PATCH: Enhance GTHREAD interface defined in gthr.h

[John David Anglin]

This patch describes an enhancement to the GTHREAD interface for systems
that define __GTHREAD_MUTEX_INIT_FUNCTION.  A new initializer macro
__GTHREAD_MUTEX_INIT_DEFAULT is introduced to provide a mechanism to
initialize structs and classes with __gthread_mutex_t members.  This
patch and the one to gthr-dce.h are needed to support the runtime
initialization of the _STL_mutex_lock struct used in libstdc++ for
STL threads under hpux 10.X.  Details on why aggregate initialization
is the preferred method of initializing this structure are discussed
int stl_threads.h.

The gthr-dce.h patch is here:
< http://gcc.gnu.org/ml/gcc-patches/2001-06/msg00879.html >.

I am being overly strong when I say that systems "must" define
__GTHREAD_MUTEX_INIT_DEFAULT if they define __GTHREAD_MUTEX_INIT_FUNCTION.
At the moment, lack of a definition will just cause a warning in the
compilation of stl-inst.cc.  However, it would be good to have a
consistent interface now that gthr.h is installed.

The files which lack defines are gthr-rtems.h and gthr-win32.h.  Hopefully,
their maintainers can determine what is needed for these systems.

OK?

Dave
-- 
J. David Anglin                                  dave.anglin@nrc.ca
National Research Council of Canada              (613) 990-0752 (FAX: 952-6605)

2001-06-12  John David Anglin  <dave@hiauly1.hia.nrc.ca>

	* gthr.h (__GTHREAD_MUTEX_INIT_DEFAULT): New interface macro.

--- gthr.h.orig	Sat Jun  9 16:07:22 2001
+++ gthr.h	Tue Jun 12 17:07:24 2001
@@ -49,11 +49,19 @@
      		to initialize __gthread_mutex_t to get a fast
 		non-recursive mutex.
      __GTHREAD_MUTEX_INIT_FUNCTION
-     		some systems can't initalize a mutex without a
+     		some systems can't initialize a mutex without a
 		function call.  On such systems, define this to a
 		function which looks like this:
 		  void __GTHREAD_MUTEX_INIT_FUNCTION (__gthread_mutex_t *)
 		Don't define __GTHREAD_MUTEX_INIT in this case
+
+   Systems that define __GTHREAD_MUTEX_INIT_FUNCTION must also
+   define:
+
+     __GTHREAD_MUTEX_INIT_DEFAULT
+		to initialize __gthread_mutex_t to an arbitrary
+		default.  This allows __gthread_mutex_t types to
+		be members of initialized structures and classes.
 
    The threads interface must define the following static functions: