Improve build portability

* Make scdoc optional; documentation is not strictly necessary
* Explicitly test for fmacro-prefix-map support
* Test for the minimum possible versions of wayland dependencies
* Reduce required meson version

meson.build

@@ -2,7 +2,7 @@ project(
 	'waypipe',
 	'c',
 	license: 'MIT/Expat',
-	meson_version: '>=0.48.0',
+	meson_version: '>=0.46.0',
 	default_options: [
 		'c_std=c11',
 		'warning_level=2',
@@ -18,9 +18,10 @@ version = '"@0@"'.format(meson.project_version())
 add_project_arguments('-DWAYPIPE_VERSION=@0@'.format(version), language: 'c')
 
 # Make build reproducible if possible
-if cc.get_id() == 'gcc'
-	r = run_command('python3', '-c', 'import os.path; print(os.path.join(os.path.relpath(\'@0@\', \'@1@\'),\'\'))'.format(meson.source_root(), meson.build_root()))
-		relative_dir = r.stdout().strip()
+if cc.has_argument('-fmacro-prefix-map=/prefix/to/hide=')
+	prefix_finder = 'import os.path; print(os.path.join(os.path.relpath(\'@0@\', \'@1@\'),\'\'))'
+	r = run_command('python3', '-c', prefix_finder.format(meson.source_root(), meson.build_root()))
+	relative_dir = r.stdout().strip()
 	add_project_arguments(
 		'-fmacro-prefix-map=@0@='.format(relative_dir),
 		language: 'c',
@@ -36,9 +37,9 @@ else
 	)
 endif
 
-wayland_client = dependency('wayland-client', version: '>=1.17')
-wayland_protos = dependency('wayland-protocols', version: '>=1.17')
-wayland_server = dependency('wayland-server', version: '>=1.17')
+wayland_client = dependency('wayland-client', version: '>=1.15') # WAYLAND_DISPLAY=path
+wayland_protos = dependency('wayland-protocols', version: '>=1.15') # WAYLAND_DISPLAY=path
+wayland_server = dependency('wayland-server', version: '>=1.12') # xdg-shell
 libffi         = dependency('libffi')
 rt             = cc.find_library('rt')
 
@@ -56,18 +57,20 @@ executable(
 	install: true
 )
 
-scdoc = dependency('scdoc', version: '>=1.9.4', native: true)
-scdoc_prog = find_program(scdoc.get_pkgconfig_variable('scdoc'), native: true)
-sh = find_program('sh', native: true)
-mandir = get_option('mandir')
-custom_target(
-	'waypipe.1',
-	input: 'waypipe.scd',
-	output: 'waypipe.1',
-	command: [
-		sh, '-c', '@0@ < @INPUT@ > @1@'.format(scdoc_prog.path(), 'waypipe.1')
-	],
-	install: true,
-	install_dir: '@0@/man1'.format(mandir)
-)
+scdoc = dependency('scdoc', version: '>=1.9.4', native: true, required: false)
+if scdoc.found()
+	scdoc_prog = find_program(scdoc.get_pkgconfig_variable('scdoc'), native: true)
+	sh = find_program('sh', native: true)
+	mandir = get_option('mandir')
+	custom_target(
+		'waypipe.1',
+		input: 'waypipe.scd',
+		output: 'waypipe.1',
+		command: [
+			sh, '-c', '@0@ < @INPUT@ > @1@'.format(scdoc_prog.path(), 'waypipe.1')
+		],
+		install: true,
+		install_dir: '@0@/man1'.format(mandir)
+	)
+endif
 

protocols/meson.build

@@ -42,7 +42,7 @@ endforeach
 lib_protocols = static_library(
 	'protocols',
 	protocols_src,
-	dependencies: []
+	dependencies: [wayland_client] # for the header files, only
 )
 protos = declare_dependency(
 	link_with: lib_protocols,