[RFC] Minimize functor copy in algos

François Dumont frs.dumont@gmail.com
Mon May 25 19:54:26 GMT 2026


In my attempt to rewrite predefined ops was also an attempt to improve 
how the functor were passed within implementation details of the 
different algos.

https://gcc.gnu.org/pipermail/libstdc++/2024-October/059677.html

As it seems to be a hot subject lately I rebased it and proposing it here.

Even if Nathan Myers approach to work on 1 algo at a time is also a good 
approach.

There are still some occasions where the functor is passed by copy, when 
building __gnu_cxx::_ops functors, I'm going to have a look at it.

Let me know if I should leave it to Nathan Myers.

François


-------------- next part --------------
diff --git a/libstdc++-v3/include/bits/move.h b/libstdc++-v3/include/bits/move.h
index 1a03db66112..89c4bc3240c 100644
--- a/libstdc++-v3/include/bits/move.h
+++ b/libstdc++-v3/include/bits/move.h
@@ -195,10 +195,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   /// @} group utilities
 
 #define _GLIBCXX_FWDREF(_Tp) _Tp&&
+#define _GLIBCXX_CP_FWDREF(_Tp) _Tp&&
 #define _GLIBCXX_MOVE(__val) std::move(__val)
 #define _GLIBCXX_FORWARD(_Tp, __val) std::forward<_Tp>(__val)
 #else
 #define _GLIBCXX_FWDREF(_Tp) const _Tp&
+#define _GLIBCXX_CP_FWDREF(_Tp) _Tp
 #define _GLIBCXX_MOVE(__val) (__val)
 #define _GLIBCXX_FORWARD(_Tp, __val) (__val)
 #endif
diff --git a/libstdc++-v3/include/bits/stl_algo.h b/libstdc++-v3/include/bits/stl_algo.h
index adf9b9e0f28..3dd5861b4c3 100644
--- a/libstdc++-v3/include/bits/stl_algo.h
+++ b/libstdc++-v3/include/bits/stl_algo.h
@@ -86,7 +86,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     void
     __move_median_to_first(_Iterator __result, _Iterator __a, _Iterator __b,
-			   _Iterator __c, _Compare __comp)
+			   _Iterator __c, _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__comp(*__a, *__b))
 	{
@@ -110,7 +110,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     inline _InputIterator
     __find_if_not(_InputIterator __first, _InputIterator __last,
-		  _Predicate __pred)
+		  _GLIBCXX_CP_FWDREF(_Predicate) __pred)
     {
       return std::__find_if(__first, __last,
 			    __gnu_cxx::__ops::not1(__pred));
@@ -122,7 +122,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   template<typename _InputIterator, typename _Predicate, typename _Distance>
     _GLIBCXX20_CONSTEXPR
     _InputIterator
-    __find_if_not_n(_InputIterator __first, _Distance& __len, _Predicate __pred)
+    __find_if_not_n(_InputIterator __first, _Distance& __len,
+		    _GLIBCXX_CP_FWDREF(_Predicate) __pred)
     {
       for (; __len; --__len,  (void) ++__first)
 	if (!__pred(*__first))
@@ -152,7 +153,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     _ForwardIterator
     __search_n_aux(_ForwardIterator __first, _ForwardIterator __last,
-		   _Integer __count, _UnaryPredicate __unary_pred,
+		   _Integer __count,
+		   _GLIBCXX_CP_FWDREF(_UnaryPredicate) __unary_pred,
 		   std::forward_iterator_tag)
     {
       __first = std::__find_if(__first, __last, __unary_pred);
@@ -185,7 +187,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     _RandomAccessIter
     __search_n_aux(_RandomAccessIter __first, _RandomAccessIter __last,
-		   _Integer __count, _UnaryPredicate __unary_pred,
+		   _Integer __count,
+		   _GLIBCXX_CP_FWDREF(_UnaryPredicate) __unary_pred,
 		   std::random_access_iterator_tag)
     {
       typedef typename std::iterator_traits<_RandomAccessIter>::difference_type
@@ -217,15 +220,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _ForwardIterator
     __search_n(_ForwardIterator __first, _ForwardIterator __last,
 	       _Integer __count,
-	       _UnaryPredicate __unary_pred)
+	       _GLIBCXX_CP_FWDREF(_UnaryPredicate) __unary_pred)
     {
       if (__count <= 0)
 	return __first;
 
       if (__count == 1)
-	return std::__find_if(__first, __last, __unary_pred);
+	return std::__find_if(__first, __last,
+			      _GLIBCXX_FORWARD(_UnaryPredicate, __unary_pred));
 
-      return std::__search_n_aux(__first, __last, __count, __unary_pred,
+      return std::__search_n_aux(__first, __last, __count,
+				_GLIBCXX_FORWARD(_UnaryPredicate, __unary_pred),
 				 std::__iter_concept_or_category(__first));
     }
 
@@ -237,7 +242,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     __find_end(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
 	       _ForwardIterator2 __first2, _ForwardIterator2 __last2,
 	       forward_iterator_tag, forward_iterator_tag,
-	       _BinaryPredicate __comp)
+	       _GLIBCXX_CP_FWDREF(_BinaryPredicate) __comp)
     {
       if (__first2 == __last2)
 	return __last1;
@@ -268,7 +273,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	       _BidirectionalIterator2 __first2,
 	       _BidirectionalIterator2 __last2,
 	       bidirectional_iterator_tag, bidirectional_iterator_tag,
-	       _BinaryPredicate __comp)
+	       _GLIBCXX_CP_FWDREF(_BinaryPredicate) __comp)
     {
       // concept requirements
       __glibcxx_function_requires(_BidirectionalIteratorConcept<
@@ -283,7 +288,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       _RevIterator2 __rlast2(__first2);
       _RevIterator1 __rresult = std::__search(_RevIterator1(__last1), __rlast1,
 					      _RevIterator2(__last2), __rlast2,
-					      __comp);
+				_GLIBCXX_FORWARD(_BinaryPredicate, __comp));
 
       if (__rresult == __rlast1)
 	return __last1;
@@ -390,7 +395,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       return std::__find_end(__first1, __last1, __first2, __last2,
 			     std::__iter_concept_or_category(__first1),
 			     std::__iter_concept_or_category(__first2),
-			     __comp);
+			     _GLIBCXX_MOVE(__comp));
     }
 
 #if __cplusplus >= 201103L
@@ -410,7 +415,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
     inline bool
     all_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-    { return __last == std::find_if_not(__first, __last, __pred); }
+    { return __last == std::find_if_not(__first, __last, std::move(__pred)); }
 
   /**
    *  @brief  Checks that a predicate is false for all the elements
@@ -428,7 +433,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
     inline bool
     none_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-    { return __last == _GLIBCXX_STD_A::find_if(__first, __last, __pred); }
+    {
+      return
+	__last == _GLIBCXX_STD_A::find_if(__first, __last, std::move(__pred));
+    }
 
   /**
    *  @brief  Checks that a predicate is true for at least one element
@@ -447,7 +455,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX_NODISCARD _GLIBCXX20_CONSTEXPR
     inline bool
     any_of(_InputIterator __first, _InputIterator __last, _Predicate __pred)
-    { return !std::none_of(__first, __last, __pred); }
+    { return !std::none_of(__first, __last, std::move(__pred)); }
 
   /**
    *  @brief  Find the first element in a sequence for which a
@@ -470,7 +478,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __glibcxx_function_requires(_UnaryPredicateConcept<_Predicate,
 	      typename iterator_traits<_InputIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
-      return std::__find_if_not(__first, __last, __pred);
+      return std::__find_if_not(__first, __last, std::move(__pred));
     }
 
   /**
@@ -493,7 +501,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       if (__first == __last)
 	return true;
       ++__first;
-      return std::none_of(__first, __last, __pred);
+      return std::none_of(__first, __last, std::move(__pred));
     }
 
