1  extern void exit (int);
       2  extern void abort (void);
       3  
       4  struct { int a; int b[5]; } x;
       5  int *y;
       6  
       7  int foo (void)
       8  {
       9    return y - x.b;
      10  }
      11  
      12  int main (void)
      13  {
      14    y = x.b;
      15    if (foo ())
      16      abort ();
      17    exit (0);
      18  }