1  struct s {
       2    unsigned char a[256];
       3  };
       4  union u {
       5    struct { struct s b; int c; } d;
       6    struct { int c; struct s b; } e;
       7  };
       8  
       9  static union u v;
      10  static struct s *p = &v.d.b;
      11  static struct s *q = &v.e.b;
      12  
      13  static struct s __attribute__((noinline)) rp(void)
      14  {
      15    return *p;
      16  }
      17  
      18  static void qp(void)
      19  {
      20    *q = rp();
      21  }
      22  
      23  int main()
      24  {
      25    int i;
      26    for (i = 0; i < 256; i++)
      27      p->a[i] = i;
      28    qp();
      29    for (i = 0; i < 256; i++)
      30      if (q->a[i] != i)
      31        __builtin_abort();
      32    return 0;
      33  }