[cairo] Recent pthread mutexes addition in cairo

[Owen Taylor]

On Fri, 2005-07-08 at 19:47 -0500, Albert Chin wrote:
> On Fri, Jul 08, 2005 at 08:34:52PM -0400, Jason Dorje Short wrote:
> > Albert Chin wrote:
> > > On Fri, Jul 08, 2005 at 07:17:09PM -0500, Albert Chin wrote:
> > > 
> > >>No. You do *not* want -lpthread. You don't need it if the stubs in
> > >>libc are usable.
> > > 
> > > Untested but you want something like below.
> > 
> > Ahh, now I understand.
> > 
> > The problem with AC_TRY_RUN is it won't work when cross-compiling.
> > Would an AC_LINK_IFELSE check be sufficient?
> 
> Yeah, I know about the cross-compiling issue. But, I don't know how to
> work around it. IRIX has the pthread_mutex_* functions in libc (though
> they don't appear to work). So, it would pass AC_LINK and
> AC_LINK_IFELSE.
> 
> I'll bug the SGI folks.

I think the simple thing here is just to use AC_CACHE_CHECK() and
the fourth argument to AC_TRY_RUN

AC_CACHE_CHECK([if posix mutexes require -lpthread], cairo_need_lpthread,
[AC_TRY_RUN([...],
            cairo_need_lpthread=no,
            cairo_need_lpthread=yes,
            cairo_need_lpthread=no)]))

if test $cairo_need_lpthread = yes ; then
   LIBS="$LIBS -lpthread"
fi

The AC_CACHE_CHECK gives an out for people who really are 
cross-compiling targeting IRIX - they can pass --cache-file to
configure. But for everybody else it just works.

See:

 http://developer.gnome.org/doc/API/2.0/glib/glib-cross-compiling.html

for a few more details of doing that.

Albert - do you think you can test out your checks in a setup like the
above on a few platforms? (Or - anybody else with access to machines
where the lack of -lpthread is causing problems want to try this?)

Thanks,
						Owen

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