#include <iostream>

struct base1
{
    virtual ~base1() {}
};
struct base2
{
    virtual ~base2() {}
};

void fn1( virtual base1& x);
void fn2( virtual base2& x);

struct derived : base2, base1
{
};

void fn1_( static derived&)   { std::cerr << "fn1_( derived& called\n";    }
void fn2_( static derived&)   { std::cerr << "fn2_( derived& called\n";    }

int main()
{
    derived d;
    
    fn1( d);
    fn2( d);
    return 0;
}