1  /* { dg-do run } */
       2  /* { dg-options "-O3 -fstrict-aliasing" } */
       3  
       4  union U {
       5    struct A { int : 2; int x : 8; } a;
       6    struct B { int : 6; int x : 8; } b;
       7  };
       8  
       9  int __attribute__((noipa))
      10  foo (union U *p, union U *q)
      11  {
      12    p->a.x = 1;
      13    q->b.x = 1;
      14    return p->a.x;
      15  }
      16  
      17  int
      18  main()
      19  {
      20    union U x;
      21    if (foo (&x, &x) != x.a.x)
      22      __builtin_abort ();
      23    return 0;
      24  }
      25  
      26  /* We support arbitrary punning through unions when it happens through
      27     the union type and thus p == q is valid here.  */