1  /* { dg-do run } */
       2  /* { dg-options "-O2" } */
       3  
       4  typedef __SIZE_TYPE__ size_t;
       5  extern void *malloc (size_t);
       6  extern void free (void *);
       7  extern void abort (void);
       8  
       9  union U
      10  {
      11    struct S { int a; int b; } s;
      12    int t;
      13  };
      14  
      15  struct T
      16  {
      17    int c;
      18    char d[1];
      19  };
      20  
      21  int
      22  main (void)
      23  {
      24    union U *u = malloc (sizeof (struct S) + sizeof (struct T) + 6);
      25    struct T *t = (struct T *) (&u->s + 1);
      26    if (__builtin_object_size (t->d, 1)
      27        != sizeof (struct T) + 6 - __builtin_offsetof (struct T, d))
      28      abort ();
      29    free (u);
      30    return 0;
      31  }