Implement C++20 p0202 - Add Constexpr Modifiers to Functions in <algorithm> and <utility> Headers.

2019-08-01  Edward Smith-Rowland  <3dw4rd@verizon.net>

	Implement C++20 p0202 - Add Constexpr Modifiers to Functions
	in <algorithm> and <utility> Headers.
	Implement C++20 p1023 - constexpr comparison operators for std::array.
	* include/bits/algorithmfwd.h (all_of, any_of, binary_search, copy,
	copy_backward, copy_if, copy_n, equal_range, fill, find_end,
	find_if_not, includes, is_heap, is_heap_until, is_partitioned,
	is_permutation, is_sorted, is_sorted_until, iter_swap, lower_bound,
	none_of, partition_copy, partition_point, remove, remove_if,
	remove_copy, remove_copy_if, replace_copy, replace_copy_if,
	reverse_copy, rotate_copy, uunique, upper_bound, adjacent_find, count,
	count_if, equal, find, find_first_of, find_if, for_each, generate,
	generate_n, lexicographical_compare, merge, mismatch, replace,
	replace_if, search, search_n, set_difference, set_intersection,
	set_symmetric_difference, set_union, transform, unique_copy):
	Mark constexpr.
	* include/bits/cpp_type_traits.h (__miter_base): Mark constexpr.
	* include/bits/predefined_ops.h (_Iter_less_val::operator(),
	_Val_less_iter::operator(), _Iter_equal_to_iter::operator(),
	_Iter_equal_to_val::operator(), _Iter_equals_val::operator()):
	 Use const ref instead of ref arg;
	(_Iter_less_val, __iter_less_val, _Val_less_iter, __val_less_iter,
	__iter_equal_to_iter, __iter_equal_to_val, __iter_comp_val,
	_Iter_comp_val, _Val_comp_iter, __val_comp_iter, __iter_equals_val,
	_Iter_equals_iter, __iter_comp_iter, _Iter_pred, __pred_iter,
	_Iter_comp_to_val, __iter_comp_val, _Iter_comp_to_iter,
	__iter_comp_iter): Mark constexpr.
	* include/bits/stl_algo.h (__find_if, __find_if_not, __find_if_not_n,
	__search, __search_n_aux, __search_n, __find_end, find_end, all_of,
	none_of, any_of, find_if_not, is_partitioned, partition_point,
	__remove_copy_if, remove_copy, remove_copy_if, copy_if, __copy_n,
	copy_n, partition_copy, __remove_if, remove, remove_if, __adjacent_find,
	__unique, unique, __unique_copy, reverse_copy, rotate_copy,
	__unguarded_linear_insert, __insertion_sort, __unguarded_insertion_sort,
	__final_insertion_sort, lower_bound, __upper_bound, upper_bound,
	__equal_range, equal_range, binary_search, __includes, includes,
	__next_permutation, __prev_permutation, __replace_copy_if, replace_copy,
	replace_copy_if, __count_if, is_sorted, __is_sorted_until,
	is_sorted_until, __is_permutation, is_permutation, for_each, find,
	find_if, find_first_of, adjacent_find, count, count_if, search,
	search_n, transform, replace, replace_if, generate, generate_n,
	unique_copy, __merge, merge, __set_union, set_union, __set_intersection,
	set_intersection, __set_difference, set_difference,
	__set_symmetric_difference, set_symmetric_difference):  Mark constexpr.
	* include/bits/stl_algobase.h (__memmove, __memcmp): New maybe constexpr
	wrappers around __builtin_memmove and __builtin_memcmp
	respectively;
	(__niter_base, __niter_wrap, __copy_m, __copy_move_a, __copy_move_a2,
	copy, move, __copy_move_b, __copy_move_backward_a,
	__copy_move_backward_a2, copy_backward, move_backward, __fill_a, fill,
	__fill_n_a, fill_n, equal, __lc_rai::__newlast1, __lc_rai::__cnd2,
	__lexicographical_compare_impl, __lexicographical_compare,
	__lexicographical_compare<true>::__lc, __lexicographical_compare_aux,
	__lower_bound, lower_bound, equal, __equal4, lexicographical_compare,
	__mismatch, mismatch, __is_heap_until, __is_heap, is_heap_until,
	is_heap): Mark constexpr.
	* include/bits/stl_heap.h (__is_heap_until, __is_heap, is_heap_until,
	is_heap): Mark constexpr.
	* include/bits/stl_iterator.h (__niter_base, __miter_base): Mark constexpr.
	* include/std/array: Make comparison ops constexpr.
	* include/std/utility: Make exchange constexpr.
	* include/std/version (__cpp_lib_constexpr_algorithms): New macro.
	* testsuite/23_containers/array/tuple_interface/get_neg.cc: Adjust.
	* testsuite/23_containers/array/tuple_interface/
	tuple_element_neg.cc: Adjust.
	* testsuite/20_util/exchange/constexpr.cc: New.
	* testsuite/23_containers/array/comparison_operators/constexpr.cc: New.
	* testsuite/25_algorithms/constexpr_macro.cc: New.
	* testsuite/25_algorithms/adjacent_find/constexpr.cc: New.
	* testsuite/25_algorithms/all_of/constexpr.cc: New.
	* testsuite/25_algorithms/any_of/constexpr.cc: New.
	* testsuite/25_algorithms/binary_search/constexpr.cc: New.
	* testsuite/25_algorithms/copy/constexpr.cc: New.
	* testsuite/25_algorithms/copy_backward/constexpr.cc: New.
	* testsuite/25_algorithms/copy_if/constexpr.cc: New.
	* testsuite/25_algorithms/copy_n/constexpr.cc: New.
	* testsuite/25_algorithms/count/constexpr.cc: New.
	* testsuite/25_algorithms/count_if/constexpr.cc: New.
	* testsuite/25_algorithms/equal/constexpr.cc: New.
	* testsuite/25_algorithms/equal_range/constexpr.cc: New.
	* testsuite/25_algorithms/fill/constexpr.cc: New.
	* testsuite/25_algorithms/fill_n/constexpr.cc: New.
	* testsuite/25_algorithms/find/constexpr.cc: New.
	* testsuite/25_algorithms/find_end/constexpr.cc: New.
	* testsuite/25_algorithms/find_first_of/constexpr.cc: New.
	* testsuite/25_algorithms/find_if/constexpr.cc: New.
	* testsuite/25_algorithms/find_if_not/constexpr.cc: New.
	* testsuite/25_algorithms/for_each/constexpr.cc: New.
	* testsuite/25_algorithms/generate/constexpr.cc: New.
	* testsuite/25_algorithms/generate_n/constexpr.cc: New.
	* testsuite/25_algorithms/is_heap/constexpr.cc: New.
	* testsuite/25_algorithms/is_heap_until/constexpr.cc: New.
	* testsuite/25_algorithms/is_partitioned/constexpr.cc: New.
	* testsuite/25_algorithms/is_permutation/constexpr.cc: New.
	* testsuite/25_algorithms/is_sorted/constexpr.cc: New.
	* testsuite/25_algorithms/is_sorted_until/constexpr.cc: New.
	* testsuite/25_algorithms/lexicographical_compare/constexpr.cc: New.
	* testsuite/25_algorithms/lower_bound/constexpr.cc: New.
	* testsuite/25_algorithms/merge/constexpr.cc: New.
	* testsuite/25_algorithms/mismatch/constexpr.cc: New.
	* testsuite/25_algorithms/none_of/constexpr.cc: New.
	* testsuite/25_algorithms/partition_copy/constexpr.cc: New.
	* testsuite/25_algorithms/partition_point/constexpr.cc: New.
	* testsuite/25_algorithms/remove/constexpr.cc: New.
	* testsuite/25_algorithms/remove_copy/constexpr.cc: New.
	* testsuite/25_algorithms/remove_copy_if/constexpr.cc: New.
	* testsuite/25_algorithms/remove_if/constexpr.cc: New.
	* testsuite/25_algorithms/replace_copy/constexpr.cc: New.
	* testsuite/25_algorithms/replace_copy_if/constexpr.cc: New.
	* testsuite/25_algorithms/replace_if/constexpr.cc: New.
	* testsuite/25_algorithms/reverse_copy/constexpr.cc: New.
	* testsuite/25_algorithms/rotate_copy/constexpr.cc: New.
	* testsuite/25_algorithms/search/constexpr.cc: New.
	* testsuite/25_algorithms/search_n/constexpr.cc: New.
	* testsuite/25_algorithms/set_difference/constexpr.cc: New.
	* testsuite/25_algorithms/set_intersection/constexpr.cc: New.
	* testsuite/25_algorithms/set_symmetric_difference/constexpr.cc: New.
	* testsuite/25_algorithms/set_union/constexpr.cc: New.
	* testsuite/25_algorithms/transform/constexpr.cc: New.
	* testsuite/25_algorithms/unique/constexpr.cc: New.
	* testsuite/25_algorithms/unique_copy/constexpr.cc: New.
	* testsuite/25_algorithms/upper_bound/constexpr.cc: New.

