1  extern void abort (void);
       2  extern void foo (void);
       3  extern void *bar (void);
       4  
       5  typedef void (*func_p) (void);
       6  
       7  extern const func_p p1;
       8  
       9  func_p p2 = &foo;
      10  func_p p3 = &foo;
      11  
      12  int
      13  main ()
      14  {
      15    void *p = bar ();
      16    p1 ();
      17    p2 ();
      18    p3 ();
      19    if (p != p1)
      20      abort ();
      21    return 0;
      22  }