[PATCH] libstdc++: Fix __cpp_impl_reflection comparisons

[Jonathan Wakely]

On Thu, 15 Jan 2026 at 07:04, Jakub Jelinek <jakub@redhat.com> wrote:
>
> Hi!
>
> Last night when applying Marek's patchset for testing I've noticed I forgot
> to change these 5 spots when changing the -freflection -std=c++26 predefined
> value from 202500 which meant we implement some reflection, but not the
> whole paper, to 202506 which is the https://eel.is/c++draft/tab:cpp.predefined.ft
> value for it.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux on top of Marek's
> v3 patchset, ok for trunk after that patch is committed?

OK, thanks


>
> 2026-01-15  Jakub Jelinek  <jakub@redhat.com>
>
>         * include/std/type_traits (std::is_reflection, std::is_fundamental,
>         std::is_reflection_v, std::is_consteval_only): Compare
>         __cpp_impl_reflection >= 202506L instead of 202500L.
>         * testsuite/20_util/variable_templates_for_traits.cc: Likewise.
>
> --- libstdc++-v3/include/std/type_traits.jj     2026-01-14 21:26:19.456842913 +0100
> +++ libstdc++-v3/include/std/type_traits        2026-01-14 22:00:46.524039884 +0100
> @@ -749,7 +749,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      : public false_type { };
>  #endif
>
> -#if __cpp_impl_reflection >= 202500L // C++ >= 26
> +#if __cpp_impl_reflection >= 202506L // C++ >= 26
>    /// is_reflection
>    template<typename _Tp>
>      struct is_reflection
> @@ -838,7 +838,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
>      struct is_fundamental
>      : public __or_<is_arithmetic<_Tp>, is_void<_Tp>,
>                    is_null_pointer<_Tp>
> -#if __cpp_impl_reflection >= 202500L
> +#if __cpp_impl_reflection >= 202506L
>                    , is_reflection<_Tp>
>  #endif
>                    >::type
> @@ -3555,7 +3555,7 @@ template <typename _Tp>
>      is_member_function_pointer<_Tp>::value;
>  #endif
>
> -#if __cpp_impl_reflection >= 202500L // C++ >= 26
> +#if __cpp_impl_reflection >= 202506L // C++ >= 26
>  template <typename _Tp>
>    inline constexpr bool is_reflection_v = false;
>  template <>
> @@ -3900,7 +3900,7 @@ template<typename _Ret, typename _Fn, ty
>  # endif
>  #endif
>
> -#if __cpp_impl_reflection >= 202500L \
> +#if __cpp_impl_reflection >= 202506L \
>      && _GLIBCXX_USE_BUILTIN_TRAIT(__builtin_is_consteval_only) // C++ >= 26
>    /// is_consteval_only - true if the type is consteval-only.
>    /// @since C++26
> --- libstdc++-v3/testsuite/20_util/variable_templates_for_traits.cc.jj  2026-01-14 21:26:19.459487116 +0100
> +++ libstdc++-v3/testsuite/20_util/variable_templates_for_traits.cc     2026-01-14 22:01:06.877697256 +0100
> @@ -331,7 +331,7 @@ static_assert(is_convertible_v<int&, con
>  static_assert(!is_convertible_v<const int&, int&>
>               && !is_convertible<const int&, int&>::value, "");
>
> -#if __cpp_impl_reflection >= 202500L
> +#if __cpp_impl_reflection >= 202506L
>  static_assert(is_reflection_v<decltype(^^int)>
>               && is_reflection<decltype(^^int)>::value, "");
>  static_assert(!is_reflection_v<int> && !is_reflection<int>::value, "");
>
>         Jakub
>