, attrs: Vec<Attribute>) -> Result<BareVariadic> {
+        Ok(BareVariadic {
+            attrs,
+            name: if input.peek(Ident) || input.peek(Token![_]) {
+                let name = input.call(Ident::parse_any)?;
+                let colon: Token![:] = input.parse()?;
+                Some((name, colon))
+            } else {
+                None
+            },
+            dots: input.parse()?,
+            comma: input.parse()?,
+        })
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Abi {
+        fn parse(input: ParseStream) -> Result<Self> {
+            Ok(Abi {
+                extern_token: input.parse()?,
+                name: input.parse()?,
+            })
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "parsing")))]
+    impl Parse for Option<Abi> {
+        fn parse(input: ParseStream) -> Result<Self> {
+            if input.peek(Token![extern]) {
+                input.parse().map(Some)
+            } else {
+                Ok(None)
+            }
+        }
+    }
+}
+
+#[cfg(feature = "printing")]
+mod printing {
+    use crate::attr::FilterAttrs;
+    use crate::path;
+    use crate::print::TokensOrDefault;
+    use crate::ty::{
+        Abi, BareFnArg, BareVariadic, ReturnType, TypeArray, TypeBareFn, TypeGroup, TypeImplTrait,
+        TypeInfer, TypeMacro, TypeNever, TypeParen, TypePath, TypePtr, TypeReference, TypeSlice,
+        TypeTraitObject, TypeTuple,
+    };
+    use proc_macro2::TokenStream;
+    use quote::{ToTokens, TokenStreamExt};
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeSlice {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.bracket_token.surround(tokens, |tokens| {
+                self.elem.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeArray {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.bracket_token.surround(tokens, |tokens| {
+                self.elem.to_tokens(tokens);
+                self.semi_token.to_tokens(tokens);
+                self.len.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypePtr {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.star_token.to_tokens(tokens);
+            match &self.mutability {
+                Some(tok) => tok.to_tokens(tokens),
+                None => {
+                    TokensOrDefault(&self.const_token).to_tokens(tokens);
+                }
+            }
+            self.elem.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeReference {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.and_token.to_tokens(tokens);
+            self.lifetime.to_tokens(tokens);
+            self.mutability.to_tokens(tokens);
+            self.elem.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeBareFn {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.lifetimes.to_tokens(tokens);
+            self.unsafety.to_tokens(tokens);
+            self.abi.to_tokens(tokens);
+            self.fn_token.to_tokens(tokens);
+            self.paren_token.surround(tokens, |tokens| {
+                self.inputs.to_tokens(tokens);
+                if let Some(variadic) = &self.variadic {
+                    if !self.inputs.empty_or_trailing() {
+                        let span = variadic.dots.spans[0];
+                        Token![,](span).to_tokens(tokens);
+                    }
+                    variadic.to_tokens(tokens);
+                }
+            });
+            self.output.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeNever {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.bang_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeTuple {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.paren_token.surround(tokens, |tokens| {
+                self.elems.to_tokens(tokens);
+                // If we only have one argument, we need a trailing comma to
+                // distinguish TypeTuple from TypeParen.
+                if self.elems.len() == 1 && !self.elems.trailing_punct() {
+                    <Token![,]>::default().to_tokens(tokens);
+                }
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypePath {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            path::printing::print_path(tokens, &self.qself, &self.path);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeTraitObject {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.dyn_token.to_tokens(tokens);
+            self.bounds.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeImplTrait {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.impl_token.to_tokens(tokens);
+            self.bounds.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeGroup {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.group_token.surround(tokens, |tokens| {
+                self.elem.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeParen {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.paren_token.surround(tokens, |tokens| {
+                self.elem.to_tokens(tokens);
+            });
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeInfer {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.underscore_token.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for TypeMacro {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.mac.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for ReturnType {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            match self {
+                ReturnType::Default => {}
+                ReturnType::Type(arrow, ty) => {
+                    arrow.to_tokens(tokens);
+                    ty.to_tokens(tokens);
+                }
+            }
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for BareFnArg {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            if let Some((name, colon)) = &self.name {
+                name.to_tokens(tokens);
+                colon.to_tokens(tokens);
+            }
+            self.ty.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for BareVariadic {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            tokens.append_all(self.attrs.outer());
+            if let Some((name, colon)) = &self.name {
+                name.to_tokens(tokens);
+                colon.to_tokens(tokens);
+            }
+            self.dots.to_tokens(tokens);
+            self.comma.to_tokens(tokens);
+        }
+    }
+
+    #[cfg_attr(doc_cfg, doc(cfg(feature = "printing")))]
+    impl ToTokens for Abi {
+        fn to_tokens(&self, tokens: &mut TokenStream) {
+            self.extern_token.to_tokens(tokens);
+            self.name.to_tokens(tokens);
+        }
+    }
+}
diff --git a/rust/syn/verbatim.rs b/rust/syn/verbatim.rs
new file mode 100644
index 0000000000000000000000000000000000000000..97bc08f70afed20254982a50599ecd8e1bb43b88
--- /dev/null
+++ b/rust/syn/verbatim.rs
@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+use crate::parse::ParseStream;
+use proc_macro2::{Delimiter, TokenStream};
+use std::cmp::Ordering;
+use std::iter;
+
+pub(crate) fn between<'a>(begin: ParseStream<'a>, end: ParseStream<'a>) -> TokenStream {
+    let end = end.cursor();
+    let mut cursor = begin.cursor();
+    assert!(crate::buffer::same_buffer(end, cursor));
+
+    let mut tokens = TokenStream::new();
+    while cursor != end {
+        let (tt, next) = cursor.token_tree().unwrap();
+
+        if crate::buffer::cmp_assuming_same_buffer(end, next) == Ordering::Less {
+            // A syntax node can cross the boundary of a None-delimited group
+            // due to such groups being transparent to the parser in most cases.
+            // Any time this occurs the group is known to be semantically
+            // irrelevant. https://github.com/dtolnay/syn/issues/1235
+            if let Some((inside, _span, after)) = cursor.group(Delimiter::None) {
+                assert!(next == after);
+                cursor = inside;
+                continue;
+            } else {
+                panic!("verbatim end must not be inside a delimited group");
+            }
+        }
+
+        tokens.extend(iter::once(tt));
+        cursor = next;
+    }
+    tokens
+}
diff --git a/rust/syn/whitespace.rs b/rust/syn/whitespace.rs
new file mode 100644
index 0000000000000000000000000000000000000000..b156043f3953d444d8834c73bc488348f97b0047
--- /dev/null
+++ b/rust/syn/whitespace.rs
@@ -0,0 +1,67 @@
+// SPDX-License-Identifier: Apache-2.0 OR MIT
+
+pub(crate) fn skip(mut s: &str) -> &str {
+    'skip: while !s.is_empty() {
+        let byte = s.as_bytes()[0];
+        if byte == b'/' {
+            if s.starts_with("//")
+                && (!s.starts_with("///") || s.starts_with("////"))
+                && !s.starts_with("//!")
+            {
+                if let Some(i) = s.find('\n') {
+                    s = &s[i + 1..];
+                    continue;
+                } else {
+                    return "";
+                }
+            } else if s.starts_with("/**/") {
+                s = &s[4..];
+                continue;
+            } else if s.starts_with("/*")
+                && (!s.starts_with("/**") || s.starts_with("/***"))
+                && !s.starts_with("/*!")
+            {
+                let mut depth = 0;
+                let bytes = s.as_bytes();
+                let mut i = 0;
+                let upper = bytes.len() - 1;
+                while i < upper {
+                    if bytes[i] == b'/' && bytes[i + 1] == b'*' {
+                        depth += 1;
+                        i += 1; // eat '*'
+                    } else if bytes[i] == b'*' && bytes[i + 1] == b'/' {
+                        depth -= 1;
+                        if depth == 0 {
+                            s = &s[i + 2..];
+                            continue 'skip;
+                        }
+                        i += 1; // eat '/'
+                    }
+                    i += 1;
+                }
+                return s;
+            }
+        }
+        match byte {
+            b' ' | 0x09..=0x0d => {
+                s = &s[1..];
+                continue;
+            }
+            b if b <= 0x7f => {}
+            _ => {
+                let ch = s.chars().next().unwrap();
+                if is_whitespace(ch) {
+                    s = &s[ch.len_utf8()..];
+                    continue;
+                }
+            }
+        }
+        return s;
+    }
+    s
+}
+
+fn is_whitespace(ch: char) -> bool {
+    // Rust treats left-to-right mark and right-to-left mark as whitespace
+    ch.is_whitespace() || ch == '\u{200e}' || ch == '\u{200f}'
+}
diff --git a/scripts/Makefile.build b/scripts/Makefile.build
index 72b1232b1f7d9a50ccf626315b2530735d7cc223..40a3fae52df2e86d006b2d78ca5ee85560e623ac 100644
--- a/scripts/Makefile.build
+++ b/scripts/Makefile.build
@@ -263,7 +263,7 @@ $(obj)/%.lst: $(obj)/%.c FORCE
 # Compile Rust sources (.rs)
 # ---------------------------------------------------------------------------
 
