1 2extern void abort(void); 3 4__attribute__ ((noinline)) 5int foo(int n) 6{ 7 if (n < 0) 8 n = ~n; 9 10 return n; 11} 12 13int main(void) 14{ 15 if (foo (-1) != 0) 16 abort (); 17 18 return 0; 19} 20