#include<iostream>
struct A { int i = 10; };
struct B : A { };

int main(){
    std::cout << "decltype(&B::i) == int A::* ? " << std::boolalpha << std::is_same<decltype(&B::i), int A::*>::value << 'n';
    A a;
    std::cout << a.*(&A::i) << 'n';
    std::cout << "decltype(&B::i) == int B::* ? " << std::is_same<decltype(&B::i), int B::*>::value << 'n';    //#1
    B b;
    std::cout << b.*(&B::i) << 'n';        //#2
}

decltype(&B::i) == int A::* ? true
10
decltype(&B::i) == int B::* ? false
10