This could be better achieved by rewriting the libstdc++-v3/configure file to fail the test for _FILE_OFFSET_BITS = 64 when fpos is not defined. But this is kind of an odd spot to be, as this is an oddity from those specific conditions on Bionic and I don't know if it's worth devising a universal test for that.
I don't know if android/bionic patches are still relevant for the community, but I still build recent versions of GCC with NDK r17c for some old embedded devices, so I felt like sharing. Em ter., 13 de jul. de 2021 às 00:16, Abraão de Santana < abraaocsant...@gmail.com> escreveu: > If C++ is enabled with Bionic on API Level < 24 ( and with NDK >= r15 as > lower versions just ignore the issue ) you get errors of ::fgetpos and > ::fsetpos error: 'fsetpos' has not been declared in '::' . > > The issue is that API Level < 24 doesn't implement large files (64 bit), > so when _FILE_OFFSET_BITS is 64 and API Level < 24, the functions fgetpos, > fsetpos, fseeko, and ftello are not defined. > > The behavior described above can be observed by going to > 'android-ndk-rxxx/sysroot/usr/include/stdio.h' and watching the condition > when those symbols are defined ( note: the control define > __USE_FILE_OFFSET64 is defined if _FILE_OFFSET_BITS if 64) > > It's a known issue and bionic's docs ask you to stop defining > _FILE_OFFSET_BITS to 64 to solve it: > https://android.googlesource.com/platform/bionic/+/master/docs/32-bit-abi.md > > Clang builds seem to get around this using libandroid_support on those > cases ( android/ndk#480 ), which is not available when building the gnu std > c++. > > > libstdc++-v3/ChangeLog > * config/os/bionic/os_defines.h: Undefines _FILE_OFFSET_BITS when > it's 64-bit and Api Level < 24 > > --- > libstdc++-v3/config/os/bionic/os_defines.h | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/libstdc++-v3/config/os/bionic/os_defines.h > b/libstdc++-v3/config/os/bionic/os_defines.h > index c534838aea3..27605fa8baa 100644 > --- a/libstdc++-v3/config/os/bionic/os_defines.h > +++ b/libstdc++-v3/config/os/bionic/os_defines.h > @@ -33,4 +33,16 @@ > // System-specific #define, typedefs, corrections, etc, go here. This > // file will come before all others. > > +// If _FILE_OFFSET_BITS is 64 and __ANDROID_API__ < 24, there will be > +// errors of undefined fgetpos, fsetpos, fseeko, and ftello because their > +//64-bit versions are only available from API Level 24 onwards. > +// > +// See https://github.com/android/ndk/issues/480 > +// > +// See also > +// > https://android.googlesource.com/platform/bionic/+/master/docs/32-bit-abi.md > +#if (_FILE_OFFSET_BITS == 64) && (__ANDROID_API__ < 24) > +#undef _FILE_OFFSET_BITS > +#endif > + > #endif > -- *Abraão C. de Santana* *Skype: * abraao.c.santana *Mobile :* +55 (21) 9307-9868