   /**
@@ -540,14 +548,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	}
       return __first;
     }
-#endif
+#endif // C++11
 
   template<typename _InputIterator, typename _OutputIterator,
 	   typename _Predicate>
     _GLIBCXX20_CONSTEXPR
     _OutputIterator
     __remove_copy_if(_InputIterator __first, _InputIterator __last,
-		     _OutputIterator __result, _Predicate __pred)
+		     _OutputIterator __result,
+		     _GLIBCXX_CP_FWDREF(_Predicate) __pred)
     {
       for (; __first != __last; ++__first)
 	if (!__pred(*__first))
@@ -620,7 +629,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    typename iterator_traits<_InputIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
 
-      return std::__remove_copy_if(__first, __last, __result, __pred);
+      return std::__remove_copy_if(__first, __last, __result,
+				   _GLIBCXX_MOVE(__pred));
     }
 
 #if __cplusplus >= 201103L
@@ -811,14 +821,15 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	    typename iterator_traits<_ForwardIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
 
-      return std::__remove_if(__first, __last, __pred);
+      return std::__remove_if(__first, __last,
+			      _GLIBCXX_MOVE(__pred));
     }
 
   template<typename _ForwardIterator, typename _BinaryPredicate>
     _GLIBCXX20_CONSTEXPR
     _ForwardIterator
     __adjacent_find(_ForwardIterator __first, _ForwardIterator __last,
-		    _BinaryPredicate __binary_pred)
+		    _GLIBCXX_CP_FWDREF(_BinaryPredicate) __binary_pred)
     {
       if (__first == __last)
 	return __last;
@@ -836,7 +847,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     _ForwardIterator
     __unique(_ForwardIterator __first, _ForwardIterator __last,
-	     _BinaryPredicate __binary_pred)
+	     _GLIBCXX_CP_FWDREF(_BinaryPredicate) __binary_pred)
     {
       // Skip the beginning, if already unique.
       __first = std::__adjacent_find(__first, __last, __binary_pred);
@@ -910,7 +921,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 		typename iterator_traits<_ForwardIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
 
-      return std::__unique(__first, __last, __binary_pred);
+      return std::__unique(__first, __last,
+			   _GLIBCXX_MOVE(__binary_pred));
     }
 
   // _GLIBCXX_RESOLVE_LIB_DEFECTS
@@ -923,7 +935,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     _OutputIterator
     __unique_copy(_ForwardIterator __first, _ForwardIterator __last,
-		  _OutputIterator __result, _BinaryPredicate __binary_pred,
+		  _OutputIterator __result,
+		  _GLIBCXX_CP_FWDREF(_BinaryPredicate) __binary_pred,
 		  forward_iterator_tag)
     {
       _ForwardIterator __prev = __first;
@@ -944,7 +957,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     _OutputIterator
     __unique_copy_1(_InputIterator __first, _InputIterator __last,
-		    _OutputIterator __result, _BinaryPredicate __binary_pred,
+		    _OutputIterator __result,
+		    _GLIBCXX_CP_FWDREF(_BinaryPredicate) __binary_pred,
 		    __false_type)
     {
       typedef typename iterator_traits<_InputIterator>::value_type _Val;
@@ -965,7 +979,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	   typename _BinaryPredicate>
     _ForwardIterator
     __unique_copy_1(_InputIterator __first, _InputIterator __last,
-		    _ForwardIterator __result, _BinaryPredicate __binary_pred,
+		    _ForwardIterator __result,
+		    _GLIBCXX_CP_FWDREF(_BinaryPredicate) __binary_pred,
 		    __true_type)
     {
       *__result = *__first;
@@ -1386,7 +1401,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX20_CONSTEXPR
     _ForwardIterator
     __partition(_ForwardIterator __first, _ForwardIterator __last,
-		_Predicate __pred, forward_iterator_tag)
+		_GLIBCXX_CP_FWDREF(_Predicate) __pred, forward_iterator_tag)
     {
       if (__first == __last)
 	return __first;
@@ -1412,7 +1427,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX20_CONSTEXPR
     _BidirectionalIterator
     __partition(_BidirectionalIterator __first, _BidirectionalIterator __last,
-		_Predicate __pred, bidirectional_iterator_tag)
+		_GLIBCXX_CP_FWDREF(_Predicate) __pred, bidirectional_iterator_tag)
     {
       while (true)
 	{
@@ -1451,7 +1466,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _ForwardIterator
     __stable_partition_adaptive(_ForwardIterator __first,
 				_ForwardIterator __last,
-				_Predicate __pred, _Distance __len,
+				_GLIBCXX_CP_FWDREF(_Predicate) __pred,
+				_Distance __len,
 				_Pointer __buffer,
 				_Distance __buffer_size)
     {
@@ -1500,7 +1516,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 
       if (__right_len)
 	__right_split =
-	  std::__stable_partition_adaptive(__right_split, __last, __pred,
+	  std::__stable_partition_adaptive(__right_split, __last,
+					   _GLIBCXX_FORWARD(_Predicate, __pred),
 					   __right_len,
 					   __buffer, __buffer_size);
 
@@ -1511,7 +1528,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX26_CONSTEXPR
     _ForwardIterator
     __stable_partition(_ForwardIterator __first, _ForwardIterator __last,
-		       _Predicate __pred)
+		       _GLIBCXX_CP_FWDREF(_Predicate) __pred)
     {
       __first = std::__find_if_not(__first, __last, __pred);
 
@@ -1540,7 +1557,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       _Temporary_buffer<_ForwardIterator, _ValueType>
 	__buf(__first, __len);
       return
-	std::__stable_partition_adaptive(__first, __last, __pred,
+	std::__stable_partition_adaptive(__first, __last,
+					 _GLIBCXX_FORWARD(_Predicate, __pred),
 					 __len,
 					 __buf.begin(),
 					 _DistanceType(__buf.size()));
@@ -1576,7 +1594,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 	    typename iterator_traits<_ForwardIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
 
-      return std::__stable_partition(__first, __last, __pred);
+      return std::__stable_partition(__first, __last,
+				     _GLIBCXX_MOVE(__pred));
     }
 #endif // HOSTED
 
@@ -1588,7 +1607,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     void
     __heap_select(_RandomAccessIterator __first,
 		  _RandomAccessIterator __middle,
-		  _RandomAccessIterator __last, _Compare __comp)
+		  _RandomAccessIterator __last,
+		  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       std::__make_heap(__first, __middle, __comp);
       for (_RandomAccessIterator __i = __middle; __i < __last; ++__i)
@@ -1605,7 +1625,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     __partial_sort_copy(_InputIterator __first, _InputIterator __last,
 			_RandomAccessIterator __result_first,
 			_RandomAccessIterator __result_last,
-			_Compare __comp)
+			_GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef typename iterator_traits<_InputIterator>::value_type
 	_InputValueType;
@@ -1632,7 +1652,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 			       _InputValueType(*__first), __comp);
 	  ++__first;
 	}
-      std::__sort_heap(__result_first, __result_real_last, __comp);
+      std::__sort_heap(__result_first, __result_real_last,
+		       _GLIBCXX_FORWARD(_Compare, __comp));
       return __result_real_last;
     }
 
@@ -1738,7 +1759,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 
       return std::__partial_sort_copy(__first, __last,
 				      __result_first, __result_last,
-				      __comp);
+				      _GLIBCXX_MOVE(__comp));
     }
 
