Re: [PATCH 2/2] libstdc++: use new built-in trait __is_signed

[Jonathan Wakely <jwakely@redhat.com>]

On Sun, 9 Jul 2023 at 09:50, Ken Matsui via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> This patch lets libstdc++ use new built-in trait __is_signed.
>
> libstdc++-v3/ChangeLog:
>
>         * include/std/type_traits (is_signed): Use __is_signed built-in trait.
>         (is_signed_v): Likewise.
>
> Signed-off-by: Ken Matsui <kmatsui@gcc.gnu.org>

OK for trunk after the front-end implementation of __is_signed is committed.


> ---
>  libstdc++-v3/include/std/type_traits | 15 ++++++++++++++-
>  1 file changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/libstdc++-v3/include/std/type_traits b/libstdc++-v3/include/std/type_traits
> index 0e7a9c9c7f3..23ab5a4b1e5 100644
> --- a/libstdc++-v3/include/std/type_traits
> +++ b/libstdc++-v3/include/std/type_traits
> @@ -865,6 +865,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      : public __bool_constant<__is_abstract(_Tp)>
>      { };
>
> +  /// is_signed
> +#if __has_builtin(__is_signed)
> +  template<typename _Tp>
> +    struct is_signed
> +    : public __bool_constant<__is_signed(_Tp)>
> +    { };
> +#else
>    /// @cond undocumented
>    template<typename _Tp,
>            bool = is_arithmetic<_Tp>::value>
> @@ -877,11 +884,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      { };
>    /// @endcond
>
> -  /// is_signed
>    template<typename _Tp>
>      struct is_signed
>      : public __is_signed_helper<_Tp>::type
>      { };
> +#endif
>
>    /// is_unsigned
>    template<typename _Tp>
> @@ -3240,8 +3247,14 @@ template <typename _Tp>
>  template <typename _Tp>
>    inline constexpr bool is_final_v = __is_final(_Tp);
>
> +#if __has_builtin(__is_signed)
> +template <typename _Tp>
> +  inline constexpr bool is_signed_v = __is_signed(_Tp);
> +#else
>  template <typename _Tp>
>    inline constexpr bool is_signed_v = is_signed<_Tp>::value;
> +#endif
> +
>  template <typename _Tp>
>    inline constexpr bool is_unsigned_v = is_unsigned<_Tp>::value;
>
> --
> 2.41.0
>