#include <iostream>

struct struct_a
{
	enum enum_a
	{
		value_1 = 123,
		value_2,
		value_3
	};
};

struct struct_b
{
	using enum_b = struct_a::enum_a;
};

int main() {
	std::cout << "struct_a::enum_a = " << struct_a::enum_a::value_1 << std::endl;
	std::cout << "struct_b::enum_b = " << struct_b::enum_b::value_1 << std::endl;
	return 0;
}