[v3 PATCH] Implement make_array and to_array from the Fundamentals v2 TS draft

[Jonathan Wakely]

On 13/07/15 13:55 +0300, Ville Voutilainen wrote:
>+template <typename _Up>
>+struct __is_reference_wrapper : false_type
>+{ };

Please indent the class-head and the body.

>+template <typename _Up>
>+struct __is_reference_wrapper<reference_wrapper<_Up>> : true_type
>+{ };

Likewise.

>+template <typename _D = void, typename... _Types>
>+constexpr auto make_array(_Types&&... __t)

Same here, everything after the 'template<...>' should be indented.

Maybe consider putting a newline after 'auto' too

And the single character name _D makes me nervous again :-)


>+  -> array<conditional_t<is_void_v<_D>,
>+                         common_type_t<_Types...>,
>+                         _D>,
>+           sizeof...(_Types)>
>+{
>+  static_assert(__or_<
>+                  __not_<is_void<_D>>,
>+                  __and_<__not_<__is_reference_wrapper<decay_t<_Types>>>...>>
>+                ::value,
>+                "make_array cannot be used without an explicit target type "
>+                "if any of the types given is a reference_wrapper");

I wonder if that would be more efficient to instantiate written as:

  __not_<__and_<is_void<_D>, __or_<__is_reference_wrapper<decay_t<_Types>>...>>>

>+  return {{forward<_Types>(__t)...}};
>+}
>+
>+template <typename _Tp, size_t _N, size_t... _Idx>

_N is a common macro in some C libs, please rename to something like _Nm.
(_D isn't listed in the docs as a name to avoid, so should be OK).

>diff --git a/libstdc++-v3/testsuite/experimental/array/make_array.cc b/libstdc++-v3/testsuite/experimental/array/make_array.cc
>new file mode 100644
>index 0000000..8456c37
>--- /dev/null
>+++ b/libstdc++-v3/testsuite/experimental/array/make_array.cc
>@@ -0,0 +1,47 @@
>+// { dg-options "-std=gnu++14" }
>+// { dg-do run }

Does this need to be dg-do run? It doesn't seem to run anything
interesting so could be dg-do compile.