From-SVN: r273975

libstdc++-v3/ChangeLog

+2019-08-01  Edward Smith-Rowland  <3dw4rd@verizon.net>
+
+	Implement C++20 p0202 - Add Constexpr Modifiers to Functions
+	in <algorithm> and <utility> Headers.
+	Implement C++20 p1023 - constexpr comparison operators for std::array.
+	* include/bits/algorithmfwd.h (all_of, any_of, binary_search, copy,
+	copy_backward, copy_if, copy_n, equal_range, fill, find_end,
+	find_if_not, includes, is_heap, is_heap_until, is_partitioned,
+	is_permutation, is_sorted, is_sorted_until, iter_swap, lower_bound,
+	none_of, partition_copy, partition_point, remove, remove_if,
+	remove_copy, remove_copy_if, replace_copy, replace_copy_if,
+	reverse_copy, rotate_copy, uunique, upper_bound, adjacent_find, count,
+	count_if, equal, find, find_first_of, find_if, for_each, generate,
+	generate_n, lexicographical_compare, merge, mismatch, replace,
+	replace_if, search, search_n, set_difference, set_intersection,
+	set_symmetric_difference, set_union, transform, unique_copy):
+	Mark constexpr.
+	* include/bits/cpp_type_traits.h (__miter_base): Mark constexpr.
+	* include/bits/predefined_ops.h (_Iter_less_val::operator(),
+	_Val_less_iter::operator(), _Iter_equal_to_iter::operator(),
+	_Iter_equal_to_val::operator(), _Iter_equals_val::operator()):
+	 Use const ref instead of ref arg;
+	(_Iter_less_val, __iter_less_val, _Val_less_iter, __val_less_iter,
+	__iter_equal_to_iter, __iter_equal_to_val, __iter_comp_val,
+	_Iter_comp_val, _Val_comp_iter, __val_comp_iter, __iter_equals_val,
+	_Iter_equals_iter, __iter_comp_iter, _Iter_pred, __pred_iter,
+	_Iter_comp_to_val, __iter_comp_val, _Iter_comp_to_iter,
+	__iter_comp_iter): Mark constexpr.
+	* include/bits/stl_algo.h (__find_if, __find_if_not, __find_if_not_n,
+	__search, __search_n_aux, __search_n, __find_end, find_end, all_of,
+	none_of, any_of, find_if_not, is_partitioned, partition_point,
+	__remove_copy_if, remove_copy, remove_copy_if, copy_if, __copy_n,
+	copy_n, partition_copy, __remove_if, remove, remove_if, __adjacent_find,
+	__unique, unique, __unique_copy, reverse_copy, rotate_copy,
+	__unguarded_linear_insert, __insertion_sort, __unguarded_insertion_sort,
+	__final_insertion_sort, lower_bound, __upper_bound, upper_bound,
+	__equal_range, equal_range, binary_search, __includes, includes,
+	__next_permutation, __prev_permutation, __replace_copy_if, replace_copy,
+	replace_copy_if, __count_if, is_sorted, __is_sorted_until,
+	is_sorted_until, __is_permutation, is_permutation, for_each, find,
+	find_if, find_first_of, adjacent_find, count, count_if, search,
+	search_n, transform, replace, replace_if, generate, generate_n,
+	unique_copy, __merge, merge, __set_union, set_union, __set_intersection,
+	set_intersection, __set_difference, set_difference,
+	__set_symmetric_difference, set_symmetric_difference):  Mark constexpr.
+	* include/bits/stl_algobase.h (__memmove, __memcmp): New maybe constexpr
+	wrappers around __builtin_memmove and __builtin_memcmp
+	respectively;
+	(__niter_base, __niter_wrap, __copy_m, __copy_move_a, __copy_move_a2,
+	copy, move, __copy_move_b, __copy_move_backward_a,
+	__copy_move_backward_a2, copy_backward, move_backward, __fill_a, fill,
+	__fill_n_a, fill_n, equal, __lc_rai::__newlast1, __lc_rai::__cnd2,
+	__lexicographical_compare_impl, __lexicographical_compare,
+	__lexicographical_compare<true>::__lc, __lexicographical_compare_aux,
+	__lower_bound, lower_bound, equal, __equal4, lexicographical_compare,
+	__mismatch, mismatch, __is_heap_until, __is_heap, is_heap_until,
+	is_heap): Mark constexpr.
+	* include/bits/stl_heap.h (__is_heap_until, __is_heap, is_heap_until,
+	is_heap): Mark constexpr.
+	* include/bits/stl_iterator.h (__niter_base, __miter_base): Mark constexpr.
+	* include/std/array: Make comparison ops constexpr.
+	* include/std/utility: Make exchange constexpr.
+	* include/std/version (__cpp_lib_constexpr_algorithms): New macro.
+	* testsuite/23_containers/array/tuple_interface/get_neg.cc: Adjust.
+	* testsuite/23_containers/array/tuple_interface/
+	tuple_element_neg.cc: Adjust.
+	* testsuite/20_util/exchange/constexpr.cc: New.
+	* testsuite/23_containers/array/comparison_operators/constexpr.cc: New.
+	* testsuite/25_algorithms/constexpr_macro.cc: New.
+	* testsuite/25_algorithms/adjacent_find/constexpr.cc: New.
+	* testsuite/25_algorithms/all_of/constexpr.cc: New.
+	* testsuite/25_algorithms/any_of/constexpr.cc: New.
+	* testsuite/25_algorithms/binary_search/constexpr.cc: New.
+	* testsuite/25_algorithms/copy/constexpr.cc: New.
