Commit 5009f2c7 authored by Thomas Haller's avatar Thomas Haller

build/clang: fix detection of valid warning compiler flags

clang does not exit with error when it is called with an
unrecognized (warning) option. Instead it just prints
a warning that makes the configure script believe the
warning is supported. Later, during build we might pass
-Werror, which causes clang to fail due to unrecognized
arguments.

Fix the script to detect compiler warnings by passing
'-Werror=unknown-warning-option', which lets clang fail too.
Signed-off-by: Thomas Haller's avatarThomas Haller <thaller@redhat.com>
parent 1de6d83e
......@@ -7,6 +7,23 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
AC_MSG_RESULT(yes)
CFLAGS="-Wall -std=gnu89 $CFLAGS"
dnl clang only warns about unknown warnings, unless
dnl called with "-Werror=unknown-warning-option"
dnl Test if the compiler supports that, and if it does
dnl attach it to the CFLAGS.
SAVE_CFLAGS="$CFLAGS"
EXTRA_CFLAGS="-Werror=unknown-warning-option"
CFLAGS="$SAVE_CFLAGS $EXTRA_CFLAGS"
AC_TRY_COMPILE([], [],
has_option=yes,
has_option=no,)
if test $has_option = no; then
EXTRA_CFLAGS=
fi
CFLAGS="$SAVE_CFLAGS"
unset has_option
unset SAVE_CFLAGS
for option in -Wshadow -Wmissing-declarations -Wmissing-prototypes \
-Wdeclaration-after-statement -Wformat-security \
-Wfloat-equal -Wno-unused-parameter -Wno-sign-compare \
......@@ -15,19 +32,22 @@ if test "$GCC" = "yes" -a "$set_more_warnings" != "no"; then
-Wpointer-arith -Winit-self \
-Wmissing-include-dirs -Waggregate-return; do
SAVE_CFLAGS="$CFLAGS"
CFLAGS="$CFLAGS $option"
CFLAGS="$CFLAGS $EXTRA_CFLAGS $option"
AC_MSG_CHECKING([whether gcc understands $option])
AC_TRY_COMPILE([], [],
has_option=yes,
has_option=no,)
if test $has_option = no; then
CFLAGS="$SAVE_CFLAGS"
else
CFLAGS="$SAVE_CFLAGS $option"
fi
AC_MSG_RESULT($has_option)
unset has_option
unset SAVE_CFLAGS
done
unset option
unset EXTRA_CFLAGS
if test "x$set_more_warnings" = xerror; then
CFLAGS="$CFLAGS -Werror"
fi
......
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