   /// @cond undocumented
@@ -1748,7 +1769,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX20_CONSTEXPR
     void
     __unguarded_linear_insert(_RandomAccessIterator __last,
-			      _Compare __comp)
+			      _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typename iterator_traits<_RandomAccessIterator>::value_type
 	__val = _GLIBCXX_MOVE(*__last);
@@ -1768,7 +1789,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX20_CONSTEXPR
     void
     __insertion_sort(_RandomAccessIterator __first,
-		     _RandomAccessIterator __last, _Compare __comp)
+		     _RandomAccessIterator __last,
+		     _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__first == __last)
 	return;
@@ -1794,7 +1816,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX20_CONSTEXPR
     inline void
     __unguarded_insertion_sort(_RandomAccessIterator __first,
-			       _RandomAccessIterator __last, _Compare __comp)
+			       _RandomAccessIterator __last,
+			       _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       for (_RandomAccessIterator __i = __first; __i != __last; ++__i)
 	std::__unguarded_linear_insert(__i, __comp);
@@ -1811,7 +1834,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX20_CONSTEXPR
     void
     __final_insertion_sort(_RandomAccessIterator __first,
-			   _RandomAccessIterator __last, _Compare __comp)
+			   _RandomAccessIterator __last,
+			   _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typename iterator_traits<_RandomAccessIterator>::difference_type
 	__threshold = _S_threshold;
@@ -1820,10 +1844,11 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 	{
 	  std::__insertion_sort(__first, __first + __threshold, __comp);
 	  std::__unguarded_insertion_sort(__first + __threshold, __last,
-					  __comp);
+					  _GLIBCXX_FORWARD(_Compare, __comp));
 	}
       else
-	std::__insertion_sort(__first, __last, __comp);
+	std::__insertion_sort(__first, __last,
+			      _GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   /// This is a helper function...
@@ -1832,7 +1857,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _RandomAccessIterator
     __unguarded_partition(_RandomAccessIterator __first,
 			  _RandomAccessIterator __last,
-			  _RandomAccessIterator __pivot, _Compare __comp)
+			  _RandomAccessIterator __pivot,
+			  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (true)
 	{
@@ -1853,7 +1879,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX20_CONSTEXPR
     inline _RandomAccessIterator
     __unguarded_partition_pivot(_RandomAccessIterator __first,
-				_RandomAccessIterator __last, _Compare __comp)
+				_RandomAccessIterator __last,
+				_GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef iterator_traits<_RandomAccessIterator> _IterTraits;
       typedef typename _IterTraits::difference_type _Dist;
@@ -1862,7 +1889,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       _RandomAccessIterator __second = __first + _Dist(1);
       std::__move_median_to_first(__first, __second, __mid, __last - _Dist(1),
 				  __comp);
-      return std::__unguarded_partition(__second, __last, __first, __comp);
+      return std::__unguarded_partition(__second, __last, __first,
+					_GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   template<typename _RandomAccessIterator, typename _Compare>
@@ -1871,10 +1899,10 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     __partial_sort(_RandomAccessIterator __first,
 		   _RandomAccessIterator __middle,
 		   _RandomAccessIterator __last,
-		   _Compare __comp)
+		   _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       std::__heap_select(__first, __middle, __last, __comp);
-      std::__sort_heap(__first, __middle, __comp);
+      std::__sort_heap(__first, __middle, _GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   /// This is a helper function for the sort routine.
@@ -1883,13 +1911,14 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     void
     __introsort_loop(_RandomAccessIterator __first,
 		     _RandomAccessIterator __last,
-		     _Size __depth_limit, _Compare __comp)
+		     _Size __depth_limit, _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__last - __first > int(_S_threshold))
 	{
 	  if (__depth_limit == 0)
 	    {
-	      std::__partial_sort(__first, __last, __last, __comp);
+	      std::__partial_sort(__first, __last, __last,
+				  _GLIBCXX_FORWARD(_Compare, __comp));
 	      return;
 	    }
 	  --__depth_limit;
@@ -1906,14 +1935,15 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX20_CONSTEXPR
     inline void
     __sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
-	   _Compare __comp)
+	   _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__first != __last)
 	{
 	  std::__introsort_loop(__first, __last,
 				std::__lg(__last - __first) * 2,
 				__comp);
-	  std::__final_insertion_sort(__first, __last, __comp);
+	  std::__final_insertion_sort(__first, __last,
+				      _GLIBCXX_FORWARD(_Compare, __comp));
 	}
     }
 
@@ -1922,7 +1952,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     void
     __introselect(_RandomAccessIterator __first, _RandomAccessIterator __nth,
 		  _RandomAccessIterator __last, _Size __depth_limit,
-		  _Compare __comp)
+		  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       _RandomAccessIterator __after_nth = __nth;
       ++__after_nth;
@@ -1931,7 +1961,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 	{
 	  if (__depth_limit == 0)
 	    {
-	      std::__heap_select(__first, __after_nth, __last, __comp);
+	      std::__heap_select(__first, __after_nth, __last,
+				 _GLIBCXX_FORWARD(_Compare, __comp));
 	      // Place the nth largest element in its final position.
 	      std::iter_swap(__first, __nth);
 	      return;
@@ -1944,7 +1975,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 	  else
 	    __last = __cut;
 	}
-      std::__insertion_sort(__first, __last, __comp);
+      std::__insertion_sort(__first, __last,
+			    _GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   /// @endcond
@@ -1981,14 +2013,16 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_partitioned_lower_pred(__first, __last,
 						__val, __comp);
 
-      return std::__lower_bound(__first, __last, __val, __comp);
+      return std::__lower_bound(__first, __last, __val,
+				_GLIBCXX_MOVE(__comp));
     }
 
   template<typename _ForwardIterator, typename _Tp, typename _Compare>
     _GLIBCXX20_CONSTEXPR
     _ForwardIterator
     __upper_bound(_ForwardIterator __first, _ForwardIterator __last,
-		  const _Tp& __val, _Compare __comp)
+		  _GLIBCXX_FWDREF(_Tp) __val,
+		  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef typename iterator_traits<_ForwardIterator>::difference_type
 	_DistanceType;
@@ -2067,14 +2101,16 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_partitioned_upper_pred(__first, __last,
 						__val, __comp);
 
-      return std::__upper_bound(__first, __last, __val, __comp);
+      return std::__upper_bound(__first, __last, __val,
+				_GLIBCXX_MOVE(__comp));
     }
 
   template<typename _ForwardIterator, typename _Tp, typename _Compare>
     _GLIBCXX20_CONSTEXPR
     pair<_ForwardIterator, _ForwardIterator>
     __equal_range(_ForwardIterator __first, _ForwardIterator __last,
-		  const _Tp& __val, _Compare __comp)
+		  const _Tp& __val,
+		  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef typename iterator_traits<_ForwardIterator>::difference_type
 	_DistanceType;
@@ -2100,7 +2136,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 		= std::__lower_bound(__first, __middle, __val, __comp);
 	      std::advance(__first, __len);
 	      _ForwardIterator __right
-		= std::__upper_bound(++__middle, __first, __val, __comp);
+		= std::__upper_bound(++__middle, __first, __val,
+				     _GLIBCXX_FORWARD(_Compare, __comp));
 	      return pair<_ForwardIterator, _ForwardIterator>(__left, __right);
 	    }
 	}
@@ -2177,7 +2214,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_partitioned_upper_pred(__first, __last,
 						__val, __comp);
 
-      return std::__equal_range(__first, __last, __val, __comp);
+      return std::__equal_range(__first, __last, __val,
+				_GLIBCXX_MOVE(__comp));
     }
 
   /**
@@ -2253,7 +2291,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     void
     __move_merge_adaptive(_InputIterator1 __first1, _InputIterator1 __last1,
 			  _InputIterator2 __first2, _InputIterator2 __last2,
-			  _OutputIterator __result, _Compare __comp)
+			  _OutputIterator __result,
+			  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__first1 != __last1 && __first2 != __last2)
 	{
@@ -2282,7 +2321,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 				   _BidirectionalIterator2 __first2,
 				   _BidirectionalIterator2 __last2,
 				   _BidirectionalIterator3 __result,
-				   _Compare __comp)
+				   _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__first1 == __last1)
 	{
@@ -2362,19 +2401,21 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 		     _BidirectionalIterator __middle,
 		     _BidirectionalIterator __last,
 		     _Distance __len1, _Distance __len2,
-		     _Pointer __buffer, _Compare __comp)
+		     _Pointer __buffer, _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__len1 <= __len2)
 	{
 	  _Pointer __buffer_end = _GLIBCXX_MOVE3(__first, __middle, __buffer);
 	  std::__move_merge_adaptive(__buffer, __buffer_end, __middle, __last,
-				     __first, __comp);
+				     __first,
+				     _GLIBCXX_FORWARD(_Compare, __comp));
 	}
       else
 	{
 	  _Pointer __buffer_end = _GLIBCXX_MOVE3(__middle, __last, __buffer);
 	  std::__move_merge_adaptive_backward(__first, __middle, __buffer,
-					      __buffer_end, __last, __comp);
+					      __buffer_end, __last,
+					     _GLIBCXX_FORWARD(_Compare, __comp));
 	}
     }
 