+	* testsuite/25_algorithms/copy_backward/constexpr.cc: New.
+	* testsuite/25_algorithms/copy_if/constexpr.cc: New.
+	* testsuite/25_algorithms/copy_n/constexpr.cc: New.
+	* testsuite/25_algorithms/count/constexpr.cc: New.
+	* testsuite/25_algorithms/count_if/constexpr.cc: New.
+	* testsuite/25_algorithms/equal/constexpr.cc: New.
+	* testsuite/25_algorithms/equal_range/constexpr.cc: New.
+	* testsuite/25_algorithms/fill/constexpr.cc: New.
+	* testsuite/25_algorithms/fill_n/constexpr.cc: New.
+	* testsuite/25_algorithms/find/constexpr.cc: New.
+	* testsuite/25_algorithms/find_end/constexpr.cc: New.
+	* testsuite/25_algorithms/find_first_of/constexpr.cc: New.
+	* testsuite/25_algorithms/find_if/constexpr.cc: New.
+	* testsuite/25_algorithms/find_if_not/constexpr.cc: New.
+	* testsuite/25_algorithms/for_each/constexpr.cc: New.
+	* testsuite/25_algorithms/generate/constexpr.cc: New.
+	* testsuite/25_algorithms/generate_n/constexpr.cc: New.
+	* testsuite/25_algorithms/is_heap/constexpr.cc: New.
+	* testsuite/25_algorithms/is_heap_until/constexpr.cc: New.
+	* testsuite/25_algorithms/is_partitioned/constexpr.cc: New.
+	* testsuite/25_algorithms/is_permutation/constexpr.cc: New.
+	* testsuite/25_algorithms/is_sorted/constexpr.cc: New.
+	* testsuite/25_algorithms/is_sorted_until/constexpr.cc: New.
+	* testsuite/25_algorithms/lexicographical_compare/constexpr.cc: New.
+	* testsuite/25_algorithms/lower_bound/constexpr.cc: New.
+	* testsuite/25_algorithms/merge/constexpr.cc: New.
+	* testsuite/25_algorithms/mismatch/constexpr.cc: New.
+	* testsuite/25_algorithms/none_of/constexpr.cc: New.
+	* testsuite/25_algorithms/partition_copy/constexpr.cc: New.
+	* testsuite/25_algorithms/partition_point/constexpr.cc: New.
+	* testsuite/25_algorithms/remove/constexpr.cc: New.
+	* testsuite/25_algorithms/remove_copy/constexpr.cc: New.
+	* testsuite/25_algorithms/remove_copy_if/constexpr.cc: New.
+	* testsuite/25_algorithms/remove_if/constexpr.cc: New.
+	* testsuite/25_algorithms/replace_copy/constexpr.cc: New.
+	* testsuite/25_algorithms/replace_copy_if/constexpr.cc: New.
+	* testsuite/25_algorithms/replace_if/constexpr.cc: New.
+	* testsuite/25_algorithms/reverse_copy/constexpr.cc: New.
+	* testsuite/25_algorithms/rotate_copy/constexpr.cc: New.
+	* testsuite/25_algorithms/search/constexpr.cc: New.
+	* testsuite/25_algorithms/search_n/constexpr.cc: New.
+	* testsuite/25_algorithms/set_difference/constexpr.cc: New.
+	* testsuite/25_algorithms/set_intersection/constexpr.cc: New.
+	* testsuite/25_algorithms/set_symmetric_difference/constexpr.cc: New.
+	* testsuite/25_algorithms/set_union/constexpr.cc: New.
+	* testsuite/25_algorithms/transform/constexpr.cc: New.
+	* testsuite/25_algorithms/unique/constexpr.cc: New.
+	* testsuite/25_algorithms/unique_copy/constexpr.cc: New.
+	* testsuite/25_algorithms/upper_bound/constexpr.cc: New.
+
 2019-07-31  Jonathan Wakely  <jwakely@redhat.com>
 
 	* include/std/memory (make_obj_using_allocator): Qualify call to

libstdc++-v3/include/bits/cpp_type_traits.h

@@ -424,6 +424,7 @@ __INT_N(__GLIBCXX_TYPE_INT_N_3)
   // Fallback implementation of the function in bits/stl_iterator.h used to
   // remove the move_iterator wrapper.
   template<typename _Iterator>
+    _GLIBCXX20_CONSTEXPR
     inline _Iterator
     __miter_base(_Iterator __it)
     { return __it; }

libstdc++-v3/include/bits/move.h

@@ -145,6 +145,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   // C++11 version of std::exchange for internal use.
   template <typename _Tp, typename _Up = _Tp>
+    _GLIBCXX20_CONSTEXPR
     inline _Tp
     __exchange(_Tp& __obj, _Up&& __new_val)
     {

libstdc++-v3/include/bits/predefined_ops.h

@@ -56,19 +56,23 @@ namespace __ops
     _Iter_less_val() { }
 #endif
 
+    _GLIBCXX20_CONSTEXPR
     explicit
     _Iter_less_val(_Iter_less_iter) { }
 
     template<typename _Iterator, typename _Value>
+      _GLIBCXX20_CONSTEXPR
       bool
       operator()(_Iterator __it, _Value& __val) const
       { return *__it < __val; }
   };
 
+  _GLIBCXX20_CONSTEXPR
   inline _Iter_less_val
   __iter_less_val()
   { return _Iter_less_val(); }
 
+  _GLIBCXX20_CONSTEXPR
   inline _Iter_less_val
   __iter_comp_val(_Iter_less_iter)
   { return _Iter_less_val(); }
@@ -81,19 +85,23 @@ namespace __ops
     _Val_less_iter() { }
 #endif
 
+    _GLIBCXX20_CONSTEXPR
     explicit
     _Val_less_iter(_Iter_less_iter) { }
 
     template<typename _Value, typename _Iterator>
+      _GLIBCXX20_CONSTEXPR
       bool
       operator()(_Value& __val, _Iterator __it) const
       { return __val < *__it; }
   };
 
