1  /* PR c/58346 */
       2  /* { dg-do compile } */
       3  /* { dg-options "-Wno-c++-compat" { target c } } */
       4  
       5  struct U {
       6  #ifdef __cplusplus
       7    char a[0];
       8  #endif
       9  };
      10  static struct U b[6];
      11  static struct U *u1, *u2;
      12  
      13  int
      14  foo (struct U *p, struct U *q)
      15  {
      16    return q - p; /* { dg-error "arithmetic on pointer to an empty aggregate" } */
      17  }
      18  
      19  void
      20  bar (void)
      21  {
      22    __PTRDIFF_TYPE__ d = u1 - u2; /* { dg-error "arithmetic on pointer to an empty aggregate" } */
      23    __asm volatile ("" : "+g" (d));
      24    foo (&b[0], &b[4]);
      25  }