LWG3765 const_sentinel should be constrained

Author: burblebee

source/iterators.tex

@@ -342,7 +342,7 @@
     concept @\exposconcept{constant-iterator}@ = @\seebelow@; // \expos
   template<@\libconcept{input_iterator}@ I>
     using const_iterator = @\seebelow@;                                               // freestanding
-  template<class S>
+  template<@\libconcept{semiregular}@ S>
     using const_sentinel = @\seebelow@;                                               // freestanding
 
   // \ref{const.iterators.iterator}, class template \tcode{basic_const_iterator}
@@ -365,7 +365,7 @@
   template<@\libconcept{input_iterator}@ I>
     constexpr const_iterator<I> make_const_iterator(I it) { return it; }            // freestanding
 
-  template<class S>
+  template<@\libconcept{semiregular}@ S>
     constexpr const_sentinel<S> make_const_sentinel(S s) { return s; }              // freestanding
 
   // \ref{move.iterators}, move iterators and sentinels
@@ -4199,7 +4199,7 @@
 \end{itemdescr}
 
 \begin{itemdecl}
-template<class S>
+template<@\libconcept{semiregular}@ S>
   using @\libglobal{const_sentinel}@ = @\seebelow@;
 \end{itemdecl}