[libc++] Implement part of P2562R1: constexpr `ranges::stable_sort` (#128860)

Drive-by: Enables test coverage for `ranges::stable_sort` with proxy
iterators, and changes "constexpr in" to "constexpr since" in comments
in `<algorithm>`.
diff --git a/libcxx/include/algorithm b/libcxx/include/algorithm
index 8758aed..7dcafbc 100644
--- a/libcxx/include/algorithm
+++ b/libcxx/include/algorithm
@@ -422,11 +422,12 @@
   template<random_access_iterator I, sentinel_for<I> S, class Comp = ranges::less,
           class Proj = identity>
     requires sortable<I, Comp, Proj>
-    I ranges::stable_sort(I first, S last, Comp comp = {}, Proj proj = {});                 // since C++20
+    constexpr I                                                                             // constexpr since C++26
+      ranges::stable_sort(I first, S last, Comp comp = {}, Proj proj = {});                 // since C++20
 
   template<random_access_range R, class Comp = ranges::less, class Proj = identity>
     requires sortable<iterator_t<R>, Comp, Proj>
-    borrowed_iterator_t<R>
+    constexpr borrowed_iterator_t<R>                                                        // constexpr since C++26
       ranges::stable_sort(R&& r, Comp comp = {}, Proj proj = {});                           // since C++20
 
   template<random_access_iterator I, sentinel_for<I> S, class Comp = ranges::less,
@@ -1167,84 +1168,84 @@
 }
 
 template <class InputIterator, class Predicate>
-    constexpr bool     // constexpr in C++20
+    constexpr bool     // constexpr since C++20
     all_of(InputIterator first, InputIterator last, Predicate pred);
 
 template <class InputIterator, class Predicate>
-    constexpr bool     // constexpr in C++20
+    constexpr bool     // constexpr since C++20
     any_of(InputIterator first, InputIterator last, Predicate pred);
 
 template <class InputIterator, class Predicate>
-    constexpr bool     // constexpr in C++20
+    constexpr bool     // constexpr since C++20
     none_of(InputIterator first, InputIterator last, Predicate pred);
 
 template <class InputIterator, class Function>
-    constexpr Function          // constexpr in C++20
+    constexpr Function          // constexpr since C++20
     for_each(InputIterator first, InputIterator last, Function f);
 
 template<class InputIterator, class Size, class Function>
-    constexpr InputIterator     // constexpr in C++20
+    constexpr InputIterator     // constexpr since C++20
     for_each_n(InputIterator first, Size n, Function f); // C++17
 
 template <class InputIterator, class T>
-    constexpr InputIterator     // constexpr in C++20
+    constexpr InputIterator     // constexpr since C++20
     find(InputIterator first, InputIterator last, const T& value);
 
 template <class InputIterator, class Predicate>
-    constexpr InputIterator     // constexpr in C++20
+    constexpr InputIterator     // constexpr since C++20
     find_if(InputIterator first, InputIterator last, Predicate pred);
 
 template<class InputIterator, class Predicate>
-    constexpr InputIterator     // constexpr in C++20
+    constexpr InputIterator     // constexpr since C++20
     find_if_not(InputIterator first, InputIterator last, Predicate pred);
 
 template <class ForwardIterator1, class ForwardIterator2>
-    constexpr ForwardIterator1  // constexpr in C++20
+    constexpr ForwardIterator1  // constexpr since C++20
     find_end(ForwardIterator1 first1, ForwardIterator1 last1,
              ForwardIterator2 first2, ForwardIterator2 last2);
 
 template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
-    constexpr ForwardIterator1  // constexpr in C++20
+    constexpr ForwardIterator1  // constexpr since C++20
     find_end(ForwardIterator1 first1, ForwardIterator1 last1,
              ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
 
 template <class ForwardIterator1, class ForwardIterator2>
-    constexpr ForwardIterator1  // constexpr in C++20
+    constexpr ForwardIterator1  // constexpr since C++20
     find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
                   ForwardIterator2 first2, ForwardIterator2 last2);
 
 template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
-    constexpr ForwardIterator1  // constexpr in C++20
+    constexpr ForwardIterator1  // constexpr since C++20
     find_first_of(ForwardIterator1 first1, ForwardIterator1 last1,
                   ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
 
