[libcxx-commits] [libcxx] 1bb2328 - [libc++] Implement `views::join_with` (#65536)
via libcxx-commits
libcxx-commits at lists.llvm.org
Sat Jun 21 02:54:54 PDT 2025
Author: Jakub Mazurkiewicz
Date: 2025-06-21T10:54:50+01:00
New Revision: 1bb2328fd3adf137cb32af4e3722a1b3e8a53a8e
URL: https://github.com/llvm/llvm-project/commit/1bb2328fd3adf137cb32af4e3722a1b3e8a53a8e
DIFF: https://github.com/llvm/llvm-project/commit/1bb2328fd3adf137cb32af4e3722a1b3e8a53a8e.diff
LOG: [libc++] Implement `views::join_with` (#65536)
* Implement "P2441R2 `views::join_with`" (https://wg21.link/P2441R2),
closes #105185
* Implement LWG4074 (https://wg21.link/LWG4074), closes #105346
* Complete implementation of "P2711R1 Making multi-param constructors of
views explicit" (https://wg21.link/P2711R1), closes #105252
* Complete implementation of "P2770R0 Stashing stashing iterators for
proper flattening" (https://wg21.link/P2770R0), closes #105250
Added:
libcxx/include/__ranges/join_with_view.h
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.nodiscard.verify.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.nodiscard.verify.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.nodiscard.verify.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/no_unique_address.compile.pass.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.nodiscard.verify.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.nodiscard.verify.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.sentinel/no_unique_address.compile.pass.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/base.nodiscard.verify.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/begin.nodiscard.verify.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/end.nodiscard.verify.cpp
libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/no_unique_address.compile.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.default.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.not_const.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/decrement.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/increment.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_swap.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/types.compile.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/example.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.default.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.non_const.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/base.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/begin.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/constraints.compile.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctad.compile.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.default.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.element.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.pattern.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/end.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/inheritance.compile.pass.cpp
libcxx/test/std/ranges/range.adaptors/range.join.with/types.h
Modified:
libcxx/docs/FeatureTestMacroTable.rst
libcxx/docs/ReleaseNotes/21.rst
libcxx/docs/Status/Cxx23Papers.csv
libcxx/docs/Status/Cxx2cIssues.csv
libcxx/include/CMakeLists.txt
libcxx/include/__ranges/concepts.h
libcxx/include/module.modulemap.in
libcxx/include/ranges
libcxx/include/version
libcxx/modules/std/ranges.inc
libcxx/test/std/language.support/support.limits/support.limits.general/ranges.version.compile.pass.cpp
libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
libcxx/utils/generate_feature_test_macro_components.py
Removed:
################################################################################
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 5ebc9bb7dcda2..3c635e5e46bbd 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -376,7 +376,7 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_ranges_iota`` ``202202L``
---------------------------------------------------------- -----------------
- ``__cpp_lib_ranges_join_with`` *unimplemented*
+ ``__cpp_lib_ranges_join_with`` ``202202L``
---------------------------------------------------------- -----------------
``__cpp_lib_ranges_repeat`` ``202207L``
---------------------------------------------------------- -----------------
diff --git a/libcxx/docs/ReleaseNotes/21.rst b/libcxx/docs/ReleaseNotes/21.rst
index 8661e5898fbc0..7e8570691200b 100644
--- a/libcxx/docs/ReleaseNotes/21.rst
+++ b/libcxx/docs/ReleaseNotes/21.rst
@@ -47,6 +47,9 @@ Implemented Papers
- P1222R4: A Standard ``flat_set`` (`Github <https://github.com/llvm/llvm-project/issues/105193>`__)
- P2897R7: ``aligned_accessor``: An mdspan accessor expressing pointer over-alignment (`Github <https://github.com/llvm/llvm-project/issues/118372>`__)
- P3247R2: Deprecate the notion of trivial types (`Github <https://github.com/llvm/llvm-project/issues/118387>`__)
+- P2441R2: ``views::join_with`` (`Github <https://github.com/llvm/llvm-project/issues/105185>`__)
+- P2711R1: Making multi-param constructors of ``views`` ``explicit`` (`Github <https://github.com/llvm/llvm-project/issues/105252>`__)
+- P2770R0: Stashing stashing ``iterators`` for proper flattening (`Github <https://github.com/llvm/llvm-project/issues/105250>`__)
Improvements and New Features
-----------------------------
diff --git a/libcxx/docs/Status/Cxx23Papers.csv b/libcxx/docs/Status/Cxx23Papers.csv
index c26363bcda796..574675175a4cf 100644
--- a/libcxx/docs/Status/Cxx23Papers.csv
+++ b/libcxx/docs/Status/Cxx23Papers.csv
@@ -47,7 +47,7 @@
"`P2273R3 <https://wg21.link/P2273R3>`__","Making ``std::unique_ptr`` constexpr","2022-02 (Virtual)","|Complete|","16",""
"`P2387R3 <https://wg21.link/P2387R3>`__","Pipe support for user-defined range adaptors","2022-02 (Virtual)","|Complete|","19",""
"`P2440R1 <https://wg21.link/P2440R1>`__","``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right``","2022-02 (Virtual)","|Partial|","","Only ``ranges::iota`` is implemented."
-"`P2441R2 <https://wg21.link/P2441R2>`__","``views::join_with``","2022-02 (Virtual)","|In Progress|","",""
+"`P2441R2 <https://wg21.link/P2441R2>`__","``views::join_with``","2022-02 (Virtual)","|Complete|","21",""
"`P2442R1 <https://wg21.link/P2442R1>`__","Windowing range adaptors: ``views::chunk`` and ``views::slide``","2022-02 (Virtual)","","",""
"`P2443R1 <https://wg21.link/P2443R1>`__","``views::chunk_by``","2022-02 (Virtual)","|Complete|","18",""
"","","","","",""
@@ -103,9 +103,9 @@
"`P2708R1 <https://wg21.link/P2708R1>`__","No Further Fundamentals TSes","2022-11 (Kona)","|Nothing To Do|","",""
"","","","","",""
"`P0290R4 <https://wg21.link/P0290R4>`__","``apply()`` for ``synchronized_value<T>``","2023-02 (Issaquah)","","",""
-"`P2770R0 <https://wg21.link/P2770R0>`__","Stashing stashing ``iterators`` for proper flattening","2023-02 (Issaquah)","|Partial|","","``join_with_view`` hasn't been done yet since this type isn't implemented yet"
+"`P2770R0 <https://wg21.link/P2770R0>`__","Stashing stashing ``iterators`` for proper flattening","2023-02 (Issaquah)","|Complete|","21",""
"`P2164R9 <https://wg21.link/P2164R9>`__","``views::enumerate``","2023-02 (Issaquah)","","",""
-"`P2711R1 <https://wg21.link/P2711R1>`__","Making multi-param constructors of ``views`` ``explicit``","2023-02 (Issaquah)","|In Progress|","","``join_with_view`` hasn't been done yet since this type isn't implemented yet"
+"`P2711R1 <https://wg21.link/P2711R1>`__","Making multi-param constructors of ``views`` ``explicit``","2023-02 (Issaquah)","|Complete|","21",""
"`P2609R3 <https://wg21.link/P2609R3>`__","Relaxing Ranges Just A Smidge","2023-02 (Issaquah)","|Complete|","20","Implemented as a DR in C++20. Other implementations will do the same."
"`P2713R1 <https://wg21.link/P2713R1>`__","Escaping improvements in ``std::format``","2023-02 (Issaquah)","|Complete|","19",""
"`P2675R1 <https://wg21.link/P2675R1>`__","``format``'s width estimation is too approximate and not forward compatible","2023-02 (Issaquah)","|Complete|","17",""
diff --git a/libcxx/docs/Status/Cxx2cIssues.csv b/libcxx/docs/Status/Cxx2cIssues.csv
index fdf381862d87b..d3feecf6513e4 100644
--- a/libcxx/docs/Status/Cxx2cIssues.csv
+++ b/libcxx/docs/Status/Cxx2cIssues.csv
@@ -66,7 +66,7 @@
"`LWG4060 <https://wg21.link/LWG4060>`__","``submdspan`` preconditions do not forbid creating invalid pointer","2024-06 (St. Louis)","","",""
"`LWG4061 <https://wg21.link/LWG4061>`__","Should ``std::basic_format_context`` be default-constructible/copyable/movable?","2024-06 (St. Louis)","|Complete|","19",""
"`LWG4071 <https://wg21.link/LWG4071>`__","``reference_wrapper`` comparisons are not SFINAE-friendly","2024-06 (St. Louis)","|Complete|","19",""
-"`LWG4074 <https://wg21.link/LWG4074>`__","``compatible-joinable-ranges`` is underconstrained","2024-06 (St. Louis)","","",""
+"`LWG4074 <https://wg21.link/LWG4074>`__","``compatible-joinable-ranges`` is underconstrained","2024-06 (St. Louis)","|Complete|","21",""
"`LWG4076 <https://wg21.link/LWG4076>`__","``concat_view`` should be freestanding","2024-06 (St. Louis)","","",""
"`LWG4079 <https://wg21.link/LWG4079>`__","Missing Preconditions in ``concat_view::iterator``\`s conversion constructor","2024-06 (St. Louis)","","",""
"`LWG4082 <https://wg21.link/LWG4082>`__","``views::concat(r)`` is well-formed when ``r`` is an ``output_range``","2024-06 (St. Louis)","","",""
diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 8931a1b35f6d3..e386f31386b60 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -706,6 +706,7 @@ set(files
__ranges/iota_view.h
__ranges/istream_view.h
__ranges/join_view.h
+ __ranges/join_with_view.h
__ranges/lazy_split_view.h
__ranges/movable_box.h
__ranges/non_propagating_cache.h
diff --git a/libcxx/include/__ranges/concepts.h b/libcxx/include/__ranges/concepts.h
index 674a3f359ff99..bf75fe8a6fef4 100644
--- a/libcxx/include/__ranges/concepts.h
+++ b/libcxx/include/__ranges/concepts.h
@@ -10,7 +10,9 @@
#ifndef _LIBCPP___RANGES_CONCEPTS_H
#define _LIBCPP___RANGES_CONCEPTS_H
+#include <__concepts/common_reference_with.h>
#include <__concepts/constructible.h>
+#include <__concepts/convertible_to.h>
#include <__concepts/movable.h>
#include <__concepts/same_as.h>
#include <__config>
@@ -25,6 +27,8 @@
#include <__ranges/enable_view.h>
#include <__ranges/size.h>
#include <__type_traits/add_pointer.h>
+#include <__type_traits/common_reference.h>
+#include <__type_traits/common_type.h>
#include <__type_traits/is_reference.h>
#include <__type_traits/remove_cvref.h>
#include <__type_traits/remove_reference.h>
@@ -133,6 +137,42 @@ concept viewable_range =
(is_lvalue_reference_v<_Tp> ||
(movable<remove_reference_t<_Tp>> && !__is_std_initializer_list<remove_cvref_t<_Tp>>))));
+# if _LIBCPP_STD_VER >= 23
+
+template <class... _Rs>
+using __concat_reference_t _LIBCPP_NODEBUG = common_reference_t<range_reference_t<_Rs>...>;
+
+template <class... _Rs>
+using __concat_value_t _LIBCPP_NODEBUG = common_type_t<range_value_t<_Rs>...>;
+
+template <class... _Rs>
+using __concat_rvalue_reference_t _LIBCPP_NODEBUG = common_reference_t<range_rvalue_reference_t<_Rs>...>;
+
+template <class _Ref, class _RRef, class _It>
+concept __concat_indirectly_readable_impl = requires(const _It __it) {
+ { *__it } -> convertible_to<_Ref>;
+ { ranges::iter_move(__it) } -> convertible_to<_RRef>;
+};
+
+template <class... _Rs>
+concept __concat_indirectly_readable =
+ common_reference_with<__concat_reference_t<_Rs...>&&, __concat_value_t<_Rs...>&> &&
+ common_reference_with<__concat_reference_t<_Rs...>&&, __concat_rvalue_reference_t<_Rs...>&&> &&
+ common_reference_with<__concat_rvalue_reference_t<_Rs...>&&, const __concat_value_t<_Rs...>&> &&
+ (__concat_indirectly_readable_impl<__concat_reference_t<_Rs...>,
+ __concat_rvalue_reference_t<_Rs...>,
+ iterator_t<_Rs>> &&
+ ...);
+
+template <class... _Rs>
+concept __concatable = requires {
+ typename __concat_reference_t<_Rs...>;
+ typename __concat_value_t<_Rs...>;
+ typename __concat_rvalue_reference_t<_Rs...>;
+} && __concat_indirectly_readable<_Rs...>;
+
+# endif // _LIBCPP_STD_VER >= 23
+
} // namespace ranges
#endif // _LIBCPP_STD_VER >= 20
diff --git a/libcxx/include/__ranges/join_with_view.h b/libcxx/include/__ranges/join_with_view.h
new file mode 100644
index 0000000000000..8ed989a664687
--- /dev/null
+++ b/libcxx/include/__ranges/join_with_view.h
@@ -0,0 +1,460 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP___RANGES_JOIN_WITH_VIEW_H
+#define _LIBCPP___RANGES_JOIN_WITH_VIEW_H
+
+#include <__concepts/common_reference_with.h>
+#include <__concepts/common_with.h>
+#include <__concepts/constructible.h>
+#include <__concepts/convertible_to.h>
+#include <__concepts/derived_from.h>
+#include <__concepts/equality_comparable.h>
+#include <__config>
+#include <__functional/bind_back.h>
+#include <__iterator/concepts.h>
+#include <__iterator/incrementable_traits.h>
+#include <__iterator/iter_move.h>
+#include <__iterator/iter_swap.h>
+#include <__iterator/iterator_traits.h>
+#include <__memory/addressof.h>
+#include <__ranges/access.h>
+#include <__ranges/all.h>
+#include <__ranges/concepts.h>
+#include <__ranges/non_propagating_cache.h>
+#include <__ranges/range_adaptor.h>
+#include <__ranges/single_view.h>
+#include <__ranges/view_interface.h>
+#include <__type_traits/conditional.h>
+#include <__type_traits/decay.h>
+#include <__type_traits/is_reference.h>
+#include <__type_traits/maybe_const.h>
+#include <__utility/as_const.h>
+#include <__utility/as_lvalue.h>
+#include <__utility/empty.h>
+#include <__utility/forward.h>
+#include <__utility/move.h>
+#include <variant>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+# pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER >= 23
+
+namespace ranges {
+template <class _Range>
+concept __bidirectional_common = bidirectional_range<_Range> && common_range<_Range>;
+
+template <input_range _View, forward_range _Pattern>
+ requires view<_View> && input_range<range_reference_t<_View>> && view<_Pattern> &&
+ __concatable<range_reference_t<_View>, _Pattern>
+class join_with_view : public view_interface<join_with_view<_View, _Pattern>> {
+ using _InnerRng _LIBCPP_NODEBUG = range_reference_t<_View>;
+
+ _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
+
+ static constexpr bool _UseOuterItCache = !forward_range<_View>;
+ using _OuterItCache _LIBCPP_NODEBUG =
+ _If<_UseOuterItCache, __non_propagating_cache<iterator_t<_View>>, __empty_cache>;
+ _LIBCPP_NO_UNIQUE_ADDRESS _OuterItCache __outer_it_;
+
+ static constexpr bool _UseInnerCache = !is_reference_v<_InnerRng>;
+ using _InnerCache _LIBCPP_NODEBUG =
+ _If<_UseInnerCache, __non_propagating_cache<remove_cvref_t<_InnerRng>>, __empty_cache>;
+ _LIBCPP_NO_UNIQUE_ADDRESS _InnerCache __inner_;
+
+ _LIBCPP_NO_UNIQUE_ADDRESS _Pattern __pattern_ = _Pattern();
+
+ template <bool _Const>
+ struct __iterator;
+
+ template <bool _Const>
+ struct __sentinel;
+
+public:
+ _LIBCPP_HIDE_FROM_ABI join_with_view()
+ requires default_initializable<_View> && default_initializable<_Pattern>
+ = default;
+
+ _LIBCPP_HIDE_FROM_ABI constexpr explicit join_with_view(_View __base, _Pattern __pattern)
+ : __base_(std::move(__base)), __pattern_(std::move(__pattern)) {}
+
+ template <input_range _Range>
+ requires constructible_from<_View, views::all_t<_Range>> &&
+ constructible_from<_Pattern, single_view<range_value_t<_InnerRng>>>
+ _LIBCPP_HIDE_FROM_ABI constexpr explicit join_with_view(_Range&& __r, range_value_t<_InnerRng> __e)
+ : __base_(views::all(std::forward<_Range>(__r))), __pattern_(views::single(std::move(__e))) {}
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
+ requires copy_constructible<_View>
+ {
+ return __base_;
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto begin() {
+ if constexpr (forward_range<_View>) {
+ constexpr bool __use_const = __simple_view<_View> && is_reference_v<_InnerRng> && __simple_view<_Pattern>;
+ return __iterator<__use_const>{*this, ranges::begin(__base_)};
+ } else {
+ __outer_it_.__emplace(ranges::begin(__base_));
+ return __iterator<false>{*this};
+ }
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto begin() const
+ requires forward_range<const _View> && forward_range<const _Pattern> &&
