Hi,

I've updated the wording, but I'm not sure should we keep the
requires-clause on "make-from-tuple-impl"?

*Wording:*

This wording is relative to N4971 <https://wg21.link/N4971>.

   1.

   Edit 22.4.6 [tuple.apply] <https://wg21.link/tuple.apply> as indicated:

template<class T, tuple-like Tuple>
  constexpr T make_from_tuple(Tuple&& t);

*-3- Let I be the pack 0, 1, ...,
(tuple_size_v<remove_reference_t<Tuple>> - 1).*

-4- Constraints:

- is_constructible_v<T, decltype(get<I>(declval<Tuple>()))...> is true, and

- if tuple_size_v<remove_reference_t<Tuple>> is 1, then
reference_constructs_from_temporary_v<T,
decltype(get<0>(declval<Tuple>()))> is false.

*-3- Mandates: If tuple_size_v<remove_reference_t<Tuple>> is 1,
then reference_constructs_from_temporary_v<T,
decltype(get<0>(declval<Tuple>()))> is false.
<https://eel.is/c++draft/tuple.apply#3.sentence-1>*

*-4-*-5- *Effects:* Given the exposition-only function:

[...]

template<class T, tuple-like Tuple, size_t... I> requires
is_constructible_v<T, decltype(get<I>(declval<Tuple>()))...>
constexpr T *make-from-tuple-impl*(Tuple&& t, index_sequence<I...>) {
   // exposition only
  return T(get<I>(std::forward<Tuple>(t))...);
}

[...]

    Equivalent to:

return *make-from-tuple-impl*<T>(
  std::forward<Tuple>(t),
  make_index_sequence<tuple_size_v<remove_reference_t<Tuple>>>{});

[*Note 1:* The type of T must be supplied as an explicit template
parameter, as it cannot be deduced from the argument list. — *end note*]