[Bug libstdc++/46455] resource leaks due to missing destructors for mutexes and condvars

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=46455

--- Comment #20 from Jonathan Wakely <redi at gcc dot gnu.org> 2010-11-16 
11:05:44 UTC ---
OK, that will be ugly though.  The cast from __gthread_recursive_mutex_t* to
__gthread_mutex_t* is not correct, because the "sema" member (the actual Win32
handle) is at a different offset in the two mutex types.

We want something like:

static inline int
__recursive_mutex_destroy(__gthread_recursive_mutex_t* __rmutex)
{
#ifdef _WIN32
  __gthread_mutex_t __tmp = { };
  __tmp.counter = __rmutex->counter;
  __tmp.sema = __rmutex->sema;
  __ghtread_mutex_t* __mutex = &__tmp;
#else
  __ghtread_mutex_t* __mutex = __rmutex;
#endif
  return ___gthread_mutex_destroy(__mutex);
}