1 struct A; 2 struct B 3 { 4 int foo; 5 struct A *bar; 6 }; 7 8 struct A 9 { 10 long a; 11 struct B *foo; 12 }; 13 14 static struct A *foo __attribute__((used)); 15 main()16 int main() 17 { 18 } 19