@@ -2386,11 +2427,12 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 			    _BidirectionalIterator __last,
 			    _Distance __len1, _Distance __len2,
 			    _Pointer __buffer, _Distance __buffer_size,
-			    _Compare __comp)
+			    _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__len1 <= __buffer_size || __len2 <= __buffer_size)
 	std::__merge_adaptive(__first, __middle, __last,
-			      __len1, __len2, __buffer, __comp);
+			      __len1, __len2, __buffer,
+			      _GLIBCXX_FORWARD(_Compare, __comp));
       else
 	{
 	  _BidirectionalIterator __first_cut = __first;
@@ -2424,7 +2466,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 	  std::__merge_adaptive_resize(__new_middle, __second_cut, __last,
 				       _Distance(__len1 - __len11),
 				       _Distance(__len2 - __len22),
-				       __buffer, __buffer_size, __comp);
+				       __buffer, __buffer_size,
+				       _GLIBCXX_FORWARD(_Compare, __comp));
 	}
     }
 
@@ -2437,7 +2480,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 			   _BidirectionalIterator __middle,
 			   _BidirectionalIterator __last,
 			   _Distance __len1, _Distance __len2,
-			   _Compare __comp)
+			   _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__len1 == 0 || __len2 == 0)
 	return;
@@ -2475,7 +2518,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       std::__merge_without_buffer(__first, __first_cut, __new_middle,
 				  __len11, __len22, __comp);
       std::__merge_without_buffer(__new_middle, __second_cut, __last,
-				  __len1 - __len11, __len2 - __len22, __comp);
+				  __len1 - __len11, __len2 - __len22,
+				  _GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   template<typename _BidirectionalIterator, typename _Compare>
@@ -2484,7 +2528,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     __inplace_merge(_BidirectionalIterator __first,
 		    _BidirectionalIterator __middle,
 		    _BidirectionalIterator __last,
-		    _Compare __comp)
+		    _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef typename iterator_traits<_BidirectionalIterator>::value_type
 	  _ValueType;
@@ -2511,17 +2555,20 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 
       if (__builtin_expect(__buf.size() == __buf._M_requested_size(), true))
 	std::__merge_adaptive
-	  (__first, __middle, __last, __len1, __len2, __buf.begin(), __comp);
+	  (__first, __middle, __last, __len1, __len2, __buf.begin(),
+	   _GLIBCXX_FORWARD(_Compare, __comp));
       else if (__builtin_expect(__buf.begin() == 0, false))
 	std::__merge_without_buffer
-	  (__first, __middle, __last, __len1, __len2, __comp);
+	  (__first, __middle, __last, __len1, __len2,
+	   _GLIBCXX_FORWARD(_Compare, __comp));
       else
 	std::__merge_adaptive_resize
 	  (__first, __middle, __last, __len1, __len2, __buf.begin(),
-	   _DistanceType(__buf.size()), __comp);
+	   _DistanceType(__buf.size()), _GLIBCXX_FORWARD(_Compare, __comp));
 #else
       std::__merge_without_buffer
-	(__first, __middle, __last, __len1, __len2, __comp);
+	(__first, __middle, __last, __len1, __len2,
+	 _GLIBCXX_FORWARD(_Compare, __comp));
 #endif
     }
 
@@ -2601,7 +2648,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_sorted_pred(__middle, __last, __comp);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      std::__inplace_merge(__first, __middle, __last, __comp);
+      std::__inplace_merge(__first, __middle, __last,
+			   _GLIBCXX_MOVE(__comp));
     }
 
 
@@ -2611,7 +2659,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _OutputIterator
     __move_merge(_InputIterator __first1, _InputIterator __last1,
 		 _InputIterator __first2, _InputIterator __last2,
-		 _OutputIterator __result, _Compare __comp)
+		 _OutputIterator __result, _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__first1 != __last1 && __first2 != __last2)
 	{
@@ -2638,7 +2686,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     __merge_sort_loop(_RandomAccessIterator1 __first,
 		      _RandomAccessIterator1 __last,
 		      _RandomAccessIterator2 __result, _Distance __step_size,
-		      _Compare __comp)
+		      _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       const _Distance __two_step = 2 * __step_size;
 
@@ -2653,7 +2701,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __step_size = std::min(_Distance(__last - __first), __step_size);
 
       std::__move_merge(__first, __first + __step_size,
-			__first + __step_size, __last, __result, __comp);
+			__first + __step_size, __last, __result,
+			_GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   template<typename _RandomAccessIterator, typename _Distance,
@@ -2662,14 +2711,16 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     void
     __chunk_insertion_sort(_RandomAccessIterator __first,
 			   _RandomAccessIterator __last,
-			   _Distance __chunk_size, _Compare __comp)
+			   _Distance __chunk_size,
+			   _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__last - __first >= __chunk_size)
 	{
 	  std::__insertion_sort(__first, __first + __chunk_size, __comp);
 	  __first += __chunk_size;
 	}
-      std::__insertion_sort(__first, __last, __comp);
+      std::__insertion_sort(__first, __last,
+			    _GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   enum { _S_chunk_size = 7 };
@@ -2678,7 +2729,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     void
     __merge_sort_with_buffer(_RandomAccessIterator __first,
 			     _RandomAccessIterator __last,
-			     _Pointer __buffer, _Compare __comp)
+			     _Pointer __buffer,
+			     _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef typename iterator_traits<_RandomAccessIterator>::difference_type
 	_Distance;
@@ -2705,14 +2757,15 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     __stable_sort_adaptive(_RandomAccessIterator __first,
 			   _RandomAccessIterator __middle,
 			   _RandomAccessIterator __last,
-			   _Pointer __buffer, _Compare __comp)
+			   _Pointer __buffer,
+			   _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       std::__merge_sort_with_buffer(__first, __middle, __buffer, __comp);
       std::__merge_sort_with_buffer(__middle, __last, __buffer, __comp);
 
       std::__merge_adaptive(__first, __middle, __last,
 			    __middle - __first, __last - __middle,
-			    __buffer, __comp);
+			    __buffer, _GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   template<typename _RandomAccessIterator, typename _Pointer,
@@ -2721,7 +2774,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     __stable_sort_adaptive_resize(_RandomAccessIterator __first,
 				  _RandomAccessIterator __last,
 				  _Pointer __buffer, _Distance __buffer_size,
-				  _Compare __comp)
+				  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       const _Distance __len = (__last - __first + 1) / 2;
       const _RandomAccessIterator __middle = __first + __len;
@@ -2735,11 +2788,11 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 				       _Distance(__middle - __first),
 				       _Distance(__last - __middle),
 				       __buffer, __buffer_size,
-				       __comp);
+				       _GLIBCXX_FORWARD(_Compare, __comp));
 	}
       else
 	std::__stable_sort_adaptive(__first, __middle, __last,
-				    __buffer, __comp);
+				__buffer, _GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   /// This is a helper function for the stable sorting routines.
@@ -2747,11 +2800,13 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX26_CONSTEXPR
     void
     __inplace_stable_sort(_RandomAccessIterator __first,
-			  _RandomAccessIterator __last, _Compare __comp)
+			  _RandomAccessIterator __last,
+			  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__last - __first < 15)
 	{
-	  std::__insertion_sort(__first, __last, __comp);
+	  std::__insertion_sort(__first, __last,
+				_GLIBCXX_FORWARD(_Compare, __comp));
 	  return;
 	}
       _RandomAccessIterator __middle = __first + (__last - __first) / 2;
@@ -2760,7 +2815,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       std::__merge_without_buffer(__first, __middle, __last,
 				  __middle - __first,
 				  __last - __middle,
-				  __comp);
+				  _GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   // stable_sort
@@ -2776,7 +2831,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     bool
     __includes(_InputIterator1 __first1, _InputIterator1 __last1,
 	       _InputIterator2 __first2, _InputIterator2 __last2,
-	       _Compare __comp)
+	       _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__first1 != __last1 && __first2 != __last2)
 	{
@@ -2875,7 +2930,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_irreflexive_pred2(__first1, __last1, __comp);
       __glibcxx_requires_irreflexive_pred2(__first2, __last2, __comp);
 
