https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91057
--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> --- Author: redi Date: Wed Oct 9 15:59:56 2019 New Revision: 276762 URL: https://gcc.gnu.org/viewcvs?rev=276762&root=gcc&view=rev Log: PR libstdc++/91057 set locale::id::_M_index atomically If two threads see _M_index==0 concurrently they will both try to set it, potentially storing the facet at two different indices in the array. Either set the _M_index data member using an atomic compare-exchange operation or while holding a mutex. Also move the LONG_DOUBLE_COMPAT code into a separate function to remove the visual noise it creates. PR libstdc++/91057 * src/c++98/locale.cc (locale::id::_M_id()) [__GTHREADS]: Use atomic compare-exchange or double-checked lock to ensure only one thread sets the _M_index variable. [_GLIBCXX_LONG_DOUBLE_COMPAT]: Call find_ldbl_sync_facet to detect facets that share another facet's ID. [_GLIBCXX_LONG_DOUBLE_COMPAT] (find_ldbl_sync_facet): New function. Modified: trunk/libstdc++-v3/ChangeLog trunk/libstdc++-v3/src/c++98/locale.cc
