#include <iostream>
 
class Surface
{
public:
    virtual ~Surface() {}
 
    virtual void Draw() = 0;
};
 
class Display : virtual public Surface
{
};
 
class Surface_OpenGL : virtual public Surface
{
public:
    void Draw()
    {
        std::cout << __PRETTY_FUNCTION__ << '\n';
    }
};
 
class Display_OpenGL : public Display, public Surface_OpenGL
{
};
 
int main ()
{
    Display *display = new Display_OpenGL();
 
    display->Draw();
    delete display;
    return 0;
}

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