LWG3533 Make base() const & consistent across iterator wrappers that supports input_iterators

Author: jensmaurer

source/ranges.tex

@@ -3337,8 +3337,7 @@
     @\exposid{iterator}@() = default;
     constexpr @\exposid{iterator}@(filter_view& parent, iterator_t<V> current);
 
-    constexpr iterator_t<V> base() const &
-      requires @\libconcept{copyable}@<iterator_t<V>>;
+    constexpr const iterator_t<V>& base() const &;
     constexpr iterator_t<V> base() &&;
     constexpr range_reference_t<V> operator*() const;
     constexpr iterator_t<V> operator->() const
@@ -3414,8 +3413,7 @@
 
 \indexlibrarymember{base}{filter_view::iterator}%
 \begin{itemdecl}
-constexpr iterator_t<V> base() const &
-  requires @\libconcept{copyable}@<iterator_t<V>>;
+constexpr const iterator_t<V>& base() const &;
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -3834,8 +3832,7 @@
     constexpr @\exposid{iterator}@(@\exposid{iterator}@<!Const> i)
       requires Const && @\libconcept{convertible_to}@<iterator_t<V>, iterator_t<@\exposid{Base}@>>;
 
-    constexpr iterator_t<@\exposid{Base}@> base() const &
-      requires @\libconcept{copyable}@<iterator_t<@\exposid{Base}@>>;
+    constexpr const iterator_t<@\exposid{Base}@>& base() const &;
     constexpr iterator_t<@\exposid{Base}@> base() &&;
     constexpr decltype(auto) operator*() const
     { return invoke(*@\exposid{parent_}@->@\exposid{fun_}@, *@\exposid{current_}@); }
@@ -3958,8 +3955,7 @@
 
 \indexlibrarymember{base}{transform_view::iterator}%
 \begin{itemdecl}
-constexpr iterator_t<@\exposid{Base}@> base() const &
-  requires @\libconcept{copyable}@<iterator_t<@\exposid{Base}@>>;
+constexpr const iterator_t<@\exposid{Base}@>& base() const &;
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -6473,8 +6469,7 @@
     constexpr @\exposid{iterator}@(@\exposid{iterator}@<!Const> i)
       requires Const && @\libconcept{convertible_to}@<iterator_t<V>, iterator_t<@\exposid{Base}@>>;
 
-    constexpr iterator_t<@\exposid{Base}@> base() const&
-      requires @\libconcept{copyable}@<iterator_t<@\exposid{Base}@>>;
+    constexpr const iterator_t<@\exposid{Base}@>& base() const&;
     constexpr iterator_t<@\exposid{Base}@> base() &&;
 
     constexpr decltype(auto) operator*() const
@@ -6600,8 +6595,7 @@
 
 \indexlibrarymember{base}{elements_view::iterator}%
 \begin{itemdecl}
-constexpr iterator_t<@\exposid{Base}@> base() const&
-  requires @\libconcept{copyable}@<iterator_t<@\exposid{Base}@>>;
+constexpr const iterator_t<@\exposid{Base}@>& base() const&;
 \end{itemdecl}
 
 \begin{itemdescr}