[Bug c/62024] New: __atomic_always_lock_free is not a constant expression

[amanieu at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=62024

            Bug ID: 62024
           Summary: __atomic_always_lock_free is not a constant expression
           Product: gcc
           Version: 4.9.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: amanieu at gmail dot com

This line causes an error despite the documentation saying that
__atomic_always_lock_free is a constant expression:

_Static_assert(__atomic_always_lock_free(sizeof(int), 0), "");

test.c:1:16: error: expression in static assertion is not constant