stl_algo.h (merge): Fix documentation.

2019-09-28  François Dumont  <fdumont@gcc.gnu.org>

	* include/bits/stl_algo.h (merge): Fix documentation.
	* include/debug/functions.h (__check_sorted_aux): Add C++20 constexpr.
	(__check_sorted): Likewise and remove nested irreflexive check.
	(__check_sorted_set_aux, __check_sorted_set): Add C++20 constexpr.
	(__check_partitioned_lower, __check_partitioned_upper): Likewise.
	(_Irreflexive_checker::_S_is_valid): Likewise.
	(__is_irreflexive, __is_irreflexive_pred): Likewise.
	* include/debug/helper_functions.h (__get_distance): Add constexpr.
	(__valid_range_aux): Add C++20 constexpr.
	(__valid_range(_Iter, _Iter, _Distance_traits<_Iter>::__type&)):
	Likewise and add std::is_constant_evaluated check.
	(__valid_range_aux(_Iter, _Iter, std::input_iterator_tag)): New.
	(__valid_range_aux(_Iter, _Iter, std::random_accss_iterator_tag)): New.
	(__valid_range_aux(_Integral, _Integral, std::__true_type)): New,
	use latter.
	(__valid_range(_Iter, _Iter)): Adapt to use latter, add constexpr and
	__builtin_is_contant_evaludated check..
	(__can_advance, __base): Add constexpr.
	* include/debug/macros.h [_GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED]
	(_GLIBCXX_DEBUG_VERIFY_COND_AT): New.
	(__glibcxx_check_sorted): Use __glibcxx_check_irreflexive.
	(__glibcxx_check_sorted_pred): Use __glibcxx_check_irreflexive_pred.
	* testsuite/25_algorithms/binary_search/constexpr.cc: Use irreflexive
	std::less.
	* testsuite/25_algorithms/is_sorted/constexpr.cc: Likewise.
	* testsuite/25_algorithms/merge/constexpr.cc: Fix order in camm. Fix
	lambda to be irreflexive.

From-SVN: r276260

8 files changed, 157 insertions, 52 deletions

diff --git a/libstdc++-v3/ChangeLog b/libstdc++-v3/ChangeLog
index 3671c17..bb19eb5 100644
--- a/libstdc++-v3/ChangeLog
+++ b/libstdc++-v3/ChangeLog
@@ -1,3 +1,33 @@
+2019-09-28  François Dumont  <fdumont@gcc.gnu.org>
+
+	* include/bits/stl_algo.h (merge): Fix documentation.
+	* include/debug/functions.h (__check_sorted_aux): Add C++20 constexpr.
+	(__check_sorted): Likewise and remove nested irreflexive check.
+	(__check_sorted_set_aux, __check_sorted_set): Add C++20 constexpr.
+	(__check_partitioned_lower, __check_partitioned_upper): Likewise.
+	(_Irreflexive_checker::_S_is_valid): Likewise.
+	(__is_irreflexive, __is_irreflexive_pred): Likewise.
+	* include/debug/helper_functions.h (__get_distance): Add constexpr.
+	(__valid_range_aux): Add C++20 constexpr.
+	(__valid_range(_Iter, _Iter, _Distance_traits<_Iter>::__type&)):
+	Likewise and add std::is_constant_evaluated check.
+	(__valid_range_aux(_Iter, _Iter, std::input_iterator_tag)): New.
+	(__valid_range_aux(_Iter, _Iter, std::random_accss_iterator_tag)): New.
+	(__valid_range_aux(_Integral, _Integral, std::__true_type)): New,
+	use latter.
+	(__valid_range(_Iter, _Iter)): Adapt to use latter, add constexpr and
+	__builtin_is_contant_evaludated check..
+	(__can_advance, __base): Add constexpr.
+	* include/debug/macros.h [_GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED]
+	(_GLIBCXX_DEBUG_VERIFY_COND_AT): New.
+	(__glibcxx_check_sorted): Use __glibcxx_check_irreflexive.
+	(__glibcxx_check_sorted_pred): Use __glibcxx_check_irreflexive_pred.
+	* testsuite/25_algorithms/binary_search/constexpr.cc: Use irreflexive
+	std::less.
+	* testsuite/25_algorithms/is_sorted/constexpr.cc: Likewise.
+	* testsuite/25_algorithms/merge/constexpr.cc: Fix order in camm. Fix
+	lambda to be irreflexive.
+
 2019-09-27  Maciej W. Rozycki  <macro@wdc.com>
 
