On Thu, Oct 13, 2011 at 02:57:56PM +0200, Michael Matz wrote:
> struct S {int * restrict p;};
> void foo (struct S *s, struct S *t) {
> s->p[0] = 0;
> t->p[0] = 1; // undefined if s->p == t->p; the caller was responsible
> // to not do that
This is undefined only if s->p == t->p && &s->p != &t->p. If both
s->p and t->p designate the same restricted pointer object,
it is fine. It is just fine to call the above with:
struct S u;
u.p = p;
foo (&u, &u);
but not with:
struct S u, v;
u.p = p;
v.p = p;
foo (&u, &v);
If you change it to
void foo (struct S *restrict s, struct S *restrict t)
then obviously even calling it with foo (&u, &u) is invalid.
Jakub