+ is_reference_v<range_reference_t<const _View>> && input_range<range_reference_t<const _View>> &&
+ __concatable<range_reference_t<const _View>, const _Pattern>
+ {
+ return __iterator<true>{*this, ranges::begin(__base_)};
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto end() {
+ constexpr bool __use_const = __simple_view<_View> && __simple_view<_Pattern>;
+ if constexpr (forward_range<_View> && is_reference_v<_InnerRng> && forward_range<_InnerRng> &&
+ common_range<_View> && common_range<_InnerRng>)
+ return __iterator<__use_const>{*this, ranges::end(__base_)};
+ else
+ return __sentinel<__use_const>{*this};
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto end() const
+ requires forward_range<const _View> && forward_range<const _Pattern> &&
+ is_reference_v<range_reference_t<const _View>> && input_range<range_reference_t<const _View>> &&
+ __concatable<range_reference_t<const _View>, const _Pattern>
+ {
+ using _InnerConstRng = range_reference_t<const _View>;
+ if constexpr (forward_range<_InnerConstRng> && common_range<const _View> && common_range<_InnerConstRng>)
+ return __iterator<true>{*this, ranges::end(__base_)};
+ else
+ return __sentinel<true>{*this};
+ }
+};
+
+template <class _Range, class _Pattern>
+join_with_view(_Range&&, _Pattern&&) -> join_with_view<views::all_t<_Range>, views::all_t<_Pattern>>;
+
+template <input_range _Range>
+join_with_view(_Range&&, range_value_t<range_reference_t<_Range>>)
+ -> join_with_view<views::all_t<_Range>, single_view<range_value_t<range_reference_t<_Range>>>>;
+
+template <class _Base, class _PatternBase, class _InnerBase = range_reference_t<_Base>>
+struct __join_with_view_iterator_category {};
+
+template <class _Base, class _PatternBase, class _InnerBase>
+ requires is_reference_v<_InnerBase> && forward_range<_Base> && forward_range<_InnerBase>
+struct __join_with_view_iterator_category<_Base, _PatternBase, _InnerBase> {
+private:
+ static consteval auto __get_iterator_category() noexcept {
+ using _OuterC = iterator_traits<iterator_t<_Base>>::iterator_category;
+ using _InnerC = iterator_traits<iterator_t<_InnerBase>>::iterator_category;
+ using _PatternC = iterator_traits<iterator_t<_PatternBase>>::iterator_category;
+
+ if constexpr (!is_reference_v<common_reference_t<iter_reference_t<iterator_t<_InnerBase>>,
+ iter_reference_t<iterator_t<_PatternBase>>>>)
+ return input_iterator_tag{};
+ else if constexpr (derived_from<_OuterC, bidirectional_iterator_tag> &&
+ derived_from<_InnerC, bidirectional_iterator_tag> &&
+ derived_from<_PatternC, bidirectional_iterator_tag> && common_range<_InnerBase> &&
+ common_range<_PatternBase>)
+ return bidirectional_iterator_tag{};
+ else if constexpr (derived_from<_OuterC, forward_iterator_tag> && derived_from<_InnerC, forward_iterator_tag> &&
+ derived_from<_PatternC, forward_iterator_tag>)
+ return forward_iterator_tag{};
+ else
+ return input_iterator_tag{};
+ }
+
+public:
+ using iterator_category = decltype(__get_iterator_category());
+};
+
+template <input_range _View, forward_range _Pattern>
+ requires view<_View> && input_range<range_reference_t<_View>> && view<_Pattern> &&
+ __concatable<range_reference_t<_View>, _Pattern>
+template <bool _Const>
+struct join_with_view<_View, _Pattern>::__iterator
+ : public __join_with_view_iterator_category<__maybe_const<_Const, _View>, __maybe_const<_Const, _Pattern>> {
+private:
+ friend join_with_view;
+
+ using _Parent _LIBCPP_NODEBUG = __maybe_const<_Const, join_with_view>;
+ using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
+ using _InnerBase _LIBCPP_NODEBUG = range_reference_t<_Base>;
+ using _PatternBase _LIBCPP_NODEBUG = __maybe_const<_Const, _Pattern>;
+
+ using _OuterIter _LIBCPP_NODEBUG = iterator_t<_Base>;
+ using _InnerIter _LIBCPP_NODEBUG = iterator_t<_InnerBase>;
+ using _PatternIter _LIBCPP_NODEBUG = iterator_t<_PatternBase>;
+
+ static_assert(!_Const || forward_range<_Base>, "Const can only be true when Base models forward_range.");
+
+ static constexpr bool __ref_is_glvalue = is_reference_v<_InnerBase>;
+
+ _Parent* __parent_ = nullptr;
+
+ static constexpr bool _OuterIterPresent = forward_range<_Base>;
+ using _OuterIterType _LIBCPP_NODEBUG = _If<_OuterIterPresent, _OuterIter, std::__empty>;
+ _LIBCPP_NO_UNIQUE_ADDRESS _OuterIterType __outer_it_ = _OuterIterType();
+
+ variant<_PatternIter, _InnerIter> __inner_it_;
+
+ _LIBCPP_HIDE_FROM_ABI constexpr __iterator(_Parent& __parent, _OuterIter __outer)
+ requires forward_range<_Base>
+ : __parent_(std::addressof(__parent)), __outer_it_(std::move(__outer)) {
+ if (__get_outer() != ranges::end(__parent_->__base_)) {
+ __inner_it_.template emplace<1>(ranges::begin(__update_inner()));
+ __satisfy();
+ }
+ }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr explicit __iterator(_Parent& __parent)
+ requires(!forward_range<_Base>)
+ : __parent_(std::addressof(__parent)) {
+ if (__get_outer() != ranges::end(__parent_->__base_)) {
+ __inner_it_.template emplace<1>(ranges::begin(__update_inner()));
+ __satisfy();
+ }
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr _OuterIter& __get_outer() {
+ if constexpr (forward_range<_Base>)
+ return __outer_it_;
+ else
+ return *__parent_->__outer_it_;
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr const _OuterIter& __get_outer() const {
+ if constexpr (forward_range<_Base>)
+ return __outer_it_;
+ else
+ return *__parent_->__outer_it_;
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto& __update_inner() {
+ if constexpr (__ref_is_glvalue)
+ return std::__as_lvalue(*__get_outer());
+ else
+ return __parent_->__inner_.__emplace_from([this]() -> decltype(auto) { return *__get_outer(); });
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto& __get_inner() {
+ if constexpr (__ref_is_glvalue)
+ return std::__as_lvalue(*__get_outer());
+ else
+ return *__parent_->__inner_;
+ }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr void __satisfy() {
+ while (true) {
+ if (__inner_it_.index() == 0) {
+ if (std::get<0>(__inner_it_) != ranges::end(__parent_->__pattern_))
+ break;
+
+ __inner_it_.template emplace<1>(ranges::begin(__update_inner()));
+ } else {
+ if (std::get<1>(__inner_it_) != ranges::end(__get_inner()))
+ break;
+
+ if (++__get_outer() == ranges::end(__parent_->__base_)) {
+ if constexpr (__ref_is_glvalue)
+ __inner_it_.template emplace<0>();
+
+ break;
+ }
+
+ __inner_it_.template emplace<0>(ranges::begin(__parent_->__pattern_));
+ }
+ }
+ }
+
+ [[nodiscard]] static consteval auto __get_iterator_concept() noexcept {
+ if constexpr (__ref_is_glvalue && bidirectional_range<_Base> && __bidirectional_common<_InnerBase> &&
+ __bidirectional_common<_PatternBase>)
+ return bidirectional_iterator_tag{};
+ else if constexpr (__ref_is_glvalue && forward_range<_Base> && forward_range<_InnerBase>)
+ return forward_iterator_tag{};
+ else
+ return input_iterator_tag{};
+ }
+
+public:
+ using iterator_concept = decltype(__get_iterator_concept());
+ using value_type = common_type_t<iter_value_t<_InnerIter>, iter_value_t<_PatternIter>>;
+ using
diff erence_type =
+ common_type_t<iter_
diff erence_t<_OuterIter>, iter_
diff erence_t<_InnerIter>, iter_
diff erence_t<_PatternIter>>;
+
+ _LIBCPP_HIDE_FROM_ABI __iterator() = default;
+
+ _LIBCPP_HIDE_FROM_ABI constexpr __iterator(__iterator<!_Const> __i)
+ requires _Const && convertible_to<iterator_t<_View>, _OuterIter> &&
+ convertible_to<iterator_t<_InnerRng>, _InnerIter> && convertible_to<iterator_t<_Pattern>, _PatternIter>
+ : __parent_(__i.__parent_), __outer_it_(std::move(__i.__outer_it_)) {
+ if (__i.__inner_it_.index() == 0) {
+ __inner_it_.template emplace<0>(std::get<0>(std::move(__i.__inner_it_)));
+ } else {
+ __inner_it_.template emplace<1>(std::get<1>(std::move(__i.__inner_it_)));
+ }
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr decltype(auto) operator*() const {
+ using __reference = common_reference_t<iter_reference_t<_InnerIter>, iter_reference_t<_PatternIter>>;
+ return std::visit([](auto& __it) -> __reference { return *__it; }, __inner_it_);
+ }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator++() {
+ std::visit([](auto& __it) { ++__it; }, __inner_it_);
+ __satisfy();
+ return *this;
+ }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr void operator++(int) { ++*this; }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator++(int)
+ requires __ref_is_glvalue && forward_iterator<_OuterIter> && forward_iterator<_InnerIter>
+ {
+ __iterator __tmp = *this;
+ ++*this;
+ return __tmp;
+ }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr __iterator& operator--()
+ requires __ref_is_glvalue
+ && bidirectional_range<_Base> && __bidirectional_common<_InnerBase> && __bidirectional_common<_PatternBase>
+ {
+ if (__outer_it_ == ranges::end(__parent_->__base_)) {
+ auto&& __inner = *--__outer_it_;
+ __inner_it_.template emplace<1>(ranges::end(__inner));
+ }
+
+ while (true) {
+ if (__inner_it_.index() == 0) {
+ auto& __it = std::get<0>(__inner_it_);
+ if (__it == ranges::begin(__parent_->__pattern_)) {
+ auto&& __inner = *--__outer_it_;
+ __inner_it_.template emplace<1>(ranges::end(__inner));
+ } else
+ break;
+ } else {
+ auto& __it = std::get<1>(__inner_it_);
+ auto&& __inner = *__outer_it_;
+ if (__it == ranges::begin(__inner))
+ __inner_it_.template emplace<0>(ranges::end(__parent_->__pattern_));
+ else
+ break;
+ }
+ }
+
+ std::visit([](auto& __it) { --__it; }, __inner_it_);
+ return *this;
+ }
+
+ _LIBCPP_HIDE_FROM_ABI constexpr __iterator operator--(int)
+ requires __ref_is_glvalue
+ && bidirectional_range<_Base> && __bidirectional_common<_InnerBase> && __bidirectional_common<_PatternBase>
+ {
+ __iterator __tmp = *this;
+ --*this;
+ return __tmp;
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(const __iterator& __x, const __iterator& __y)
+ requires __ref_is_glvalue && forward_range<_Base> && equality_comparable<_InnerIter>
+ {
+ return __x.__outer_it_ == __y.__outer_it_ && __x.__inner_it_ == __y.__inner_it_;
+ }
+
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr decltype(auto) iter_move(const __iterator& __x) {
+ using __rvalue_reference =
+ common_reference_t<iter_rvalue_reference_t<_InnerIter>, iter_rvalue_reference_t<_PatternIter>>;
+ return std::visit<__rvalue_reference>(ranges::iter_move, __x.__inner_it_);
+ }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr void iter_swap(const __iterator& __x, const __iterator& __y)
+ requires indirectly_swappable<_InnerIter, _PatternIter>
+ {
+ std::visit(ranges::iter_swap, __x.__inner_it_, __y.__inner_it_);
+ }
+};
+
+template <input_range _View, forward_range _Pattern>
+ requires view<_View> && input_range<range_reference_t<_View>> && view<_Pattern> &&
+ __concatable<range_reference_t<_View>, _Pattern>
+template <bool _Const>
+struct join_with_view<_View, _Pattern>::__sentinel {
+private:
+ friend join_with_view;
+
+ using _Parent _LIBCPP_NODEBUG = __maybe_const<_Const, join_with_view>;
+ using _Base _LIBCPP_NODEBUG = __maybe_const<_Const, _View>;
+
+ _LIBCPP_NO_UNIQUE_ADDRESS sentinel_t<_Base> __end_ = sentinel_t<_Base>();
+
+ _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(_Parent& __parent) : __end_(ranges::end(__parent.__base_)) {}
+
+ template <bool _OtherConst>
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI static constexpr auto& __get_outer_of(const __iterator<_OtherConst>& __x) {
+ return __x.__get_outer();
+ }
+
+public:
+ _LIBCPP_HIDE_FROM_ABI __sentinel() = default;
+
+ _LIBCPP_HIDE_FROM_ABI constexpr __sentinel(__sentinel<!_Const> __s)
+ requires _Const && convertible_to<sentinel_t<_View>, sentinel_t<_Base>>
+ : __end_(std::move(__s.__end_)) {}
+
+ template <bool _OtherConst>
+ requires sentinel_for<sentinel_t<_Base>, iterator_t<__maybe_const<_OtherConst, _View>>>
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI friend constexpr bool
+ operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
+ return __get_outer_of(__x) == __y.__end_;
+ }
+};
+
+namespace views {
+namespace __join_with_view {
+struct __fn {
+ template <class _Range, class _Pattern>
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Range&& __range, _Pattern&& __pattern) const
+ noexcept(noexcept(/**/ join_with_view(std::forward<_Range>(__range), std::forward<_Pattern>(__pattern))))
+ -> decltype(/*--*/ join_with_view(std::forward<_Range>(__range), std::forward<_Pattern>(__pattern))) {
+ return /*-------------*/ join_with_view(std::forward<_Range>(__range), std::forward<_Pattern>(__pattern));
+ }
+
+ template <class _Pattern>
+ requires constructible_from<decay_t<_Pattern>, _Pattern>
+ [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Pattern&& __pattern) const
+ noexcept(is_nothrow_constructible_v<decay_t<_Pattern>, _Pattern>) {
+ return __pipeable(std::__bind_back(*this, std::forward<_Pattern>(__pattern)));
+ }
+};
+} // namespace __join_with_view
+
+inline namespace __cpo {
+inline constexpr auto join_with = __join_with_view::__fn{};
+} // namespace __cpo
+} // namespace views
+} // namespace ranges
+
+#endif // _LIBCPP_STD_VER >= 23
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP___RANGES_JOIN_WITH_VIEW_H
diff --git a/libcxx/include/module.modulemap.in b/libcxx/include/module.modulemap.in
index f5fd970934e9b..4a081e65cb7f1 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -1865,6 +1865,7 @@ module std [system] {
module iota_view { header "__ranges/iota_view.h" }
module istream_view { header "__ranges/istream_view.h" }
module join_view { header "__ranges/join_view.h" }
+ module join_with_view { header "__ranges/join_with_view.h" }
module lazy_split_view {
header "__ranges/lazy_split_view.h"
export std.functional.bind_back
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
index 49fea7c3f84ec..2a6321bd2c5d8 100644
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -285,6 +285,15 @@ namespace std::ranges {
requires view<V> && input_range<range_reference_t<V>>
class join_view;
+ // [range.join.with], join with view
+ template<input_range V, forward_range Pattern>
+ requires view<V> && input_range<range_reference_t<V>>
+ && view<Pattern>
+ && concatable<range_reference_t<V>, Pattern>
+ class join_with_view; // since C++23
+
+ namespace views { inline constexpr unspecified join_with = unspecified; } // since C++23
+
// [range.lazy.split], lazy split view
template<class R>
concept tiny-range = see below; // exposition only
@@ -427,6 +436,7 @@ namespace std {
# include <__ranges/as_rvalue_view.h>
# include <__ranges/chunk_by_view.h>
# include <__ranges/from_range.h>
+# include <__ranges/join_with_view.h>
# include <__ranges/repeat_view.h>
# include <__ranges/to.h>
# include <__ranges/zip_view.h>
diff --git a/libcxx/include/version b/libcxx/include/version
index f430c7edff2b2..91fe48351e161 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -519,7 +519,7 @@ __cpp_lib_void_t 201411L <type_traits>
# define __cpp_lib_ranges_contains 202207L
# define __cpp_lib_ranges_find_last 202207L
# define __cpp_lib_ranges_iota 202202L
-// # define __cpp_lib_ranges_join_with 202202L
+# define __cpp_lib_ranges_join_with 202202L
# define __cpp_lib_ranges_repeat 202207L
// # define __cpp_lib_ranges_slide 202202L
# define __cpp_lib_ranges_starts_ends_with 202106L
diff --git a/libcxx/modules/std/ranges.inc b/libcxx/modules/std/ranges.inc
index a5e2a2b4583c1..adabeeb22d551 100644
--- a/libcxx/modules/std/ranges.inc
+++ b/libcxx/modules/std/ranges.inc
@@ -223,13 +223,16 @@ export namespace std {
namespace views {
using std::ranges::views::join;
} // namespace views
-#if 0
+
+#if _LIBCPP_STD_VER >= 23
+ // [range.join.with]
using std::ranges::join_with_view;
namespace views {
using std::ranges::views::join_with;
} // namespace views
-#endif
+#endif // _LIBCPP_STD_VER >= 23
+
using std::ranges::lazy_split_view;
// [range.split], split view
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.nodiscard.verify.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.nodiscard.verify.cpp
new file mode 100644
index 0000000000000..97133613bf58a
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.nodiscard.verify.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// Test the libc++ extension that std::ranges::join_with_view::iterator<Const>::operator* is marked as [[nodiscard]].
