#include <stdio.h>

template<typename t, typename return_type, typename... xs>
using memfun_ptr = return_type(t::*)(xs...);

template<typename t, typename u>
void whatever(t datum, memfun_ptr<t, u> ptr)
{
    (datum.*ptr)();
}

struct dupa
{
    void call()
    {
        printf("dupa\n");
    }
};

int main(void)
{
    dupa x{};
    whatever<dupa, void>(x, &dupa::call);
}