[Bug libstdc++/56002] New: [mutex] allow generic classes to be used without requiring plattform support for threads

["npl at chello dot at" <gcc-bugzilla@gcc.gnu.org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56002

             Bug #: 56002
           Summary: [mutex] allow generic classes to be used without
                    requiring plattform support for threads
    Classification: Unclassified
           Product: gcc
           Version: 4.7.2
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: libstdc++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: npl@chello.at


Created attachment 29179
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=29179
patch for mutex. diffed against 4.7.2

I am using gcc & libstdc++ on a plattform that isnt natively supported and thus
thread-functionality is not available from libstdc++.
However I would like to be able to still use std::lock_guard, std::unique_lock,
std::lock with my own mutex-classes. There ist no technical reason to prevent
use of those generic classes and functions which are deliberately designed to
work with custom implementations.

---mutex like it is now (all-or-nothing):

#if HAS_GCC_THREADS
<mutexes definiton>

<generic stuff like defer_lock_t,lock_guard, unique_lock, lock>

<once_flag>
#endif
----------------------------------------

---mutex like it should be:
#if HAS_GCC_THREADS
<mutexes definiton>
#endif

<generic stuff like defer_lock_t,lock_guard, unique_lock, lock>

#if HAS_GCC_THREADS
<once_flag>
#endif
----------------------------------------