+
+#include <ranges>
+#include <utility>
+
+void test() {
+ char range[3][2] = {{'x', 'x'}, {'y', 'y'}, {'z', 'z'}};
+ char pattern[2] = {',', ' '};
+
+ std::ranges::join_with_view view(range, pattern);
+
+ // clang-format off
+ *view.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ *std::as_const(view).begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // clang-format on
+}
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.nodiscard.verify.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.nodiscard.verify.cpp
new file mode 100644
index 0000000000000..823d8def98085
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.nodiscard.verify.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// Test the libc++ extension that std::ranges::join_with_view::iterator<Const>::operator== is marked as [[nodiscard]].
+
+#include <ranges>
+#include <utility>
+
+void test() {
+ char16_t range[3][1] = {{u'x'}, {u'y'}, {u'z'}};
+ char16_t pattern[1] = {u'-'};
+
+ std::ranges::join_with_view view(range, pattern);
+
+ // clang-format off
+ (view.begin() == view.end()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ (std::as_const(view).begin() == view.end()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ (view.begin() == std::as_const(view).end()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ (std::as_const(view).begin() == std::as_const(view).end()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // clang-format on
+}
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.nodiscard.verify.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.nodiscard.verify.cpp
new file mode 100644
index 0000000000000..9e046ef43fda3
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.nodiscard.verify.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// Test the libc++ extension that std::ranges::join_with_view::iterator<Const>::iter_move is marked as [[nodiscard]].
+
+#include <ranges>
+#include <utility>
+
+void test() {
+ long range[2][1] = {{0L}, {2L}};
+ long pattern[1] = {1L};
+
+ std::ranges::join_with_view view(range, pattern);
+
+ // clang-format off
+ iter_move(view.begin()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ iter_move(std::as_const(view).begin()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // clang-format on
+}
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/no_unique_address.compile.pass.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/no_unique_address.compile.pass.cpp
new file mode 100644
index 0000000000000..6b2abb5c80539
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/no_unique_address.compile.pass.cpp
@@ -0,0 +1,56 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// This test ensures that we use `[[no_unique_address]]` in `join_with_view::iterator`.
+
+#include <cstddef>
+#include <ranges>
+#include <variant>
+
+struct IntRange : std::ranges::view_base {
+ int* begin();
+ int* end();
+};
+
+class Iter {
+public:
+ using value_type = IntRange;
+ using
diff erence_type = ptr
diff _t;
+
+ Iter& operator++();
+ void operator++(int);
+ value_type& operator*() const;
+ bool operator==(std::default_sentinel_t) const;
+
+private:
+ int* ptr_;
+};
+
+static_assert(std::input_iterator<Iter>);
+static_assert(!std::forward_iterator<Iter>);
+
+struct View : std::ranges::view_base {
+ Iter begin();
+ std::default_sentinel_t end();
+};
+
+static_assert(std::ranges::input_range<View>);
+static_assert(!std::ranges::forward_range<View>);
+
+using JWV = std::ranges::join_with_view<View, IntRange>;
+
+// Expected JWV::iterator layout:
+// _Parent* __parent_; // offset: 0
+// [[no_unique_address]] __empty __outer_it; // 0
+// variant<_PatternIter, _InnerIter> __pattern_; // sizeof(pointer)
+static_assert(sizeof(std::ranges::iterator_t<JWV>) ==
+ sizeof(void*) + sizeof(std::variant<int*, int*>)); // sizeof(__parent_) + sizeof(__inner_it_)
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.nodiscard.verify.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.nodiscard.verify.cpp
new file mode 100644
index 0000000000000..3efe77a3765d5
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.nodiscard.verify.cpp
@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// Test the libc++ extension that std::views::join_with is marked as [[nodiscard]].
+
+#include <ranges>
+
+void test() {
+ int range[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
+ int pattern_base[2] = {-1, -1};
+ auto pattern = std::views::all(pattern_base);
+
+ // clang-format off
+ std::views::join_with(pattern); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::views::join_with(range, pattern); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ range | std::views::join_with(pattern); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::views::reverse | std::views::join_with(pattern); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+ std::views::join_with(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::views::join_with(range, 0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ range | std::views::join_with(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::views::reverse | std::views::join_with(0); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // clang-format on
+}
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.nodiscard.verify.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.nodiscard.verify.cpp
new file mode 100644
index 0000000000000..e7e4d262eedb9
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.nodiscard.verify.cpp
@@ -0,0 +1,35 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// Test the libc++ extension that std::ranges::join_with_view::sentinel<Const>::operator== is marked as [[nodiscard]].
+
+#include <array>
+#include <ranges>
+#include <utility>
+
+#include "test_iterators.h"
+#include "test_range.h"
+
+void test() {
+ std::array<test_range<cpp20_input_iterator>, 0> range;
+ std::array<int, 0> pattern;
+
+ std::ranges::join_with_view view(range, pattern);
+ static_assert(!std::ranges::common_range<decltype(view)>);
+
+ // clang-format off
+ (view.begin() == view.end()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ (std::as_const(view).begin() == view.end()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ (view.begin() == std::as_const(view).end()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ (std::as_const(view).begin() == std::as_const(view).end()); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // clang-format on
+}
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.sentinel/no_unique_address.compile.pass.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.sentinel/no_unique_address.compile.pass.cpp
new file mode 100644
index 0000000000000..3badac162ce7c
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.sentinel/no_unique_address.compile.pass.cpp
@@ -0,0 +1,48 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// XFAIL: msvc
+
+// <ranges>
+
+// This test ensures that we use `[[no_unique_address]]` in `join_with_view::sentinel`.
+
+#include <cstddef>
+#include <ranges>
+#include <string_view>
+
+template <bool Const>
+struct Iter {
+ using value_type = std::string_view;
+ using
diff erence_type = std::ptr
diff _t;
+
+ Iter& operator++();
+ Iter operator++(int);
+ value_type& operator*() const;
+ bool operator==(const Iter&) const;
+ bool operator==(std::default_sentinel_t) const;
+};
+
+struct View : std::ranges::view_base {
+ Iter<false> begin();
+ Iter<true> begin() const;
+ std::default_sentinel_t end() const;
+};
+
+using JWV = std::ranges::join_with_view<View, std::string_view>;
+
+template <class View>
+struct Test {
+ [[no_unique_address]] std::ranges::sentinel_t<View> se;
+ unsigned char pad;
+};
+
+static_assert(sizeof(Test<JWV>) == 1);
+static_assert(sizeof(Test<const JWV>) == 1);
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/base.nodiscard.verify.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/base.nodiscard.verify.cpp
new file mode 100644
index 0000000000000..ddf1ebdc5e46c
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/base.nodiscard.verify.cpp
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// Test the libc++ extension that std::ranges::join_with_view::base is marked as [[nodiscard]].
+
+#include <ranges>
+#include <utility>
+
+void test() {
+ int range[3][3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
+ int pattern[2] = {-1, -1};
+
+ std::ranges::join_with_view view(range, pattern);
+
+ // clang-format off
+ view.base(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::as_const(view).base(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::move(std::as_const(view)).base(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::move(view).base(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // clang-format on
+}
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/begin.nodiscard.verify.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/begin.nodiscard.verify.cpp
new file mode 100644
index 0000000000000..858490a82c75d
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/begin.nodiscard.verify.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// Test the libc++ extension that std::ranges::join_with_view::begin is marked as [[nodiscard]].
+
+#include <ranges>
+#include <utility>
+
+void test() {
+ int range[3][2] = {{1, 3}, {4, 6}, {7, 9}};
+ int pattern[1] = {-2};
+
+ std::ranges::join_with_view view(range, pattern);
+
+ // clang-format off
+ view.begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::as_const(view).begin(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // clang-format on
+}
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/end.nodiscard.verify.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/end.nodiscard.verify.cpp
new file mode 100644
index 0000000000000..e57e0ee3f0d06
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/end.nodiscard.verify.cpp
@@ -0,0 +1,28 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// Test the libc++ extension that std::ranges::join_with_view::end is marked as [[nodiscard]].
+
+#include <ranges>
+#include <utility>
+
+void test() {
+ int range[3][2] = {{1, 2}, {4, 5}, {7, 8}};
+ int pattern[1] = {-3};
+
+ std::ranges::join_with_view view(range, pattern);
+
+ // clang-format off
+ view.end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ std::as_const(view).end(); // expected-warning {{ignoring return value of function declared with 'nodiscard' attribute}}
+ // clang-format on
+}
diff --git a/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/no_unique_address.compile.pass.cpp b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/no_unique_address.compile.pass.cpp
new file mode 100644
index 0000000000000..aa6eeafe4be13
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/no_unique_address.compile.pass.cpp
@@ -0,0 +1,47 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// XFAIL: msvc
+
+// <ranges>
+
+// This test ensures that we use `[[no_unique_address]]` in `join_with_view`.
