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.
ec40967f13