On Mon, 4 Aug 2014, Marek Polacek wrote:
+/* { dg-do compile } */
+
+void
+foo (void)
+{
+ volatile __PTRDIFF_TYPE__ t;
+ int i;
+ int *p = &i;
+ int *q = &i + 1;
+ t = q - (q - 1);
+ t = (q - 1) - q; /* { dg-warning "integer overflow in expression" } */
+ t = p - (p - 1);
+ t = (p - 1) - p ; /* { dg-warning "integer overflow in expression" } */
+}
Why do you want a warning for (q - 1) - q ? It looks like a perfectly
correct way to say -1 to me (ptrdiff_t is a signed type for a reason).
--
Marc Glisse