+  _GLIBCXX20_CONSTEXPR
   inline _Val_less_iter
   __val_less_iter()
   { return _Val_less_iter(); }
 
+  _GLIBCXX20_CONSTEXPR
   inline _Val_less_iter
   __val_comp_iter(_Iter_less_iter)
   { return _Val_less_iter(); }
@@ -101,11 +109,13 @@ namespace __ops
   struct _Iter_equal_to_iter
   {
     template<typename _Iterator1, typename _Iterator2>
+      _GLIBCXX20_CONSTEXPR
       bool
       operator()(_Iterator1 __it1, _Iterator2 __it2) const
       { return *__it1 == *__it2; }
   };
 
+  _GLIBCXX20_CONSTEXPR
   inline _Iter_equal_to_iter
   __iter_equal_to_iter()
   { return _Iter_equal_to_iter(); }
@@ -113,15 +123,18 @@ namespace __ops
   struct _Iter_equal_to_val
   {
     template<typename _Iterator, typename _Value>
+      _GLIBCXX20_CONSTEXPR
       bool
       operator()(_Iterator __it, _Value& __val) const
       { return *__it == __val; }
   };
 
+  _GLIBCXX20_CONSTEXPR
   inline _Iter_equal_to_val
   __iter_equal_to_val()
   { return _Iter_equal_to_val(); }
 
+  _GLIBCXX20_CONSTEXPR
   inline _Iter_equal_to_val
   __iter_comp_val(_Iter_equal_to_iter)
   { return _Iter_equal_to_val(); }
@@ -154,17 +167,20 @@ namespace __ops
     {
       _Compare _M_comp;
 
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Iter_comp_val(_Compare __comp)
 	: _M_comp(_GLIBCXX_MOVE(__comp))
       { }
 
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Iter_comp_val(const _Iter_comp_iter<_Compare>& __comp)
 	: _M_comp(__comp._M_comp)
       { }
 
 #if __cplusplus >= 201103L
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Iter_comp_val(_Iter_comp_iter<_Compare>&& __comp)
 	: _M_comp(std::move(__comp._M_comp))
@@ -172,17 +188,20 @@ namespace __ops
 #endif
 
       template<typename _Iterator, typename _Value>
+	_GLIBCXX20_CONSTEXPR
 	bool
 	operator()(_Iterator __it, _Value& __val)
 	{ return bool(_M_comp(*__it, __val)); }
     };
 
   template<typename _Compare>
-   inline _Iter_comp_val<_Compare>
+    _GLIBCXX20_CONSTEXPR
+    inline _Iter_comp_val<_Compare>
     __iter_comp_val(_Compare __comp)
     { return _Iter_comp_val<_Compare>(_GLIBCXX_MOVE(__comp)); }
 
   template<typename _Compare>
+    _GLIBCXX20_CONSTEXPR
     inline _Iter_comp_val<_Compare>
     __iter_comp_val(_Iter_comp_iter<_Compare> __comp)
     { return _Iter_comp_val<_Compare>(_GLIBCXX_MOVE(__comp)); }
@@ -192,17 +211,20 @@ namespace __ops
     {
       _Compare _M_comp;
 
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Val_comp_iter(_Compare __comp)
 	: _M_comp(_GLIBCXX_MOVE(__comp))
       { }
 
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Val_comp_iter(const _Iter_comp_iter<_Compare>& __comp)
 	: _M_comp(__comp._M_comp)
       { }
 
 #if __cplusplus >= 201103L
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Val_comp_iter(_Iter_comp_iter<_Compare>&& __comp)
 	: _M_comp(std::move(__comp._M_comp))
@@ -210,17 +232,20 @@ namespace __ops
 #endif
 
       template<typename _Value, typename _Iterator>
+	_GLIBCXX20_CONSTEXPR
 	bool
 	operator()(_Value& __val, _Iterator __it)
 	{ return bool(_M_comp(__val, *__it)); }
     };
 
   template<typename _Compare>
+    _GLIBCXX20_CONSTEXPR
     inline _Val_comp_iter<_Compare>
     __val_comp_iter(_Compare __comp)
     { return _Val_comp_iter<_Compare>(_GLIBCXX_MOVE(__comp)); }
 
   template<typename _Compare>
+    _GLIBCXX20_CONSTEXPR
     inline _Val_comp_iter<_Compare>
     __val_comp_iter(_Iter_comp_iter<_Compare> __comp)
     { return _Val_comp_iter<_Compare>(_GLIBCXX_MOVE(__comp)); }
@@ -230,18 +255,21 @@ namespace __ops
     {
       _Value& _M_value;
 
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Iter_equals_val(_Value& __value)
 	: _M_value(__value)
       { }
 
       template<typename _Iterator>
+	_GLIBCXX20_CONSTEXPR
 	bool
 	operator()(_Iterator __it)
 	{ return *__it == _M_value; }
     };
 
   template<typename _Value>
+    _GLIBCXX20_CONSTEXPR
     inline _Iter_equals_val<_Value>
     __iter_equals_val(_Value& __val)
     { return _Iter_equals_val<_Value>(__val); }
@@ -251,18 +279,21 @@ namespace __ops
     {
       _Iterator1 _M_it1;
 
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Iter_equals_iter(_Iterator1 __it1)
 	: _M_it1(__it1)
       { }
 
       template<typename _Iterator2>
+	_GLIBCXX20_CONSTEXPR
 	bool
 	operator()(_Iterator2 __it2)
 	{ return *__it2 == *_M_it1; }
     };
 
   template<typename _Iterator>
+    _GLIBCXX20_CONSTEXPR
     inline _Iter_equals_iter<_Iterator>
     __iter_comp_iter(_Iter_equal_to_iter, _Iterator __it)
     { return _Iter_equals_iter<_Iterator>(__it); }
@@ -272,18 +303,21 @@ namespace __ops
     {
       _Predicate _M_pred;
 
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Iter_pred(_Predicate __pred)
 	: _M_pred(_GLIBCXX_MOVE(__pred))
       { }
 
       template<typename _Iterator>
+	_GLIBCXX20_CONSTEXPR
 	bool
 	operator()(_Iterator __it)
 	{ return bool(_M_pred(*__it)); }
     };
 
   template<typename _Predicate>
+    _GLIBCXX20_CONSTEXPR
     inline _Iter_pred<_Predicate>
     __pred_iter(_Predicate __pred)
     { return _Iter_pred<_Predicate>(_GLIBCXX_MOVE(__pred)); }
@@ -294,11 +328,13 @@ namespace __ops
       _Compare _M_comp;
       _Value& _M_value;
 
