[Bug libstdc++/13583] New: __use_cache not threadsafe

["peturr02 at ru dot is" <gcc-bugzilla at gcc dot gnu dot org>]

This fragment in __use_cache (taken from the 3.3 branch) is not threadsafe:

      if (__builtin_expect(!__cache, false))
        {
          __cache = new __locale_cache<_Facet>(__loc);
          __loc._M_impl->_M_install_cache(__cache, __i);
        }

If this code is executed by two threads at the same time, two instances of
the cache are created, of which one will be leaked.

The version on mainline has the same problem.

Since __use_cache first appeard in 3.3.1, this is a regression.

-- 
           Summary: __use_cache not threadsafe
           Product: gcc
           Version: 3.3.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: libstdc++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: peturr02 at ru dot is
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=13583