LWG3482 drop_view's const begin should additionally require sized_range

Author: burblebee

source/ranges.tex

@@ -4743,9 +4743,10 @@
     constexpr V base() && { return std::move(@\exposid{base_}@); }
 
     constexpr auto begin()
-      requires (!(@\exposconcept{simple-view}@<V> && @\libconcept{random_access_range}@<V>));
+      requires (!(@\exposconcept{simple-view}@<V> &&
+		  @\libconcept{random_access_range}@<const V> && @\libconcept{sized_range}@<const V>));
     constexpr auto begin() const
-      requires @\libconcept{random_access_range}@<const V>;
+      requires @\libconcept{random_access_range}@<const V> && @\libconcept{sized_range}@<const V>;
 
     constexpr auto end()
       requires (!@\exposconcept{simple-view}@<V>)
@@ -4799,9 +4800,10 @@
 \indexlibrarymember{begin}{drop_view}%
 \begin{itemdecl}
 constexpr auto begin()
-  requires (!(@\exposconcept{simple-view}@<V> && @\libconcept{random_access_range}@<V>));
+  requires (!(@\exposconcept{simple-view}@<V> &&
+	      @\libconcept{random_access_range}@<const V> && @\libconcept{sized_range}@<const V>));
 constexpr auto begin() const
-  requires random_access_range<const V>;
+  requires random_access_range<const V> && @\libconcept{sized_range}@<const V>;
 \end{itemdecl}
 
 \begin{itemdescr}