1  #include <stdio.h>
       2  
       3  volatile int x;
       4  extern void abort ();
       5  
       6  __attribute__((weak))
       7  void foobar (void) { x++; }
       8  
       9  int main (void)
      10  {
      11    foobar ();
      12    if (x != -1)
      13      abort ();
      14    printf ("PASS\n");
      15    return 0;
      16  }