+
+#include <ranges>
+#include <string>
+
+struct ForwardView : std::ranges::view_base {
+ std::string* begin() const;
+ std::string* end() const;
+};
+
+static_assert(std::ranges::forward_range<ForwardView>);
+static_assert(std::is_reference_v<std::ranges::range_reference_t<ForwardView>>);
+
+struct Pattern : std::ranges::view_base {
+ char* begin() const;
+ char* end() const;
+};
+
+template <class View>
+struct Test {
+ [[no_unique_address]] View view;
+ unsigned char pad;
+};
+
+using JWV = std::ranges::join_with_view<ForwardView, Pattern>;
+
+// Expected JWV layout:
+// [[no_unique_address]] _View __base_ // offset: 0
+// [[no_unique_address]] __empty_cache __outer_it; // 0
+// [[no_unique_address]] __empty_cache __inner_; // 1
+// [[no_unique_address]] _Patter __pattern_ // 0
+static_assert(sizeof(JWV) == 2);
+static_assert(sizeof(Test<JWV>) == 2);
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/ranges.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/ranges.version.compile.pass.cpp
index c7c8112e123cd..4cf5178dd7b8f 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/ranges.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/ranges.version.compile.pass.cpp
@@ -278,17 +278,11 @@
# error "__cpp_lib_ranges_concat should not be defined before c++26"
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_ranges_join_with
-# error "__cpp_lib_ranges_join_with should be defined in c++23"
-# endif
-# if __cpp_lib_ranges_join_with != 202202L
-# error "__cpp_lib_ranges_join_with should have the value 202202L in c++23"
-# endif
-# else
-# ifdef __cpp_lib_ranges_join_with
-# error "__cpp_lib_ranges_join_with should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_ranges_join_with
+# error "__cpp_lib_ranges_join_with should be defined in c++23"
+# endif
+# if __cpp_lib_ranges_join_with != 202202L
+# error "__cpp_lib_ranges_join_with should have the value 202202L in c++23"
# endif
# ifndef __cpp_lib_ranges_repeat
@@ -406,17 +400,11 @@
# endif
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_ranges_join_with
-# error "__cpp_lib_ranges_join_with should be defined in c++26"
-# endif
-# if __cpp_lib_ranges_join_with != 202202L
-# error "__cpp_lib_ranges_join_with should have the value 202202L in c++26"
-# endif
-# else
-# ifdef __cpp_lib_ranges_join_with
-# error "__cpp_lib_ranges_join_with should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_ranges_join_with
+# error "__cpp_lib_ranges_join_with should be defined in c++26"
+# endif
+# if __cpp_lib_ranges_join_with != 202202L
+# error "__cpp_lib_ranges_join_with should have the value 202202L in c++26"
# endif
# ifndef __cpp_lib_ranges_repeat
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index cef334f70c078..e546719142231 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -5633,17 +5633,11 @@
# error "__cpp_lib_ranges_iota should have the value 202202L in c++23"
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_ranges_join_with
-# error "__cpp_lib_ranges_join_with should be defined in c++23"
-# endif
-# if __cpp_lib_ranges_join_with != 202202L
-# error "__cpp_lib_ranges_join_with should have the value 202202L in c++23"
-# endif
-# else
-# ifdef __cpp_lib_ranges_join_with
-# error "__cpp_lib_ranges_join_with should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_ranges_join_with
+# error "__cpp_lib_ranges_join_with should be defined in c++23"
+# endif
+# if __cpp_lib_ranges_join_with != 202202L
+# error "__cpp_lib_ranges_join_with should have the value 202202L in c++23"
# endif
# ifndef __cpp_lib_ranges_repeat
@@ -7549,17 +7543,11 @@
# error "__cpp_lib_ranges_iota should have the value 202202L in c++26"
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_ranges_join_with
-# error "__cpp_lib_ranges_join_with should be defined in c++26"
-# endif
-# if __cpp_lib_ranges_join_with != 202202L
-# error "__cpp_lib_ranges_join_with should have the value 202202L in c++26"
-# endif
-# else
-# ifdef __cpp_lib_ranges_join_with
-# error "__cpp_lib_ranges_join_with should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_ranges_join_with
+# error "__cpp_lib_ranges_join_with should be defined in c++26"
+# endif
+# if __cpp_lib_ranges_join_with != 202202L
+# error "__cpp_lib_ranges_join_with should have the value 202202L in c++26"
# endif
# ifndef __cpp_lib_ranges_repeat
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.default.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.default.pass.cpp
new file mode 100644
index 0000000000000..0d9df493305da
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.default.pass.cpp
@@ -0,0 +1,79 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// iterator() = default;
+
+#include <ranges>
+
+#include <cassert>
+#include <initializer_list>
+#include <iterator>
+#include <type_traits>
+#include <utility>
+
+#include "../types.h"
+#include "test_comparisons.h"
+#include "test_iterators.h"
+
+constexpr bool test() {
+ { // `V` and `Pattern` model forward range
+ using Inner = BasicVectorView<int, ViewProperties{}, forward_iterator>;
+ using V = BasicVectorView<Inner, ViewProperties{}, forward_iterator>;
+ using Pattern = Inner;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using ConstIter = std::ranges::iterator_t<const JWV>;
+
+ // Default constructor of iterator<false> should not be explicit
+ Iter iter = {};
+ assert(testEquality(iter, Iter{}, true));
+
+ // Default constructor of iterator<true> should not be explicit
+ ConstIter citer = {};
+ assert(testEquality(citer, ConstIter{}, true));
+ assert(testEquality(iter, citer, true));
+
+ std::ranges::join_with_view<V, Pattern> jwv(V{Inner{1, 2}, Inner{2, 1}}, Pattern{3, 3});
+ Iter jwv_iter = jwv.begin();
+ ConstIter jwv_citer = std::as_const(jwv).begin();
+ assert(testEquality(jwv_iter, jwv_citer, true));
+
+ assert(testEquality(jwv_iter, iter, false));
+ assert(testEquality(jwv_iter, citer, false));
+ assert(testEquality(jwv_citer, iter, false));
+ assert(testEquality(jwv_citer, citer, false));
+ }
+
+ { // `InnerIter` is not default constructible (does not model forward iterator, JWV cannot be const-accessed)
+ using Inner = BasicVectorView<char, ViewProperties{.common = false}, EqComparableInputIter>;
+ using V = BasicVectorView<Inner, ViewProperties{.common = false}, forward_iterator>;
+ using Pattern = BasicVectorView<char, ViewProperties{}, forward_iterator>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+
+ Iter iter;
+ assert(testEquality(iter, Iter{}, true));
+
+ std::ranges::join_with_view<V, Pattern> jwv(V{Inner{'a', 'b'}, Inner{'c', 'd'}}, Pattern{',', ' '});
+ Iter jwv_iter = jwv.begin();
+ assert(testEquality(jwv_iter, iter, false));
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.not_const.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.not_const.pass.cpp
new file mode 100644
index 0000000000000..0ca31392ed8fa
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.not_const.pass.cpp
@@ -0,0 +1,111 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// constexpr iterator(iterator<!Const> i)
+// requires Const && convertible_to<iterator_t<V>, OuterIter> &&
+// convertible_to<iterator_t<InnerRng>, InnerIter> &&
+// convertible_to<iterator_t<Pattern>, PatternIter>;
+
+#include <ranges>
+
+#include <cassert>
+#include <vector>
+
+#include "../types.h"
+
+constexpr bool test() {
+ { // Regular conversion from `!Const` to `Const` iterator
+ std::vector<std::vector<int>> vec = {{1, 2}, {3, 4}, {5, 6}};
+ int pattern = 0;
+ std::ranges::join_with_view jwv(vec, pattern);
+
+ using JWV = decltype(jwv);
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!std::same_as<Iter, CIter>);
+ static_assert(std::convertible_to<Iter, CIter>);
+ static_assert(std::constructible_from<CIter, Iter>);
+
+ Iter it = jwv.begin();
+ assert(*it == 1);
+
+ const CIter cit1 = it; // `cit1` points to element of `V`; this constructor should not be explicit
+ assert(*cit1 == 1);
+ assert(cit1 == it);
+
+ std::ranges::advance(it, 2);
+ assert(*it == 0);
+ CIter cit2 = it; // `cit2` points to element of `Pattern`
+ assert(*cit2 == 0);
+ assert(cit2 == it);
+
+ ++it;
+ assert(*it == 3);
+ CIter cit3 = it;
+ assert(*cit3 == 3);
+ assert(cit3 == it);
+
+ --cit3;
+ assert(cit2 == cit3);
+ }
+
+ { // Test conversion from `Const` to `!Const` (should be invalid)
+ using V = std::vector<std::vector<int>>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<std::views::all_t<V>, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!std::convertible_to<CIter, Iter>);
+ static_assert(!std::constructible_from<Iter, CIter>);
+ }
+
+ { // When `convertible_to<iterator_t<V>, OuterIter>` is not modeled
+ using Inner = std::vector<short>;
+ using V = ConstOppositeView<Inner>;
+ using Pattern = std::ranges::single_view<short>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!std::convertible_to<CIter, Iter>);
+ static_assert(!std::constructible_from<Iter, CIter>);
+ }
+
+ { // When `convertible_to<iterator_t<InnerRng>, InnerIter>` is not modeled
+ using Inner = ConstOppositeView<long>;
+ using V = std::vector<Inner>;
+ using Pattern = std::ranges::single_view<long>;
+ using JWV = std::ranges::join_with_view<std::views::all_t<V>, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!std::convertible_to<CIter, Iter>);
+ static_assert(!std::constructible_from<Iter, CIter>);
+ }
+
+ { // When `convertible_to<iterator_t<Pattern>, PatternIter>` is not modeled
+ using V = std::vector<std::vector<long long>>;
+ using Pattern = ConstOppositeView<long long>;
+ using JWV = std::ranges::join_with_view<std::views::all_t<V>, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!std::convertible_to<CIter, Iter>);
+ static_assert(!std::constructible_from<Iter, CIter>);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/decrement.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/decrement.pass.cpp
new file mode 100644
index 0000000000000..207d60a7296fc
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/decrement.pass.cpp
@@ -0,0 +1,283 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// constexpr iterator& operator--()
+// requires ref-is-glvalue && bidirectional_range<Base> &&
+// bidirectional-common<InnerBase> && bidirectional-common<PatternBase>;
+// constexpr iterator operator--(int)
+// requires ref-is-glvalue && bidirectional_range<Base> &&
+// bidirectional-common<InnerBase> && bidirectional-common<PatternBase>;
+
+#include <ranges>
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <forward_list>
+#include <string>
+#include <string_view>
+#include <vector>
+
+#include "../types.h"
+
+template <class I>
+concept CanPreDecrement = requires(I& i) {
+ { --i } -> std::same_as<I&>;
+};
+
+template <class I>
+concept CanPostDecrement = requires(I& i) {
+ { i-- } -> std::same_as<I>;
+};
+
+template <class I>
+concept CanDecrement = CanPreDecrement<I> && CanPostDecrement<I>;
+
+constexpr bool test() {
+ { // `V` and `Pattern` are not empty. Test return type too.
+ using V = std::ranges::owning_view<std::vector<std::string>>;
+ using Pattern = std::ranges::single_view<char>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(CanDecrement<Iter>);
+ static_assert(CanDecrement<CIter>);
+
+ JWV jwv(V{{"01", "23", "45"}}, Pattern{'_'});
+
+ {
+ auto it = jwv.end();
+ std::same_as<Iter&> decltype(auto) it_ref = --it;
+ assert(it_ref == it);
+ assert(*it == '5');
+ std::same_as<Iter> decltype(auto) it_copy = it--;
+ assert(--it_copy == it);
+ --it;
+ assert(*it == '_');
+ it--;
+ assert(*it == '3');
+ --it;
+ it--;
+ assert(*it == '_');
+ }
+
+ {
+ auto cit = std::as_const(jwv).end();
+ std::same_as<CIter&> decltype(auto) cit_ref = --cit;
+ assert(cit_ref == cit);
+ assert(*cit == '5');
+ std::same_as<CIter> decltype(auto) cit_copy = cit--;
+ assert(--cit_copy == cit);
+ --cit;
+ assert(*cit == '_');
+ cit--;
+ assert(*cit == '3');
+ --cit;
+ cit--;
+ assert(*cit == '_');
+ }
+
+ assert(std::ranges::equal(std::views::reverse(std::move(jwv)), std::string_view{"54_32_10"}));
+ }
+
+ { // `Pattern` is empty, `V` is not.
+ using Inner = std::array<int, 1>;
+ using V = std::ranges::owning_view<std::array<Inner, 3>>;
+ using Pattern = std::ranges::owning_view<std::array<int, 0>>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ JWV jwv(V{{Inner{-9}, Inner{-99}, Inner{-999}}}, Pattern{});
+
+ {
+ auto it = jwv.end();
+ --it;
+ assert(*it == -999);
+ it--;
+ assert(*it == -99);
+ --it;
+ assert(*it == -9);
+ assert(it == jwv.begin());
+ }
+
+ {
+ auto cit = std::as_const(jwv).end();
+ --cit;
+ assert(*cit == -999);
+ cit--;
+ assert(*cit == -99);
+ --cit;
+ assert(*cit == -9);
+ assert(cit == std::as_const(jwv).begin());
+ }
+ }
+
+#if !defined(TEST_COMPILER_GCC) // GCC c++/101777
+ { // `V` has empty subrange in the middle, `Pattern` is not empty. Try to go back and forth.
+ using V = std::array<std::vector<int>, 3>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, Pattern>;
+
+ JWV jwv(V{{{5}, {}, {125}}}, Pattern{1});
+
+ {
+ auto it = jwv.end();
+ --it;
+ assert(*it == 125);
+ it--;
+ assert(*it == 1);
+ --it;
+ assert(*it == 1);
+ it--;
+ assert(*it == 5);
+ ++it;
+ assert(*it == 1);
+ --it;
+ assert(*it == 5);
+ std::ranges::advance(it, 4);
+ it--;
+ assert(*it == 125);
+ }
+
+ {
+ auto cit = std::as_const(jwv).end();
+ --cit;
+ assert(*cit == 125);
+ cit--;
+ assert(*cit == 1);
+ --cit;
+ assert(*cit == 1);
+ cit--;
+ assert(*cit == 5);
+ ++cit;
+ assert(*cit == 1);
+ --cit;
+ assert(*cit == 5);
+ std::ranges::advance(cit, 4);
+ cit--;
+ assert(*cit == 125);
+ }
+ }
+
+ { // Only first element of `V` is not empty. `Pattern` is empty. Try to go back and forth.
