#include <iostream>

struct foo_t
{
    int& a;
};

struct bar_t
{
    int* a;
};

int main()
{
    bar_t bar{ 0 };
    foo_t foo( *reinterpret_cast< foo_t* >( &bar ) );

    int& nullref = foo.a;

    std::cout << "&nulref: "<< &nullref << std::endl;
}