1  struct s {
       2    unsigned long long a:8, b:32;
       3  };
       4  
       5  struct s
       6  f(struct s x)
       7  {
       8    x.b = 0xcdef1234;
       9    return x;
      10  }
      11  
      12  main()
      13  {
      14    static struct s i;
      15    i.a = 12;
      16    i = f(i);
      17    if (i.a != 12 || i.b != 0xcdef1234)
      18      abort();
      19    exit(0);
      20  }