 template <class ForwardIterator>
-    constexpr ForwardIterator   // constexpr in C++20
+    constexpr ForwardIterator   // constexpr since C++20
     adjacent_find(ForwardIterator first, ForwardIterator last);
 
 template <class ForwardIterator, class BinaryPredicate>
-    constexpr ForwardIterator   // constexpr in C++20
+    constexpr ForwardIterator   // constexpr since C++20
     adjacent_find(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);
 
 template <class InputIterator, class T>
-    constexpr typename iterator_traits<InputIterator>::difference_type  // constexpr in C++20
+    constexpr typename iterator_traits<InputIterator>::difference_type  // constexpr since C++20
     count(InputIterator first, InputIterator last, const T& value);
 
 template <class InputIterator, class Predicate>
-    constexpr typename iterator_traits<InputIterator>::difference_type // constexpr in C++20
+    constexpr typename iterator_traits<InputIterator>::difference_type // constexpr since C++20
     count_if(InputIterator first, InputIterator last, Predicate pred);
 
 template <class InputIterator1, class InputIterator2>
-    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
+    constexpr pair<InputIterator1, InputIterator2>   // constexpr since C++20
     mismatch(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2);
 
 template <class InputIterator1, class InputIterator2>
     constexpr pair<InputIterator1, InputIterator2>
     mismatch(InputIterator1 first1, InputIterator1 last1,
-             InputIterator2 first2, InputIterator2 last2);              // since C++14, constexpr in C++20
+             InputIterator2 first2, InputIterator2 last2);              // since C++14, constexpr since C++20
 
 template <class InputIterator1, class InputIterator2, class BinaryPredicate>
-    constexpr pair<InputIterator1, InputIterator2>   // constexpr in C++20
+    constexpr pair<InputIterator1, InputIterator2>   // constexpr since C++20
     mismatch(InputIterator1 first1, InputIterator1 last1,
              InputIterator2 first2, BinaryPredicate pred);
 
@@ -1252,19 +1253,19 @@
     constexpr pair<InputIterator1, InputIterator2>
     mismatch(InputIterator1 first1, InputIterator1 last1,
              InputIterator2 first2, InputIterator2 last2,
-             BinaryPredicate pred);                                     // since C++14, constexpr in C++20
+             BinaryPredicate pred);                                     // since C++14, constexpr since C++20
 
 template <class InputIterator1, class InputIterator2>
-    constexpr bool      // constexpr in C++20
+    constexpr bool      // constexpr since C++20
     equal(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2);
 
 template <class InputIterator1, class InputIterator2>
     constexpr bool
     equal(InputIterator1 first1, InputIterator1 last1,
-          InputIterator2 first2, InputIterator2 last2);                 // since C++14, constexpr in C++20
+          InputIterator2 first2, InputIterator2 last2);                 // since C++14, constexpr since C++20
 
 template <class InputIterator1, class InputIterator2, class BinaryPredicate>
-    constexpr bool      // constexpr in C++20
+    constexpr bool      // constexpr since C++20
     equal(InputIterator1 first1, InputIterator1 last1,
           InputIterator2 first2, BinaryPredicate pred);
 
@@ -1272,20 +1273,20 @@
     constexpr bool
     equal(InputIterator1 first1, InputIterator1 last1,
           InputIterator2 first2, InputIterator2 last2,
-          BinaryPredicate pred);                                        // since C++14, constexpr in C++20
+          BinaryPredicate pred);                                        // since C++14, constexpr since C++20
 
 template<class ForwardIterator1, class ForwardIterator2>
-    constexpr bool      // constexpr in C++20
+    constexpr bool      // constexpr since C++20
     is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
                    ForwardIterator2 first2);
 
 template<class ForwardIterator1, class ForwardIterator2>
     constexpr bool
     is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
-                   ForwardIterator2 first2, ForwardIterator2 last2);    // since C++14, constexpr in C++20
+                   ForwardIterator2 first2, ForwardIterator2 last2);    // since C++14, constexpr since C++20
 
 template<class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
-    constexpr bool      // constexpr in C++20
+    constexpr bool      // constexpr since C++20
     is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
                    ForwardIterator2 first2, BinaryPredicate pred);
 