-      return std::__includes(__first1, __last1, __first2, __last2, __comp);
+      return std::__includes(__first1, __last1, __first2, __last2,
+			     _GLIBCXX_MOVE(__comp));
     }
 
   // nth_element
@@ -2892,7 +2948,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX20_CONSTEXPR
     bool
     __next_permutation(_BidirectionalIterator __first,
-		       _BidirectionalIterator __last, _Compare __comp)
+		       _BidirectionalIterator __last,
+		       _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__first == __last)
 	return false;
@@ -2985,14 +3042,16 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_valid_range(__first, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      return std::__next_permutation(__first, __last, __comp);
+      return std::__next_permutation
+	(__first, __last, _GLIBCXX_MOVE(__comp));
     }
 
   template<typename _BidirectionalIterator, typename _Compare>
     _GLIBCXX20_CONSTEXPR
     bool
     __prev_permutation(_BidirectionalIterator __first,
-		       _BidirectionalIterator __last, _Compare __comp)
+		       _BidirectionalIterator __last,
+		       _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__first == __last)
 	return false;
@@ -3086,7 +3145,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_valid_range(__first, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      return std::__prev_permutation(__first, __last, __comp);
+      return std::__prev_permutation(__first, __last,
+				     _GLIBCXX_MOVE(__comp));
     }
 
   // replace
@@ -3098,7 +3158,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _OutputIterator
     __replace_copy_if(_InputIterator __first, _InputIterator __last,
 		      _OutputIterator __result,
-		      _Predicate __pred, const _Tp& __new_value)
+		      _GLIBCXX_CP_FWDREF(_Predicate) __pred,
+		      const _Tp& __new_value)
     {
       for (; __first != __last; ++__first, (void)++__result)
 	if (__pred(*__first))
@@ -3173,8 +3234,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 	    typename iterator_traits<_InputIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
 
-      return std::__replace_copy_if(__first, __last, __result, __pred,
-				    __new_value);
+      return std::__replace_copy_if(__first, __last, __result,
+				    _GLIBCXX_MOVE(__pred), __new_value);
     }
 
 #if __cplusplus >= 201103L
@@ -3205,13 +3266,15 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     inline bool
     is_sorted(_ForwardIterator __first, _ForwardIterator __last,
 	      _Compare __comp)
-    { return std::is_sorted_until(__first, __last, __comp) == __last; }
+    {
+      return std::is_sorted_until(__first, __last, std::move(__comp)) == __last;
+    }
 
   template<typename _ForwardIterator, typename _Compare>
     _GLIBCXX20_CONSTEXPR
     _ForwardIterator
     __is_sorted_until(_ForwardIterator __first, _ForwardIterator __last,
-		      _Compare __comp)
+		      _Compare&& __comp)
     {
       if (__first == __last)
 	return __last;
@@ -3270,7 +3333,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_valid_range(__first, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      return std::__is_sorted_until(__first, __last, __comp);
+      return std::__is_sorted_until(__first, __last,
+				    std::move(__comp));
     }
 
   /**
@@ -3315,7 +3379,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     _GLIBCXX14_CONSTEXPR
     pair<_ForwardIterator, _ForwardIterator>
     __minmax_element(_ForwardIterator __first, _ForwardIterator __last,
-		     _Compare __comp)
+		     _Compare&& __comp)
     {
       _ForwardIterator __next = __first;
       if (__first == __last
@@ -3423,7 +3487,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_valid_range(__first, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      return std::__minmax_element(__first, __last, __comp);
+      return std::__minmax_element(__first, __last,
+				   std::move(__comp));
     }
 
   template<typename _Tp>
@@ -3445,7 +3510,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     {
       __glibcxx_requires_irreflexive_pred(__l.begin(), __l.end(), __comp);
       pair<const _Tp*, const _Tp*> __p =
-	std::__minmax_element(__l.begin(), __l.end(), __comp);
+	std::__minmax_element(__l.begin(), __l.end(),
+			      std::move(__comp));
       return std::make_pair(*__p.first, *__p.second);
     }
 
@@ -3478,7 +3544,8 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
 	    typename iterator_traits<_ForwardIterator2>::value_type>)
       __glibcxx_requires_valid_range(__first1, __last1);
 
-      return std::__is_permutation(__first1, __last1, __first2, __pred);
+      return std::__is_permutation(__first1, __last1, __first2,
+				   std::move(__pred));
     }
 
 #if __glibcxx_robust_nonmodifying_seq_ops // C++ >= 14
@@ -3490,7 +3557,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
     bool
     __is_permutation(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
 		     _ForwardIterator2 __first2, _ForwardIterator2 __last2,
-		     _BinaryPredicate __pred)
+		     _BinaryPredicate&& __pred)
     {
       using _Cat1 = decltype(std::__iter_concept_or_category<_ForwardIterator1>());
       using _Cat2 = decltype(std::__iter_concept_or_category<_ForwardIterator2>());
@@ -3593,7 +3660,7 @@ _GLIBCXX_END_INLINE_ABI_NAMESPACE(_V2)
       __glibcxx_requires_valid_range(__first2, __last2);
 
       return std::__is_permutation(__first1, __last1, __first2, __last2,
-				   __pred);
+				   std::move(__pred));
     }
 #endif // __glibcxx_robust_nonmodifying_seq_ops
 
@@ -3896,7 +3963,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 	      typename iterator_traits<_InputIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
 
-      return std::__find_if(__first, __last, __pred);
+      return std::__find_if(__first, __last,
+			    _GLIBCXX_MOVE(__pred));
     }
 
   /**
@@ -4028,7 +4096,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 	    typename iterator_traits<_ForwardIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
 
-      return std::__adjacent_find(__first, __last, __binary_pred);
+      return std::__adjacent_find(__first, __last,
+				  _GLIBCXX_MOVE(__binary_pred));
     }
 
   /**
@@ -4075,7 +4144,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 	    typename iterator_traits<_InputIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
 
-      return std::__count_if(__first, __last, __pred);
+      return std::__count_if(__first, __last,
+			     _GLIBCXX_MOVE(__pred));
     }
 
   /**
@@ -4485,7 +4555,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 
       if (__first == __last)
 	return __result;
-      return std::__unique_copy(__first, __last, __result, __binary_pred,
+      return std::__unique_copy(__first, __last, __result,
+				_GLIBCXX_MOVE(__binary_pred),
 				std::__iter_concept_or_category(__first));
     }
 
@@ -4631,7 +4702,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 	    typename iterator_traits<_ForwardIterator>::value_type>)
       __glibcxx_requires_valid_range(__first, __last);
 
-      return std::__partition(__first, __last, __pred,
+      return std::__partition(__first, __last, _GLIBCXX_MOVE(__pred),
 			      std::__iterator_category(__first));
     }
 
@@ -4708,7 +4779,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__middle, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      std::__partial_sort(__first, __middle, __last, __comp);
+      std::__partial_sort(__first, __middle, __last,
+			  _GLIBCXX_MOVE(__comp));
     }
 
   /**
@@ -4785,7 +4857,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 
       std::__introselect(__first, __nth, __last,
 			 std::__lg(__last - __first) * 2,
-			 __comp);
+			 _GLIBCXX_MOVE(__comp));
     }
 
   /**
@@ -4846,7 +4918,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      std::__sort(__first, __last, __comp);
+      std::__sort(__first, __last, _GLIBCXX_MOVE(__comp));
     }
 
   template<typename _InputIterator1, typename _InputIterator2,
@@ -4855,7 +4927,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     _OutputIterator
     __merge(_InputIterator1 __first1, _InputIterator1 __last1,
 	    _InputIterator2 __first2, _InputIterator2 __last2,
-	    _OutputIterator __result, _Compare __comp)
+	    _OutputIterator __result, _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__first1 != __last1 && __first2 != __last2)
 	{
@@ -4967,15 +5039,16 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_irreflexive_pred2(__first1, __last1, __comp);
       __glibcxx_requires_irreflexive_pred2(__first2, __last2, __comp);
 
