vlc/m4/c17.m4
2024-02-06 08:32:48 +00:00

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# Copyright © 2015 Rémi Denis-Courmont
# This file (c17.m4) is free software; unlimited permission to
# copy and/or distribute it , with or without modifications, as long
# as this notice is preserved.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY, to the extent permitted by law; without
# even the implied warranty of MERCHANTABILITY or FITNESS FOR A
# PARTICULAR PURPOSE.
AC_DEFUN([VLC_PROG_CC_C17], [
AC_LANG_ASSERT(C)
for opt in "" -std=gnu17 -std=c17 -c17
do
cachevar=AS_TR_SH([ax_cv_c_compile_c17_$opt])
AC_CACHE_CHECK([whether $CC $opt supports C17], [$cachevar], [
CFLAGS_save="$CFLAGS"
CFLAGS="$CFLAGS $opt"
dnl PREPROC is not enough due to CFLAGS usage
AC_COMPILE_IFELSE([AC_LANG_SOURCE([
[#ifndef __STDC_VERSION__
# error Not a C compiler!
#endif
#if (__STDC_VERSION__ < 201710L)
# error Too old C compiler!
#endif
_Static_assert(1, "Not C17!");
const int varname = _Generic(1, int: 1, default: 0);
]])], [
eval $cachevar="yes"
], [
eval $cachevar="no"
])
CFLAGS="$CFLAGS_save"
])
if eval test "\$$cachevar" = "yes"
then
CFLAGS="$CFLAGS $opt"
break
fi
done
])