Andreas Rheinhardt: > C11 provides static assertions via _Static_assert and > provides static_assert as a convenience define for this > in assert.h. Our codebase uses the latter, as _Static_assert > has actually already been deprecated in C23. > > Not all toolchains that declare support for C11 actually > support it; e.g. MSVC 19.27 does not support _Static_assert, > but somehow supports static_assert. MSVC 19.27 admits to be > a "preview implementation of the ISO C11 standard", > so this is not surprising (MSVC 19.28 does not come with > this caveat). > > Furthermore some FATE boxes [1] use old GCC toolchains (with > only experimental support for C11) where _Static_assert is > supported, but assert.h does not provide the fallback define. > They are broken since the first usage of static_assert. > > This commit therefore checks whether static_assert and > _Static_assert work with assert.h included; if not, > configure errors out. > > This intentionally drops support for MSVC 19.27. Users like > the old FATE boxes above can still add -Dstatic_assert=_Static_assert > to cflags as a workaround if desired. > > [1]: > https://fate.ffmpeg.org/report.cgi?time=20240321123620&slot=sh4-debian-qemu-gcc-4.7 > > Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@outlook.com> > --- > configure | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/configure b/configure > index 343edb38ab..fc366549bc 100755 > --- a/configure > +++ b/configure > @@ -5589,6 +5589,19 @@ check_cxxflags_cc -std=$stdcxx ctype.h "__cplusplus >= > 201103L" || > check_cflags_cc -std=$stdc ctype.h "__STDC_VERSION__ >= 201112L" || > { check_cflags_cc -std=c11 ctype.h "__STDC_VERSION__ >= 201112L" && > stdc="c11" || die "Compiler lacks C11 support"; } > > +test_cc <<EOF || die "Compiler lacks support for C11 static assertions" > +#include <assert.h> > +#include <stddef.h> > +struct Foo { > + int a; > + void *ptr; > +} obj; > +static_assert(offsetof(struct Foo, a) == 0, > + "First element of struct does not have offset 0"); > +_Static_assert(offsetof(struct Foo, ptr) >= offsetof(struct Foo, a) + > sizeof(obj.a), > + "elements not properly ordered in struct"); > +EOF > + > check_cppflags -D_FILE_OFFSET_BITS=64 > check_cppflags -D_LARGEFILE_SOURCE >
Will apply this patch tomorrow unless there are objections. - Andreas _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