 	* configure: Regenerate.
diff --git a/libstdc++-v3/include/bits/stl_algo.h b/libstdc++-v3/include/bits/stl_algo.h
index 7fe1d8a..b326c63 100644
--- a/libstdc++-v3/include/bits/stl_algo.h
+++ b/libstdc++-v3/include/bits/stl_algo.h
@@ -5057,8 +5057,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
    *  @param  __last1   Another iterator.
    *  @param  __last2   Another iterator.
    *  @param  __result  An iterator pointing to the end of the merged range.
-   *  @return         An iterator pointing to the first element <em>not less
-   *                  than</em> @e val.
+   *  @return   An output iterator equal to @p __result + (__last1 - __first1)
+   *            + (__last2 - __first2).
    *
    *  Merges the ranges @p [__first1,__last1) and @p [__first2,__last2) into
    *  the sorted range @p [__result, __result + (__last1-__first1) +
@@ -5105,8 +5105,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
    *  @param  __last2   Another iterator.
    *  @param  __result  An iterator pointing to the end of the merged range.
    *  @param  __comp    A functor to use for comparisons.
-   *  @return         An iterator pointing to the first element "not less
-   *                  than" @e val.
+   *  @return   An output iterator equal to @p __result + (__last1 - __first1)
+   *            + (__last2 - __first2).
    *
    *  Merges the ranges @p [__first1,__last1) and @p [__first2,__last2) into
    *  the sorted range @p [__result, __result + (__last1-__first1) +
diff --git a/libstdc++-v3/include/debug/functions.h b/libstdc++-v3/include/debug/functions.h
index f878386..8c385b8 100644
--- a/libstdc++-v3/include/debug/functions.h
+++ b/libstdc++-v3/include/debug/functions.h
@@ -219,6 +219,7 @@ namespace __gnu_debug
   // Can't check if an input iterator sequence is sorted, because we
   // can't step through the sequence.
   template<typename _InputIterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_aux(const _InputIterator&, const _InputIterator&,
                        std::input_iterator_tag)
@@ -227,6 +228,7 @@ namespace __gnu_debug
   // Can verify if a forward iterator sequence is in fact sorted using
   // std::__is_sorted
   template<typename _ForwardIterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_aux(_ForwardIterator __first, _ForwardIterator __last,
                        std::forward_iterator_tag)
@@ -245,6 +247,7 @@ namespace __gnu_debug
   // Can't check if an input iterator sequence is sorted, because we can't step
   // through the sequence.
   template<typename _InputIterator, typename _Predicate>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_aux(const _InputIterator&, const _InputIterator&,
                        _Predicate, std::input_iterator_tag)
@@ -253,6 +256,7 @@ namespace __gnu_debug
   // Can verify if a forward iterator sequence is in fact sorted using
   // std::__is_sorted
   template<typename _ForwardIterator, typename _Predicate>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_aux(_ForwardIterator __first, _ForwardIterator __last,
                        _Predicate __pred, std::forward_iterator_tag)
@@ -270,31 +274,26 @@ namespace __gnu_debug
 
   // Determine if a sequence is sorted.
   template<typename _InputIterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted(const _InputIterator& __first, const _InputIterator& __last)
     {
-      // Verify that the < operator for elements in the sequence is a
-      // StrictWeakOrdering by checking that it is irreflexive.
-      __glibcxx_assert(__first == __last || !(*__first < *__first));
-
       return __check_sorted_aux(__first, __last,
 				std::__iterator_category(__first));
     }
 
   template<typename _InputIterator, typename _Predicate>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted(const _InputIterator& __first, const _InputIterator& __last,
                    _Predicate __pred)
     {
-      // Verify that the predicate is StrictWeakOrdering by checking that it
-      // is irreflexive.
-      __glibcxx_assert(__first == __last || !__pred(*__first, *__first));
-
       return __check_sorted_aux(__first, __last, __pred,
 				std::__iterator_category(__first));
     }
 
   template<typename _InputIterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_set_aux(const _InputIterator& __first,
 			   const _InputIterator& __last,
@@ -302,6 +301,7 @@ namespace __gnu_debug
     { return __check_sorted(__first, __last); }
 
   template<typename _InputIterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_set_aux(const _InputIterator&,
 			   const _InputIterator&,
@@ -309,6 +309,7 @@ namespace __gnu_debug
     { return true; }
 
   template<typename _InputIterator, typename _Predicate>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_set_aux(const _InputIterator& __first,
 			   const _InputIterator& __last,
@@ -316,6 +317,7 @@ namespace __gnu_debug
     { return __check_sorted(__first, __last, __pred); }
 
   template<typename _InputIterator, typename _Predicate>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_set_aux(const _InputIterator&,
 			   const _InputIterator&, _Predicate,
@@ -324,6 +326,7 @@ namespace __gnu_debug
 
