Компиляция кода с ромбовидным наследованием

class A {
protected:
    int a;
public:
    A(int i) : a(i) {}
};
 
class B : public A {
public:
    B(int i) : A(i) {}
};
 
class C : public B, public A {
public:
    C(int i1, int i2) : B(i1), A(i2) {}
    void print() { std::cout << "B(" << B::a << "), A(" << A::a << ")"; }
};
 
int main()
{
    C cc(2, 1);
    cc.print();
}

#include <iostream>
class A {
protected:
    int a;
public:
    A(int i) : a(i) {}
};
 
class B : virtual public A {
public:
    B(int i) : A(i) {}
};
 
class C : public B, virtual public A {
public:
    C(int i1, int i2) : B(i1), A(i2) {}
    void print() { std::cout << "B(" << B::a << "), A(" << A::a << ")"; }
};
 
int main()
{
    C cc(2, 1);
    cc.print();
}

#include <iostream>
 
class A
{};
 
class B: virtual public A
{};
 
class C: virtual public A
{};
 
class D: public B, public C
{ };
 
int main()
{
  return 0;
}

class cPC : public cVideoAdapter, public cHDD, public cCPU, public cRAM

class cVideoAdapter : public cRAM, public cGPU