+      _GLIBCXX20_CONSTEXPR
       _Iter_comp_to_val(_Compare __comp, _Value& __value)
 	: _M_comp(_GLIBCXX_MOVE(__comp)), _M_value(__value)
       { }
 
       template<typename _Iterator>
+	_GLIBCXX20_CONSTEXPR
 	bool
 	operator()(_Iterator __it)
 	{ return bool(_M_comp(*__it, _M_value)); }
@@ -306,6 +342,7 @@ namespace __ops
 
   template<typename _Compare, typename _Value>
     _Iter_comp_to_val<_Compare, _Value>
+    _GLIBCXX20_CONSTEXPR
     __iter_comp_val(_Compare __comp, _Value &__val)
     {
       return _Iter_comp_to_val<_Compare, _Value>(_GLIBCXX_MOVE(__comp), __val);
@@ -317,17 +354,20 @@ namespace __ops
       _Compare _M_comp;
       _Iterator1 _M_it1;
 
+      _GLIBCXX20_CONSTEXPR
       _Iter_comp_to_iter(_Compare __comp, _Iterator1 __it1)
 	: _M_comp(_GLIBCXX_MOVE(__comp)), _M_it1(__it1)
       { }
 
       template<typename _Iterator2>
+	_GLIBCXX20_CONSTEXPR
 	bool
 	operator()(_Iterator2 __it2)
 	{ return bool(_M_comp(*__it2, *_M_it1)); }
     };
 
   template<typename _Compare, typename _Iterator>
+    _GLIBCXX20_CONSTEXPR
     inline _Iter_comp_to_iter<_Compare, _Iterator>
     __iter_comp_iter(_Iter_comp_iter<_Compare> __comp, _Iterator __it)
     {
@@ -340,18 +380,21 @@ namespace __ops
     {
       _Predicate _M_pred;
 
+      _GLIBCXX20_CONSTEXPR
       explicit
       _Iter_negate(_Predicate __pred)
 	: _M_pred(_GLIBCXX_MOVE(__pred))
       { }
 
       template<typename _Iterator>
+	_GLIBCXX20_CONSTEXPR
 	bool
 	operator()(_Iterator __it)
 	{ return !bool(_M_pred(*__it)); }
     };
 
   template<typename _Predicate>
+    _GLIBCXX20_CONSTEXPR
     inline _Iter_negate<_Predicate>
     __negate(_Iter_pred<_Predicate> __pred)
     { return _Iter_negate<_Predicate>(_GLIBCXX_MOVE(__pred._M_pred)); }

libstdc++-v3/include/bits/stl_heap.h

@@ -70,6 +70,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   template<typename _RandomAccessIterator, typename _Distance,
 	   typename _Compare>
+    _GLIBCXX20_CONSTEXPR
     _Distance
     __is_heap_until(_RandomAccessIterator __first, _Distance __n,
 		    _Compare& __comp)
@@ -88,6 +89,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
   // __is_heap, a predicate testing whether or not a range is a heap.
   // This function is an extension, not part of the C++ standard.
   template<typename _RandomAccessIterator, typename _Distance>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __is_heap(_RandomAccessIterator __first, _Distance __n)
     {
@@ -97,6 +99,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
   template<typename _RandomAccessIterator, typename _Compare,
 	   typename _Distance>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __is_heap(_RandomAccessIterator __first, _Compare __comp, _Distance __n)
     {
@@ -106,11 +109,13 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     }
 
   template<typename _RandomAccessIterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
     { return std::__is_heap(__first, std::distance(__first, __last)); }
 
   template<typename _RandomAccessIterator, typename _Compare>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     __is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,
 	      _Compare __comp)
@@ -473,6 +478,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    *  the range [__first, i) is a heap.
   */
   template<typename _RandomAccessIterator>
+    _GLIBCXX20_CONSTEXPR
     inline _RandomAccessIterator
     is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last)
     {
@@ -501,6 +507,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    *  the range [__first, i) is a heap.  Comparisons are made using __comp.
   */
   template<typename _RandomAccessIterator, typename _Compare>
+    _GLIBCXX20_CONSTEXPR
     inline _RandomAccessIterator
     is_heap_until(_RandomAccessIterator __first, _RandomAccessIterator __last,
 		  _Compare __comp)
@@ -525,6 +532,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    *  @ingroup heap_algorithms
   */
   template<typename _RandomAccessIterator>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last)
     { return std::is_heap_until(__first, __last) == __last; }
@@ -538,6 +546,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
    *  @ingroup heap_algorithms
   */
   template<typename _RandomAccessIterator, typename _Compare>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     is_heap(_RandomAccessIterator __first, _RandomAccessIterator __last,
 	    _Compare __comp)

libstdc++-v3/include/bits/stl_iterator.h

@@ -446,7 +446,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 #if __cplusplus >= 201103L
   template<typename _Iterator>
-    auto
+    _GLIBCXX20_CONSTEXPR auto
     __niter_base(reverse_iterator<_Iterator> __it)
     -> decltype(__make_reverse_iterator(__niter_base(__it.base())))
     { return __make_reverse_iterator(__niter_base(__it.base())); }
@@ -457,7 +457,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     { };
 
   template<typename _Iterator>
-    auto
+    _GLIBCXX20_CONSTEXPR auto
     __miter_base(reverse_iterator<_Iterator> __it)
     -> decltype(__make_reverse_iterator(__miter_base(__it.base())))
     { return __make_reverse_iterator(__miter_base(__it.base())); }

libstdc++-v3/include/std/array

@@ -248,16 +248,19 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
 
   // Array comparisons.
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator==(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return std::equal(__one.begin(), __one.end(), __two.begin()); }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator!=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return !(__one == __two); }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator<(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
     {
@@ -266,16 +269,19 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
     }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator>(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return __two < __one; }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator<=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return !(__one > __two); }
 
   template<typename _Tp, std::size_t _Nm>
+    _GLIBCXX20_CONSTEXPR
     inline bool
     operator>=(const array<_Tp, _Nm>& __one, const array<_Tp, _Nm>& __two)
     { return !(__one < __two); }
@@ -289,6 +295,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CONTAINER
       _GLIBCXX_STD_C::__array_traits<_Tp, _Nm>::_Is_swappable::value
     >::type
 #else
+    _GLIBCXX20_CONSTEXPR
     void
 #endif
     swap(array<_Tp, _Nm>& __one, array<_Tp, _Nm>& __two)

libstdc++-v3/include/std/utility

@@ -280,11 +280,17 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 #define __cpp_lib_exchange_function 201304
 
+#if __cplusplus > 201703L
+#  define __cpp_lib_constexpr_algorithms 201711L
+#endif
+
   /// Assign @p __new_val to @p __obj and return its previous value.
   template <typename _Tp, typename _Up = _Tp>
+    _GLIBCXX20_CONSTEXPR
     inline _Tp
     exchange(_Tp& __obj, _Up&& __new_val)
     { return std::__exchange(__obj, std::forward<_Up>(__new_val)); }
+
 #endif
 
