std::experimental::make_array(3)

NAME
std::experimental::make_array - std::experimental::make_array

Synopsis
   Defined in header <experimental/array>
   template <class D = void, class... Types>
   constexpr std::array<VT /* see below */, (library fundamentals TS v2)
   sizeof...(Types)> make_array(Types&&... t);
   Creates a std::array whose size is equal to the number of arguments and whose
   elements are initialized from the corresponding arguments. Returns std::array<VT,
   sizeof...(Types)>{std::forward<Types>(t)...}
   If D is void, then the deduced type VT is std::common_type_t<Types...>. Otherwise,
   it is D.
   If D is void and any of std::decay_t<Types>... is a specialization of
   std::reference_wrapper, the program is ill-formed.

Notes
   make_array is removed in Library Fundamentals TS v3 because the deduction guide for
   std::array and std::to_array have been already in C++20.

Possible implementation
 namespace details {
   template<class> struct is_ref_wrapper : std::false_type {};
   template<class T> struct is_ref_wrapper<std::reference_wrapper<T>> : std::true_type {};
   template<class T>
   using not_ref_wrapper = std::negation<is_ref_wrapper<std::decay_t<T>>>;
   template <class D, class...> struct return_type_helper { using type = D; };
   template <class... Types>
   struct return_type_helper<void, Types...> : std::common_type<Types...> {
       static_assert(std::conjunction_v<not_ref_wrapper<Types>...>,
                     "Types cannot contain reference_wrappers when D is void");
   };
   template <class D, class... Types>
   using return_type = std::array<typename return_type_helper<D, Types...>::type,
                        sizeof...(Types)>;
 }
 template < class D = void, class... Types>
 constexpr details::return_type<D, Types...> make_array(Types&&... t) {
   return {std::forward<Types>(t)... };
 }

Example
// Run this code
 #include <experimental/array>
 #include <iostream>
 #include <type_traits>
 int main()
 {
     auto arr = std::experimental::make_array(1, 2, 3, 4, 5);
     bool is_array_of_5_ints = std::is_same<decltype(arr), std::array<int, 5>>::value;
     std::cout << "Returns an array of five ints? ";
     std::cout << std::boolalpha << is_array_of_5_ints << '\n';
 }

Output:
 Returns an array of five ints? true

See also
   to_array Creates a std::array object from a built-in array
            (function template)