   // ... special variant used in std::merge, std::includes, std::set_*.
   template<typename _InputIterator1, typename _InputIterator2>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_set(const _InputIterator1& __first,
 		       const _InputIterator1& __last,
@@ -341,6 +344,7 @@ namespace __gnu_debug
 
   template<typename _InputIterator1, typename _InputIterator2,
 	   typename _Predicate>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_sorted_set(const _InputIterator1& __first,
 		       const _InputIterator1& __last,
@@ -360,6 +364,7 @@ namespace __gnu_debug
   // 270. Binary search requirements overly strict
   // Determine if a sequence is partitioned w.r.t. this element.
   template<typename _ForwardIterator, typename _Tp>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_partitioned_lower(_ForwardIterator __first,
 			      _ForwardIterator __last, const _Tp& __value)
@@ -376,6 +381,7 @@ namespace __gnu_debug
     }
 
   template<typename _ForwardIterator, typename _Tp>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_partitioned_upper(_ForwardIterator __first,
 			      _ForwardIterator __last, const _Tp& __value)
@@ -393,6 +399,7 @@ namespace __gnu_debug
 
   // Determine if a sequence is partitioned w.r.t. this element.
   template<typename _ForwardIterator, typename _Tp, typename _Pred>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_partitioned_lower(_ForwardIterator __first,
 			      _ForwardIterator __last, const _Tp& __value,
@@ -410,6 +417,7 @@ namespace __gnu_debug
     }
 
   template<typename _ForwardIterator, typename _Tp, typename _Pred>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __check_partitioned_upper(_ForwardIterator __first,
 			      _ForwardIterator __last, const _Tp& __value,
@@ -435,35 +443,41 @@ namespace __gnu_debug
 
     template<typename _It,
 	     typename = decltype(__deref<_It>() < __deref<_It>())>
+      _GLIBCXX20_CONSTEXPR
       static bool
       _S_is_valid(_It __it)
       { return !(*__it < *__it); }
 
     // Fallback method if operator doesn't exist.
     template<typename... _Args>
+      _GLIBCXX20_CONSTEXPR
       static bool
       _S_is_valid(_Args...)
       { return true; }
 
     template<typename _It, typename _Pred, typename
 	= decltype(std::declval<_Pred>()(__deref<_It>(), __deref<_It>()))>
+      _GLIBCXX20_CONSTEXPR
       static bool
       _S_is_valid_pred(_It __it, _Pred __pred)
       { return !__pred(*__it, *__it); }
 
     // Fallback method if predicate can't be invoked.
     template<typename... _Args>
+      _GLIBCXX20_CONSTEXPR
       static bool
       _S_is_valid_pred(_Args...)
       { return true; }
   };
 
   template<typename _Iterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __is_irreflexive(_Iterator __it)
     { return _Irreflexive_checker::_S_is_valid(__it); }
 
   template<typename _Iterator, typename _Pred>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __is_irreflexive_pred(_Iterator __it, _Pred __pred)
     { return _Irreflexive_checker::_S_is_valid_pred(__it, __pred); }
diff --git a/libstdc++-v3/include/debug/helper_functions.h b/libstdc++-v3/include/debug/helper_functions.h
index b7aeafe..475fdda 100644
--- a/libstdc++-v3/include/debug/helper_functions.h
+++ b/libstdc++-v3/include/debug/helper_functions.h
@@ -87,12 +87,14 @@ namespace __gnu_debug
    *	precision.
   */
   template<typename _Iterator>
+    _GLIBCXX_CONSTEXPR
     inline typename _Distance_traits<_Iterator>::__type
     __get_distance(_Iterator __lhs, _Iterator __rhs,
 		   std::random_access_iterator_tag)
     { return std::make_pair(__rhs - __lhs, __dp_exact); }
 
