LWG3347 std::pair<T, U> now requires T and U to be less-than-comparable

Author: Dawn Perchik

source/containers.tex

@@ -3121,6 +3121,12 @@
   // \ref{array}, class template \tcode{array}
   template<class T, size_t N> struct array;
 
+template<class T, size_t N>
+  constexpr bool operator==(const array<T, N>& x, const array<T, N>& y);
+template<class T, size_t N>
+  constexpr @\placeholder{synth-three-way-result}@<T>
+    operator<=>(const array<T, N>& x, const array<T, N>& y);
+
   template<class T, size_t N>
     constexpr void swap(array<T, N>& x, array<T, N>& y) noexcept(noexcept(x.swap(y)));
 
@@ -3383,10 +3389,6 @@
 
     constexpr T *       data() noexcept;
     constexpr const T * data() const noexcept;
-
-    friend constexpr bool operator==(const array&, const array&) = default;
-    friend constexpr @\placeholder{synth-three-way-result}@<value_type>
-      operator<=>(const array&, const array&);
   };
 
   template<class T, class... U>

source/utilities.tex

@@ -100,6 +100,13 @@
     struct pair;
 
   // \ref{pairs.spec}, pair specialized algorithms
+  template<class T1, class T2>
+    constexpr bool operator==(const pair<T1, T2>&, const pair<T1, T2>&);
+  template<class T1, class T2>
+    constexpr common_comparison_category_t<@\placeholder{synth-three-way-result}@<T1>,
+                                           @\placeholder{synth-three-way-result}@<T2>>
+      operator<=>(const pair<T1, T2>&, const pair<T1, T2>&);
+
   template<class T1, class T2>
     constexpr void swap(pair<T1, T2>& x, pair<T1, T2>& y) noexcept(noexcept(x.swap(y)));
 
@@ -496,15 +503,6 @@
       constexpr pair& operator=(pair<U1, U2>&& p);
 
     constexpr void swap(pair& p) noexcept(@\seebelow@);
-
-    // \ref{pairs.spec}, pair specialized algorithms
-    friend constexpr bool operator==(const pair&, const pair&) = default;
-    friend constexpr bool operator==(const pair& x, const pair& y)
-      requires (is_reference_v<T1> || is_reference_v<T2>)
-      { return x.first == y.first && x.second == y.second; }
-    friend constexpr common_comparison_category_t<@\placeholder{synth-three-way-result}@<T1>,
-                                                  @\placeholder{synth-three-way-result}@<T2>>
-      operator<=>(const pair& x, const pair& y) { @\seebelow@ }
   };
 
   template<class T1, class T2>
@@ -790,11 +788,24 @@
 
 \rSec2[pairs.spec]{Specialized algorithms}
 
+\indexlibrarymember{operator==}{pair}%
+\begin{itemdecl}
+template<class T1, class T2>
+  constexpr bool operator==(const pair<T1, T2>& x, const pair<T1, T2>& y);
+\end{itemdecl}
+
+\begin{itemdescr}
+\pnum
+\returns
+\tcode{x.first == y.first \&\& x.second == y.second}.
+\end{itemdescr}
+
 \indexlibrarymember{operator<=>}{pair}%
 \begin{itemdecl}
-friend constexpr
-  common_comparison_category_t<@\placeholder{synth-three-way-result}@<T1>, @\placeholder{synth-three-way-result}@<T2>>
-    operator<=>(const pair& x, const pair& y);
+template<class T1, class T2>
+  constexpr common_comparison_category_t<@\placeholder{synth-three-way-result}@<T1>,
+                                         @\placeholder{synth-three-way-result}@<T2>>
+    operator<=>(const pair<T1, T2>& x, const pair<T1, T2>& y);
 \end{itemdecl}
 
 \begin{itemdescr}