LWG4074 compatible-joinable-ranges is underconstrained

Author: burblebee

source/ranges.tex

@@ -334,13 +334,8 @@
   namespace views { inline constexpr @\unspecnc@ join = @\unspecnc@; }              // freestanding
 
   // \ref{range.join.with}, join with view
-  template<class R, class P>
-    concept @\exposconcept{compatible-joinable-ranges}@ = @\seebelow@; // \expos
-
   template<@\libconcept{input_range}@ V, @\libconcept{forward_range}@ Pattern>
-    requires @\libconcept{view}@<V> && @\libconcept{input_range}@<range_reference_t<V>>
-          && @\libconcept{view}@<Pattern>
-          && @\exposconcept{compatible-joinable-ranges}@<range_reference_t<V>, Pattern>
+    requires @\seebelow@
   class join_with_view;                                                             // freestanding
 
   namespace views { inline constexpr @\unspecnc@ join_with = @\unspecnc@; }         // freestanding
@@ -7023,19 +7018,13 @@
 
 \begin{codeblock}
 namespace std::ranges {
-  template<class R, class P>
-  concept @\defexposconcept{compatible-joinable-ranges}@ =            // \expos
-      @\libconcept{common_with}@<range_value_t<R>, range_value_t<P>> &&
-      @\libconcept{common_reference_with}@<range_reference_t<R>, range_reference_t<P>> &&
-      @\libconcept{common_reference_with}@<range_rvalue_reference_t<R>, range_rvalue_reference_t<P>>;
-
   template<class R>
   concept @\defexposconcept{bidirectional-common}@ = @\libconcept{bidirectional_range}@<R> && @\libconcept{common_range}@<R>;    // \expos
 
   template<@\libconcept{input_range}@ V, @\libconcept{forward_range}@ Pattern>
     requires @\libconcept{view}@<V> && @\libconcept{input_range}@<range_reference_t<V>>
           && @\libconcept{view}@<Pattern>
-          && @\exposconcept{compatible-joinable-ranges}@<range_reference_t<V>, Pattern>
+          && @\exposconcept{concatable}@<range_reference_t<V>, Pattern>
   class join_with_view : public view_interface<join_with_view<V, Pattern>> {
     using @\exposid{InnerRng}@ = range_reference_t<V>;                  // \expos
 
@@ -7081,7 +7070,8 @@
       requires @\libconcept{forward_range}@<const V> &&
                @\libconcept{forward_range}@<const Pattern> &&
                is_reference_v<range_reference_t<const V>> &&
-               @\libconcept{input_range}@<range_reference_t<const V>> {
+               @\libconcept{input_range}@<range_reference_t<const V>> &&
+               @\exposconcept{concatable}@<range_reference_t<const V>, const Pattern> {
       return @\exposid{iterator}@<true>{*this, ranges::begin(@\exposid{base_}@)};
     }
 
@@ -7096,7 +7086,8 @@
     constexpr auto end() const
       requires @\libconcept{forward_range}@<const V> && @\libconcept{forward_range}@<const Pattern> &&
                is_reference_v<range_reference_t<const V>> &&
-               @\libconcept{input_range}@<range_reference_t<const V>> {
+               @\libconcept{input_range}@<range_reference_t<const V>> &&
+               @\exposconcept{concatable}@<range_reference_t<const V>, const Pattern> {
       using InnerConstRng = range_reference_t<const V>;
       if constexpr (@\libconcept{forward_range}@<InnerConstRng> &&
                     @\libconcept{common_range}@<const V> && @\libconcept{common_range}@<InnerConstRng>)
@@ -7146,7 +7137,7 @@
 namespace std::ranges {
   template<@\libconcept{input_range}@ V, @\libconcept{forward_range}@ Pattern>
     requires @\libconcept{view}@<V> && @\libconcept{input_range}@<range_reference_t<V>>
-          && @\libconcept{view}@<Pattern> && @\exposconcept{compatible-joinable-ranges}@<range_reference_t<V>, Pattern>
+          && @\libconcept{view}@<Pattern> && @\exposconcept{concatable}@<range_reference_t<V>, Pattern>
   template<bool Const>
   class join_with_view<V, Pattern>::@\exposid{iterator}@ {
     using @\exposid{Parent}@ = @\exposid{maybe-const}@<Const, join_with_view>;                  // \expos
@@ -7553,7 +7544,7 @@
 namespace std::ranges {
   template<@\libconcept{input_range}@ V, @\libconcept{forward_range}@ Pattern>
     requires @\libconcept{view}@<V> && @\libconcept{input_range}@<range_reference_t<V>>
-          && @\libconcept{view}@<Pattern> && @\exposconcept{compatible-joinable-ranges}@<range_reference_t<V>, Pattern>
+          && @\libconcept{view}@<Pattern> && @\exposconcept{concatable}@<range_reference_t<V>, Pattern>
   template<bool Const>
   class join_with_view<V, Pattern>::@\exposid{sentinel}@ {
     using @\exposid{Parent}@ = @\exposid{maybe-const}@<Const, join_with_view>;  // \expos