1  extern void abort (void);
       2  
       3  typedef unsigned long my_uintptr_t;
       4  
       5  int check_a(my_uintptr_t tagged_ptr);
       6  
       7  int __attribute__((noinline)) try_a(my_uintptr_t x)
       8  {
       9    my_uintptr_t heap[2];
      10    my_uintptr_t *hp = heap;
      11  
      12    hp[0] = x;
      13    hp[1] = 0;
      14    return check_a((my_uintptr_t)(void*)((char*)hp + 1));
      15  }
      16  
      17  int __attribute__((noinline)) check_a(my_uintptr_t tagged_ptr)
      18  {
      19    my_uintptr_t *hp = (my_uintptr_t*)(void*)((char*)tagged_ptr - 1);
      20  
      21    if (hp[0] == 42 && hp[1] == 0)
      22      return 0;
      23    return -1;
      24  }
      25  
      26  int main(void)
      27  {
      28    if (try_a(42) < 0)
      29      abort ();
      30    return 0;
      31  }
      32