How use nested enum of one class as a nested enum of another?

Question

The code bellow will give compile error on line enum en = A::en; but it describes what I want to do (to make nested enum of A to be nested enum of B as well).

#include <iostream>
using namespace std;
struct A
{
    enum a_en{X = 0, Y = 1};
};
struct B
{
    enum b_en = A::a_en; //syntax error
};
int main()
{
    cout << B::X << endl;
    return 0;
}

So the question is how can I do such thing in c++?

Answer 1

Put the enum in a base class that both A and B can inherit from.