@@ -1293,42 +1294,42 @@
     constexpr bool
     is_permutation(ForwardIterator1 first1, ForwardIterator1 last1,
                    ForwardIterator2 first2, ForwardIterator2 last2,
-                   BinaryPredicate pred);                               // since C++14, constexpr in C++20
+                   BinaryPredicate pred);                               // since C++14, constexpr since C++20
 
 template <class ForwardIterator1, class ForwardIterator2>
-    constexpr ForwardIterator1      // constexpr in C++20
+    constexpr ForwardIterator1      // constexpr since C++20
     search(ForwardIterator1 first1, ForwardIterator1 last1,
            ForwardIterator2 first2, ForwardIterator2 last2);
 
 template <class ForwardIterator1, class ForwardIterator2, class BinaryPredicate>
-    constexpr ForwardIterator1      // constexpr in C++20
+    constexpr ForwardIterator1      // constexpr since C++20
     search(ForwardIterator1 first1, ForwardIterator1 last1,
            ForwardIterator2 first2, ForwardIterator2 last2, BinaryPredicate pred);
 
 template <class ForwardIterator, class Size, class T>
-    constexpr ForwardIterator       // constexpr in C++20
+    constexpr ForwardIterator       // constexpr since C++20
     search_n(ForwardIterator first, ForwardIterator last, Size count, const T& value);
 
 template <class ForwardIterator, class Size, class T, class BinaryPredicate>
-    constexpr ForwardIterator       // constexpr in C++20
+    constexpr ForwardIterator       // constexpr since C++20
     search_n(ForwardIterator first, ForwardIterator last,
              Size count, const T& value, BinaryPredicate pred);
 
 template <class InputIterator, class OutputIterator>
-    constexpr OutputIterator      // constexpr in C++20
+    constexpr OutputIterator      // constexpr since C++20
     copy(InputIterator first, InputIterator last, OutputIterator result);
 
 template<class InputIterator, class OutputIterator, class Predicate>
-    constexpr OutputIterator      // constexpr in C++20
+    constexpr OutputIterator      // constexpr since C++20
     copy_if(InputIterator first, InputIterator last,
             OutputIterator result, Predicate pred);
 
 template<class InputIterator, class Size, class OutputIterator>
-    constexpr OutputIterator      // constexpr in C++20
+    constexpr OutputIterator      // constexpr since C++20
     copy_n(InputIterator first, Size n, OutputIterator result);
 
 template <class BidirectionalIterator1, class BidirectionalIterator2>
-    constexpr BidirectionalIterator2      // constexpr in C++20
+    constexpr BidirectionalIterator2      // constexpr since C++20
     copy_backward(BidirectionalIterator1 first, BidirectionalIterator1 last,
                   BidirectionalIterator2 result);
 
@@ -1343,7 +1344,7 @@
                   BidirectionalIterator2 result);
 
 template <class ForwardIterator1, class ForwardIterator2>
-    constexpr ForwardIterator2    // constexpr in C++20
+    constexpr ForwardIterator2    // constexpr since C++20
     swap_ranges(ForwardIterator1 first1, ForwardIterator1 last1, ForwardIterator2 first2);
 
 namespace ranges {
@@ -1362,97 +1363,97 @@
 }
 
 template <class ForwardIterator1, class ForwardIterator2>
-    constexpr void                // constexpr in C++20
+    constexpr void                // constexpr since C++20
     iter_swap(ForwardIterator1 a, ForwardIterator2 b);
 
 template <class InputIterator, class OutputIterator, class UnaryOperation>
-    constexpr OutputIterator      // constexpr in C++20
+    constexpr OutputIterator      // constexpr since C++20
     transform(InputIterator first, InputIterator last, OutputIterator result, UnaryOperation op);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator, class BinaryOperation>
-    constexpr OutputIterator      // constexpr in C++20
+    constexpr OutputIterator      // constexpr since C++20
     transform(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2,
               OutputIterator result, BinaryOperation binary_op);
 
