copy reference

test.cc

// Example program
#include <iostream>
#include <string>

struct nocopy {
    nocopy(int i_) : i(i_) {}
    nocopy( const nocopy& ) = delete;
    int i;
};

struct test { 
    test( nocopy& n_ ) : n( n_ ) {}
    test( const test& other ): n(other.n) {}
    nocopy& n;
};

int main()
{
    nocopy n{ 1 };
    test t{ n };
    test t1{ t };
    std::cout << "I: " << t1.n.i << '\n';
}