C1118: Only bases and class member functions can be virtual

[ERROR]

Because virtual functions are called only for objects of class types, you cannot declare global functions or union member functions as 'virtual'.

  virtual void f(void); // ERROR: definition of a global

  

                        // virtual function.

  

  union U {

  

    virtual void f(void); // ERROR: virtual union member

  

                          // function

  

  };

  

Do not declare a global function or a union member function as virtual.