https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97549
--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:7e647d71d556b73e84f4edd0733bcc83bc70ae1e commit r11-7339-g7e647d71d556b73e84f4edd0733bcc83bc70ae1e Author: Jakub Jelinek <ja...@redhat.com> Date: Tue Feb 23 09:26:23 2021 +0100 libstdc++: Fix up parallel_backend_serial.h [PR97549] In GCC 10, parallel_backend.h just included parallel_backend_{serial,tbb}.h and did nothing beyond that, and parallel_backend_tbb.h provided directly namespace __pstl { namespace __par_backend { ... } } and defined everything in there, while parallel_backend_serial.h did: namespace __pstl { namespace __serial { ... } } and had this namespace __pstl { namespace __par_backend { using namespace __pstl::__serial; } } at the end. In GCC 11, parallel_backend.h does: namespace __pstl { namespace __par_backend = __serial_backend; } after including parallel_backend_serial.h or namespace __pstl { namespace __par_backend = __tbb_backend; } after including parallel_backend_tbb.h. The latter then has: namespace __pstl { namespace __tbb_backend { ... } } and no using etc. at the end, while parallel_backend_serial.h changed to: namespace __pstl { namespace __serial_backend { ... } } but has this leftover block from the GCC 10 times. Even changing that using namespace __pstl::__serial; to using namespace __pstl::__serial_backend; doesn't work, as it clashes with namespace __pstl { namespace __par_backend = __serial_backend; } in parallel_backend.h. 2021-02-23 Jakub Jelinek <ja...@redhat.com> PR libstdc++/97549 * include/pstl/parallel_backend_serial.h: Remove __pstl::__par_backend.
