为什么编译器没有在main()中为p->f4();行抛出错误。根据我的理解，类B隐藏了f4()，应该抛出错误

class A
{
    public:
        void f1(){}
        virtual void f2(){}
        virtual void f3(){}
        virtual void f4(){}
};

class B : public A
{
    public:
        void f1(){}
        void f2(){}
        void f4(int x){}
};

int main()
{
    A *p;
    B o2;
    p = &o2;
    
    p->f1();
    p->f2();
    p->f3();
    p->f4();  //why doesn't it throw an error for this line as class B hides f4()
    p->f4(5);  
    
    return 0;
}