gcc/testsuite/gcc.dg/Wstrict-aliasing-bogus-ref-all.c

   1 /* { dg-do compile } */
   2 /* { dg-options "-O2 -Wall" } */
   3
   4 struct g { long a; };
   5 unsigned long f(struct g *a) { return *(unsigned long *)&a->a; }
   6
   7 struct A
   8 {
   9   void *a;
  10 };
  11
  12 int g(const struct A *x, long *y)
  13 {
  14   typedef long __attribute__ ((may_alias)) long_a;
  15   *y = *(const long_a *) (&x->a);
  16   return 1;
  17 }
  18
  19 void *a;
  20
  21 int
  22 f0 (long *y)
  23 {
  24   *y = *(const long *) &a; /* { dg-warning "will break" } */
  25   return 1;
  26 }
  27
  28 int
  29 f1 (long *y)
  30 {
  31   typedef long __attribute__ ((may_alias)) long_a;
  32   *y = *(const long_a *) &a;
  33   return 1;
  34 }
  35
  36 int
  37 f2 (long *y)
  38 {
  39   *y = *(const long *) &a; /* { dg-warning "will break" } */
  40   return 1;
  41 }