-      return _GLIBCXX_STD_A::__merge(__first1, __last1, __first2, __last2,
-				     __result, __comp);
+      return _GLIBCXX_STD_A::__merge(__first1, __last1,
+				__first2, __last2, __result,
+				_GLIBCXX_MOVE(__comp));
     }
 
   template<typename _RandomAccessIterator, typename _Compare>
     _GLIBCXX26_CONSTEXPR
     inline void
     __stable_sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
-		  _Compare __comp)
+		  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef typename iterator_traits<_RandomAccessIterator>::value_type
 	_ValueType;
@@ -4988,7 +5061,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 #if _GLIBCXX_HOSTED
 # if __glibcxx_constexpr_algorithms >= 202306L // >= C++26
       if consteval {
-	return std::__inplace_stable_sort(__first, __last, __comp);
+	return std::__inplace_stable_sort(__first, __last,
+					  std::forward<_Compare>(__comp));
       }
 # endif
 
@@ -5000,14 +5074,18 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       if (__builtin_expect(__buf._M_requested_size() == __buf.size(), true))
 	std::__stable_sort_adaptive(__first,
 				    __first + _DistanceType(__buf.size()),
-				    __last, __buf.begin(), __comp);
+				    __last, __buf.begin(),
+				    _GLIBCXX_FORWARD(_Compare, __comp));
       else if (__builtin_expect(__buf.begin() == 0, false))
-	std::__inplace_stable_sort(__first, __last, __comp);
+	std::__inplace_stable_sort(__first, __last,
+				   _GLIBCXX_FORWARD(_Compare, __comp));
       else
 	std::__stable_sort_adaptive_resize(__first, __last, __buf.begin(),
-					   _DistanceType(__buf.size()), __comp);
+					   _DistanceType(__buf.size()),
+					   _GLIBCXX_FORWARD(_Compare, __comp));
 #else
-      std::__inplace_stable_sort(__first, __last, __comp);
+      std::__inplace_stable_sort
+	(__first, __last, _GLIBCXX_FORWARD(_Compare, __comp));
 #endif
     }
 
@@ -5076,7 +5154,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      _GLIBCXX_STD_A::__stable_sort(__first, __last, __comp);
+      _GLIBCXX_STD_A::__stable_sort(__first, __last,
+				    _GLIBCXX_MOVE(__comp));
     }
 
   template<typename _InputIterator1, typename _InputIterator2,
@@ -5085,7 +5164,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     _OutputIterator
     __set_union(_InputIterator1 __first1, _InputIterator1 __last1,
 		_InputIterator2 __first2, _InputIterator2 __last2,
-		_OutputIterator __result, _Compare __comp)
+		_OutputIterator __result, _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__first1 != __last1 && __first2 != __last2)
 	{
@@ -5206,8 +5285,9 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_irreflexive_pred2(__first1, __last1, __comp);
       __glibcxx_requires_irreflexive_pred2(__first2, __last2, __comp);
 
-      return _GLIBCXX_STD_A::__set_union(__first1, __last1, __first2, __last2,
-					 __result, __comp);
+      return _GLIBCXX_STD_A::__set_union(__first1, __last1,
+				__first2, __last2, __result,
+				_GLIBCXX_MOVE(__comp));
     }
 
   template<typename _InputIterator1, typename _InputIterator2,
@@ -5216,7 +5296,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     _OutputIterator
     __set_intersection(_InputIterator1 __first1, _InputIterator1 __last1,
 		       _InputIterator2 __first2, _InputIterator2 __last2,
-		       _OutputIterator __result, _Compare __comp)
+		       _OutputIterator __result,
+		       _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__first1 != __last1 && __first2 != __last2)
 	if (__comp(*__first1, *__first2))
@@ -5327,7 +5408,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 
       return _GLIBCXX_STD_A::
 	       __set_intersection(__first1, __last1, __first2, __last2,
-				  __result, __comp);
+				  __result, _GLIBCXX_MOVE(__comp));
     }
 
   template<typename _InputIterator1, typename _InputIterator2,
@@ -5336,7 +5417,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     _OutputIterator
     __set_difference(_InputIterator1 __first1, _InputIterator1 __last1,
 		     _InputIterator2 __first2, _InputIterator2 __last2,
-		     _OutputIterator __result, _Compare __comp)
+		     _OutputIterator __result, _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__first1 != __last1 && __first2 != __last2)
 	if (__comp(*__first1, *__first2))
@@ -5453,7 +5534,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 
       return _GLIBCXX_STD_A::
 	       __set_difference(__first1, __last1, __first2, __last2, __result,
-				__comp);
+				_GLIBCXX_MOVE(__comp));
     }
 
   template<typename _InputIterator1, typename _InputIterator2,
@@ -5466,7 +5547,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 			       _InputIterator2 __first2,
 			       _InputIterator2 __last2,
 			       _OutputIterator __result,
-			       _Compare __comp)
+			       _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__first1 != __last1 && __first2 != __last2)
 	if (__comp(*__first1, *__first2))
@@ -5589,14 +5670,14 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 
       return _GLIBCXX_STD_A::
 	       __set_symmetric_difference(__first1, __last1, __first2, __last2,
-					  __result, __comp);
+					  __result, _GLIBCXX_MOVE(__comp));
     }
 
   template<typename _ForwardIterator, typename _Compare>
     _GLIBCXX14_CONSTEXPR
     _ForwardIterator
     __min_element(_ForwardIterator __first, _ForwardIterator __last,
-		  _Compare __comp)
+		  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__first == __last)
 	return __first;
@@ -5653,14 +5734,15 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      return _GLIBCXX_STD_A::__min_element(__first, __last, __comp);
+      return _GLIBCXX_STD_A::__min_element(__first, __last,
+					   _GLIBCXX_MOVE(__comp));
     }
 
   template<typename _ForwardIterator, typename _Compare>
     _GLIBCXX14_CONSTEXPR
     _ForwardIterator
     __max_element(_ForwardIterator __first, _ForwardIterator __last,
-		  _Compare __comp)
+		  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       if (__first == __last) return __first;
       _ForwardIterator __result = __first;
@@ -5716,7 +5798,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      return _GLIBCXX_STD_A::__max_element(__first, __last, __comp);
+      return _GLIBCXX_STD_A::__max_element(__first, __last,
+					   _GLIBCXX_MOVE(__comp));
     }
 
 #if __cplusplus >= 201103L
@@ -5737,7 +5820,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     min(initializer_list<_Tp> __l, _Compare __comp)
     {
       __glibcxx_requires_irreflexive_pred(__l.begin(), __l.end(), __comp);
-      return *_GLIBCXX_STD_A::__min_element(__l.begin(), __l.end(), __comp);
+      return *_GLIBCXX_STD_A::__min_element(__l.begin(), __l.end(),
+					    std::move(__comp));
     }
 
   template<typename _Tp>
@@ -5756,7 +5840,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     max(initializer_list<_Tp> __l, _Compare __comp)
     {
       __glibcxx_requires_irreflexive_pred(__l.begin(), __l.end(), __comp);
-      return *_GLIBCXX_STD_A::__max_element(__l.begin(), __l.end(), __comp);
+      return *_GLIBCXX_STD_A::__max_element(__l.begin(), __l.end(),
+					    std::move(__comp));
     }
 #endif // C++11
 
