LWG3761 cartesian_product_view::iterator::operator- should pass by reference

Author: burblebee

source/ranges.tex

@@ -14498,9 +14498,9 @@
     friend constexpr difference_type operator-(const @\exposid{iterator}@& x, const @\exposid{iterator}@& y)
       requires @\exposconcept{cartesian-is-sized-sentinel}@<Const, iterator_t, First, Vs...>;
 
-    friend constexpr difference_type operator-(@\exposid{iterator}@ i, default_sentinel_t)
+    friend constexpr difference_type operator-(const @\exposid{iterator}@& i, default_sentinel_t)
       requires @\exposconcept{cartesian-is-sized-sentinel}@<Const, sentinel_t, First, Vs...>;
-    friend constexpr difference_type operator-(default_sentinel_t, @\exposid{iterator}@ i)
+    friend constexpr difference_type operator-(default_sentinel_t, const @\exposid{iterator}@& i)
       requires @\exposconcept{cartesian-is-sized-sentinel}@<Const, sentinel_t, First, Vs...>;
 
     friend constexpr auto iter_move(const @\exposid{iterator}@& i) noexcept(@\seebelow@);
@@ -14522,7 +14522,7 @@
       constexpr void @\exposidnc{prev}@();                                            // \expos
 
     template<class Tuple>
-      constexpr difference_type @\exposidnc{distance-from}@(Tuple t);                 // \expos
+      constexpr difference_type @\exposidnc{distance-from}@(const Tuple& t) const;    // \expos
 
     constexpr @\exposid{iterator}@(@\exposid{Parent}@& parent, tuple<iterator_t<@\exposid{maybe-const}@<Const, First>>,
       iterator_t<@\exposidnc{maybe-const}@<Const, Vs>>...> current);                  // \expos
@@ -14608,7 +14608,7 @@
 
 \begin{itemdecl}
 template<class Tuple>
-  constexpr difference_type @\exposid{distance-from}@(Tuple t);
+  constexpr difference_type @\exposid{distance-from}@(const Tuple& t) const;
 \end{itemdecl}
 
 \begin{itemdescr}
@@ -14893,7 +14893,7 @@
 \end{itemdescr}
 
 \begin{itemdecl}
-friend constexpr difference_type operator-(@\exposid{iterator}@ i, default_sentinel_t)
+friend constexpr difference_type operator-(const @\exposid{iterator}@& i, default_sentinel_t)
   requires @\exposconcept{cartesian-is-sized-sentinel}@<Const, sentinel_t, First, Vs...>;
 \end{itemdecl}
 
@@ -14917,7 +14917,7 @@
 \end{itemdescr}
 
 \begin{itemdecl}
-friend constexpr difference_type operator-(default_sentinel_t s, @\exposid{iterator}@ i)
+friend constexpr difference_type operator-(default_sentinel_t s, const @\exposid{iterator}@& i)
   requires @\exposconcept{cartesian-is-sized-sentinel}@<Const, sentinel_t, First, Vs...>;
 \end{itemdecl}