How do I choose the base class when overriding a function in c++?

Question

I have two base classes and a class that inherits both base classes. Both base classes have a virtual function with the same signature, and I want to provide different implementations in the derived class to each virtual function.

class A{
    virtual void f() = 0;
}
class B{
    virtual void f() = 0;
}
class Derived:public A, public B{
    void A::f() override{ // Error
        ...
    }
    void B::f() override{ // Error
        ...
    }
}

What is the correct way to do this? (I cannot rename the virtual function. Actually the two base classes are generated from the same template class.)

Answer 1

template <typename T>
class AShim : public A {
  void f() override {
    static_cast<T*>(this)->A_f();
  }
};

template <typename T>
class BShim : public B {
  void f() override {
    static_cast<T*>(this)->B_f();
  }
};

class Derived: public AShim<Derived>, public BShim<Derived> {
  void A_f();
  void B_f();
};