[Bug c/69404] atomic builtins accept incompatible pointers

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69404

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2016-2-2
      Known to fail|                            |4.9.3, 5.3.0, 6.0

--- Comment #7 from Martin Sebor <msebor at gcc dot gnu.org> ---
This bug also allows the atomic intrinsics to change the representation of
_Bool objects to other than 0 1, violating the GCC invariant.  This is a
loophole that the fix bug 69404 was intended to close (and did for
__atomic_fetch_xxx) but missed for __atomic_load and __atomic_exchange.  As a
result, GCC compiles the following test case without a warning:

$ cat u.c && /home/msebor/build/gcc-trunk-git/gcc/xgcc
-B/home/msebor/build/gcc-trunk-git/gcc -S -Wall -Wextra -Wpedantic -o/dev/null
u.c
void f (char *a, _Bool *b)
{
    __atomic_load (a, b, 0);
}