   template<typename _Iterator>
+    _GLIBCXX_CONSTEXPR
     inline typename _Distance_traits<_Iterator>::__type
     __get_distance(_Iterator __lhs, _Iterator __rhs,
 		   std::input_iterator_tag)
@@ -104,6 +106,7 @@ namespace __gnu_debug
     }
 
   template<typename _Iterator>
+    _GLIBCXX_CONSTEXPR
     inline typename _Distance_traits<_Iterator>::__type
     __get_distance(_Iterator __lhs, _Iterator __rhs)
     { return __get_distance(__lhs, __rhs, std::__iterator_category(__lhs)); }
@@ -113,6 +116,13 @@ namespace __gnu_debug
    *  iterators.
   */
   template<typename _Integral>
+    _GLIBCXX_CONSTEXPR
+    inline bool
+    __valid_range_aux(_Integral, _Integral, std::__true_type)
+    { return true; }
+
+  template<typename _Integral>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __valid_range_aux(_Integral, _Integral,
 		      typename _Distance_traits<_Integral>::__type& __dist,
@@ -122,10 +132,35 @@ namespace __gnu_debug
       return true;
     }
 
+  template<typename _InputIterator>
+    _GLIBCXX_CONSTEXPR
+    inline bool
+    __valid_range_aux(_InputIterator __first, _InputIterator __last,
+		      std::input_iterator_tag)
+    { return true; }
+
+  template<typename _InputIterator>
+    _GLIBCXX_CONSTEXPR
+    inline bool
+    __valid_range_aux(_InputIterator __first, _InputIterator __last,
+		      std::random_access_iterator_tag)
+    { return __first <= __last; }
+
   /** We have iterators, so figure out what kind of iterators they are
    *  to see if we can check the range ahead of time.
   */
   template<typename _InputIterator>
+    _GLIBCXX_CONSTEXPR
+    inline bool
+    __valid_range_aux(_InputIterator __first, _InputIterator __last,
+		      std::__false_type)
+    {
+      return __valid_range_aux(__first, __last,
+			       std::__iterator_category(__first));
+    }
+
+  template<typename _InputIterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __valid_range_aux(_InputIterator __first, _InputIterator __last,
 		      typename _Distance_traits<_InputIterator>::__type& __dist,
@@ -155,10 +190,16 @@ namespace __gnu_debug
    *  otherwise.
   */
   template<typename _InputIterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __valid_range(_InputIterator __first, _InputIterator __last,
 		  typename _Distance_traits<_InputIterator>::__type& __dist)
     {
+#ifdef __cpp_lib_is_constant_evaluated
+      if (std::is_constant_evaluated())
+	// Detected by the compiler directly.
+	return true;
+#endif
       typedef typename std::__is_integer<_InputIterator>::__type _Integral;
       return __valid_range_aux(__first, __last, __dist, _Integral());
     }
@@ -178,11 +219,17 @@ namespace __gnu_debug
 #endif
 
   template<typename _InputIterator>
+    _GLIBCXX_CONSTEXPR
     inline bool
     __valid_range(_InputIterator __first, _InputIterator __last)
     {
-      typename _Distance_traits<_InputIterator>::__type __dist;
-      return __valid_range(__first, __last, __dist);
+#ifdef _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED
+      if (__builtin_is_constant_evaluated())
+	// Detected by the compiler directly.
+	return true;
+#endif
+      typedef typename std::__is_integer<_InputIterator>::__type _Integral;
+      return __valid_range_aux(__first, __last, _Integral());
     }
 
   template<typename _Iterator, typename _Sequence, typename _Category>
@@ -199,6 +246,7 @@ namespace __gnu_debug
 
