Generalized lambda capture on param-pack?

Question

In C++14, generalized lambda capture let us do:

template<class T>
auto pack(T t)
{
    return [t=std::move(t)](auto&& f){f(t);};
};

But it doesn't play with param-pack:

template<class... T>
auto pack(T... t)
{
    return [t=std::move(t)...](auto&& f){f(t...);};
};

Is there any special syntax or further standard proposal to address this?

Answer 1

My draft of C++14 says ([expr.prim.lambda]/24):

A simple-capture followed by an ellipsis is a pack expansion (14.5.3). An init-capture followed by an ellipsis is ill-formed.

So it looks like there is no way to do a variadic generalized capture. A possible workaround is to just capture the arguments in a tuple and then use one of the solutions suggested here: "unpacking" a tuple to call a matching function pointer

auto pack(T... t)
{
    return [args=make_tuple(std::move(t)...)](auto&& f){
               // find a way to call f with args
           };
};

EDIT:

It's now voted into C++20, made by this proposal. Although the syntax is a bit different:

template<class... T>
auto pack(T... t)
{
    return [...t=std::move(t)](auto&& f){f(t...);};
};

Note that the ... is before the init-capture.