I have a class inherits from 2 sets base classes, according to variadic template arguments. One of those sets defines a virtual function. I want to do something like this but I’m not sure how it could compile:

template<class T>
struct Base{
    void virtual foo(T t) = 0;
};


template<class T>
struct Holder{
    T t;
};

template<class... T>
struct Child :  Base<T>..., Holder<T>... {
    template<class O>
    void Base<O>::foo(O t) override { // << this won't compile
        Holder<O>::t = t;
    }