gcc/testsuite/gcc.dg/c23-tag-incomplete-alias-1.c

   1 /* { dg-do run }
   2  * { dg-options "-std=c23 -O2" } */
   3
   4 [[gnu::noinline]]
   5 void *alias(void *ap, void *bp, void *x, void *y)
   6 {
   7         struct foo { struct bar *f; } *a = ap;
   8         struct bar { long x; };
   9
  10         a->f = x;
  11
  12         {
  13                 struct bar;
  14                 struct foo { struct bar *f; } *b = bp;
  15                 struct bar { long x; };
  16
  17                 // after completing bar, the two struct foo should be compatible
  18
  19                 b->f = y;
  20         }
  21
  22
  23         return a->f;
  24 }
  25
  26 int main()
  27 {
  28         struct bar { long x; };
  29         struct foo { struct bar *f; } a;
  30         struct bar x, y;
  31         if (&y != alias(&a, &a, &x, &y))
  32                 __builtin_abort();
  33
  34         return 0;
  35 }
  36