Consequence of diamond inheritance

diamond.cpp

#include <iostream>

struct X
{
    protected:
    int i;
};

struct A : X
{
    void action() {}
};

struct Av : virtual X
{
    void action() {}
};

struct B : X
{
    void action() {}
};

struct Bv : virtual X
{
    void action() {}
};

struct C : A, B
{
    void setAi(int j) { A::i = j; }
    void setBi(int j) { B::i = j; }
    int getAi() { return A::i; }
    int getBi() { return B::i; }
    void doActionA() { A::action(); }
    void doActionB() { B::action(); }
};

struct V : Av, Bv
{
	void setAi(int j) { Av::i = j; }
	void setBi(int j) { Bv::i = j; }
	int getAi() { return Av::i; }
	int getBi() { return Bv::i; }
    void doActionA() { Av::action(); }
    void doActionB() { Bv::action(); }
};

int main(void)
{
    C c;

    c.setAi(1);
    c.setBi(2);

    std::cout << "c.getAi: " << c.getAi() << std::endl;
    std::cout << "c.getBi: " << c.getBi() << std::endl;

    c.doActionA();
    c.doActionB();

    V v;

    v.setAi(1);
    v.setBi(2);

    std::cout << "v.getAi: " << v.getAi() << std::endl;
    std::cout << "v.getBi: " << v.getBi() << std::endl;

    v.doActionA();
    v.doActionB();

    return 0;
}