   // Stores a tuple of indices.  Used by tuple and pair, and by bind() to

libstdc++-v3/include/std/version

@@ -164,6 +164,7 @@
 #endif
 #define __cpp_lib_list_remove_return_type 201806L
 #define __cpp_lib_math_constants 201907L
+#define __cpp_lib_constexpr_algorithms 201711L
 #endif // C++2a
 #endif // C++17
 #endif // C++14

libstdc++-v3/testsuite/20_util/exchange/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <utility>
+
+constexpr bool
+test()
+{
+  constexpr double e_v = 2.71828182846;
+  double e = e_v;
+  constexpr double pi_v = 3.14159265359;
+  const auto x = std::exchange(e, pi_v);
+
+  return x == e_v && e == pi_v;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/23_containers/array/comparison_operators/constexpr.cc

+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+//
+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+#include <array>
+
+constexpr std::array<int, 3> a1{{1, 2, 3}};
+constexpr std::array<int, 3> a2{{4, 5, 6}};
+constexpr std::array<int, 3> a3{{1, 2, 4}};
+constexpr std::array<int, 3> a4{{1, 3, 3}};
+
+static_assert(a1 == a1);
+static_assert(a1 != a2);
+static_assert(a1 < a3);
+static_assert(a4 > a1);
+static_assert(a1 <= a3);
+static_assert(a4 >= a1);

libstdc++-v3/testsuite/23_containers/array/tuple_interface/get_neg.cc

@@ -27,6 +27,6 @@ int n1 = std::get<1>(a);
 int n2 = std::get<1>(std::move(a));
 int n3 = std::get<1>(ca);
 
-// { dg-error "static assertion failed" "" { target *-*-* } 309 }
-// { dg-error "static assertion failed" "" { target *-*-* } 318 }
-// { dg-error "static assertion failed" "" { target *-*-* } 326 }
+// { dg-error "static assertion failed" "" { target *-*-* } 316 }
+// { dg-error "static assertion failed" "" { target *-*-* } 325 }
+// { dg-error "static assertion failed" "" { target *-*-* } 333 }

libstdc++-v3/testsuite/23_containers/array/tuple_interface/tuple_element_neg.cc

@@ -22,4 +22,4 @@
 
 typedef std::tuple_element<1, std::array<int, 1>>::type type;
 
-// { dg-error "static assertion failed" "" { target *-*-* } 365 }
+// { dg-error "static assertion failed" "" { target *-*-* } 372 }

libstdc++-v3/testsuite/25_algorithms/adjacent_find/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> car{{0, 1, 2, 3, 4, 5, 6, 6, 8, 9, 9, 11}};
+
+constexpr auto out0x = std::adjacent_find(car.begin(), car.end());
+
+constexpr auto out1x = std::adjacent_find(car.begin(), car.end(),
+					  std::equal_to<int>());
+
+constexpr bool
+test()
+{
+  return out0x == car.begin() + 6 && out1x == car.begin() + 6;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/all_of/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 6> cae{{0, 2, 4, 6, 8, 10}};
+
+constexpr auto out2 = std::all_of(cae.begin(), cae.end(),
+			          [](int i){ return i % 2 == 0; });
+
+constexpr bool
+test()
+{
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/any_of/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+  const auto out3 = std::any_of(ca0.begin(), ca0.end(),
+			        [](int i){ return i % 2 == 0; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/binary_search/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+  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>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/constexpr_macro.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <version>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing in <version>"
+#elif __cpp_lib_constexpr_algorithms != 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value in <version>"
+#endif

libstdc++-v3/testsuite/25_algorithms/copy/58982.cc

@@ -36,6 +36,7 @@ void
 test01(T* result)
 {
   T t[1];
-  std::copy(t, t+1, result); // { dg-error "here" }
+  std::copy(t, t+1, result); // { dg-error "here|deleted" }
 }
 // { dg-prune-output "not assignable" }
+// { dg-prune-output "use of deleted" }

libstdc++-v3/testsuite/25_algorithms/copy/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+  std::array<int, 12> ma0{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
+
+  const auto out6 = std::copy(ca0.begin(), ca0.begin() + 8, ma0.begin() + 2);
+
+  return out6 == ma0.begin() + 10;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/copy/move_iterators/69478.cc

@@ -37,3 +37,4 @@ test01()
   trivial_rvalstruct a[1], b[1];
   copy(std::make_move_iterator(a), std::make_move_iterator(a + 1), b);
 }
+// { dg-prune-output "use of deleted" }

libstdc++-v3/testsuite/25_algorithms/copy_backward/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+  std::array<int, 12> ma0{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
+  const auto out7 = std::copy_backward(ca0.begin(), ca0.begin() + 8,
+				       ma0.begin() + 10);
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/copy_backward/move_iterators/69478.cc

@@ -37,3 +37,4 @@ test01()
   trivial_rvalstruct a[1], b[1];
   copy_backward(std::make_move_iterator(a), std::make_move_iterator(a+1), b);
 }
+// { dg-prune-output "use of deleted" }

libstdc++-v3/testsuite/25_algorithms/copy_if/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ma0{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
+  const auto out1 = std::copy_if(ca0.begin(), ca0.end(), ma0.begin(),
+				 [](int i){ return i % 2 == 1; });
+
+  return out1 == ma0.begin() + 6;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/copy_n/58982.cc

@@ -36,6 +36,7 @@ void
 test01(T* result)
 {
   T t[1];
-  std::copy_n(t, 1, result); // { dg-error "here" }
+  std::copy_n(t, 1, result); // { dg-error "here|deleted" }
 }
 // { dg-prune-output "not assignable" }
+// { dg-prune-output "use of deleted" }

