c++ - Why can't I call protected virtual base class function in the derived class overridden function? -

class base { protected:     virtual void show()     {         // stuff.     } };  class derived : public base { protected:     virtual void show()     {         // stuff.     } };  class derived_2 : public derived { protected:     virtual void show()     {         this->show();    // error: base::show() in accessible         show();          // error: base::show() in accessible         derived::show(); // error: base::show() in accessible     } }; 

in above case calling virtual base class function (overridden in derived classes) gives error.

the error can find, call show itsel leading infinite recursion , ending in stack overflow error.

but code compiles , run without warning :

class derived_2 : public derived { public:     virtual void show()     {         //this->show();    // infinite recursion => stack overflow         base::show();    // ok calls show() base         derived::show();    // ok calls show() derived         std::cout << "derived2" << std::endl;     } }; 

(i declared public call directly in test)