| Message ID | GV1P250MB07378BBA38F77B2B91BA80C58F552@GV1P250MB0737.EURP250.PROD.OUTLOOK.COM |
|---|---|
| State | Accepted |
| Commit | 25e0e087c4314730d42ac16061962904b8fb3ae6 |
| Headers | show |
| Series | [FFmpeg-devel] configure: Disable linker warnings for common symbols | expand |
| Context | Check | Description |
|---|---|---|
| yinshiyou/make_loongarch64 | success | Make finished |
| yinshiyou/make_fate_loongarch64 | success | Make fate finished |
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | success | Make fate finished |
Andreas Rheinhardt: > Common symbols are not part of ISO-C and therefore not used > by FFmpeg at all. Yet linker warnings to ensure it stays > that way are nevertheless wrong, because the existence of > common symbols does not imply that there is a bug in our code. > > More precisely, Clang's ASAN implementation uses a common symbol > ___asan_globals_registered when used on Elf targets with > the -fsanitize-address-globals-dead-stripping option; > said option is the default since Clang 17 [1]. > This leads to 1883 warnings about ___asan_globals_registered > when linking here. > (Even without that option there were warnings like > _ZN14__interception10real_vforkE being overridden.) > > Said warning is also unnecessary: The proper way to ensure > that our code is free of common symbols is to let the compiler > enforce this. But this is already the default since GCC 10 > and Clang 11, so there is no risk of introducing our own > common symbols. > > [1]: https://reviews.llvm.org/D152604 > > Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com> > --- > There is btw a second incompatibility between our configure script > and Clang ASAN: Since version 16 it defaults to > -fsanitize-address-use-odr-indicator and with this option set, > it creates a __odr_asan_gen_FOO symbol for every object FOO > in addition to the symbol FOO itself; configure therefore sets > extern_prefix (used for ASM name mangling) to "__odr_asan_gen_". > > configure | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/configure b/configure > index 197f762b58..108816bd1e 100755 > --- a/configure > +++ b/configure > @@ -7337,7 +7337,6 @@ void (^block)(void); > EOF > > # add some linker flags > -check_ldflags -Wl,--warn-common > check_ldflags -Wl,-rpath-link=:libpostproc:libswresample:libswscale:libavfilter:libavdevice:libavformat:libavcodec:libavutil > enabled rpath && add_ldexeflags -Wl,-rpath,$libdir && add_ldsoflags -Wl,-rpath,$libdir > test_ldflags -Wl,-Bsymbolic && append SHFLAGS -Wl,-Bsymbolic Will apply this patch tomorrow unless there are objections. - Andreas
diff --git a/configure b/configure index 197f762b58..108816bd1e 100755 --- a/configure +++ b/configure @@ -7337,7 +7337,6 @@ void (^block)(void); EOF # add some linker flags -check_ldflags -Wl,--warn-common check_ldflags -Wl,-rpath-link=:libpostproc:libswresample:libswscale:libavfilter:libavdevice:libavformat:libavcodec:libavutil enabled rpath && add_ldexeflags -Wl,-rpath,$libdir && add_ldsoflags -Wl,-rpath,$libdir test_ldflags -Wl,-Bsymbolic && append SHFLAGS -Wl,-Bsymbolic
Common symbols are not part of ISO-C and therefore not used by FFmpeg at all. Yet linker warnings to ensure it stays that way are nevertheless wrong, because the existence of common symbols does not imply that there is a bug in our code. More precisely, Clang's ASAN implementation uses a common symbol ___asan_globals_registered when used on Elf targets with the -fsanitize-address-globals-dead-stripping option; said option is the default since Clang 17 [1]. This leads to 1883 warnings about ___asan_globals_registered when linking here. (Even without that option there were warnings like _ZN14__interception10real_vforkE being overridden.) Said warning is also unnecessary: The proper way to ensure that our code is free of common symbols is to let the compiler enforce this. But this is already the default since GCC 10 and Clang 11, so there is no risk of introducing our own common symbols. [1]: https://reviews.llvm.org/D152604 Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com> --- There is btw a second incompatibility between our configure script and Clang ASAN: Since version 16 it defaults to -fsanitize-address-use-odr-indicator and with this option set, it creates a __odr_asan_gen_FOO symbol for every object FOO in addition to the symbol FOO itself; configure therefore sets extern_prefix (used for ASM name mangling) to "__odr_asan_gen_". configure | 1 - 1 file changed, 1 deletion(-)