libstdc++-v3/testsuite/25_algorithms/copy_n/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ma0{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
+  std::copy_n(ca0.begin(), 12, ma0.begin());
+
+  return ma0[3] == ca0[3];
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/count/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+  const auto out8 = std::count(ca0.begin(), ca0.end(), 6);
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/count_if/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+constexpr auto out9 = std::count_if(ca0.begin(), ca0.end(),
+				    [](int i){ return i % 2 == 0; });
+
+constexpr bool
+test()
+{
+  return out9 == 6;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/equal/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+  constexpr std::array<int, 12> ca1{{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}};
+
+  const auto outa = std::equal(ca0.begin(), ca0.end(), ca1.begin());
+
+  const auto outb = std::equal(ca0.begin(), ca0.end(), cas.begin(),
+			       [](int i, int j){ return i + 3 == j; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/equal_range/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> car{{0, 1, 2, 3, 4, 5, 6, 6, 8, 9, 9, 11}};
+
+  const auto outc = std::equal_range(car.begin(), car.end(), 6);
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/fill/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ma0{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
+  std::fill(ma0.begin(), ma0.end(), 66);
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/fill_n/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ma0{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
+
+  const auto outd = std::fill_n(ma0.begin(), 6, 77);
+
+  return outd == ma0.begin() + 6;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/find/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5,  6, 7, 8,  9, 10, 11}};
+
+constexpr auto oute = std::find(ca0.begin(), ca0.end(), 5);
+
+constexpr bool
+test()
+{
+  return oute == ca0.begin() + 5;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/find_end/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5,  6, 7, 8,  9, 10, 11}};
+  constexpr std::array<int, 3> cam{{4, 5, 6}};
+  constexpr std::array<int, 3> camm{{-4, -5, -6}};
+
+  const auto outf = std::find_end(ca0.begin(), ca0.end(),
+				  cam.begin(), cam.end());
+
+  const auto outg = std::find_end(ca0.begin(), ca0.end(),
+				  camm.begin(), camm.end(),
+				  [](int i, int j){ return i + 1 == -j; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/find_first_of/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+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 auto outh = std::find_first_of(ca0.begin(), ca0.end(),
+					 cas.begin(), cas.end());
+
+constexpr auto outi = std::find_first_of(ca0.begin(), ca0.end(),
+					 cas.begin(), cas.end(),
+					[](int i, int j){ return i + 1 == j; });
+
+constexpr bool
+test()
+{
+  return outh == ca0.begin() + 3 && outi == ca0.begin() + 2;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/find_if/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5,  6, 7, 8,  9, 10, 11}};
+
+  const auto outj = std::find_if(ca0.begin(), ca0.end(),
+				 [](int i){ return i == 6; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/find_if_not/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+constexpr auto outk = std::find_if_not(ca0.begin(), ca0.end(),
+				       [](int i){ return i <= 6; });
+
+constexpr bool
+test()
+{
+  return outk == ca0.begin() + 7;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/for_each/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+constexpr bool
+test()
+{
+  int tot = 0;
+  auto sum = [&total = tot](int i){ total += i; };
+  auto sum2 = std::for_each(ca0.begin(), ca0.end(), sum);
+
+  return tot == 66;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/generate/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ma0{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
+
+  std::generate(ma0.begin(), ma0.begin() + 6, [](){ return 42; });
+
+  return ma0[5] == 42;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/generate_n/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ma0{{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}};
+
+  const auto outl = std::generate_n(ma0.begin(), 6, [](){ return 42; });
+
+  return outl == ma0.begin() + 6;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/is_heap/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+// heap
+constexpr std::array<int, 23>
+ah{{22,
+    21, 20,
+    17, 16, 19, 18,
+    11, 10, 9, 8, 15, 14, 13, 12, 3, 2, 1, 0, 7, 6, 5, 4}};
+
+constexpr auto outo = std::is_heap(ah.begin(), ah.end());
+
+constexpr auto outp = std::is_heap(ah.begin(), ah.end(), std::less<int>());
+
+constexpr bool
+test()
+{
+  return outo && outp;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/is_heap_until/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+// heap
+constexpr std::array<int, 23>
+ahu{{22,
+     21, 20,
+     17, 16, 19, 18,//v
+     11, 10,  9,  8, 23, 14, 13, 12, 3, 2, 1, 0, 7, 6, 5, 4}};
+
+constexpr auto outq = std::is_heap_until(ahu.begin(), ahu.end());
+
+constexpr auto outr = std::is_heap_until(ahu.begin(), ahu.end(),
+					 std::less<int>());
+
+constexpr bool
+test()
+{
+  return outq == ahu.begin() + 11 && outr == ahu.begin() + 11;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/is_partitioned/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> caeo{{0, 2, 4, 6, 8, 10, 1, 3, 5, 7, 9, 11}};
+
+  const auto outs = std::is_partitioned(caeo.begin(), caeo.end(),
+					[](int i){ return i % 2 == 0; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/is_permutation/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+  constexpr std::array<int, 12> cap{{2, 1, 3, 6, 7, 5, 4, 8, 10, 9, 0, 11}};
+
+  const auto outt = std::is_permutation(ca0.begin(), ca0.end(), cap.begin());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/is_sorted/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+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>());
+
+constexpr bool
+test()
+{
+  return outv && outw;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/is_sorted_until/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> aus{{0, 1, 2, 3, 4, 5, 66, 7, 8, 9, 10, 11}};
+
+  const auto outx = std::is_sorted_until(aus.begin(), aus.end());
+
+  const auto outy = std::is_sorted_until(aus.begin(), aus.end(),
+					 std::less<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/lexicographical_compare/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+  constexpr std::array<int, 12> ca1{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+  const auto outz = !std::lexicographical_compare(ca0.begin(), ca0.end(),
+						  ca1.begin(), ca1.end());
+
+  const auto outaa = !std::lexicographical_compare(ca0.begin(), ca0.end(),
+						   ca1.begin(), ca1.end(),
+						   std::less<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/lower_bound/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+  const auto outbb = std::lower_bound(ca0.begin(), ca0.end(), 6);
+
+  const auto outcc = std::lower_bound(ca0.begin(), ca0.end(), 6,
+				      std::less<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/merge/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+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}};
+  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(),
+				cas.begin(), cas.end(), out0.begin());
+
+  const auto outee = std::merge(ca0.begin(), ca0.end(),
+				camm.begin(), camm.end(), out0.begin(),
+				[](int i, int j){ return i < -j; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/mismatch/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5,  6, 7, 8,  9, 10, 11}};
+  constexpr std::array<int, 12> cax{{0, 1, 2, 3, 4, 5, 66, 7, 8, 99, 10, 11}};
+
+  const auto outff = std::mismatch(ca0.begin(), ca0.end(), cax.begin());
+
+  const auto outgg = std::mismatch(ca0.begin(), ca0.end(), cax.begin(),
+				   std::equal_to<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/move/69478.cc

