https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100164
--- Comment #13 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-11 branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:0857fc3820bee04771f60a86b9dd5627b3ea1904 commit r11-8270-g0857fc3820bee04771f60a86b9dd5627b3ea1904 Author: Jakub Jelinek <ja...@redhat.com> Date: Wed Apr 21 11:09:25 2021 +0200 Fix AIX libstdc++ semaphore support [PR100164] > > The #error would not be hit if _GLIBCXX_HAVE_POSIX_SEMAPHORE were defined, > > but it shows up in your error report. > You now have pinpointed the problem. > It's not that AIX doesn't have semaphore, but that the code previously > had a fallback that hid a bug in the macros: // Use futex if available and didn't force use of POSIX using __fast_semaphore = __atomic_semaphore<__detail::__platform_wait_t>; using __fast_semaphore = __platform_semaphore; using __fast_semaphore = __atomic_semaphore<ptrdiff_t>; > The problem is that libstdc++ configure defines > _GLIBCXX_HAVE_POSIX_SEMAPHORE in config.h. libstdc++ uses sed to > rewrite config.h to c++config.h and prepends _GLIBCXX_, so c++config.h > contains > And bits/semaphore_base.h is not testing that corrupted macro. Either > semaphore_base.h needs to test for the corrupted macro, or libtsdc++ > configure needs to define HAVE_POSIX_SEMAPHORE without itself > prepending _GLIBCXX_ so that the c++config.h rewriting works > correctly and defines the correct macro for semaphore_base.h. The include/Makefile.am sed is: sed -e 's/HAVE_/_GLIBCXX_HAVE_/g' \ -e 's/PACKAGE/_GLIBCXX_PACKAGE/g' \ -e 's/VERSION/_GLIBCXX_VERSION/g' \ -e 's/WORDS_/_GLIBCXX_WORDS_/g' \ -e 's/_DARWIN_USE_64_BIT_INODE/_GLIBCXX_DARWIN_USE_64_BIT_INODE/g' \ -e 's/_FILE_OFFSET_BITS/_GLIBCXX_FILE_OFFSET_BITS/g' \ -e 's/_LARGE_FILES/_GLIBCXX_LARGE_FILES/g' \ -e 's/ICONV_CONST/_GLIBCXX_ICONV_CONST/g' \ -e '/[ ]_GLIBCXX_LONG_DOUBLE_COMPAT[ ]/d' \ -e '/[ ]_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT[ ]/d' \ < ${CONFIG_HEADER} >> $@ ;\ so for many macros one needs _GLIBCXX_ prefixes already in configure, as can be seen in grep AC_DEFINE.*_GLIBCXX configure.ac acinclude.m4 But _GLIBCXX_HAVE_POSIX_SEMAPHORE is the only one that shouldn't have that prefix because the sed is adding that. E.g. on i686-linux, I see grep _GLIBCXX__GLIBCXX c++config.h that proves it is the only broken one. So this change fixes the acinclude.m4 side. 2021-04-21 Jakub Jelinek <ja...@redhat.com> PR libstdc++/100164 * acinclude.m4: For POSIX semaphores AC_DEFINE HAVE_POSIX_SEMAPHORE rather than _GLIBCXX_HAVE_POSIX_SEMAPHORE. * configure: Regenerated. * config.h.in: Regenerated. (cherry picked from commit 2d4c3af94f84c874cfddc753dc0f34ebf7fc11d9)