 template <class ForwardIterator, class T>
-    constexpr void      // constexpr in C++20
+    constexpr void      // constexpr since C++20
     replace(ForwardIterator first, ForwardIterator last, const T& old_value, const T& new_value);
 
 template <class ForwardIterator, class Predicate, class T>
-    constexpr void      // constexpr in C++20
+    constexpr void      // constexpr since C++20
     replace_if(ForwardIterator first, ForwardIterator last, Predicate pred, const T& new_value);
 
 template <class InputIterator, class OutputIterator, class T>
-    constexpr OutputIterator      // constexpr in C++20
+    constexpr OutputIterator      // constexpr since C++20
     replace_copy(InputIterator first, InputIterator last, OutputIterator result,
                  const T& old_value, const T& new_value);
 
 template <class InputIterator, class OutputIterator, class Predicate, class T>
-    constexpr OutputIterator      // constexpr in C++20
+    constexpr OutputIterator      // constexpr since C++20
     replace_copy_if(InputIterator first, InputIterator last, OutputIterator result, Predicate pred, const T& new_value);
 
 template <class ForwardIterator, class T>
-    constexpr void      // constexpr in C++20
+    constexpr void      // constexpr since C++20
     fill(ForwardIterator first, ForwardIterator last, const T& value);
 
 template <class OutputIterator, class Size, class T>
-    constexpr OutputIterator      // constexpr in C++20
+    constexpr OutputIterator      // constexpr since C++20
     fill_n(OutputIterator first, Size n, const T& value);
 
 template <class ForwardIterator, class Generator>
-    constexpr void      // constexpr in C++20
+    constexpr void      // constexpr since C++20
     generate(ForwardIterator first, ForwardIterator last, Generator gen);
 
 template <class OutputIterator, class Size, class Generator>
-    constexpr OutputIterator      // constexpr in C++20
+    constexpr OutputIterator      // constexpr since C++20
     generate_n(OutputIterator first, Size n, Generator gen);
 
 template <class ForwardIterator, class T>
-    constexpr ForwardIterator     // constexpr in C++20
+    constexpr ForwardIterator     // constexpr since C++20
     remove(ForwardIterator first, ForwardIterator last, const T& value);
 
 template <class ForwardIterator, class Predicate>
-    constexpr ForwardIterator     // constexpr in C++20
+    constexpr ForwardIterator     // constexpr since C++20
     remove_if(ForwardIterator first, ForwardIterator last, Predicate pred);
 
 template <class InputIterator, class OutputIterator, class T>
-    constexpr OutputIterator     // constexpr in C++20
+    constexpr OutputIterator     // constexpr since C++20
     remove_copy(InputIterator first, InputIterator last, OutputIterator result, const T& value);
 
 template <class InputIterator, class OutputIterator, class Predicate>
-    constexpr OutputIterator     // constexpr in C++20
+    constexpr OutputIterator     // constexpr since C++20
     remove_copy_if(InputIterator first, InputIterator last, OutputIterator result, Predicate pred);
 
 template <class ForwardIterator>
-    constexpr ForwardIterator    // constexpr in C++20
+    constexpr ForwardIterator    // constexpr since C++20
     unique(ForwardIterator first, ForwardIterator last);
 
 template <class ForwardIterator, class BinaryPredicate>
-    constexpr ForwardIterator    // constexpr in C++20
+    constexpr ForwardIterator    // constexpr since C++20
     unique(ForwardIterator first, ForwardIterator last, BinaryPredicate pred);
 
 template <class InputIterator, class OutputIterator>
-    constexpr OutputIterator     // constexpr in C++20
+    constexpr OutputIterator     // constexpr since C++20
     unique_copy(InputIterator first, InputIterator last, OutputIterator result);
 
 template <class InputIterator, class OutputIterator, class BinaryPredicate>
-    constexpr OutputIterator     // constexpr in C++20
+    constexpr OutputIterator     // constexpr since C++20
     unique_copy(InputIterator first, InputIterator last, OutputIterator result, BinaryPredicate pred);
 
 template <class BidirectionalIterator>
-    constexpr void               // constexpr in C++20
+    constexpr void               // constexpr since C++20
     reverse(BidirectionalIterator first, BidirectionalIterator last);
 
