1  int flag;
       2  extern void abort (void);
       3  int main()
       4  {
       5    int x;
       6    if (flag)
       7      x = -1;
       8    else 
       9      x &= 0xff;
      10    if (x & ~0xff)
      11      abort ();
      12    return 0;
      13  }