Question

Why can B::Func call A::Func using syntax that makes it look like a static method call? Shouldn’t this fail because it is an instance method?

class A {
public:
    void Func() { 
        printf( "test" );
    }
};

class B : private A {
public:
    void Func() {
        A::Func();  // why does it work? (look below in main())
    }
};

int main() {
    B obj;

    obj.Func();
    // but we cannot write here, because it's not static
    // A::Func();

    return 0;
}

Answer 1

That isn’t “called like static”. That’s merely the syntax used to explicitly specify which member function to call. Even if Func were virtual, that syntax could be used to call a base class version.

class B : public A {
public:
    void Func() {
        this->A::Func(); /* this-> can be omitted */
    }
};

int main() {
    B obj;
    obj.A::Func();
    return 0;
}

Edit: obj.A::Func() would be invalid actually, in your case, because the inheritance is private, so main cannot see that A is a base of B. I’ve changed B‘s inheritance to public to make the answer correct, but it would otherwise still work outside of the class, when in a friend function.