> > Bootstrapped/regtested x86_64-linux, OK?
>
> OK and thanks for the elaborate write-up and comments in the code ;)
Unforutnately our discussion on IRC let me construct another wrong code
testcase based on mixing up base alias sets
union U { long long i; long f; };
struct a {union U u;};
struct aa {struct a a;};
struct b {union U u;};
struct bb {struct b b;};
long
foo (struct bb *bv, void *ptr)
{
struct aa *a = ptr;
struct bb *b = ptr;
bv->b.u.f = 1;
a->a.u.i = 0;
b->b.u.f = 0;
return bv->b.u.f;
}
int
main ()
{
union C {struct aa aa; struct bb bb;} v;
if (foo (&v.bb, &v) != 0)
__builtin_abort ();
return 0;
}
I think there is no undefined behaviour here (at least if we assume that
first store to v.aa changes the type inmplied by earlier store to v.bb.
Honza