 template <class BidirectionalIterator, class OutputIterator>
-    constexpr OutputIterator       // constexpr in C++20
+    constexpr OutputIterator       // constexpr since C++20
     reverse_copy(BidirectionalIterator first, BidirectionalIterator last, OutputIterator result);
 
 template <class ForwardIterator>
-    constexpr ForwardIterator      // constexpr in C++20
+    constexpr ForwardIterator      // constexpr since C++20
     rotate(ForwardIterator first, ForwardIterator middle, ForwardIterator last);
 
 template <class ForwardIterator, class OutputIterator>
-    constexpr OutputIterator       // constexpr in C++20
+    constexpr OutputIterator       // constexpr since C++20
     rotate_copy(ForwardIterator first, ForwardIterator middle, ForwardIterator last, OutputIterator result);
 
 template <class RandomAccessIterator>
@@ -1485,125 +1486,125 @@
                 typename iterator_traits<ForwardIterator>::difference_type n); // C++20
 
 template <class InputIterator, class Predicate>
-    constexpr bool  // constexpr in C++20
+    constexpr bool  // constexpr since C++20
     is_partitioned(InputIterator first, InputIterator last, Predicate pred);
 
 template <class ForwardIterator, class Predicate>
-    constexpr ForwardIterator  // constexpr in C++20
+    constexpr ForwardIterator  // constexpr since C++20
     partition(ForwardIterator first, ForwardIterator last, Predicate pred);
 
 template <class InputIterator, class OutputIterator1,
           class OutputIterator2, class Predicate>
-    constexpr pair<OutputIterator1, OutputIterator2>   // constexpr in C++20
+    constexpr pair<OutputIterator1, OutputIterator2>   // constexpr since C++20
     partition_copy(InputIterator first, InputIterator last,
                    OutputIterator1 out_true, OutputIterator2 out_false,
                    Predicate pred);
 
 template <class ForwardIterator, class Predicate>
-    constexpr ForwardIterator                          // constexpr in C++26
+    constexpr ForwardIterator                          // constexpr since C++26
     stable_partition(ForwardIterator first, ForwardIterator last, Predicate pred);
 
 template<class ForwardIterator, class Predicate>
-    constexpr ForwardIterator  // constexpr in C++20
+    constexpr ForwardIterator  // constexpr since C++20
     partition_point(ForwardIterator first, ForwardIterator last, Predicate pred);
 
 template <class ForwardIterator>
-    constexpr bool  // constexpr in C++20
+    constexpr bool  // constexpr since C++20
     is_sorted(ForwardIterator first, ForwardIterator last);
 
 template <class ForwardIterator, class Compare>
-    constexpr bool  // constexpr in C++20
+    constexpr bool  // constexpr since C++20
     is_sorted(ForwardIterator first, ForwardIterator last, Compare comp);
 
 template<class ForwardIterator>
-    constexpr ForwardIterator    // constexpr in C++20
+    constexpr ForwardIterator    // constexpr since C++20
     is_sorted_until(ForwardIterator first, ForwardIterator last);
 
 template <class ForwardIterator, class Compare>
-    constexpr ForwardIterator    // constexpr in C++20
+    constexpr ForwardIterator    // constexpr since C++20
     is_sorted_until(ForwardIterator first, ForwardIterator last, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr void               // constexpr in C++20
+    constexpr void               // constexpr since C++20
     sort(RandomAccessIterator first, RandomAccessIterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr void               // constexpr in C++20
+    constexpr void               // constexpr since C++20
     sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr void               // constexpr in C++26
+    constexpr void               // constexpr since C++26
     stable_sort(RandomAccessIterator first, RandomAccessIterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr void               // constexpr in C++26
+    constexpr void               // constexpr since C++26
     stable_sort(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr void                    // constexpr in C++20
+    constexpr void                    // constexpr since C++20
     partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr void                    // constexpr in C++20
+    constexpr void                    // constexpr since C++20
     partial_sort(RandomAccessIterator first, RandomAccessIterator middle, RandomAccessIterator last, Compare comp);
 
 template <class InputIterator, class RandomAccessIterator>
-    constexpr RandomAccessIterator    // constexpr in C++20
+    constexpr RandomAccessIterator    // constexpr since C++20
     partial_sort_copy(InputIterator first, InputIterator last,
                       RandomAccessIterator result_first, RandomAccessIterator result_last);
 
