> I agree, that assigning a non-BLKmode to structures with zero-sized arrays
> should be considered a bug.
Fine, then let's apply Martin's patch, on mainline at least.
> And again, this is not only a problem of structures with zero-sized
> arrays at the end. Remember my previous example code:
> On ARM (or anything with STRICT_ALIGNMENT) this union has the
> same problems:
>
> /* PR middle-end/57748 */
> /* arm-eabi-gcc -mcpu=cortex-a9 -O3 */
> #include <stdlib.h>
>
> union x
> {
> short a[2];
> char x[4];
> } __attribute__((packed, aligned(4))) ;
> typedef volatile union x *s;
>
> void __attribute__((noinline, noclone))
> check (void)
> {
> s xx=(s)(0x80000002);
> /* although volatile xx->x[3] reads 4 bytes here */
> if (xx->x[3] != 3)
> abort ();
> }
>
> void __attribute__((noinline, noclone))
> foo (void)
> {
> s xx=(s)(0x80000002);
> xx->x[3] = 3;
> }
>
> int
> main ()
> {
> foo ();
> check ();
> return 0;
> }
But this testcase is invalid on STRICT_ALIGNMENT platforms: xx is pointer to a
type with 4-byte alignment so its value must be a multiple of 4.
--
Eric Botcazou
