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

[Ken Matsui]

Ping for the use of __is_volatile built-in.

Sincerely,
Ken Matsui

On Fri, Jul 7, 2023 at 10:19 PM Ken Matsui <kmatsui@gcc.gnu.org> wrote:
>
> This patch lets libstdc++ use new built-in trait __is_volatile.
>
> libstdc++-v3/ChangeLog:
>
>         * include/std/type_traits (is_volatile): Use __is_volatile built-in
>         trait.
>         (is_volatile_v): Likewise.
>
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>
> ---
>  libstdc++-v3/include/std/type_traits | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> index 0e7a9c9c7f3..db74b884b35 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -773,6 +773,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      : public true_type { };
>
>    /// is_volatile
> +#if __has_builtin(__is_volatile)
> +  template<typename _Tp>
> +    struct is_volatile
> +    : public __bool_constant<__is_volatile(_Tp)>
> +    { };
> +#else
>    template<typename>
>      struct is_volatile
>      : public false_type { };
> @@ -780,6 +786,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>    template<typename _Tp>
>      struct is_volatile<_Tp volatile>
>      : public true_type { };
> +#endif
>
>    /// is_trivial
>    template<typename _Tp>
> @@ -3214,10 +3221,16 @@ template <typename _Tp>
>    inline constexpr bool is_const_v = false;
>  template <typename _Tp>
>    inline constexpr bool is_const_v<const _Tp> = true;
> +
> +#if __has_builtin(__is_volatile)
> +template <typename _Tp>
> +  inline constexpr bool is_volatile_v = __is_volatile(_Tp);
> +#else
>  template <typename _Tp>
>    inline constexpr bool is_volatile_v = false;
>  template <typename _Tp>
>    inline constexpr bool is_volatile_v<volatile _Tp> = true;
> +#endif
>
>  template <typename _Tp>
>    inline constexpr bool is_trivial_v = __is_trivial(_Tp);
> --
> 2.41.0
>