+ using Inner = std::vector<int>;
+ using V = std::ranges::owning_view<std::array<Inner, 3>>;
+ using Pattern = std::ranges::empty_view<int>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ JWV jwv(V{{Inner{999}, {}, {}}}, Pattern{});
+
+ {
+ auto it = jwv.end();
+ --it;
+ assert(*it == 999);
+ ++it;
+ assert(it == jwv.end());
+ it--;
+ assert(*it == 999);
+ }
+
+ {
+ auto cit = std::as_const(jwv).end();
+ --cit;
+ assert(*cit == 999);
+ ++cit;
+ assert(cit == std::as_const(jwv).end());
+ cit--;
+ assert(*cit == 999);
+ }
+ }
+#endif // !defined(TEST_COMPILER_GCC)
+
+ { // `ref-is-glvalue` is false
+ using V = RvalueVector<std::vector<int>>;
+ using Pattern = std::ranges::empty_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ static_assert(!CanPreDecrement<Iter>);
+ static_assert(!CanPostDecrement<Iter>);
+ }
+
+ { // `Base` does not model bidirectional range
+ using V = std::ranges::owning_view<std::forward_list<std::vector<int>>>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!CanPreDecrement<Iter>);
+ static_assert(!CanPostDecrement<Iter>);
+ static_assert(!CanPreDecrement<CIter>);
+ static_assert(!CanPostDecrement<CIter>);
+ }
+
+ { // InnerBase does not model bidirectional-common
+ { // InnerBase does not model bidirectional range
+ using V = std::ranges::owning_view<std::vector<std::forward_list<int>>>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!CanPreDecrement<Iter>);
+ static_assert(!CanPostDecrement<Iter>);
+ static_assert(!CanPreDecrement<CIter>);
+ static_assert(!CanPostDecrement<CIter>);
+ }
+
+ { // InnerBase does not model common range
+ using InnerBase = BasicVectorView<int, ViewProperties{.common = false}, bidirectional_iterator>;
+ using V = std::ranges::owning_view<std::vector<InnerBase>>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!CanPreDecrement<Iter>);
+ static_assert(!CanPostDecrement<Iter>);
+ static_assert(!CanPreDecrement<CIter>);
+ static_assert(!CanPostDecrement<CIter>);
+ }
+ }
+
+ { // PatternBase does not model bidirectional-common
+ { // PatternBase does not model bidirectional range
+ using V = std::ranges::owning_view<std::vector<std::vector<int>>>;
+ using Pattern = std::ranges::owning_view<std::forward_list<int>>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!CanPreDecrement<Iter>);
+ static_assert(!CanPostDecrement<Iter>);
+ static_assert(!CanPreDecrement<CIter>);
+ static_assert(!CanPostDecrement<CIter>);
+ }
+
+ { // PatternBase does not model common range
+ using V = std::ranges::owning_view<std::vector<std::vector<int>>>;
+ using Pattern = BasicVectorView<int, ViewProperties{.common = false}, bidirectional_iterator>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!CanPreDecrement<Iter>);
+ static_assert(!CanPostDecrement<Iter>);
+ static_assert(!CanPreDecrement<CIter>);
+ static_assert(!CanPostDecrement<CIter>);
+ }
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.pass.cpp
new file mode 100644
index 0000000000000..b2eeddd2941d6
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.pass.cpp
@@ -0,0 +1,225 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// constexpr decltype(auto) operator*() const;
+
+#include <ranges>
+
+#include <array>
+#include <cassert>
+#include <cstddef>
+#include <string>
+#include <string_view>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+#include "../types.h"
+
+struct ProxyRef {
+ int& val;
+};
+
+class CommonProxyRef {
+public:
+ constexpr CommonProxyRef(ProxyRef i) : val(i.val) {}
+ constexpr CommonProxyRef(int i) : val(i) {}
+
+ constexpr int get() const { return val; }
+
+private:
+ int val;
+};
+
+template <template <class> class TQual, template <class> class UQual>
+struct std::basic_common_reference<ProxyRef, int, TQual, UQual> {
+ using type = CommonProxyRef;
+};
+
+template <template <class> class TQual, template <class> class UQual>
+struct std::basic_common_reference<int, ProxyRef, TQual, UQual> {
+ using type = CommonProxyRef;
+};
+
+static_assert(std::common_reference_with<int&, ProxyRef>);
+static_assert(std::common_reference_with<int&, CommonProxyRef>);
+
+class ProxyIter {
+public:
+ using value_type = int;
+ using
diff erence_type = std::ptr
diff _t;
+
+ constexpr ProxyIter() : ptr_(nullptr) {}
+ constexpr explicit ProxyIter(int* p) : ptr_(p) {}
+
+ constexpr ProxyRef operator*() const { return ProxyRef{*ptr_}; }
+
+ constexpr ProxyIter& operator++() {
+ ++ptr_;
+ return *this;
+ }
+
+ constexpr ProxyIter operator++(int) {
+ ProxyIter tmp = *this;
+ ++ptr_;
+ return tmp;
+ }
+
+ constexpr bool operator==(const ProxyIter& other) const { return ptr_ == other.ptr_; }
+
+private:
+ int* ptr_;
+};
+
+static_assert(std::forward_iterator<ProxyIter>);
+
+constexpr bool test() {
+ { // Result of `operator*` is (maybe const) lvalue reference
+ using V = std::ranges::owning_view<std::vector<std::string>>;
+ using Pattern = std::ranges::owning_view<std::string>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ JWV jwv(V{{"ab", "cd", "ef"}}, Pattern{"><"});
+
+ {
+ auto it = jwv.begin();
+ std::same_as<char&> decltype(auto) v_ref = *std::as_const(it);
+ assert(v_ref == 'a');
+ std::ranges::advance(it, 2);
+ std::same_as<char&> decltype(auto) pattern_ref = *it;
+ assert(pattern_ref == '>');
+ }
+
+ {
+ auto cit = std::as_const(jwv).begin();
+ std::same_as<const char&> decltype(auto) cv_ref = *cit;
+ assert(cv_ref == 'a');
+ std::ranges::advance(cit, 3);
+ std::same_as<const char&> decltype(auto) cpattern_ref = *std::as_const(cit);
+ assert(cpattern_ref == '<');
+ }
+ }
+
+ { // Result of `operator*` is const lvalue reference
+ using V = std::ranges::owning_view<std::vector<std::string_view>>;
+ using Pattern = std::string_view;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ JWV jwv(V{{"123", "456", "789"}}, Pattern{"._."});
+
+ {
+ auto it = jwv.begin();
+ std::same_as<const char&> decltype(auto) v_ref = *it;
+ assert(v_ref == '1');
+ std::ranges::advance(it, 3);
+ std::same_as<const char&> decltype(auto) pattern_ref = *std::as_const(it);
+ assert(pattern_ref == '.');
+ }
+
+ {
+ auto cit = std::as_const(jwv).begin();
+ std::same_as<const char&> decltype(auto) cv_ref = *std::as_const(cit);
+ assert(cv_ref == '1');
+ std::ranges::advance(cit, 4);
+ std::same_as<const char&> decltype(auto) cpattern_ref = *cit;
+ assert(cpattern_ref == '_');
+ }
+ }
+
+ { // Result of `operator*` is prvalue
+ using V = std::vector<std::string_view>;
+ using Pattern = RvalueVector<char>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ JWV jwv(V{"x^2", "y^2", "z^2"}, Pattern{{' ', '+', ' '}});
+
+ {
+ auto it = jwv.begin();
+ std::same_as<char> decltype(auto) v_ref = *std::as_const(it);
+ assert(v_ref == 'x');
+ std::ranges::advance(it, 3);
+ std::same_as<char> decltype(auto) pattern_ref = *it;
+ assert(pattern_ref == ' ');
+ }
+
+ {
+ auto cit = std::as_const(jwv).begin();
+ std::same_as<char> decltype(auto) cv_ref = *cit;
+ assert(cv_ref == 'x');
+ std::ranges::advance(cit, 4);
+ std::same_as<char> decltype(auto) cpattern_ref = *std::as_const(cit);
+ assert(cpattern_ref == '+');
+ }
+ }
+
+ { // Result of `operator*` is (maybe const) rvalue reference
+ using Inner = std::ranges::as_rvalue_view<std::ranges::owning_view<std::string>>;
+ using V = std::ranges::owning_view<std::vector<Inner>>;
+ using Pattern = std::ranges::as_rvalue_view<std::ranges::owning_view<std::array<char, 2>>>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ std::vector<Inner> vec;
+ vec.emplace_back(Inner{{"x*y"}});
+ vec.emplace_back(Inner{{"y*z"}});
+ vec.emplace_back(Inner{{"z*x"}});
+ JWV jwv(V(std::move(vec)), Pattern(std::array{',', ' '}));
+
+ {
+ auto it = jwv.begin();
+ std::same_as<char&&> decltype(auto) v_ref = *it;
+ assert(v_ref == 'x');
+ std::ranges::advance(it, 3);
+ std::same_as<char&&> decltype(auto) pattern_ref = *std::as_const(it);
+ assert(pattern_ref == ',');
+ }
+
+ {
+ auto cit = std::as_const(jwv).begin();
+ std::same_as<const char&&> decltype(auto) cv_ref = *std::as_const(cit);
+ assert(cv_ref == 'x');
+ std::ranges::advance(cit, 4);
+ std::same_as<const char&&> decltype(auto) cpattern_ref = *cit;
+ assert(cpattern_ref == ' ');
+ }
+ }
+
+ { // Result of `operator*` is type
diff erent from range_reference_t<InnerRng> and range_reference_t<Pattern>
+ using Inner = std::vector<int>;
+ using V = std::vector<Inner>;
+ using Pattern = std::ranges::subrange<ProxyIter, ProxyIter>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, Pattern>;
+
+ static_assert(!std::same_as<std::ranges::range_reference_t<V>, std::ranges::range_reference_t<JWV>>);
+ static_assert(!std::same_as<std::ranges::range_reference_t<Pattern>, std::ranges::range_reference_t<JWV>>);
+
+ std::array<int, 2> pattern = {-1, -1};
+ Pattern pattern_as_subrange(ProxyIter{pattern.data()}, ProxyIter{pattern.data() + pattern.size()});
+
+ JWV jwv(V{Inner{1, 1}, Inner{2, 2}, Inner{3, 3}}, pattern_as_subrange);
+
+ auto it = jwv.begin();
+ std::same_as<CommonProxyRef> decltype(auto) v_ref = *it;
+ assert(v_ref.get() == 1);
+ std::ranges::advance(it, 7);
+ std::same_as<CommonProxyRef> decltype(auto) pattern_ref = *std::as_const(it);
+ assert(pattern_ref.get() == -1);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.pass.cpp
new file mode 100644
index 0000000000000..daf07c854933b
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.pass.cpp
@@ -0,0 +1,259 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// friend constexpr bool operator==(const iterator& x, const iterator& y)
+// requires ref-is-glvalue && forward_range<Base> &&
+// equality_comparable<InnerIter>;
+
+#include <ranges>
+
+#include <array>
+#include <cassert>
+#include <utility>
+
+#include "../types.h"
+#include "test_comparisons.h"
+
+template <class I1, class I2 = I1>
+concept CanEq = requires(const I1& i1, const I2& i2) {
+ { i1 == i2 } -> std::same_as<bool>;
+ { i2 == i1 } -> std::same_as<bool>;
+ { i1 != i2 } -> std::same_as<bool>;
+ { i2 != i1 } -> std::same_as<bool>;
+};
+
+constexpr bool test() {
+ { // `V` and `Pattern` are not empty. Test return types too.
+ using V = std::array<std::array<int, 2>, 3>;
+ using Pattern = std::array<long, 1>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!std::same_as<Iter, CIter>);
+ static_assert(CanEq<Iter>);
+ static_assert(CanEq<CIter>);
+ static_assert(CanEq<Iter, CIter>);
+
+ JWV jwv(V{{{9, 8}, {7, 6}, {5, 4}}}, Pattern{0L});
+
+ Iter it1 = jwv.begin();
+ assert(*it1 == 9);
+ assert(testEquality(it1, it1, true));
+
+ Iter it2 = std::ranges::prev(jwv.end());
+ assert(*it2 == 4);
+ assert(testEquality(it2, it2, true));
+ assert(testEquality(it1, it2, false));
+
+ CIter cit1 = std::as_const(jwv).begin();
+ assert(*cit1 == 9);
+ assert(testEquality(cit1, cit1, true));
+ assert(testEquality(it1, cit1, true));
+ assert(testEquality(it2, cit1, false));
+
+ CIter cit2 = std::ranges::prev(std::as_const(jwv).end());
+ assert(*cit2 == 4);
+ assert(testEquality(cit2, cit2, true));
+ assert(testEquality(cit1, cit2, false));
+ assert(testEquality(it1, cit2, false));
+ assert(testEquality(it2, cit2, true));
+
+ // `it1.inner_it_` and `it2.inner_it_` are equal, but `it1.outer_it_` and `it2.outer_it_` are not.
+ std::ranges::advance(it1, 2);
+ assert(*it1 == 0);
+ std::ranges::advance(it2, -2);
+ assert(*it2 == 0);
+ assert(testEquality(it1, it2, false));
+
+ // `cit1.inner_it_` and `cit2.inner_it_` are equal, but `cit1.outer_it_` and `cit2.outer_it_` are not.
+ std::ranges::advance(cit1, 2);
+ assert(*cit1 == 0);
+ assert(testEquality(it1, cit1, true));
+ std::ranges::advance(cit2, -2);
+ assert(*cit2 == 0);
+ assert(testEquality(it2, cit2, true));
+ assert(testEquality(cit1, cit2, false));
+
+ // `it1.inner_it_` and `it2.inner_it_` are equal, `it1.outer_it_` and `it2.outer_it_` are equal too.
+ // `it1.inner_it_index()` and `it2.inner_it_index()` are equal to 1.
+ ++it1;
+ assert(*it1 == 7);
+ std::ranges::advance(it2, -2);
+ assert(*it2 == 7);
+ assert(testEquality(it1, it2, true));
+
+ // `cit1.inner_it_` and `cit2.inner_it_` are equal, `cit1.outer_it_` and `cit2.outer_it_` are equal too.
+ // `cit1.inner_it_index()` and `cit2.inner_it_index()` are equal to 1.
+ ++cit1;
+ assert(*cit1 == 7);
+ assert(testEquality(it1, cit1, true));
+ std::ranges::advance(cit2, -2);
+ assert(*cit2 == 7);
+ assert(testEquality(it2, cit2, true));
+ assert(testEquality(cit1, cit2, true));
+
+ // `it1.inner_it_` and `it2.inner_it_` are equal, `it1.outer_it_` and `it2.outer_it_` are equal too.
+ // `it1.inner_it_index()` and `it2.inner_it_index()` are equal to 0.
+ --it1;
+ assert(*it1 == 0);
+ --it2;
+ assert(*it2 == 0);
+ assert(testEquality(it1, it2, true));
+
+ // `cit1.inner_it_` and `cit2.inner_it_` are equal, `cit1.outer_it_` and `cit2.outer_it_` are equal too.
+ // `cit1.inner_it_index()` and `cit2.inner_it_index()` are equal to 0.
+ --cit1;
+ assert(*cit1 == 0);
+ assert(testEquality(it1, cit1, true));
+ --cit2;
+ assert(*cit2 == 0);
+ assert(testEquality(it2, cit2, true));
+ assert(testEquality(cit2, cit2, true));
+ }
+
+ { // `InnerIter` models input iterator and equality comparable. `Pattern` is empty.
+ using Inner = BasicVectorView<int, ViewProperties{.common = false}, EqComparableInputIter>;
+ using V = std::vector<Inner>;
+ using Pattern = std::ranges::empty_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!std::same_as<Iter, CIter>);
+ static_assert(CanEq<Iter>);
+ static_assert(CanEq<CIter>);
+ static_assert(!CanEq<CIter, Iter>);
+
+ JWV jwv(V{Inner{1, 2}, Inner{5, 6}, Inner{9, 0}}, Pattern{});
+
+ {
+ Iter it1 = jwv.begin();
+ assert(*it1 == 1);
+ Iter it2 = std::ranges::next(jwv.begin(), 2);
+ assert(*it2 == 5);
+ assert(testEquality(it1, it2, false));
+ ++it1;
+ ++it1;
+ assert(testEquality(it1, it2, true));
+ ++it1;
+ assert(testEquality(it1, it2, false));
+ }
+
+ {
+ CIter cit1 = std::as_const(jwv).begin();
+ assert(*cit1 == 1);
+ CIter cit2 = std::ranges::next(std::as_const(jwv).begin(), 2);
+ assert(*cit2 == 5);
+ assert(testEquality(cit1, cit2, false));
+ ++cit1;
+ ++cit1;
+ assert(testEquality(cit1, cit2, true));
+ ++cit1;
+ assert(testEquality(cit1, cit2, false));
+ }
+ }
+
+ { // `Pattern` is not empty. Some elements of `V` are.
+ using Inner = BasicVectorView<int, ViewProperties{.common = false}, EqComparableInputIter>;
+ using V = BasicVectorView<Inner, ViewProperties{}, forward_iterator>;
+ using Pattern = BasicVectorView<int, ViewProperties{.common = false}, forward_iterator>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!std::same_as<Iter, CIter>);
+ static_assert(CanEq<Iter>);
+ static_assert(CanEq<CIter>);
+ static_assert(!CanEq<CIter, Iter>);
+
+ JWV jwv(V{Inner{1}, Inner{}, Inner{27}}, Pattern{0});
+
+ {
+ Iter it1 = jwv.begin();
+ assert(*it1 == 1);
+ ++it1;
+ assert(*it1 == 0);
+ Iter it2 = jwv.begin();
+ assert(testEquality(it1, it2, false));
+ ++it2;
+ assert(testEquality(it1, it2, true));
+
+ ++it2;
+ assert(*it1 == *it2);
+ assert(testEquality(it1, it2, false));
+
+ std::ranges::advance(it1, 2);
+ ++it2;
+ assert(*it1 == *it2);
+ assert(testEquality(it1, it2, true));
+ }
+
+ {
+ CIter cit1 = std::as_const(jwv).begin();
+ assert(*cit1 == 1);
+ ++cit1;
+ assert(*cit1 == 0);
+ CIter cit2 = std::as_const(jwv).begin();
+ assert(testEquality(cit1, cit2, false));
+ ++cit2;
+ assert(testEquality(cit1, cit2, true));
+
+ ++cit2;
+ assert(*cit1 == *cit2);
+ assert(testEquality(cit1, cit2, false));
+
+ std::ranges::advance(cit1, 2);
+ ++cit2;
+ assert(*cit1 == *cit2);
+ assert(testEquality(cit1, cit2, true));
+ }
+ }
+
+ { // `ref-is-glvalue` is false
+ using Inner = std::vector<int>;
+ using V = RvalueVector<Inner>;
+ using Pattern = std::ranges::empty_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ static_assert(!CanEq<Iter>);
+ }
+
+ { // `Base` does not model forward range
+ using Inner = std::vector<int>;
+ using V = BasicVectorView<Inner, ViewProperties{}, DefaultCtorInputIter>;
+ using Pattern = std::ranges::empty_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ static_assert(!CanEq<Iter>);
+ }
+
+ { // `InnerIter` does not model equality comparable
+ using Inner = BasicVectorView<int, ViewProperties{.common = false}, cpp20_input_iterator>;
+ using V = std::vector<Inner>;
+ using Pattern = std::ranges::empty_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!CanEq<Iter>);
+ static_assert(!CanEq<CIter>);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/increment.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/increment.pass.cpp
new file mode 100644
index 0000000000000..af14b516b2deb
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/increment.pass.cpp
@@ -0,0 +1,372 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// constexpr iterator& operator++();
+// constexpr void operator++(int);
+// constexpr iterator operator++(int)
+// requires ref-is-glvalue && forward_iterator<OuterIter> &&
+// forward_iterator<InnerIter>;
+
+#include <ranges>
+
+#include <array>
+#include <cassert>
+#include <type_traits>
+#include <vector>
+
+#include "../types.h"
+
+template <class I>
+concept CanPreIncrement = requires(I& i) { ++i; };
+
+template <class I>
+concept CanPostIncrement = requires(I& i) { i++; };
+
+template <bool RefIsGlvalue, class Inner>
+using VRange = std::conditional_t<RefIsGlvalue, std::vector<Inner>, RvalueVector<Inner>>;
+
+template <bool RefIsGlvalue>
+constexpr void test_pre_increment() {
+ { // `V` and `Pattern` are not empty. Test return type too.
