On Tue, Nov 3, 2020 at 11:01 PM D'Alessandro, Luke K via Std-Proposals <std-proposals@lists.isocpp.org> wrote:
Does this seem like something I should go ahead and put together officially?

Consider that it is currently impossible, per [array.creation], to use std::to_array to create a zero-length array. We believe that this is merely an oversight, and not intentional.

It is certainly consistent, and looks intentional to me.

    auto i3 = std::to_array({1, 2, 3});  // OK
    auto d3 = std::to_array({1., 2., 3.});  // OK
    auto i1 = std::to_array({1});  // OK
    auto d1 = std::to_array({1.});  // OK

    auto i0 = std::to_array({});  // ill-formed for obvious reasons
    auto d0 = std::to_array({});  // ill-formed for obvious reasons

i0 and d0 can't both be well-formed. If you have an empty braced-initializer-list, it's impossible to tell what the array element type was intended to be.

If you're trying to use std::to_array with explicit template arguments, as in
    auto f3 = std::to_array<float>({1, 2, 3});
    auto f0 = std::to_array<float>({});
then I think that usage needs justification (by which I actually mean, that usage is wrong). Right now, in most cases, the standard library reserves the right to replace
    template<class T, size_t N> auto to_array(T(&)[N]);
    template<size_t N, class T> auto to_array(T(&)[N]);
i.e. to alter "the number and order of deducible template parameters." When a library function has deducible parameters, you should always let them be deduced.

Why do you think you need this new overload?  What use-case do you envision for "std::arrays of maybe zero length" that wouldn't be better solved with
    auto fn = std::array<float, sizeof...(args)>{ args... };