[Bug c/68966] New: atomic_fetch_* on atomic_bool not diagnosed

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68966

            Bug ID: 68966
           Summary: atomic_fetch_* on atomic_bool not diagnosed
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mpolacek at gcc dot gnu.org
  Target Milestone: ---

As Martin pointed out here
<https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68908#c13>, C doesn't allow the
atomic_fetch_xxx operations to be used with the atomic_bool type (it says
they're "not applicable" without spelling what that means, but that will be the
subject of a future defect).
But we don't diagnose this.

typedef _Atomic _Bool atomic_bool;
void
fn (void)
{
  atomic_bool a = 1;
  __atomic_fetch_add (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_fetch_sub (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_fetch_and (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_fetch_xor (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_fetch_or (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_fetch_nand (&a, 1, __ATOMIC_SEQ_CST);

  __atomic_add_fetch (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_sub_fetch (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_and_fetch (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_xor_fetch (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_or_fetch (&a, 1, __ATOMIC_SEQ_CST);
  __atomic_nand_fetch (&a, 1, __ATOMIC_SEQ_CST);
}

There's related bug 64843 for atomic_fetch_* on pointers.