-rust_allowed_features := new_uninit
+rust_allowed_features := new_uninit,const_refs_to_static
 
 # `--out-dir` is required to avoid temporaries being created by `rustc` in the
 # current working directory, which may be not accessible in the out-of-tree
diff --git a/scripts/generate_rust_analyzer.py b/scripts/generate_rust_analyzer.py
index d2bc63cde8c6a39e74c95abc7329190fe460207d..a3c907dafdf8867eca8c038dcc20c475d52b06bd 100755
--- a/scripts/generate_rust_analyzer.py
+++ b/scripts/generate_rust_analyzer.py
@@ -8,13 +8,14 @@ import json
 import logging
 import os
 import pathlib
+import shlex
 import sys
 
 def args_crates_cfgs(cfgs):
     crates_cfgs = {}
     for cfg in cfgs:
         crate, vals = cfg.split("=", 1)
-        crates_cfgs[crate] = vals.replace("--cfg", "").split()
+        crates_cfgs[crate] = shlex.split(vals.replace("--cfg", ""))
 
     return crates_cfgs
 
@@ -71,10 +72,31 @@ def generate_crates(srctree, objtree, sysroot_src, external_src, cfgs):
         cfg=crates_cfgs.get("alloc", []),
     )
 
+    append_crate(
+        "proc_macro2",
+        srctree / "rust" / "proc-macro2" / "lib.rs",
+        [],
+        cfg=crates_cfgs.get("proc_macro2", []),
+    )
+
+    append_crate(
+        "quote",
+        srctree / "rust" / "quote" / "lib.rs",
+        ["proc_macro2"],
+        cfg=crates_cfgs.get("quote", []),
+    )
+
+    append_crate(
+        "syn",
+        srctree / "rust" / "syn" / "lib.rs",
+        ["proc_macro2", "quote"],
+        cfg=crates_cfgs.get("syn", []),
+    )
+
     append_crate(
         "macros",
         srctree / "rust" / "macros" / "lib.rs",
-        [],
+        ["proc_macro2", "quote", "syn"],
         is_proc_macro=True,
     )
     crates[-1]["proc_macro_dylib_path"] = f"{objtree}/rust/libmacros.so"