//A.h
// TODO: add guards
class B; // we need this forward declaration, but just this one
class A {
private:
    B* bMmbr;
public:
    A() {}

    void AMthd(){
        std::cout<<"AMthd()"<<std::endl;
    }

    void Qwe() {
        bMmbr->BMthd();
    }
};

//B.h
// TODO: add guards
class B {
private:
    A* aMmbr;
public:
    B() {}
    void BMthd() {
        std::cout<<"BMthd()"<<std::endl;
    }

    void Qwe() {
        aMmbr->AMthd();
    }
};

//Program.h
class Program {
public:
    Program() {}

    void main() {
        A a;
        a.Qwe();
    }
};

// main.cpp
#include <iostream>

struct Prog {
#include "A.h"
#include "B.h"
#include "Program.h"

    static Program p;
};

Prog::Program Prog::p;

void main() {
    Prog::p.main();
}