> On Jan 18, 2017, at 6:26 PM, Andy Wingo <wingo@pobox.com> wrote:
> 
> We are pleased to announce GNU Guile release 2.1.6.
> 
> Guile 2.1.6 is the sixth pre-release in what will eventually become the
> 2.2 release series.  We encourage you to test this release and provide
> feedback to guile-devel@gnu.org.

So I am trying to compile using clang.  This has detected issues with atomics-internal.h.  I can fix most issues with casts:
 static inline uint32_t
 scm_atomic_subtract_uint32 (uint32_t *loc, uint32_t arg)
 {
-  return atomic_fetch_sub (loc, arg);
+  return atomic_fetch_sub ((_Atomic uint32_t *)loc, arg);
 }

But problems remain with scm_atomic_set_pointer and scm_atomic_ref_pointer which use void** and is apparently not defined for use with atomics.

Apparently gcc does not have a problem with this use but I’m guessing the C11 standard may have an issue with it.

Matt