1  struct X {
       2    char i;
       3  };
       4  
       5  struct W {
       6    struct U *p;
       7    struct X *q;
       8  };
       9  
      10  struct U {
      11    struct W a[1];
      12  };
      13  
      14  void bar(struct U *ptr)
      15  {
      16    ptr->a[0].p = 0;
      17  }