[Bug libstdc++/94936] pmr::synchronized_pool_resource crashes without -pthread

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94936

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:

https://gcc.gnu.org/g:ec40967f1323069da3a5a45286f71fa4f80926df

commit r11-40-gec40967f1323069da3a5a45286f71fa4f80926df
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon May 4 13:34:23 2020 +0100

    libstdc++: Make pmr::synchronized_pool_resource work without libpthread (PR
94936)

    I implicitly assumed that programs using pmr::synchronized_pool_resource
    would also be using multiple threads, and so the weak symbols in
    gthr-posix.h would be resolved by linking to libpthread. If that isn't
    true then it crashes when trying to use pthread_key_create.

    This commit makes the pool resource check __gthread_active_p() before
    using thread-specific data, and just use a single set of memory pools
    when there's only a single thread.

            PR libstdc++/94936
            * src/c++17/memory_resource.cc
(synchronized_pool_resource::_TPools):
            Add comment about single-threaded behaviour.
            (synchronized_pool_resource::_TPools::move_nonempty_chunks()):
Hoist
            class member access out of loop.
            (synchronized_pool_resource::synchronized_pool_resource())
            (synchronized_pool_resource::~synchronized_pool_resource())
            (synchronized_pool_resource::release()): Check __gthread_active_p
            before creating and/or deleting the thread-specific data key.
            (synchronized_pool_resource::_M_thread_specific_pools()): Adjust
            assertions.
            (synchronized_pool_resource::do_allocate(size_t, size_t)): Add fast
            path for single-threaded case.
            (synchronized_pool_resource::do_deallocate(void*, size_t, size_t)):
            Likewise. Return if unable to find a pool that owns the allocation.
            * testsuite/20_util/synchronized_pool_resource/allocate_single.cc:
            New test.
            * testsuite/20_util/synchronized_pool_resource/cons_single.cc: New
            test.
            * testsuite/20_util/synchronized_pool_resource/release_single.cc:
New
            test.