如何从派生类到基类ptr访问受保护的基类函数

class Base {
protected:
    int protected_member;

    friend void accessProtectedMember(Base* ptr);
};

class Derived : public Base {
public:
    void accessProtectedMember() {
        accessProtectedMember(this);
    }
};

void accessProtectedMember(Base* ptr) {
    ptr->protected_member = 42;
}

class Base {
protected:
    int protected_member;

    virtual void accessProtectedMember() {
        protected_member = 42;
    }
};

class Derived : public Base {
public:
    void accessProtectedMember() override {
        Base::accessProtectedMember();
    }
};

class Base {
protected:
    int protected_member;

    void accessProtectedMember() {
        protected_member = 42;
    }
};

class Derived : public Base {
public:
    using Base::accessProtectedMember;
};