1  extern void abort (void);
       2  int foo (int i)
       3  {
       4    return -2 * __builtin_abs(i - 2);
       5  }
       6  int main()
       7  {
       8    if (foo(1) != -2
       9        || foo(3) != -2)
      10      abort ();
      11    return 0;
      12  }