[gcc r11-9819] libstdc++: Implement LWG 3535 changes to ranges::join_view

[Patrick Palka]

https://gcc.gnu.org/g:b0561bc86b3d70f823b506c6baa738303869dda1

commit r11-9819-gb0561bc86b3d70f823b506c6baa738303869dda1
Author: Patrick Palka <ppalka@redhat.com>
Date:   Wed Oct 20 21:34:21 2021 -0400

    libstdc++: Implement LWG 3535 changes to ranges::join_view
    
    libstdc++-v3/ChangeLog:
    
            * include/std/ranges (join_view::__iter_cat::_S_iter_cat): Adjust
            criteria for returning bidirectional_iterator_tag as per LWG 3535.
            (join_view::_Iterator::_S_iter_concept): Likewise.
    
    (cherry picked from commit 6667274b0593a64dd3de3c7c3565bec42af35b62)

Diff:
---
 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 99404acda3d..52ca9080759 100644
--- a/libstdc++-v3/include/std/ranges
+++ b/libstdc++-v3/include/std/ranges
@@ -2471,7 +2471,8 @@ 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>)
@@ -2523,7 +2524,8 @@ 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>