+ using V = VRange<RefIsGlvalue, std::array<int, 2>>;
+ using Pattern = std::array<int, 2>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ JWV jwv(V{{1, 1}, {2, 2}, {3, 3}}, Pattern{0, 0});
+
+ {
+ using Iter = std::ranges::iterator_t<JWV>;
+ static_assert(CanPreIncrement<Iter>);
+ static_assert(!CanPreIncrement<const Iter>);
+
+ auto it = jwv.begin();
+ assert(*it == 1);
+ std::same_as<Iter&> decltype(auto) it_ref = ++it;
+ if constexpr (RefIsGlvalue) {
+ assert(it_ref == it);
+ }
+
+ ++it;
+ assert(*it == 0);
+ ++it_ref;
+ ++it_ref;
+ assert(*it_ref == 2);
+ ++it;
+ ++it_ref;
+ assert(*it == 0);
+ }
+
+ if constexpr (RefIsGlvalue) {
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(CanPreIncrement<CIter>);
+ static_assert(!CanPreIncrement<const CIter>);
+
+ auto cit = std::as_const(jwv).begin();
+ assert(*cit == 1);
+ std::same_as<CIter&> decltype(auto) cit_ref = ++cit;
+ assert(cit_ref == cit);
+ ++cit;
+ assert(*cit == 0);
+ ++cit_ref;
+ ++cit_ref;
+ assert(*cit_ref == 2);
+ ++cit;
+ ++cit_ref;
+ assert(*cit == 0);
+ }
+ }
+
+ { // `V` and `Pattern` are empty.
+ using V = VRange<RefIsGlvalue, std::ranges::empty_view<int>>;
+ using Pattern = std::ranges::empty_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ JWV jwv = {};
+
+ {
+ auto it = jwv.begin();
+ assert(it == jwv.end());
+ }
+
+ if constexpr (RefIsGlvalue) {
+ auto cit = std::as_const(jwv).begin();
+ assert(cit == std::as_const(jwv).end());
+ }
+ }
+
+ { // `Pattern` is empty, `V` is not.
+ using V = VRange<RefIsGlvalue, std::vector<int>>;
+ using Pattern = std::vector<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ JWV jwv(V{{{-1}, {-2}, {-3}}}, Pattern{});
+
+ {
+ auto it = jwv.begin();
+ assert(*it == -1);
+ ++it;
+ assert(*it == -2);
+ ++it;
+ assert(*it == -3);
+ ++it;
+ assert(it == jwv.end());
+ }
+
+ if constexpr (RefIsGlvalue) {
+ auto cit = std::as_const(jwv).begin();
+ assert(*cit == -1);
+ ++cit;
+ assert(*cit == -2);
+ ++cit;
+ assert(*cit == -3);
+ ++cit;
+ assert(cit == std::as_const(jwv).end());
+ }
+ }
+
+ { // `V` has empty subrange in the middle, `Pattern` is not empty.
+ using V = VRange<RefIsGlvalue, std::vector<int>>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, Pattern>;
+
+ JWV jwv(V{{1}, {}, {3}}, Pattern{0});
+
+ {
+ auto it = jwv.begin();
+ assert(*it == 1);
+ ++it;
+ assert(*it == 0);
+ ++it;
+ assert(*it == 0);
+ ++it;
+ assert(*it == 3);
+ }
+
+ if constexpr (RefIsGlvalue) {
+ auto cit = std::as_const(jwv).begin();
+ assert(*cit == 1);
+ ++cit;
+ assert(*cit == 0);
+ ++cit;
+ assert(*cit == 0);
+ ++cit;
+ assert(*cit == 3);
+ }
+ }
+
+ { // Only last element of `V` is not empty. `Pattern` is not empty.
+ using V = VRange<RefIsGlvalue, std::vector<int>>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, Pattern>;
+
+ JWV jwv(V{{}, {}, {555}}, Pattern{1});
+
+ {
+ auto it = jwv.begin();
+ assert(*it == 1);
+ ++it;
+ assert(*it == 1);
+ ++it;
+ assert(*it == 555);
+ ++it;
+ assert(it == jwv.end());
+ }
+
+ if constexpr (RefIsGlvalue) {
+ auto cit = std::as_const(jwv).begin();
+ assert(*cit == 1);
+ ++cit;
+ assert(*cit == 1);
+ ++cit;
+ assert(*cit == 555);
+ ++cit;
+ assert(cit == std::as_const(jwv).end());
+ }
+ }
+
+ { // Only first element of `V` is not empty. `Pattern` is empty.
+ using V = VRange<RefIsGlvalue, std::vector<int>>;
+ using Pattern = std::ranges::empty_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, Pattern>;
+
+ JWV jwv(V{{777}, {}, {}}, Pattern{});
+
+ {
+ auto it = jwv.begin();
+ assert(*it == 777);
+ ++it;
+ assert(it == jwv.end());
+ }
+
+ if constexpr (RefIsGlvalue) {
+ auto cit = std::as_const(jwv).begin();
+ assert(*cit == 777);
+ ++cit;
+ assert(cit == std::as_const(jwv).end());
+ }
+ }
+
+ { // Only last element of `V` is not empty. `Pattern` is empty. `V` models input range.
+ using V = BasicView<VRange<RefIsGlvalue, std::string>, ViewProperties{}, DefaultCtorInputIter>;
+ using Pattern = std::ranges::empty_view<char>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ JWV jwv(V{{}, {}, {'a'}}, Pattern{});
+
+ auto it = jwv.begin();
+ assert(*it == 'a');
+ ++it;
+ assert(it == jwv.end());
+ }
+
+ { // Only first element of `V` is not empty. `Pattern` is not empty. `V` models input range.
+ using V = BasicView<VRange<RefIsGlvalue, std::string>, ViewProperties{}, DefaultCtorInputIter>;
+ using Pattern = std::ranges::single_view<char>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ JWV jwv(V{{'b'}, {}, {}}, Pattern{'.'});
+
+ auto it = jwv.begin();
+ assert(*it == 'b');
+ ++it;
+ assert(*it == '.');
+ ++it;
+ assert(*it == '.');
+ ++it;
+ assert(it == jwv.end());
+ }
+}
+
+constexpr void test_post_increment() {
+ { // `V` and `Pattern` are not empty. Return type should be `iterator`.
+ using V = std::array<std::array<int, 3>, 2>;
+ using Pattern = std::array<int, 1>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(CanPostIncrement<Iter>);
+ static_assert(!CanPostIncrement<const Iter>);
+ static_assert(CanPostIncrement<CIter>);
+ static_assert(!CanPostIncrement<const CIter>);
+
+ JWV jwv(V{{{6, 5, 4}, {3, 2, 1}}}, Pattern{-5});
+
+ {
+ auto it = jwv.begin();
+ assert(*it == 6);
+ std::same_as<Iter> decltype(auto) it_copy = it++;
+ assert(++it_copy == it);
+ it++;
+ it++;
+ assert(*it == -5);
+ it_copy++;
+ it_copy++;
+ assert(*it_copy == -5);
+ it++;
+ it_copy++;
+ assert(*it == 3);
+ assert(*it_copy == 3);
+ }
+
+ {
+ auto cit = std::as_const(jwv).begin();
+ assert(*cit == 6);
+ std::same_as<CIter> decltype(auto) cit_copy = cit++;
+ assert(++cit_copy == cit);
+ cit++;
+ cit++;
+ assert(*cit == -5);
+ cit_copy++;
+ cit_copy++;
+ assert(*cit_copy == -5);
+ cit++;
+ cit_copy++;
+ assert(*cit == 3);
+ assert(*cit_copy == 3);
+ }
+ }
+
+ { // `Pattern` is empty, `V` is not. Value of `ref-is-glvalue` is false (return type should be `void`).
+ using Inner = std::vector<int>;
+ using V = RvalueVector<Inner>;
+ using Pattern = std::ranges::empty_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ JWV jwv(V{Inner{-3}, Inner{-2}, Inner{-1}}, Pattern{});
+
+ auto it = jwv.begin();
+ assert(*it == -3);
+ it++;
+ assert(*it == -2);
+ it++;
+ assert(*it == -1);
+ it++;
+ assert(it == jwv.end());
+ static_assert(std::is_void_v<decltype(it++)>);
+ }
+
+ { // `V` has empty subrange in the middle, `Pattern` is not empty.
+ // OuterIter does not model forward iterator (return type should be `void`).
+ using Inner = std::vector<int>;
+ using V = BasicVectorView<Inner, ViewProperties{.common = false}, cpp20_input_iterator>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+
+ JWV jwv(V{Inner{7}, {}, Inner{9}}, Pattern{8});
+
+ auto it = jwv.begin();
+ assert(*it == 7);
+ it++;
+ assert(*it == 8);
+ it++;
+ assert(*it == 8);
+ it++;
+ assert(*it == 9);
+ it++;
+ assert(it == jwv.end());
+ static_assert(std::is_void_v<decltype(it++)>);
+ }
+
+#if !defined(TEST_COMPILER_GCC) // GCC c++/101777
+ { // Only first element of `V` is not empty. `Pattern` is empty. InnerIter does not model forward
+ // iterator (return type should be `void`).
+ using Inner = BasicVectorView<char32_t, ViewProperties{.common = false}, cpp17_input_iterator>;
+ using V = std::array<Inner, 3>;
+ using Pattern = std::ranges::empty_view<char32_t>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, Pattern>;
+
+ JWV jwv(V{Inner{U'?'}, Inner{}, Inner{}}, Pattern{});
+
+ auto it = jwv.begin();
+ assert(*it == U'?');
+ it++;
+ assert(it == jwv.end());
+ static_assert(std::is_void_v<decltype(it++)>);
+ }
+#endif // !defined(TEST_COMPILER_GCC)
+}
+
+constexpr bool test() {
+ test_pre_increment<false>();
+ test_pre_increment<true>();
+ test_post_increment();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.pass.cpp
new file mode 100644
index 0000000000000..4a68f10b11c31
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.pass.cpp
@@ -0,0 +1,420 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// friend constexpr decltype(auto) iter_move(const iterator& x);
+
+#include <ranges>
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <cstddef>
+#include <utility>
+#include <vector>
+
+#include "../types.h"
+
+class MoveOnlyInt {
+public:
+ enum Status { constructed, move_constructed, moved_from_this };
+
+ MoveOnlyInt() = default;
+ constexpr MoveOnlyInt(int val) : val_(val) {}
+
+ constexpr MoveOnlyInt(MoveOnlyInt&& other) noexcept : val_(other.val_), status_(move_constructed) {
+ other.val_ = -1;
+ other.status_ = moved_from_this;
+ }
+
+ constexpr MoveOnlyInt(const MoveOnlyInt&& other) noexcept : val_(other.val_), status_(move_constructed) {
+ other.val_ = -1;
+ other.status_ = moved_from_this;
+ }
+
+ MoveOnlyInt(const MoveOnlyInt&) { assert(false); } // Should never be called in this test.
+
+ MoveOnlyInt& operator=(MoveOnlyInt&&) { // Should never be called in this test.
+ assert(false);
+ return *this;
+ }
+
+ constexpr bool was_normally_constructed() const { return status_ == constructed; }
+ constexpr bool was_move_constructed() const { return status_ == move_constructed; }
+ constexpr bool was_moved_from() const { return status_ == moved_from_this; }
+
+ friend constexpr bool operator==(const MoveOnlyInt& left, int right) { return left.val_ == right; }
+ friend constexpr bool operator==(const MoveOnlyInt& left, const MoveOnlyInt& right) {
+ return left.val_ == right.val_;
+ }
+
+private:
+ mutable int val_ = -1;
+ mutable Status status_ = constructed;
+};
+
+static_assert(std::movable<MoveOnlyInt>);
+
+struct ProxyRvalueRef {
+ MoveOnlyInt&& val;
+};
+
+class CommonProxyRvalueRef {
+public:
+ constexpr CommonProxyRvalueRef(ProxyRvalueRef i) : val_(std::move(i.val)) {}
+ constexpr CommonProxyRvalueRef(MoveOnlyInt i) : val_(std::move(i)) {}
+
+ constexpr MoveOnlyInt&& get() { return std::move(val_); }
+
+private:
+ MoveOnlyInt val_;
+};
+
+template <template <class> class TQual, template <class> class UQual>
+struct std::basic_common_reference<ProxyRvalueRef, MoveOnlyInt, TQual, UQual> {
+ using type = CommonProxyRvalueRef;
+};
+
+template <template <class> class TQual, template <class> class UQual>
+struct std::basic_common_reference<MoveOnlyInt, ProxyRvalueRef, TQual, UQual> {
+ using type = CommonProxyRvalueRef;
+};
+
+static_assert(std::common_reference_with<MoveOnlyInt&&, ProxyRvalueRef>);
+static_assert(std::common_reference_with<MoveOnlyInt&&, CommonProxyRvalueRef>);
+
+class ProxyIter {
+public:
+ using value_type = MoveOnlyInt;
+ using
diff erence_type = std::ptr
diff _t;
+
+ constexpr ProxyIter() : ptr_(nullptr) {}
+ constexpr explicit ProxyIter(MoveOnlyInt* it) : ptr_(std::move(it)) {}
+
+ constexpr decltype(auto) operator*() const { return *ptr_; }
+
+ constexpr ProxyIter& operator++() {
+ ++ptr_;
+ return *this;
+ }
+
+ constexpr ProxyIter operator++(int) {
+ ProxyIter copy = *this;
+ ++ptr_;
+ return copy;
+ }
+
+ constexpr ProxyIter& operator--() {
+ --ptr_;
+ return *this;
+ }
+
+ constexpr ProxyIter operator--(int) {
+ ProxyIter copy = *this;
+ --ptr_;
+ return copy;
+ }
+
+ friend bool operator==(const ProxyIter&, const ProxyIter&) = default;
+
+ friend constexpr ProxyRvalueRef iter_move(const ProxyIter iter) {
+ return ProxyRvalueRef{std::ranges::iter_move(iter.ptr_)};
+ }
+
+private:
+ MoveOnlyInt* ptr_;
+};
+
+static_assert(std::forward_iterator<ProxyIter>);
+
+template <std::forward_iterator Iter>
+class IterMoveTrackingIterator {
+public:
+ using value_type = std::iter_value_t<Iter>;
+ using
diff erence_type = std::iter_
diff erence_t<Iter>;
+
+ IterMoveTrackingIterator() = default;
+ constexpr explicit IterMoveTrackingIterator(Iter iter, bool* flag = nullptr) : iter_(std::move(iter)), flag_(flag) {}
+
+ constexpr IterMoveTrackingIterator& operator++() {
+ ++iter_;
+ return *this;
+ }
+
+ constexpr IterMoveTrackingIterator operator++(int) {
+ auto tmp = *this;
+ ++*this;
+ return tmp;
+ }
+
+ constexpr decltype(auto) operator*() const { return *iter_; }
+
+ constexpr bool operator==(const IterMoveTrackingIterator& other) const { return iter_ == other.iter_; }
+
+ friend constexpr decltype(auto) iter_move(const IterMoveTrackingIterator& iter) {
+ assert(iter.flag_ != nullptr);
+ *iter.flag_ = true;
+ return std::ranges::iter_move(iter.iter_);
+ }
+
+private:
+ Iter iter_ = Iter();
+ bool* flag_ = nullptr;
+};
+
+static_assert(std::forward_iterator<IterMoveTrackingIterator<int*>> &&
+ !std::bidirectional_iterator<IterMoveTrackingIterator<int*>>);
+
+constexpr bool test() {
+ { // Test `iter_move` when result is true rvalue reference. Test return types.