@@ -37,3 +37,4 @@ test01()
   trivial_rvalstruct a[1], b[1];
   std::move(a, a + 1, b);
 }
+// { dg-prune-output "use of deleted" }

libstdc++-v3/testsuite/25_algorithms/move_backward/69478.cc

@@ -37,3 +37,4 @@ test01()
   trivial_rvalstruct a[1], b[1];
   std::move_backward(a, a + 1, b);
 }
+// { dg-prune-output "use of deleted" }

libstdc++-v3/testsuite/25_algorithms/none_of/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+  const auto outhh = std::none_of(ca0.begin(), ca0.end(),
+				  [](int i){ return i > 12; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/partition_copy/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+  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}};
+  std::array<int, 24> out1{{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 outii = std::partition_copy(ca0.begin(), ca0.end(),
+					 out0.begin(), out1.begin(),
+					 [](int i){ return i % 2 == 0; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/partition_point/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> caeo{{0, 2, 4, 6, 8, 10, 1, 3, 5, 7, 9, 11}};
+
+constexpr bool
+test()
+{
+  const auto outjj = std::partition_point(caeo.begin(), caeo.end(),
+					  [](int i){ return i % 2 == 0; });
+
+  return outjj == caeo.begin() + 6;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/remove/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ar4{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+  const auto outkk = std::remove(ar4.begin(), ar4.end(), 7);
+
+  return outkk == ar4.begin() + 11;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/remove_copy/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5,  6, 7, 8,  9, 10, 11}};
+  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 outmm = std::remove_copy(ca0.begin(), ca0.end(), out0.begin(), 6);
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/remove_copy_if/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+  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 outnn = std::remove_copy_if(ca0.begin(), ca0.end(), out0.begin(),
+					 [](int i){ return i == 7; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/remove_if/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ac2{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+
+  const auto outll = std::remove_if(ac2.begin(), ac2.end(),
+				    [](int i){ return i == 7; });
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/replace_copy/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8,  9, 10, 11}};
+
+constexpr bool
+test()
+{
+  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 outoo = std::replace_copy(ca0.begin(), ca0.end(),
+				       out0.begin(), 6, 66);
+
+  return outoo == out0.begin() + (ca0.end() - ca0.begin());
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/replace_copy_if/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+constexpr bool
+test()
+{
+  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 outpp = std::replace_copy_if(ca0.begin(), ca0.end(),
+					  out0.begin(),
+					  [](int i){ return i < 6; }, 66);
+
+  return outpp == out0.begin() + (ca0.end() - ca0.begin());
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/replace_if/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ar0{{0, 1, 2, 3, 4, 5, 6, 6, 8, 9, 9, 11}};
+
+  std::replace_if(ar0.begin(), ar0.end(), [](int i){ return i % 2 == 1; }, 42);
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/reverse_copy/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+  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 outqq = std::reverse_copy(ca0.rbegin(), ca0.rend(), out0.begin());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/rotate_copy/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5,  6, 7, 8,  9, 10, 11}};
+  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 outrr = std::rotate_copy(ca0.begin(), ca0.begin() + 6,
+				      ca0.end(), out0.begin());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/search/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5,  6, 7, 8,  9, 10, 11}};
+  constexpr std::array<int, 3> cam{{4, 5, 6}};
+
+  const auto outtt = std::search(ca0.begin(), ca0.end(),
+				 cam.begin(), cam.end(),
+				 std::equal_to<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/search_n/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> car{{0, 1, 2, 3, 4, 5, 6, 6, 8, 9, 9, 11}};
+
+constexpr auto outuu = std::search_n(car.begin(), car.end(), 2, 6);
+
+constexpr auto outuv = std::search_n(car.begin(), car.end(), 2, 9,
+				     [](int i, int j){ return i == j; });
+
+constexpr bool
+test()
+{
+  return outuu == car.begin() + 6 && outuv == car.begin() + 9 ;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/set_difference/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+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}};
+  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 outvv = std::set_difference(ca0.begin(), ca0.end(),
+					 cas.begin(), cas.end(), out0.begin());
+
+  const auto outww = std::set_difference(ca0.begin(), ca0.end(),
+				         cas.begin(), cas.end(),
+				         out0.begin(), std::less<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/set_intersection/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+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}};
+  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 outxx = std::set_intersection(ca0.begin(), ca0.end(),
+					   cas.begin(), cas.end(),
+					   out0.begin());
+
+  const auto outyy = std::set_intersection(ca0.begin(), ca0.end(),
+					   cas.begin(), cas.end(),
+					   out0.begin(), std::less<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/set_symmetric_difference/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+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}};
+  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 outvv = std::set_difference(ca0.begin(), ca0.end(),
+					 cas.begin(), cas.end(), out0.begin());
+
+  const auto outww = std::set_difference(ca0.begin(), ca0.end(),
+				         cas.begin(), cas.end(),
+				         out0.begin(), std::less<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/set_union/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+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}};
+  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 out11 = std::set_union(ca0.begin(), ca0.end(),
+				    cas.begin(), cas.end(), out0.begin());
+
+  const auto out22 = std::set_union(ca0.begin(), ca0.end(),
+				    cas.begin(), cas.end(),
+				    out0.begin(), std::less<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/transform/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}};
+constexpr bool
+test()
+{
+  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 out99 = std::transform(ca0.begin(), ca0.end(), out0.begin(),
+				    [del = 6](int i){ return i + del; });
+
+  const auto out11 = std::transform(ca0.begin(), ca0.end(), ca0.begin(),
+				    out0.begin(),
+				    [](int i, int j){ return i + j; });
+
+  return out99 == out0.begin() + (ca0.end() - ca0.begin())
+      && out11 == out0.begin() + (ca0.end() - ca0.begin());
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/unique/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ar1{{0, 1, 2, 3, 4, 5, 6, 6, 8, 9, 9, 11}};
+  std::array<int, 12> ar2{{0, 1, 2, 3, 4, 5, 6, 6, 8, 9, 9, 11}};
+
+  const auto out33 = std::unique(ar1.begin(), ar1.end());
+
+  const auto out44 = std::unique(ar2.begin(), ar2.end(), std::equal_to<int>());
+
+  return out33 == ar1.begin() + 10 && out44 == ar2.begin() + 10;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/unique_copy/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  std::array<int, 12> ar3{{0, 1, 2, 3, 4, 5, 6, 6, 8, 9, 9, 11}};
+  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 out55 = std::unique_copy(ar3.begin(), ar3.end(), out0.begin());
+
+  const auto out66 = std::unique_copy(ar3.begin(), ar3.end(), out0.begin(),
+				      std::equal_to<int>());
+
+  return true;
+}
+
+static_assert(test());

libstdc++-v3/testsuite/25_algorithms/upper_bound/constexpr.cc

+// Copyright (C) 2019 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// You should have received a copy of the GNU General Public License along
+// with this library; see the file COPYING3.  If not see
+// <http://www.gnu.org/licenses/>.
+
+// { dg-options "-std=gnu++2a" }
+// { dg-do compile { target c++2a } }
+
+#include <algorithm>
+#include <array>
+
+#ifndef __cpp_lib_constexpr_algorithms
+# error "Feature-test macro for constexpr algorithms missing"
+#elif __cpp_lib_constexpr_algorithms < 201711L
+# error "Feature-test macro for constexpr algorithms has wrong value"
+#endif
+
+constexpr bool
+test()
+{
+  constexpr std::array<int, 12> ca0{{0, 1, 2, 3, 4, 5,  6, 7, 8,  9, 10, 11}};
+
+  const auto out77 = std::upper_bound(ca0.begin(), ca0.end(), 6);
+
+  const auto out88 = std::upper_bound(ca0.begin(), ca0.end(), 6,
+				      std::less<int>());
+
+  return true;
+}
+
+static_assert(test());