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struct Drawable {};
struct Shape : Drawable {};
struct Polygon : Shape {};
struct Rectangle : Shape {};
 
void func(Rectangle*, Drawable*, Drawable*)  {}
void func(Rectangle*, Rectangle*, Drawable*)  {}
void func(Polygon*, Rectangle*, Rectangle*)  {}
 
Rectangle* create_rectangle()
{
   return new Rectangle;
}
 
int main()
{
   Drawable* x = create_rectangle();
   Drawable* y = create_rectangle();
   Drawable* z = create_rectangle();
   func(x, y, z);
}
 

prog.cpp: In function ‘int main()’:
prog.cpp:20:16: error: invalid conversion from ‘Drawable*’ to ‘Rectangle*’ [-fpermissive]
    func(x, y, z);
                ^
prog.cpp:6:6: note:   initializing argument 1 of ‘void func(Rectangle*, Drawable*, Drawable*)’
 void func(Rectangle*, Drawable*, Drawable*)  {}
      ^~~~

Standard output is empty