How to declare a variadic template function as a friend?

Question

How to declare a variadic template function as a friend?

For example as follows:

template
class A
{
    friend ??? MakeA ??? ; // What         


        

Answer 1

It's quite straightforward. It's simply a template declaration with the added friend specifier:

template<class T>
class A
{
    template<class T1, class... Args>
    friend A<T1> MakeA(Args&&... args);

    A(T) { }
};