[PING][PATCH v3 2/2] libstdc++: use new built-in trait __is_array

[Ken Matsui <kmatsui@cs.washington.edu>]

Ping for the use of __is_array built-in.

Sincerely,
Ken Matsui

On Fri, Jul 7, 2023 at 10:24 PM Ken Matsui <kmatsui@gcc.gnu.org> wrote:
>
> This patch lets libstdc++ use new built-in trait __is_array.
>
> libstdc++-v3/ChangeLog:
>
>         * include/std/type_traits (is_array): Use __is_array built-in trait.
>         (is_array_v): Likewise.
>
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> ---
>  libstdc++-v3/include/std/type_traits | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> index 0e7a9c9c7f3..f2a3a327e7d 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -503,6 +503,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      { };
>
>    /// is_array
> +#if __has_builtin(__is_array)
> +  template<typename _Tp>
> +    struct is_array
> +    : public __bool_constant<__is_array(_Tp)>
> +    { };
> +#else
>    template<typename>
>      struct is_array
>      : public false_type { };
> @@ -514,6 +520,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    template<typename _Tp>
>      struct is_array<_Tp[]>
>      : public true_type { };
> +#endif
>
>    template<typename>
>      struct __is_pointer_helper
> @@ -3161,12 +3168,17 @@ template <typename _Tp>
>  template <typename _Tp>
>    inline constexpr bool is_floating_point_v = is_floating_point<_Tp>::value;
>
> +#if __has_builtin(__is_array)
> +template <typename _Tp>
> +  inline constexpr bool is_array_v = __is_array(_Tp);
> +#else
>  template <typename _Tp>
>    inline constexpr bool is_array_v = false;
>  template <typename _Tp>
>    inline constexpr bool is_array_v<_Tp[]> = true;
>  template <typename _Tp, size_t _Num>
>    inline constexpr bool is_array_v<_Tp[_Num]> = true;
> +#endif
>
>  template <typename _Tp>
>    inline constexpr bool is_pointer_v = is_pointer<_Tp>::value;
> --
> 2.41.0
>