[m-rev.] for review: Account for Winpthreads in configure.

[Julien Fischer]

On Wed, 13 Aug 2014, Peter Wang wrote:

> On Wed, 13 Aug 2014 15:01:00 +1000 (EST), Julien Fischer <jfischer at opturion.com> wrote:
>>
>> On Wed, 13 Aug 2014, Peter Wang wrote:
>>
>>> Branches: master, 14.01
>>>
>>> configure.ac:
>>> 	Always build Boehm GC with GC_WIN32_PTHREADS when pthread.h is
>>> 	detected on MinGW* systems.
>>
>> Even in non par grades when parallel marking is not enabled?  What
>> pthreads calls could we make then then?   I think libc on MinGW-w64
>> requires winpthread to support some C11 features, so maybe it's always
>> needed on that system, but shouldn't it remain possible to build non
>> .par grades on plain MinGW without requiring pthreads?
>
> I guess it wasn't clear that it only affects .par grades and the par_gc
> library.  New description:
>
> configure.ac:
>        Always build the par_gc library with GC_WIN32_PTHREADS when
>        pthread.h is detected on MinGW* systems.  Previously, if the
>        pthread implementation is not pthread-win32 we would fallback to
>        building Boehm GC with GC_WIN32_THREADS (no "P"), so it would
>        NOT provide pthread wrapper functions.  But since pthread.h was
>        found the Mercury implementation would make pthread calls, calls
>        which are not intercepted by Boehm GC, and thus unsafe.

Yes, that's more clear -- the rest of the change is fine.

Cheers,
Julien.