In the next code, I get ambiguous error when calling D::f in _tmain(..) since B::f overrides A::f, the pointer to f in A::vtable points to B::f.
1) Why the compiler then gives ambiguous error? could someone please clear that?
2) I tried to overload A::f(int) by changing B::f(int) to be B::f(char) but the error didn't disappear! why is that?
The inheritance diagram:
............A......
........../.|.\....
........A1..B..C...
..........\.|./....
............D......
The code:
struct A {
virtual void f(int x) {cout << "A::f";};
virtual void g(int x) {cout << "A::g";};
private: int n;
};
struct A1: A {
virtual void h(int x) {f(x);};
};
struct B : virtual A {
void f(int x) {cout << "B::f";};
};
struct C : virtual A {
void g(int x) {cout << "C::g";};
};
struct D : A1, B , C {
};
int _tmain(int argc, _TCHAR* argv[])
{
D* d = new D();
d->f(1);
return 0;
}
You need to change your inheritance definition for struct A1:
struct A1: virtual A {
The reason, diamond inheritance ambiguity. struct D is getting the method f() from both A1 and B. To inherit it only once, all qualifying classes must inherit the method virtually.