 template <class InputIterator, class RandomAccessIterator, class Compare>
-    constexpr RandomAccessIterator    // constexpr in C++20
+    constexpr RandomAccessIterator    // constexpr since C++20
     partial_sort_copy(InputIterator first, InputIterator last,
                       RandomAccessIterator result_first, RandomAccessIterator result_last, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr void                    // constexpr in C++20
+    constexpr void                    // constexpr since C++20
     nth_element(RandomAccessIterator first, RandomAccessIterator nth, RandomAccessIterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr void                    // constexpr in C++20
+    constexpr void                    // constexpr since C++20
     nth_element(RandomAccessIterator first, RandomAccessIterator nth, RandomAccessIterator last, Compare comp);
 
 template <class ForwardIterator, class T>
-    constexpr ForwardIterator                         // constexpr in C++20
+    constexpr ForwardIterator                         // constexpr since C++20
     lower_bound(ForwardIterator first, ForwardIterator last, const T& value);
 
 template <class ForwardIterator, class T, class Compare>
-    constexpr ForwardIterator                         // constexpr in C++20
+    constexpr ForwardIterator                         // constexpr since C++20
     lower_bound(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
 
 template <class ForwardIterator, class T>
-    constexpr ForwardIterator                         // constexpr in C++20
+    constexpr ForwardIterator                         // constexpr since C++20
     upper_bound(ForwardIterator first, ForwardIterator last, const T& value);
 
 template <class ForwardIterator, class T, class Compare>
-    constexpr ForwardIterator                         // constexpr in C++20
+    constexpr ForwardIterator                         // constexpr since C++20
     upper_bound(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
 
 template <class ForwardIterator, class T>
-    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++20
+    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr since C++20
     equal_range(ForwardIterator first, ForwardIterator last, const T& value);
 
 template <class ForwardIterator, class T, class Compare>
-    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++20
+    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr since C++20
     equal_range(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
 
 template <class ForwardIterator, class T>
-    constexpr bool                                    // constexpr in C++20
+    constexpr bool                                    // constexpr since C++20
     binary_search(ForwardIterator first, ForwardIterator last, const T& value);
 
 template <class ForwardIterator, class T, class Compare>
-    constexpr bool                                    // constexpr in C++20
+    constexpr bool                                    // constexpr since C++20
     binary_search(ForwardIterator first, ForwardIterator last, const T& value, Compare comp);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                          // constexpr in C++20
+    constexpr OutputIterator                          // constexpr since C++20
     merge(InputIterator1 first1, InputIterator1 last1,
           InputIterator2 first2, InputIterator2 last2, OutputIterator result);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                          // constexpr in C++20
+    constexpr OutputIterator                          // constexpr since C++20
     merge(InputIterator1 first1, InputIterator1 last1,
           InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
 
@@ -1616,123 +1617,123 @@
     inplace_merge(BidirectionalIterator first, BidirectionalIterator middle, BidirectionalIterator last, Compare comp);
 
 template <class InputIterator1, class InputIterator2>
-    constexpr bool                                    // constexpr in C++20
+    constexpr bool                                    // constexpr since C++20
     includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
 
 template <class InputIterator1, class InputIterator2, class Compare>
-    constexpr bool                                    // constexpr in C++20
+    constexpr bool                                    // constexpr since C++20
     includes(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2, Compare comp);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                          // constexpr in C++20
+    constexpr OutputIterator                          // constexpr since C++20
     set_union(InputIterator1 first1, InputIterator1 last1,
               InputIterator2 first2, InputIterator2 last2, OutputIterator result);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                          // constexpr in C++20
+    constexpr OutputIterator                          // constexpr since C++20
     set_union(InputIterator1 first1, InputIterator1 last1,
               InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                         // constexpr in C++20
+    constexpr OutputIterator                         // constexpr since C++20
     set_intersection(InputIterator1 first1, InputIterator1 last1,
                      InputIterator2 first2, InputIterator2 last2, OutputIterator result);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                         // constexpr in C++20
+    constexpr OutputIterator                         // constexpr since C++20
     set_intersection(InputIterator1 first1, InputIterator1 last1,
                      InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                         // constexpr in C++20
+    constexpr OutputIterator                         // constexpr since C++20
     set_difference(InputIterator1 first1, InputIterator1 last1,
                    InputIterator2 first2, InputIterator2 last2, OutputIterator result);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                         // constexpr in C++20
+    constexpr OutputIterator                         // constexpr since C++20
     set_difference(InputIterator1 first1, InputIterator1 last1,
                    InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator>
-    constexpr OutputIterator                         // constexpr in C++20
+    constexpr OutputIterator                         // constexpr since C++20
     set_symmetric_difference(InputIterator1 first1, InputIterator1 last1,
                              InputIterator2 first2, InputIterator2 last2, OutputIterator result);
 