+ using V = std::array<std::array<char, 1>, 2>;
+ using Pattern = std::array<char, 1>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ JWV jwv(V{{{'0'}, {'1'}}}, Pattern{','});
+
+ {
+ auto it = jwv.begin();
+ std::same_as<char&&> decltype(auto) v_rref1 = iter_move(it);
+ std::same_as<char&&> decltype(auto) v_rref2 = iter_move(std::as_const(it));
+ std::same_as<char&&> decltype(auto) v_rref3 = std::ranges::iter_move(it);
+ std::same_as<char&&> decltype(auto) v_rref4 = std::ranges::iter_move(std::as_const(it));
+ assert(std::ranges::equal(std::array{v_rref1, v_rref2, v_rref3, v_rref4}, std::views::repeat('0', 4)));
+
+ ++it; // `it` points to element of `Pattern` from here
+ std::same_as<char&&> decltype(auto) pattern_rref1 = iter_move(it);
+ std::same_as<char&&> decltype(auto) pattern_rref2 = iter_move(std::as_const(it));
+ std::same_as<char&&> decltype(auto) pattern_rref3 = std::ranges::iter_move(it);
+ std::same_as<char&&> decltype(auto) pattern_rref4 = std::ranges::iter_move(std::as_const(it));
+ assert(std::ranges::equal(
+ std::array{pattern_rref1, pattern_rref2, pattern_rref3, pattern_rref4}, std::views::repeat(',', 4)));
+ }
+
+ {
+ auto cit = std::prev(std::as_const(jwv).end());
+ std::same_as<const char&&> decltype(auto) cv_rref1 = iter_move(cit);
+ std::same_as<const char&&> decltype(auto) cv_rref2 = iter_move(std::as_const(cit));
+ std::same_as<const char&&> decltype(auto) cv_rref3 = std::ranges::iter_move(cit);
+ std::same_as<const char&&> decltype(auto) cv_rref4 = std::ranges::iter_move(std::as_const(cit));
+ assert(std::ranges::equal(std::array{cv_rref1, cv_rref2, cv_rref3, cv_rref4}, std::views::repeat('1', 4)));
+
+ cit--; // `cit` points to element of `Pattern` from here
+ std::same_as<const char&&> decltype(auto) cpattern_rref1 = iter_move(cit);
+ std::same_as<const char&&> decltype(auto) cpattern_rref2 = iter_move(std::as_const(cit));
+ std::same_as<const char&&> decltype(auto) cpattern_rref3 = std::ranges::iter_move(cit);
+ std::same_as<const char&&> decltype(auto) cpattern_rref4 = std::ranges::iter_move(std::as_const(cit));
+ assert(std::ranges::equal(
+ std::array{cpattern_rref1, cpattern_rref2, cpattern_rref3, cpattern_rref4}, std::views::repeat(',', 4)));
+ }
+ }
+
+ { // Test `iter_move` when result is true rvalue reference. Test moving.
+ using Inner = std::vector<MoveOnlyInt>;
+ using V = std::vector<Inner>;
+ using Pattern = std::vector<MoveOnlyInt>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+ V v;
+ v.reserve(2);
+ v.emplace_back(std::ranges::to<Inner>(std::views::iota(0, 4)));
+ v.emplace_back(std::ranges::to<Inner>(std::views::iota(12, 16)));
+ JWV jwv(std::move(v), std::ranges::to<Pattern>(std::views::iota(4, 12)));
+ assert(std::ranges::all_of(jwv, &MoveOnlyInt::was_normally_constructed));
+
+ {
+ std::vector<MoveOnlyInt> values;
+ values.reserve(8);
+
+ auto it = jwv.begin();
+ values.emplace_back(iter_move(it));
+ ++it;
+ values.emplace_back(iter_move(std::as_const(it)));
+ it++;
+ values.emplace_back(std::ranges::iter_move(it));
+ ++it;
+ values.emplace_back(std::ranges::iter_move(std::as_const(it)));
+ it++; // `it` points to element of `Pattern` from here
+ values.emplace_back(iter_move(it));
+ ++it;
+ values.emplace_back(iter_move(std::as_const(it)));
+ it++;
+ values.emplace_back(std::ranges::iter_move(it));
+ ++it;
+ values.emplace_back(std::ranges::iter_move(std::as_const(it)));
+
+ assert(std::ranges::equal(values, std::views::iota(0, 8)));
+ assert(std::ranges::all_of(values, &MoveOnlyInt::was_move_constructed));
+ }
+
+ {
+ std::vector<MoveOnlyInt> values;
+ values.reserve(8);
+
+ auto cit = std::prev(std::as_const(jwv).end());
+ values.emplace_back(iter_move(cit));
+ cit--;
+ values.emplace_back(iter_move(std::as_const(cit)));
+ --cit;
+ values.emplace_back(std::ranges::iter_move(cit));
+ cit--;
+ values.emplace_back(std::ranges::iter_move(std::as_const(cit)));
+ --cit; // `it` points to element of `Pattern` from here
+ values.emplace_back(iter_move(cit));
+ cit--;
+ values.emplace_back(iter_move(std::as_const(cit)));
+ --cit;
+ values.emplace_back(std::ranges::iter_move(cit));
+ cit--;
+ values.emplace_back(std::ranges::iter_move(std::as_const(cit)));
+
+ assert(std::ranges::equal(std::views::reverse(values), std::views::iota(8, 16)));
+ assert(std::ranges::all_of(values, &MoveOnlyInt::was_move_constructed));
+ }
+
+ assert(std::ranges::all_of(jwv, &MoveOnlyInt::was_moved_from));
+ }
+
+ { // Test `iter_move` when result is proxy rvalue reference type, which is
diff erent from
+ // range_rvalue_reference_t<InnerRng> and range_rvalue_reference_t<Pattern>.
+ using Inner = std::vector<MoveOnlyInt>;
+ using V = std::vector<Inner>;
+ using Pattern = std::ranges::subrange<ProxyIter, ProxyIter>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, Pattern>;
+
+ static_assert(!std::same_as<std::ranges::range_rvalue_reference_t<V>, std::ranges::range_rvalue_reference_t<JWV>>);
+ static_assert(
+ !std::same_as<std::ranges::range_rvalue_reference_t<Pattern>, std::ranges::range_rvalue_reference_t<JWV>>);
+ static_assert(std::same_as<CommonProxyRvalueRef, std::ranges::range_rvalue_reference_t<JWV>>);
+
+ V v;
+ v.reserve(2);
+ v.emplace_back(std::ranges::to<Inner>(std::views::iota(0, 4)));
+ v.emplace_back(std::ranges::to<Inner>(std::views::iota(12, 16)));
+
+ auto pattern = std::ranges::to<std::vector<MoveOnlyInt>>(std::views::iota(4, 12));
+ Pattern pattern_as_subrange(ProxyIter{pattern.data()}, ProxyIter{pattern.data() + pattern.size()});
+
+ JWV jwv(std::move(v), pattern_as_subrange);
+ assert(std::ranges::all_of(jwv, &MoveOnlyInt::was_normally_constructed));
+
+ {
+ std::vector<MoveOnlyInt> values;
+ values.reserve(8);
+
+ auto it = jwv.begin();
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref1 = iter_move(it);
+ values.emplace_back(rref1.get());
+ ++it;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref2 = iter_move(std::as_const(it));
+ values.emplace_back(rref2.get());
+ it++;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref3 = std::ranges::iter_move(it);
+ values.emplace_back(rref3.get());
+ ++it;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref4 = std::ranges::iter_move(std::as_const(it));
+ values.emplace_back(rref4.get());
+ it++; // `it` points to element of `Pattern` from here
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref5 = iter_move(it);
+ values.emplace_back(rref5.get());
+ ++it;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref6 = iter_move(std::as_const(it));
+ values.emplace_back(rref6.get());
+ it++;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref7 = std::ranges::iter_move(it);
+ values.emplace_back(rref7.get());
+ ++it;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref8 = std::ranges::iter_move(std::as_const(it));
+ values.emplace_back(rref8.get());
+
+ assert(std::ranges::equal(values, std::views::iota(0, 8)));
+ assert(std::ranges::all_of(values, &MoveOnlyInt::was_move_constructed));
+ }
+
+ {
+ std::vector<MoveOnlyInt> values;
+ values.reserve(8);
+
+ auto cit = std::prev(std::as_const(jwv).end());
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref1 = iter_move(cit);
+ values.emplace_back(rref1.get());
+ cit--;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref2 = iter_move(std::as_const(cit));
+ values.emplace_back(rref2.get());
+ --cit;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref3 = std::ranges::iter_move(cit);
+ values.emplace_back(rref3.get());
+ cit--;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref4 = std::ranges::iter_move(std::as_const(cit));
+ values.emplace_back(rref4.get());
+ --cit; // `it` points to element of `Pattern` from here
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref5 = iter_move(cit);
+ values.emplace_back(rref5.get());
+ cit--;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref6 = iter_move(std::as_const(cit));
+ values.emplace_back(rref6.get());
+ --cit;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref7 = std::ranges::iter_move(cit);
+ values.emplace_back(rref7.get());
+ cit--;
+ std::same_as<CommonProxyRvalueRef> decltype(auto) rref8 = std::ranges::iter_move(std::as_const(cit));
+ values.emplace_back(rref8.get());
+
+ assert(std::ranges::equal(std::views::reverse(values), std::views::iota(8, 16)));
+ assert(std::ranges::all_of(values, &MoveOnlyInt::was_move_constructed));
+ }
+
+ assert(std::ranges::all_of(jwv, &MoveOnlyInt::was_moved_from));
+ }
+
+ { // Make sure `iter_move` calls underlying's iterator `iter_move` (not `std::move(*i)`).
+ using Inner = std::vector<int>;
+ using InnerTrackingIter = IterMoveTrackingIterator<Inner::iterator>;
+ using TrackingInner = std::ranges::subrange<InnerTrackingIter>;
+ using Pattern = std::array<int, 1>;
+ using PatternTrackingIter = IterMoveTrackingIterator<Pattern::iterator>;
+ using TrackingPattern = std::ranges::subrange<PatternTrackingIter>;
+ using JWV = std::ranges::join_with_view<std::span<TrackingInner>, TrackingPattern>;
+
+ std::array<Inner, 2> v{{{1}, {2}}};
+ Pattern pat{-1};
+
+ bool v_moved = false;
+ std::array<TrackingInner, 2> tracking_v{
+ TrackingInner(InnerTrackingIter(v[0].begin(), &v_moved), InnerTrackingIter(v[0].end())),
+ TrackingInner(InnerTrackingIter(v[1].begin()), InnerTrackingIter(v[1].end()))};
+
+ bool pat_moved = false;
+ TrackingPattern tracking_pat(PatternTrackingIter(pat.begin(), &pat_moved), PatternTrackingIter(pat.end()));
+
+ JWV jwv(tracking_v, tracking_pat);
+ auto it = jwv.begin();
+
+ // Test calling `iter_move` when `it` points to element of `v`
+ assert(!v_moved);
+ assert(iter_move(it) == 1);
+ assert(v_moved);
+
+ // Test calling `iter_move` when `it` points to element of `pat`
+ ++it;
+ assert(!pat_moved);
+ assert(iter_move(it) == -1);
+ assert(pat_moved);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_swap.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_swap.pass.cpp
new file mode 100644
index 0000000000000..7385921752283
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_swap.pass.cpp
@@ -0,0 +1,186 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// friend constexpr void iter_swap(const iterator& x, const iterator& y);
+
+#include <ranges>
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <span>
+#include <string>
+#include <string_view>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+template <class I>
+concept CanIterSwap = requires(I i) { iter_swap(i); };
+
+enum class SwapKind { no_swap, with_same_type, with_
diff erent_type };
+enum class IterKind { inner_view, pattern };
+
+template <std::forward_iterator Iter, IterKind Kind>
+class IterSwapTrackingIterator {
+public:
+ using value_type = std::iter_value_t<Iter>;
+ using
diff erence_type = std::iter_
diff erence_t<Iter>;
+
+ constexpr Iter get_iter() const { return iter_; }
+
+ constexpr SwapKind* get_flag() const { return flag_; }
+
+ IterSwapTrackingIterator() = default;
+ constexpr explicit IterSwapTrackingIterator(Iter iter, SwapKind* flag = nullptr)
+ : iter_(std::move(iter)), flag_(flag) {}
+
+ constexpr IterSwapTrackingIterator& operator++() {
+ ++iter_;
+ return *this;
+ }
+
+ constexpr IterSwapTrackingIterator operator++(int) {
+ auto tmp = *this;
+ ++*this;
+ return tmp;
+ }
+
+ constexpr decltype(auto) operator*() const { return *iter_; }
+
+ constexpr bool operator==(const IterSwapTrackingIterator& other) const { return iter_ == other.iter_; }
+
+ friend constexpr decltype(auto) iter_swap(const IterSwapTrackingIterator& lhs, const IterSwapTrackingIterator& rhs) {
+ assert(lhs.flag_ != nullptr && rhs.flag_ != nullptr);
+ *lhs.flag_ = *rhs.flag_ = SwapKind::with_same_type;
+ return std::ranges::iter_swap(lhs.iter_, rhs.iter_);
+ }
+
+ template <std::indirectly_swappable<Iter> OtherIter, IterKind OtherKind>
+ friend constexpr decltype(auto)
+ iter_swap(const IterSwapTrackingIterator& lhs, const IterSwapTrackingIterator<OtherIter, OtherKind>& rhs) {
+ assert(lhs.flag_ != nullptr && rhs.get_flag() != nullptr);
+ *lhs.flag_ = *rhs.get_flag() = SwapKind::with_
diff erent_type;
+ return std::ranges::iter_swap(lhs.iter_, rhs.get_iter());
+ }
+
+private:
+ Iter iter_ = Iter();
+ SwapKind* flag_ = nullptr;
+};
+
+static_assert(std::forward_iterator<IterSwapTrackingIterator<int*, IterKind::inner_view>> &&
+ !std::bidirectional_iterator<IterSwapTrackingIterator<int*, IterKind::inner_view>>);
+
+constexpr bool test() {
+ { // Test common usage
+ using V = std::vector<std::string>;
+ using Pattern = std::string;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+ using namespace std::string_view_literals;
+
+ JWV jwv(V{"std", "ranges", "views", "join_with_view"}, Pattern{":: "});
+ assert(std::ranges::equal(jwv, "std:: ranges:: views:: join_with_view"sv));
+
+ auto it = jwv.begin();
+ iter_swap(it, std::ranges::next(it, 2)); // Swap elements of the same inner range.
+ assert(std::ranges::equal(jwv, "dts:: ranges:: views:: join_with_view"sv));
+
+ std::ranges::advance(it, 3);
+ iter_swap(std::as_const(it), std::ranges::next(it, 2)); // Swap elements of the pattern.
+ assert(std::ranges::equal(jwv, "dts ::ranges ::views ::join_with_view"sv));
+
+ std::ranges::advance(it, 3);
+ const auto it2 = jwv.begin();
+ iter_swap(std::as_const(it), it2); // Swap elements of
diff erent inner ranges.
+ assert(std::ranges::equal(jwv, "rts ::danges ::views ::join_with_view"sv));
+
+ std::ranges::advance(it, 6);
+ iter_swap(std::as_const(it), it2); // Swap element from inner range with element from the pattern.
+ assert(std::ranges::equal(jwv, " tsr::dangesr::viewsr::join_with_view"sv));
+
+ static_assert(std::is_void_v<decltype(iter_swap(it, it))>);
+ static_assert(std::is_void_v<decltype(iter_swap(it2, it2))>);
+ static_assert(!CanIterSwap<std::ranges::iterator_t<const JWV>>);
+ static_assert(!CanIterSwap<const std::ranges::iterator_t<const JWV>>);
+ }
+
+ { // Make sure `iter_swap` calls underlying's iterator `iter_swap` (not `ranges::swap(*i1, *i2)`).