diff --git a/libstdc++-v3/include/bits/stl_algobase.h b/libstdc++-v3/include/bits/stl_algobase.h
index 1350736a8d8..b4f682f2afd 100644
--- a/libstdc++-v3/include/bits/stl_algobase.h
+++ b/libstdc++-v3/include/bits/stl_algobase.h
@@ -1327,7 +1327,7 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     bool
     __lexicographical_compare_impl(_II1 __first1, _II1 __last1,
 				   _II2 __first2, _II2 __last2,
-				   _Compare __comp)
+				   _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef __decltype(std::__iter_concept_or_category<_II1>()) _Category1;
       typedef __decltype(std::__iter_concept_or_category<_II2>()) _Category2;
@@ -1500,7 +1500,8 @@ _GLIBCXX_END_NAMESPACE_CONTAINER
     _GLIBCXX20_CONSTEXPR
     _ForwardIterator
     __lower_bound(_ForwardIterator __first, _ForwardIterator __last,
-		  const _Tp& __val, _Compare __comp)
+		  _GLIBCXX_FWDREF(_Tp) __val,
+		  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef typename iterator_traits<_ForwardIterator>::difference_type
 	_DistanceType;
@@ -1670,7 +1671,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     _GLIBCXX20_CONSTEXPR
     inline bool
     __equal4(_II1 __first1, _II1 __last1, _II2 __first2, _II2 __last2,
-	     _BinaryPredicate __binary_pred)
+	     _BinaryPredicate&& __binary_pred)
     {
       using _RATag = random_access_iterator_tag;
       using _Cat1 = decltype(std::__iter_concept_or_category<_II1>());
@@ -1681,7 +1682,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
 	  if ((__last1 - __first1) != (__last2 - __first2))
 	    return false;
 	  return _GLIBCXX_STD_A::equal(__first1, __last1, __first2,
-				       __binary_pred);
+	     std::forward<_BinaryPredicate>(__binary_pred));
 	}
       else
 	{
@@ -1755,7 +1756,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first2, __last2);
 
       return _GLIBCXX_STD_A::__equal4(__first1, __last1, __first2, __last2,
-				      __binary_pred);
+				      std::move(__binary_pred));
     }
 #endif // __glibcxx_robust_nonmodifying_seq_ops
 
@@ -1822,7 +1823,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first2, __last2);
 
       return std::__lexicographical_compare_impl
-	(__first1, __last1, __first2, __last2, __comp);
+	(__first1, __last1, __first2, __last2, _GLIBCXX_MOVE(__comp));
     }
 
 #if __cpp_lib_three_way_comparison
@@ -1928,7 +1929,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     _GLIBCXX20_CONSTEXPR
     pair<_InputIterator1, _InputIterator2>
     __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
-	       _InputIterator2 __first2, _BinaryPredicate __binary_pred)
+	       _InputIterator2 __first2,
+	       _GLIBCXX_CP_FWDREF(_BinaryPredicate) __binary_pred)
     {
       while (__first1 != __last1 && __binary_pred(*__first1, *__first2))
 	{
@@ -1998,7 +2000,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first1, __last1);
 
       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2,
-					__binary_pred);
+					_GLIBCXX_MOVE(__binary_pred));
     }
 
 #if __glibcxx_robust_nonmodifying_seq_ops // C++ >= 14
@@ -2008,7 +2010,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
     pair<_InputIterator1, _InputIterator2>
     __mismatch(_InputIterator1 __first1, _InputIterator1 __last1,
 	       _InputIterator2 __first2, _InputIterator2 __last2,
-	       _BinaryPredicate __binary_pred)
+	       _BinaryPredicate&& __binary_pred)
     {
       while (__first1 != __last1 && __first2 != __last2
 	     && __binary_pred(*__first1, *__first2))
@@ -2084,7 +2086,7 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first2, __last2);
 
       return _GLIBCXX_STD_A::__mismatch(__first1, __last1, __first2, __last2,
-			     __binary_pred);
+					_GLIBCXX_MOVE(__binary_pred));
     }
 #endif // __glibcxx_robust_nonmodifying_seq_ops
 
@@ -2094,7 +2096,8 @@ _GLIBCXX_END_NAMESPACE_ALGO
   template<typename _Iterator, typename _Predicate>
     _GLIBCXX20_CONSTEXPR
     inline _Iterator
-    __find_if(_Iterator __first, _Iterator __last, _Predicate __pred)
+    __find_if(_Iterator __first, _Iterator __last,
+	      _GLIBCXX_CP_FWDREF(_Predicate) __pred)
     {
 #pragma GCC unroll 4
       while (__first != __last && !__pred(*__first))
@@ -2105,7 +2108,8 @@ _GLIBCXX_END_NAMESPACE_ALGO
   template<typename _InputIterator, typename _Predicate>
     _GLIBCXX20_CONSTEXPR
     typename iterator_traits<_InputIterator>::difference_type
-    __count_if(_InputIterator __first, _InputIterator __last, _Predicate __pred)
+    __count_if(_InputIterator __first, _InputIterator __last,
+	       _GLIBCXX_CP_FWDREF(_Predicate) __pred)
     {
       typename iterator_traits<_InputIterator>::difference_type __n = 0;
       for (; __first != __last; ++__first)
@@ -2118,7 +2122,7 @@ _GLIBCXX_END_NAMESPACE_ALGO
     _GLIBCXX20_CONSTEXPR
     _ForwardIterator
     __remove_if(_ForwardIterator __first, _ForwardIterator __last,
-		_Predicate __pred)
+		_GLIBCXX_CP_FWDREF(_Predicate) __pred)
     {
       __first = std::__find_if(__first, __last, __pred);
       if (__first == __last)
@@ -2140,7 +2144,7 @@ _GLIBCXX_END_NAMESPACE_ALGO
     _ForwardIterator1
     __search(_ForwardIterator1 __first1, _ForwardIterator1 __last1,
 	     _ForwardIterator2 __first2, _ForwardIterator2 __last2,
-	     _BinaryPredicate  __predicate)
+	     _GLIBCXX_CP_FWDREF(_BinaryPredicate)  __predicate)
     {
       // Test for empty ranges
       if (__first1 == __last1 || __first2 == __last2)
@@ -2290,7 +2294,8 @@ _GLIBCXX_BEGIN_NAMESPACE_ALGO
       __glibcxx_requires_valid_range(__first1, __last1);
       __glibcxx_requires_valid_range(__first2, __last2);
 
-      return std::__search(__first1, __last1, __first2, __last2, __predicate);
+      return std::__search(__first1, __last1, __first2, __last2,
+			   _GLIBCXX_MOVE(__predicate));
     }
 
 _GLIBCXX_END_NAMESPACE_ALGO
diff --git a/libstdc++-v3/include/bits/stl_heap.h b/libstdc++-v3/include/bits/stl_heap.h
index 8c5c5df5266..53de394a555 100644
--- a/libstdc++-v3/include/bits/stl_heap.h
+++ b/libstdc++-v3/include/bits/stl_heap.h
@@ -74,7 +74,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     _Distance
     __is_heap_until(_RandomAccessIterator __first, _Distance __n,
-		    _Compare& __comp)
+		    _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
 #if __cplusplus >= 201103L
       using _IterTraits = iterator_traits<_RandomAccessIterator>;
@@ -109,10 +109,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	   typename _Distance>
     _GLIBCXX20_CONSTEXPR
     inline bool
-    __is_heap(_RandomAccessIterator __first, _Compare __comp, _Distance __n)
+    __is_heap(_RandomAccessIterator __first,
+	      _GLIBCXX_CP_FWDREF(_Compare) __comp,
+	      _Distance __n)
     {
       typename iterator_traits<_RandomAccessIterator>::difference_type __d(__n);
-      return std::__is_heap_until(__first, __d, __comp) == __n;
+      return std::__is_heap_until
+	(__first, __d, _GLIBCXX_FORWARD(_Compare, __comp)) == __n;
     }
 
   template<typename _RandomAccessIterator>
@@ -125,9 +128,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     inline bool
     __is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,
-	      _Compare __comp)
+	      _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
-      return std::__is_heap(__first, _GLIBCXX_MOVE(__comp),
+      return std::__is_heap(__first, _GLIBCXX_FORWARD(_Compare, __comp),
 			    std::distance(__first, __last));
     }
 
