From: Patrick Palka <ppalka@redhat.com>
Date: Thu, 21 Oct 2021 01:34:21 +0000 (-0400)
Subject: libstdc++: Implement LWG 3535 changes to ranges::join_view
X-Git-Tag: basepoints/gcc-13~3725
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6667274b0593a64dd3de3c7c3565bec42af35b62;p=thirdparty%2Fgcc.git

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.
---

diff --git a/libstdc++-v3/include/std/ranges b/libstdc++-v3/include/std/ranges
index 273699aa7900..c1519c7dbd5f 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>