1 template <typename> struct pair {}; 2 struct A { 3 using iterator = pair<char *>; 4 pair<char *> a_[]; 5 }; 6 struct B { 7 using iterator = A::iterator; 8 iterator begin(); 9 A *tag_set_; 10 }; 11 B b; main()12 int main() {}; 13