@@ -139,8 +142,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     void
     __push_heap(_RandomAccessIterator __first,
-		_Distance __holeIndex, _Distance __topIndex, _Tp __value,
-		_Compare& __comp)
+		_Distance __holeIndex, _Distance __topIndex,
+		_GLIBCXX_CP_FWDREF(_Tp) __value,
+		_GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       _Distance __parent = (__holeIndex - 1) / 2;
       while (__holeIndex > __topIndex && __comp(*(__first + __parent), __value))
@@ -149,7 +153,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  __holeIndex = __parent;
 	  __parent = (__holeIndex - 1) / 2;
 	}
-      *(__first + __holeIndex) = _GLIBCXX_MOVE(__value);
+      *(__first + __holeIndex) = _GLIBCXX_FORWARD(_Tp, __value);
     }
 
   /**
@@ -218,7 +222,8 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       _ValueType __value = _GLIBCXX_MOVE(*(__last - _DistanceType(1)));
       std::__push_heap(__first, _DistanceType((__last - __first) - 1),
-		       _DistanceType(0), _GLIBCXX_MOVE(__value), __comp);
+		       _DistanceType(0), _GLIBCXX_MOVE(__value),
+		       _GLIBCXX_MOVE(__comp));
     }
 
   template<typename _RandomAccessIterator, typename _Distance,
@@ -226,7 +231,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     void
     __adjust_heap(_RandomAccessIterator __first, _Distance __holeIndex,
-		  _Distance __len, _Tp __value, _Compare __comp)
+		  _Distance __len,
+		  _GLIBCXX_CP_FWDREF(_Tp) __value,
+		  _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       const _Distance __topIndex = __holeIndex;
       _Distance __secondChild = __holeIndex;
@@ -247,14 +254,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 	  __holeIndex = __secondChild - 1;
 	}
       std::__push_heap(__first, __holeIndex, __topIndex,
-		       _GLIBCXX_MOVE(__value), __comp);
+		       _GLIBCXX_FORWARD(_Tp, __value),
+		       _GLIBCXX_MOVE(__comp));
     }
 
   template<typename _RandomAccessIterator, typename _Compare>
     _GLIBCXX20_CONSTEXPR
     inline void
     __pop_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,
-	       _RandomAccessIterator __result, _Compare& __comp)
+	       _RandomAccessIterator __result,
+	       _GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef typename iterator_traits<_RandomAccessIterator>::value_type
 	_ValueType;
@@ -265,7 +274,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       *__result = _GLIBCXX_MOVE(*__first);
       std::__adjust_heap(__first, _DistanceType(0),
 			 _DistanceType(__last - __first),
-			 _GLIBCXX_MOVE(__value), __comp);
+		_GLIBCXX_MOVE(__value), _GLIBCXX_FORWARD(_Compare, __comp));
     }
 
   /**
@@ -330,7 +339,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       if (__last - __first > 1)
 	{
 	  --__last;
-	  std::__pop_heap(__first, __last, __last, __comp);
+	  std::__pop_heap(__first, __last, __last, _GLIBCXX_MOVE(__comp));
 	}
     }
 
@@ -338,7 +347,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     _GLIBCXX20_CONSTEXPR
     void
     __make_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,
-		_Compare& __comp)
+		_GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       typedef typename iterator_traits<_RandomAccessIterator>::value_type
 	  _ValueType;
@@ -408,14 +417,14 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __glibcxx_requires_valid_range(__first, __last);
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
-      std::__make_heap(__first, __last, __comp);
+      std::__make_heap(__first, __last, _GLIBCXX_MOVE(__comp));
     }
 
   template<typename _RandomAccessIterator, typename _Compare>
     _GLIBCXX20_CONSTEXPR
     void
     __sort_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,
-		_Compare& __comp)
+		_GLIBCXX_CP_FWDREF(_Compare) __comp)
     {
       while (__last - __first > 1)
 	{
@@ -473,7 +482,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
       __glibcxx_requires_heap_pred(__first, __last, __comp);
 
-      std::__sort_heap(__first, __last, __comp);
+      std::__sort_heap(__first, __last, _GLIBCXX_MOVE(__comp));
     }
 
 #if __cplusplus >= 201103L
@@ -530,7 +539,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
       return __first
 	+ std::__is_heap_until(__first, std::distance(__first, __last),
-			       __comp);
+			       std::move(__comp));
     }
 
   /**
@@ -567,9 +576,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       __glibcxx_requires_irreflexive_pred(__first, __last, __comp);
 
       const auto __dist = std::distance(__first, __last);
-      return std::__is_heap_until(__first, __dist, __comp) == __dist;
+      return std::__is_heap_until(__first, __dist,
+				  std::move(__comp)) == __dist;
     }
-#endif
+#endif // C++11
 
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
diff --git a/libstdc++-v3/src/c++17/memory_resource.cc b/libstdc++-v3/src/c++17/memory_resource.cc
index d8b36554e9f..15e59d36e90 100644
--- a/libstdc++-v3/src/c++17/memory_resource.cc
+++ b/libstdc++-v3/src/c++17/memory_resource.cc
@@ -26,6 +26,7 @@
 #include <algorithm>			// lower_bound, rotate
 #include <atomic>
 #include <bit>				// has_single_bit, bit_ceil, bit_width
+#include <functional>			// less_equal
 #include <new>
 #include <bits/move.h>			// std::__exchange
 #if ATOMIC_POINTER_LOCK_FREE != 2
diff --git a/libstdc++-v3/testsuite/25_algorithms/inplace_merge/1.cc b/libstdc++-v3/testsuite/25_algorithms/inplace_merge/1.cc
index 2908ec9a3d0..a83a6765bd4 100644
--- a/libstdc++-v3/testsuite/25_algorithms/inplace_merge/1.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/inplace_merge/1.cc
@@ -21,6 +21,7 @@
 // { dg-require-effective-target hosted }
 
 #include <algorithm>
+#include <vector>
 #include <testsuite_hooks.h>
 #include <testsuite_iterators.h>
 #include <testsuite_new_operators.h>
@@ -119,6 +120,17 @@ test4()
     }
 }
 
+bool bs[] = { false, false, true, false, true, true };
+std::vector<bool> v(6);
+
+void
+test5()
+{
+  v.assign(bs, bs + 6);
+  inplace_merge(v.begin(), v.begin() + 3, v.end());
+  VERIFY( !v[0] && !v[1] && !v[2] && v[3] && v[4] && v[5] );
+}
+
 int 
 main()
 {
@@ -129,14 +141,17 @@ main()
   __gnu_test::set_new_limit(sizeof(S) * 4);
   test3();
   test4();
+  test5();
 
   __gnu_test::set_new_limit(sizeof(S));
   test3();
   test4();
+  test5();
 
   __gnu_test::set_new_limit(0);
   test3();
   test4();
+  test5();
 
   return 0;
 }
diff --git a/libstdc++-v3/testsuite/25_algorithms/stable_sort/1.cc b/libstdc++-v3/testsuite/25_algorithms/stable_sort/1.cc
index 11cf0c70108..595dc186fa0 100644
--- a/libstdc++-v3/testsuite/25_algorithms/stable_sort/1.cc
+++ b/libstdc++-v3/testsuite/25_algorithms/stable_sort/1.cc
@@ -84,6 +84,26 @@ test3()
     VERIFY(array[i].j == i % 2);
 }
 
+struct NotConstLess
+{
+  bool
+  operator()(S& s1, S& s2)
+  { return s1.i < s2.i; }
+};
+
+void
+test4()
+{
+#if __cplusplus >= 201103L
+  NotConstLess less;
+  S array[] = { -1, -2, 1, 2, -3 ,-5 ,3 , -4, 5, 4 };
+  test_container<S, random_access_iterator_wrapper> con(array,array + 10);
+  stable_sort(con.begin(), con.end(), less);
+  for(int i = 0; i < 10; ++i)
+    VERIFY(array[i].j == i % 2);
+#endif
+}
+
 int 
 main()
 {
@@ -91,13 +111,17 @@ main()
   test2();
 
   test3();
+  test4();
 
   __gnu_test::set_new_limit(sizeof(S) * 5);
   test3();
+  test4();
 
   __gnu_test::set_new_limit(sizeof(S));
   test3();
+  test4();
 
   __gnu_test::set_new_limit(0);
   test3();
+  test4();
 }


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