Re: [PATCH] libstdc++: Implement LWG 3535 changes to ranges::join_view

[Jonathan Wakely <jwakely@redhat.com>]

On Wed, 20 Oct 2021 at 18:03, Patrick Palka via Libstdc++
<libstdc++@gcc.gnu.org> wrote:
>
> Tested on x86_64-pc-linux-gnu, does this look OK for trunk, and branches
> after a while?

Yes for all.


>
> libstdc++-v3/ChangeLog:
>
>         * include/std/ranges (join_view::__iter_cat::_S_iter_cat): Adjust
>         criteria for returning bidirectional_iterator_tag as per LWG3535.
>         (join_view::_Iterator::_S_iter_concept): Likewise.
> ---
>  libstdc++-v3/include/std/ranges | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
> index 273699aa790..c1519c7dbd5 100644
> --- a/libstdc++-v3/include/std/ranges
> +++ b/libstdc++-v3/include/std/ranges
> @@ -2523,7 +2523,8 @@ namespace views::__adaptor
>             using _OuterCat = typename iterator_traits<_Outer_iter>::iterator_category;
>             using _InnerCat = typename iterator_traits<_Inner_iter>::iterator_category;
>             if constexpr (derived_from<_OuterCat, bidirectional_iterator_tag>
> -                         && derived_from<_InnerCat, bidirectional_iterator_tag>)
> +                         && derived_from<_InnerCat, bidirectional_iterator_tag>
> +                         && common_range<range_reference_t<_Base<_Const>>>)
>               return bidirectional_iterator_tag{};
>             else if constexpr (derived_from<_OuterCat, forward_iterator_tag>
>                                && derived_from<_InnerCat, forward_iterator_tag>)
> @@ -2575,7 +2576,8 @@ namespace views::__adaptor
>           {
>             if constexpr (_S_ref_is_glvalue
>                           && bidirectional_range<_Base>
> -                         && bidirectional_range<range_reference_t<_Base>>)
> +                         && bidirectional_range<range_reference_t<_Base>>
> +                         && common_range<range_reference_t<_Base>>)
>               return bidirectional_iterator_tag{};
>             else if constexpr (_S_ref_is_glvalue
>                                && forward_range<_Base>
> --
> 2.33.1.711.g9d530dc002
>