   // Fallback method, always ok.
   template<typename _InputIterator, typename _Size>
+    _GLIBCXX_CONSTEXPR
     inline bool
     __can_advance(_InputIterator, _Size)
     { return true; }
@@ -216,6 +264,7 @@ namespace __gnu_debug
    *  thanks to the < operator.
    */
   template<typename _Iterator>
+    _GLIBCXX_CONSTEXPR
     inline _Iterator
     __base(_Iterator __it)
     { return __it; }
diff --git a/libstdc++-v3/include/debug/macros.h b/libstdc++-v3/include/debug/macros.h
index b598192c..97e54fd 100644
--- a/libstdc++-v3/include/debug/macros.h
+++ b/libstdc++-v3/include/debug/macros.h
@@ -38,10 +38,20 @@
  * the user error and where the error is reported.
  *
  */
-#define _GLIBCXX_DEBUG_VERIFY_COND_AT(_Cond,_ErrMsg,_File,_Line,_Func)	\
+#if 0 /* defined _GLIBCXX_HAVE_BUILTIN_IS_CONSTANT_EVALUATED */
+# define _GLIBCXX_DEBUG_VERIFY_COND_AT(_Cond,_ErrMsg,_File,_Line,_Func)	\
+  if (__builtin_is_constant_evaluated())				\
+    /* FIXME: Compilation error here when !_Cond. */			\
+    break;								\
   if (! (_Cond))							\
     __gnu_debug::_Error_formatter::_S_at(_File, _Line, _Func)		\
       ._ErrMsg._M_error()
+#else
+# define _GLIBCXX_DEBUG_VERIFY_COND_AT(_Cond,_ErrMsg,_File,_Line,_Func)	\
+  if (! (_Cond))							\
+    __gnu_debug::_Error_formatter::_S_at(_File, _Line, _Func)		\
+      ._ErrMsg._M_error()
+#endif
 
 #define _GLIBCXX_DEBUG_VERIFY_AT_F(_Cond,_ErrMsg,_File,_Line,_Func)	\
   do									\
@@ -291,9 +301,43 @@ _GLIBCXX_DEBUG_VERIFY(! this->empty(),					\
 		      _M_message(__gnu_debug::__msg_empty)	        \
                       ._M_sequence(*this, "this"))
 
+// Verify that a predicate is irreflexive
+#define __glibcxx_check_irreflexive(_First,_Last)			\
+  _GLIBCXX_DEBUG_VERIFY(_First == _Last || !(*_First < *_First),	\
+			_M_message(__gnu_debug::__msg_irreflexive_ordering) \
+			._M_iterator_value_type(_First, "< operator type"))
+
+#if __cplusplus >= 201103L
+# define __glibcxx_check_irreflexive2(_First,_Last)			\
+  _GLIBCXX_DEBUG_VERIFY(_First == _Last					\
+			|| __gnu_debug::__is_irreflexive(_First),	\
+			_M_message(__gnu_debug::__msg_irreflexive_ordering) \
+			._M_iterator_value_type(_First, "< operator type"))
+#else
+# define __glibcxx_check_irreflexive2(_First,_Last)
+#endif
+
+#define __glibcxx_check_irreflexive_pred(_First,_Last,_Pred)		\
+  _GLIBCXX_DEBUG_VERIFY(_First == _Last || !_Pred(*_First, *_First),	\
+			_M_message(__gnu_debug::__msg_irreflexive_ordering) \
+			._M_instance(_Pred, "functor")			\
+			._M_iterator_value_type(_First, "ordered type"))
+
+#if __cplusplus >= 201103L
+# define __glibcxx_check_irreflexive_pred2(_First,_Last,_Pred)		\
+  _GLIBCXX_DEBUG_VERIFY(_First == _Last					\
+			||__gnu_debug::__is_irreflexive_pred(_First, _Pred), \
+			_M_message(__gnu_debug::__msg_irreflexive_ordering) \
+			._M_instance(_Pred, "functor")			\
+			._M_iterator_value_type(_First, "ordered type"))
+#else
+# define __glibcxx_check_irreflexive_pred2(_First,_Last,_Pred)
+#endif
+
 // Verify that the iterator range [_First, _Last) is sorted
 #define __glibcxx_check_sorted(_First,_Last)				\
 __glibcxx_check_valid_range(_First,_Last);				\
+__glibcxx_check_irreflexive(_First,_Last);				\
  _GLIBCXX_DEBUG_VERIFY(__gnu_debug::__check_sorted(			\
 			__gnu_debug::__base(_First),			\
 			__gnu_debug::__base(_Last)),			\
@@ -305,6 +349,7 @@ __glibcxx_check_valid_range(_First,_Last);				\
     predicate _Pred. */
 #define __glibcxx_check_sorted_pred(_First,_Last,_Pred)			\
 __glibcxx_check_valid_range(_First,_Last);				\
+__glibcxx_check_irreflexive_pred(_First,_Last,_Pred);			\
 _GLIBCXX_DEBUG_VERIFY(__gnu_debug::__check_sorted(			\
 			__gnu_debug::__base(_First),			\
 			__gnu_debug::__base(_Last), _Pred),		\
@@ -423,37 +468,4 @@ _GLIBCXX_DEBUG_VERIFY(_This.get_allocator() == _Other.get_allocator(),	\
 #define __glibcxx_check_string_len(_String,_Len) \
   _GLIBCXX_DEBUG_PEDASSERT(_String != 0 || _Len == 0)
 
