1  /* { dg-do compile } */
       2  /* { dg-options "-Wc++-compat" } */
       3  struct A {}; /* { dg-warning "empty struct has size 0 in C" } */
       4  union B {}; /* { dg-warning "empty union has size 0 in C" } */
       5  struct C { struct D {}; int x; }; /* { dg-warning "empty struct has size 0 in C|declaration does not declare anything" } */
       6  struct E { union F {}; int x; }; /* { dg-warning "empty union has size 0 in C|declaration does not declare anything" } */
       7  union G { union H {}; int x; }; /* { dg-warning "empty union has size 0 in C|declaration does not declare anything" } */
       8  union I { struct J {}; int x; }; /* { dg-warning "empty struct has size 0 in C|declaration does not declare anything" } */