 template <class InputIterator1, class InputIterator2, class OutputIterator, class Compare>
-    constexpr OutputIterator                         // constexpr in C++20
+    constexpr OutputIterator                         // constexpr since C++20
     set_symmetric_difference(InputIterator1 first1, InputIterator1 last1,
                              InputIterator2 first2, InputIterator2 last2, OutputIterator result, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr void                                   // constexpr in C++20
+    constexpr void                                   // constexpr since C++20
     push_heap(RandomAccessIterator first, RandomAccessIterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr void                                   // constexpr in C++20
+    constexpr void                                   // constexpr since C++20
     push_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr void                                   // constexpr in C++20
+    constexpr void                                   // constexpr since C++20
     pop_heap(RandomAccessIterator first, RandomAccessIterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr void                                   // constexpr in C++20
+    constexpr void                                   // constexpr since C++20
     pop_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr void                                   // constexpr in C++20
+    constexpr void                                   // constexpr since C++20
     make_heap(RandomAccessIterator first, RandomAccessIterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr void                                   // constexpr in C++20
+    constexpr void                                   // constexpr since C++20
     make_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr void                                   // constexpr in C++20
+    constexpr void                                   // constexpr since C++20
     sort_heap(RandomAccessIterator first, RandomAccessIterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr void                                   // constexpr in C++20
+    constexpr void                                   // constexpr since C++20
     sort_heap(RandomAccessIterator first, RandomAccessIterator last, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr bool   // constexpr in C++20
+    constexpr bool   // constexpr since C++20
     is_heap(RandomAccessIterator first, RandomAccessiterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr bool   // constexpr in C++20
+    constexpr bool   // constexpr since C++20
     is_heap(RandomAccessIterator first, RandomAccessiterator last, Compare comp);
 
 template <class RandomAccessIterator>
-    constexpr RandomAccessIterator   // constexpr in C++20
+    constexpr RandomAccessIterator   // constexpr since C++20
     is_heap_until(RandomAccessIterator first, RandomAccessiterator last);
 
 template <class RandomAccessIterator, class Compare>
-    constexpr RandomAccessIterator   // constexpr in C++20
+    constexpr RandomAccessIterator   // constexpr since C++20
     is_heap_until(RandomAccessIterator first, RandomAccessiterator last, Compare comp);
 
 template <class ForwardIterator>
-    constexpr ForwardIterator        // constexpr in C++14
+    constexpr ForwardIterator        // constexpr since C++14
     min_element(ForwardIterator first, ForwardIterator last);
 
 template <class ForwardIterator, class Compare>
-    constexpr ForwardIterator        // constexpr in C++14
+    constexpr ForwardIterator        // constexpr since C++14
     min_element(ForwardIterator first, ForwardIterator last, Compare comp);
 
 template <class T>
-    constexpr const T&               // constexpr in C++14
+    constexpr const T&               // constexpr since C++14
     min(const T& a, const T& b);
 
 template <class T, class Compare>
-    constexpr const T&               // constexpr in C++14
+    constexpr const T&               // constexpr since C++14
     min(const T& a, const T& b, Compare comp);
 
 template<class T>
-    constexpr T                      // constexpr in C++14
+    constexpr T                      // constexpr since C++14
     min(initializer_list<T> t);
 
 template<class T, class Compare>
-    constexpr T                      // constexpr in C++14
+    constexpr T                      // constexpr since C++14
     min(initializer_list<T> t, Compare comp);
 
