Variadic Templates - different types of expansion

Question

Andrei Alexandrescu gave an excellent talk entitled: Variadic Templates are Funadic.

He presents the following 3 expansions which are subltey different:

Answer 1

Cases 2 and 3 really are very common in any kind of code involving variadic packs.

template
void f(T&&... t)
{
    // Case 2:
    auto t2 = std::tuple(t...);

    // Case 3:
    auto t3 = std::make_tuple(std::forward(t)...);
}

Looking at my own code, I can't find any surviving example of case 1. I may have used it in the past in some detail namespace for a helper tempate, but I'm not sure. I don't think it's going to be common or even necessary most of the time.