-// Verify that a predicate is irreflexive
-#define __glibcxx_check_irreflexive(_First,_Last)			\
-  _GLIBCXX_DEBUG_VERIFY(_First == _Last || !(*_First < *_First),	\
-			_M_message(__gnu_debug::__msg_irreflexive_ordering) \
-			._M_iterator_value_type(_First, "< operator type"))
-
-#if __cplusplus >= 201103L
-# define __glibcxx_check_irreflexive2(_First,_Last)			\
-  _GLIBCXX_DEBUG_VERIFY(_First == _Last					\
-			|| __gnu_debug::__is_irreflexive(_First),	\
-			_M_message(__gnu_debug::__msg_irreflexive_ordering) \
-			._M_iterator_value_type(_First, "< operator type"))
-#else
-# define __glibcxx_check_irreflexive2(_First,_Last)
-#endif
-
-#define __glibcxx_check_irreflexive_pred(_First,_Last,_Pred)		\
-  _GLIBCXX_DEBUG_VERIFY(_First == _Last	|| !_Pred(*_First, *_First),		\
-			_M_message(__gnu_debug::__msg_irreflexive_ordering) \
-			._M_instance(_Pred, "functor")			\
-			._M_iterator_value_type(_First, "ordered type"))
-
-#if __cplusplus >= 201103L
-# define __glibcxx_check_irreflexive_pred2(_First,_Last,_Pred)		\
-  _GLIBCXX_DEBUG_VERIFY(_First == _Last					\
-			||__gnu_debug::__is_irreflexive_pred(_First, _Pred), \
-			_M_message(__gnu_debug::__msg_irreflexive_ordering) \
-			._M_instance(_Pred, "functor")			\
-			._M_iterator_value_type(_First, "ordered type"))
-#else
-# define __glibcxx_check_irreflexive_pred2(_First,_Last,_Pred)
-#endif
-
 #endif
diff --git a/libstdc++-v3/testsuite/25_algorithms/binary_search/constexpr.cc b/libstdc++-v3/testsuite/25_algorithms/binary_search/constexpr.cc
index 8406b3d..205a96a 100644
--- a/libstdc++-v3/testsuite/25_algorithms/binary_search/constexpr.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/binary_search/constexpr.cc
@@ -29,7 +29,7 @@ test()
   const auto out4 = std::binary_search(ca0.begin(), ca0.end(), 5);
 
   const auto out5 = std::binary_search(ca0.begin(), ca0.end(), 5,
-				       std::equal_to<int>());
+				       std::less<int>());
 
   return true;
 }
diff --git a/libstdc++-v3/testsuite/25_algorithms/is_sorted/constexpr.cc b/libstdc++-v3/testsuite/25_algorithms/is_sorted/constexpr.cc
index 0be2f5f..f549b3d 100644
--- a/libstdc++-v3/testsuite/25_algorithms/is_sorted/constexpr.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/is_sorted/constexpr.cc
@@ -26,7 +26,7 @@ constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
 constexpr auto outv = std::is_sorted(ca0.begin(), ca0.end());
 
 constexpr auto outw = std::is_sorted(ca0.begin(), ca0.end(),
-				     std::equal_to<int>());
+				     std::less<int>());
 
 constexpr bool
 test()
diff --git a/libstdc++-v3/testsuite/25_algorithms/merge/constexpr.cc b/libstdc++-v3/testsuite/25_algorithms/merge/constexpr.cc
index cc8d375..794453d 100644
--- a/libstdc++-v3/testsuite/25_algorithms/merge/constexpr.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/merge/constexpr.cc
@@ -26,7 +26,7 @@ test()
 {
   constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
   constexpr std::array<int, 12> cas{{3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14}};
-  constexpr std::array<int, 3> camm{{-4, -5, -6}};
+  constexpr std::array<int, 3> camm{{-6, -5, -4}};
   std::array<int, 24> out0{{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0}};
 
   const auto outdd = std::merge(ca0.begin(), ca0.end(),
@@ -34,7 +34,7 @@ test()
 
   const auto outee = std::merge(ca0.begin(), ca0.end(),
 				camm.begin(), camm.end(), out0.begin(),
-				[](int i, int j){ return i < -j; });
+				[](int i, int j){ return i < j; });
 
   return true;
 }