 template<class T>
@@ -1742,59 +1743,59 @@
     constexpr const T& clamp(const T& v, const T& lo, const T& hi, Compare comp); // C++17
 
 template <class ForwardIterator>
-    constexpr ForwardIterator        // constexpr in C++14
+    constexpr ForwardIterator        // constexpr since C++14
     max_element(ForwardIterator first, ForwardIterator last);
 
 template <class ForwardIterator, class Compare>
-    constexpr ForwardIterator        // constexpr in C++14
+    constexpr ForwardIterator        // constexpr since C++14
     max_element(ForwardIterator first, ForwardIterator last, Compare comp);
 
 template <class T>
-    constexpr const T&               // constexpr in C++14
+    constexpr const T&               // constexpr since C++14
     max(const T& a, const T& b);
 
 template <class T, class Compare>
-    constexpr const T&               // constexpr in C++14
+    constexpr const T&               // constexpr since C++14
     max(const T& a, const T& b, Compare comp);
 
 template<class T>
-    constexpr T                      // constexpr in C++14
+    constexpr T                      // constexpr since C++14
     max(initializer_list<T> t);
 
 template<class T, class Compare>
-    constexpr T                      // constexpr in C++14
+    constexpr T                      // constexpr since C++14
     max(initializer_list<T> t, Compare comp);
 
 template<class ForwardIterator>
-    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++14
+    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr since C++14
     minmax_element(ForwardIterator first, ForwardIterator last);
 
 template<class ForwardIterator, class Compare>
-    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr in C++14
+    constexpr pair<ForwardIterator, ForwardIterator>  // constexpr since C++14
     minmax_element(ForwardIterator first, ForwardIterator last, Compare comp);
 
 template<class T>
-    constexpr pair<const T&, const T&>  // constexpr in C++14
+    constexpr pair<const T&, const T&>  // constexpr since C++14
     minmax(const T& a, const T& b);
 
 template<class T, class Compare>
-    constexpr pair<const T&, const T&>  // constexpr in C++14
+    constexpr pair<const T&, const T&>  // constexpr since C++14
     minmax(const T& a, const T& b, Compare comp);
 
 template<class T>
-    constexpr pair<T, T>                // constexpr in C++14
+    constexpr pair<T, T>                // constexpr since C++14
     minmax(initializer_list<T> t);
 
 template<class T, class Compare>
-    constexpr pair<T, T>                // constexpr in C++14
+    constexpr pair<T, T>                // constexpr since C++14
     minmax(initializer_list<T> t, Compare comp);
 
 template <class InputIterator1, class InputIterator2>
-    constexpr bool     // constexpr in C++20
+    constexpr bool     // constexpr since C++20
     lexicographical_compare(InputIterator1 first1, InputIterator1 last1, InputIterator2 first2, InputIterator2 last2);
 
 template <class InputIterator1, class InputIterator2, class Compare>
-    constexpr bool     // constexpr in C++20
+    constexpr bool     // constexpr since C++20
     lexicographical_compare(InputIterator1 first1, InputIterator1 last1,
                             InputIterator2 first2, InputIterator2 last2, Compare comp);
 
@@ -1811,19 +1812,19 @@
                                       InputIterator2 first2, InputIterator2 last2);      // since C++20
 
 template <class BidirectionalIterator>
-    constexpr bool     // constexpr in C++20
+    constexpr bool     // constexpr since C++20
     next_permutation(BidirectionalIterator first, BidirectionalIterator last);
 
 template <class BidirectionalIterator, class Compare>
-    constexpr bool     // constexpr in C++20
+    constexpr bool     // constexpr since C++20
     next_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
 
 template <class BidirectionalIterator>
-    constexpr bool     // constexpr in C++20
+    constexpr bool     // constexpr since C++20
     prev_permutation(BidirectionalIterator first, BidirectionalIterator last);
 
 template <class BidirectionalIterator, class Compare>
-    constexpr bool     // constexpr in C++20
+    constexpr bool     // constexpr since C++20
     prev_permutation(BidirectionalIterator first, BidirectionalIterator last, Compare comp);
 }  // std