Merge 2019-07 LWG Motion 13

P0325R4 to_array from LFTS with updates

Fixes #3017.

Author: zygoloid

source/containers.tex

@@ -3148,7 +3148,13 @@
   template<class T, size_t N>
     constexpr void swap(array<T, N>& x, array<T, N>& y) noexcept(noexcept(x.swap(y)));
 
-  // \ref{array.tuple}, tuple interface to class template \tcode{array}
+  // \ref{array.creation}, array creation functions
+  template<class T, size_t N>
+    constexpr array<remove_cv_t<T>, N> to_array(T (&a)[N]);
+  template<class T, size_t N>
+    constexpr array<remove_cv_t<T>, N> to_array(T (&&a)[N]);
+
+  // \ref{array.tuple}, tuple interface
   template<class T> struct tuple_size;
   template<size_t I, class T> struct tuple_element;
   template<class T, size_t N>
@@ -3520,6 +3526,49 @@
 Member function \tcode{swap()} shall have a
 non-throwing exception specification.
 
+\rSec3[array.creation]{Array creation functions}
+\indextext{\idxcode{array}!creation}%
+
+\indexlibrary{\idxcode{to_array}}%
+\begin{itemdecl}
+template<class T, size_t N>
+  constexpr array<remove_cv_t<T>, N> to_array(T (&a)[N]);
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\mandates
+\tcode{is_array_v<T>} is \tcode{false} and
+\tcode{is_constructible_v<T, T\&>} is \tcode{true}.
+
+\pnum
+\expects
+\tcode{T} meets the \oldconcept{CopyConstructible} requirements.
+
+\pnum
+\returns \tcode{\{\{ a[0], $\dotsc$, a[N - 1] \}\}}.
+\end{itemdescr}
+
+\indexlibrary{\idxcode{to_array}}%
+\begin{itemdecl}
+template<class T, size_t N>
+  constexpr array<remove_cv_t<T>, N> to_array(T (&&a)[N]);
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\mandates
+\tcode{is_array_v<T>} is \tcode{false} and
+\tcode{is_move_constructible_v<T>} is \tcode{true}.
+
+\pnum
+\expects
+\tcode{T} meets the \oldconcept{MoveConstructible} requirements.
+
+\pnum
+\returns \tcode{\{\{ std::move(a[0]), $\dotsc$, std::move(a[N - 1]) \}\}}.
+\end{itemdescr}
+
 \rSec3[array.tuple]{Tuple interface}
 \indexlibrary{\idxcode{array}}%
 \indexlibrary{\idxcode{tuple}}%

source/support.tex

@@ -708,6 +708,8 @@
   \tcode{<string>} \tcode{<string_view>} \\ \rowsep
 \defnlibxname{cpp_lib_three_way_comparison}                 & \tcode{201711L} &
   \tcode{<compare>} \\ \rowsep
+\defnlibxname{cpp_lib_to_array}                             & \tcode{201907L} &
+  \tcode{<array>} \\ \rowsep
 \defnlibxname{cpp_lib_to_chars}                             & \tcode{201611L} &
   \tcode{<charconv>} \\ \rowsep
 \defnlibxname{cpp_lib_transformation_trait_aliases}         & \tcode{201304L} &