+ using Inner = std::vector<int>;
+ using InnerTrackingIter = IterSwapTrackingIterator<Inner::iterator, IterKind::inner_view>;
+ using TrackingInner = std::ranges::subrange<InnerTrackingIter>;
+ using Pattern = std::array<int, 2>;
+ using PatternTrackingIter = IterSwapTrackingIterator<Pattern::iterator, IterKind::pattern>;
+ using TrackingPattern = std::ranges::subrange<PatternTrackingIter>;
+ using JWV = std::ranges::join_with_view<std::span<TrackingInner>, TrackingPattern>;
+
+ std::array<Inner, 3> v{{{1, 2, 3}, {4, 5}}};
+ Pattern pat{-1, -2};
+
+ SwapKind v_swap_kind = SwapKind::no_swap;
+ std::array<TrackingInner, 2> tracking_v{
+ TrackingInner(InnerTrackingIter(v[0].begin(), &v_swap_kind), InnerTrackingIter(v[0].end())),
+ TrackingInner(InnerTrackingIter(v[1].begin(), &v_swap_kind), InnerTrackingIter(v[1].end()))};
+
+ SwapKind pat_swap_kind = SwapKind::no_swap;
+ TrackingPattern tracking_pat(PatternTrackingIter(pat.begin(), &pat_swap_kind), PatternTrackingIter(pat.end()));
+
+ JWV jwv(tracking_v, tracking_pat);
+ auto it1 = jwv.begin();
+ auto it2 = std::ranges::next(it1);
+
+ // Test calling `iter_swap` when both `it1` and `it2` point to elements of `v`.
+ assert(v_swap_kind == SwapKind::no_swap);
+ iter_swap(it1, it2);
+ assert(*it1 == 2 && *it2 == 1);
+ assert(v_swap_kind == SwapKind::with_same_type && pat_swap_kind == SwapKind::no_swap);
+
+ // Test calling `iter_swap` when `it1` points to element of `v` and `it2` points to element of `pat`.
+ std::ranges::advance(it2, 2);
+ v_swap_kind = SwapKind::no_swap;
+ assert(pat_swap_kind == SwapKind::no_swap);
+ iter_swap(it1, it2);
+ assert(*it1 == -1 && *it2 == 2);
+ assert(v_swap_kind == SwapKind::with_
diff erent_type && pat_swap_kind == SwapKind::with_
diff erent_type);
+
+ // Test calling `iter_swap` when `it1` and `it2` point to elements of `pat`.
+ std::ranges::advance(it1, 4);
+ v_swap_kind = pat_swap_kind = SwapKind::no_swap;
+ iter_swap(it1, it2);
+ assert(*it1 == 2 && *it2 == -2);
+ assert(v_swap_kind == SwapKind::no_swap && pat_swap_kind == SwapKind::with_same_type);
+
+ // Test calling `iter_swap` when `it1` points to element of `pat` and `it2` points to element of `v`.
+ std::ranges::advance(it2, 3);
+ v_swap_kind = pat_swap_kind = SwapKind::no_swap;
+ iter_swap(it1, it2);
+ assert(*it1 == 5 && *it2 == 2);
+ assert(v_swap_kind == SwapKind::with_
diff erent_type && pat_swap_kind == SwapKind::with_
diff erent_type);
+ }
+
+ { // InnerIter and PatternIter don't model indirectly swappable
+ using JWV = std::ranges::join_with_view<std::span<std::string>, std::string_view>;
+ static_assert(!CanIterSwap<std::ranges::iterator_t<JWV>>);
+ static_assert(!CanIterSwap<const std::ranges::iterator_t<JWV>>);
+ static_assert(!CanIterSwap<std::ranges::iterator_t<const JWV>>);
+ static_assert(!CanIterSwap<const std::ranges::iterator_t<const JWV>>);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/types.compile.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/types.compile.pass.cpp
new file mode 100644
index 0000000000000..a373e17dddbf3
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/types.compile.pass.cpp
@@ -0,0 +1,456 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// using iterator_concept = see below;
+// using iterator_category = see below; // not always present
+// using value_type = see below;
+// using
diff erence_type = see below;
+
+#include <ranges>
+
+#include <iterator>
+#include <vector>
+
+#include "../types.h"
+#include "test_iterators.h"
+
+namespace test_iterator_concept {
+template <template <class> class InnerIt>
+using InnerRange = BasicView<std::vector<int>, ViewProperties{}, InnerIt>;
+
+template <template <class> class It, template <class> class InnerIt>
+using View = BasicView<std::vector<InnerRange<InnerIt>>, ViewProperties{}, It>;
+
+template <template <class> class It, template <class> class InnerIt>
+using RvalueView = BasicView<RvalueVector<InnerRange<InnerIt>>, ViewProperties{}, It>;
+
+template <template <class> class It>
+using Pattern = BasicView<std::vector<int>, ViewProperties{}, It>;
+
+template <class V, class Pat>
+using IteratorConcept = std::ranges::iterator_t<std::ranges::join_with_view<V, Pat>>::iterator_concept;
+
+template <class V, class Pat, class Concept>
+concept IteratorConceptIs = std::same_as<IteratorConcept<V, Pat>, Concept>;
+
+// When `iterator<false>::iterator_concept` is `bidirectional_iterator_tag`
+static_assert(IteratorConceptIs<View<bidirectional_iterator, bidirectional_iterator>,
+ Pattern<bidirectional_iterator>,
+ std::bidirectional_iterator_tag>);
+
+// When `iterator<false>::iterator_concept` is `forward_iterator_tag`
+static_assert(IteratorConceptIs<View<forward_iterator, bidirectional_iterator>,
+ Pattern<bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorConceptIs<View<bidirectional_iterator, forward_iterator>,
+ Pattern<bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorConceptIs<View<bidirectional_iterator, bidirectional_iterator>,
+ Pattern<forward_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorConceptIs<View<forward_iterator, forward_iterator>,
+ Pattern<bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorConceptIs<View<forward_iterator, bidirectional_iterator>,
+ Pattern<forward_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorConceptIs<View<bidirectional_iterator, forward_iterator>,
+ Pattern<forward_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorConceptIs<View<forward_iterator, forward_iterator>, //
+ Pattern<forward_iterator>,
+ std::forward_iterator_tag>);
+
+// When `iterator<false>::iterator_concept` is `input_iterator_tag`
+static_assert(IteratorConceptIs<View<DefaultCtorInputIter, forward_iterator>,
+ Pattern<forward_iterator>,
+ std::input_iterator_tag>);
+static_assert(IteratorConceptIs<View<forward_iterator, DefaultCtorInputIter>,
+ Pattern<forward_iterator>,
+ std::input_iterator_tag>);
+static_assert(IteratorConceptIs<View<DefaultCtorInputIter, DefaultCtorInputIter>,
+ Pattern<forward_iterator>,
+ std::input_iterator_tag>);
+static_assert(IteratorConceptIs<RvalueView<bidirectional_iterator, bidirectional_iterator>,
+ Pattern<bidirectional_iterator>,
+ std::input_iterator_tag>);
+static_assert(IteratorConceptIs<RvalueView<forward_iterator, forward_iterator>,
+ Pattern<forward_iterator>,
+ std::input_iterator_tag>);
+
+template <class V, class Pat>
+using ConstIteratorConcept = std::ranges::iterator_t<const std::ranges::join_with_view<V, Pat>>::iterator_concept;
+
+template <class V, class Pat, class Concept>
+concept ConstIteratorConceptIs = std::same_as<ConstIteratorConcept<V, Pat>, Concept>;
+
+// When `iterator<true>::iterator_concept` is `bidirectional_iterator_tag`
+static_assert(ConstIteratorConceptIs<View<bidirectional_iterator, bidirectional_iterator>,
+ Pattern<bidirectional_iterator>,
+ std::bidirectional_iterator_tag>);
+
+// When `iterator<true>::iterator_concept` is `forward_iterator_tag`
+static_assert(ConstIteratorConceptIs<View<forward_iterator, bidirectional_iterator>,
+ Pattern<bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorConceptIs<View<bidirectional_iterator, forward_iterator>,
+ Pattern<bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorConceptIs<View<bidirectional_iterator, bidirectional_iterator>,
+ Pattern<forward_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorConceptIs<View<forward_iterator, forward_iterator>,
+ Pattern<bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorConceptIs<View<forward_iterator, bidirectional_iterator>,
+ Pattern<forward_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorConceptIs<View<bidirectional_iterator, forward_iterator>,
+ Pattern<forward_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorConceptIs<View<forward_iterator, forward_iterator>,
+ Pattern<forward_iterator>,
+ std::forward_iterator_tag>);
+
+// `iterator<true>::iterator_concept` cannot be `input_iterator_tag`
+} // namespace test_iterator_concept
+
+namespace test_iterator_category {
+template <template <class> class InnerIt>
+using InnerRange = BasicView<std::vector<float>, ViewProperties{}, InnerIt>;
+
+template <bool Common, template <class> class InnerIt>
+using MaybeCommonInnerRange = BasicView<std::vector<float>, ViewProperties{.common = Common}, InnerIt>;
+
+template <template <class> class It, template <class> class InnerIt>
+using View = BasicView<std::vector<InnerRange<InnerIt>>, ViewProperties{}, It>;
+
+template <template <class> class It, template <class> class InnerIt>
+using RvalueView = BasicView<RvalueVector<InnerRange<InnerIt>>, ViewProperties{}, It>;
+
+template <bool Common, template <class> class It, bool CommonInner, template <class> class InnerIt>
+using MaybeCommonView =
+ BasicView<std::vector<MaybeCommonInnerRange<CommonInner, InnerIt>>, ViewProperties{.common = Common}, It>;
+
+template <template <class> class It>
+using Pattern = BasicView<std::vector<float>, ViewProperties{}, It>;
+
+template <template <class> class It>
+using RvaluePattern = BasicView<RvalueVector<float>, ViewProperties{}, It>;
+
+template <bool Common, template <class> class It>
+using MaybeCommonPattern = BasicView<std::vector<float>, ViewProperties{.common = Common}, It>;
+
+template <class V, class Pattern>
+using IteratorCategory = std::ranges::iterator_t<std::ranges::join_with_view<V, Pattern>>::iterator_category;
+
+template <class V, class Pattern>
+concept HasIteratorCategory = requires { typename IteratorCategory<V, Pattern>; };
+
+template <class V, class Pat, class Category>
+concept IteratorCategoryIs = std::same_as<IteratorCategory<V, Pat>, Category>;
+
+// When `iterator<false>::iterator_category` is not defined
+static_assert(!HasIteratorCategory<View<cpp20_input_iterator, forward_iterator>, Pattern<forward_iterator>>);
+static_assert(!HasIteratorCategory<View<forward_iterator, cpp20_input_iterator>, Pattern<forward_iterator>>);
+static_assert(!HasIteratorCategory<View<forward_iterator, forward_iterator>, Pattern<cpp20_input_iterator>>);
+static_assert(!HasIteratorCategory<RvalueView<forward_iterator, forward_iterator>, Pattern<forward_iterator>>);
+static_assert(HasIteratorCategory<View<forward_iterator, forward_iterator>, Pattern<forward_iterator>>);
+
+// When
+// is_reference_v<common_reference_t<iter_reference_t<InnerIter>,
+// iter_reference_t<PatternIter>>>
+// has
diff erent values for `iterator<false>`
+static_assert(IteratorCategoryIs<View<forward_iterator, forward_iterator>,
+ RvaluePattern<forward_iterator>,
+ std::input_iterator_tag>);
+
+// When `iterator<false>::iterator_category` is `bidirectional_iterator_tag`
+static_assert(IteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::bidirectional_iterator_tag>);
+static_assert(IteratorCategoryIs<MaybeCommonView<false, bidirectional_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::bidirectional_iterator_tag>);
+
+// When `iterator<false>::iterator_category` is `forward_iterator_tag`
+static_assert(IteratorCategoryIs<MaybeCommonView<true, forward_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, true, forward_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<true, forward_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, false, bidirectional_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<false, bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(IteratorCategoryIs<MaybeCommonView<false, forward_iterator, false, forward_iterator>,
+ MaybeCommonPattern<false, forward_iterator>,
+ std::forward_iterator_tag>);
+
+// When `iterator<false>::iterator_category` is `input_iterator_tag`
+static_assert(IteratorCategoryIs<View<ForwardIteratorWithInputCategory, forward_iterator>,
+ Pattern<forward_iterator>,
+ std::input_iterator_tag>);
+static_assert(IteratorCategoryIs<View<forward_iterator, ForwardIteratorWithInputCategory>,
+ Pattern<forward_iterator>,
+ std::input_iterator_tag>);
+static_assert(IteratorCategoryIs<View<forward_iterator, forward_iterator>,
+ Pattern<ForwardIteratorWithInputCategory>,
+ std::input_iterator_tag>);
+static_assert(IteratorCategoryIs<View<ForwardIteratorWithInputCategory, ForwardIteratorWithInputCategory>,
+ Pattern<ForwardIteratorWithInputCategory>,
+ std::input_iterator_tag>);
+
+template <class V, class Pattern>
+using ConstIteratorCategory = std::ranges::iterator_t<const std::ranges::join_with_view<V, Pattern>>::iterator_category;
+
+template <class V, class Pattern>
+concept HasConstIteratorCategory = requires { typename ConstIteratorCategory<V, Pattern>; };
+
+template <class V, class Pat, class Category>
+concept ConstIteratorCategoryIs = std::same_as<ConstIteratorCategory<V, Pat>, Category>;
+
+// `iterator<true>::iterator_category` is not defined in those
+// cases because `join_with_view<V, Pattern>` cannot const-accessed
+static_assert(!HasConstIteratorCategory<View<cpp20_input_iterator, forward_iterator>, Pattern<forward_iterator>>);
+static_assert(!HasConstIteratorCategory<View<forward_iterator, cpp20_input_iterator>, Pattern<forward_iterator>>);
+static_assert(!HasConstIteratorCategory<View<forward_iterator, forward_iterator>, Pattern<cpp20_input_iterator>>);
+static_assert(!HasConstIteratorCategory<RvalueView<forward_iterator, forward_iterator>, Pattern<forward_iterator>>);
+static_assert(HasConstIteratorCategory<View<forward_iterator, forward_iterator>, Pattern<forward_iterator>>);
+
+// When
+// is_reference_v<common_reference_t<iter_reference_t<InnerIter>,
+// iter_reference_t<PatternIter>>>
+// has
diff erent values for `iterator<true>`
+static_assert(ConstIteratorCategoryIs<View<forward_iterator, forward_iterator>,
+ RvaluePattern<forward_iterator>,
+ std::input_iterator_tag>);
+
+// When `iterator<true>::iterator_category` is `bidirectional_iterator_tag`
+static_assert(ConstIteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::bidirectional_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<MaybeCommonView<false, bidirectional_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::bidirectional_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<
+ BasicVectorView<
+ BasicVectorView<float, ViewProperties{.common = true}, forward_iterator, bidirectional_iterator>,
+ ViewProperties{.common = true},
+ forward_iterator,
+ bidirectional_iterator>,
+ BasicVectorView<float, ViewProperties{.common = true}, forward_iterator, bidirectional_iterator>,
+ std::bidirectional_iterator_tag>);
+
+// When `iterator<true>::iterator_category` is `forward_iterator_tag`
+static_assert(ConstIteratorCategoryIs<MaybeCommonView<true, forward_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, true, forward_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<true, forward_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, false, bidirectional_iterator>,
+ MaybeCommonPattern<true, bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<MaybeCommonView<true, bidirectional_iterator, true, bidirectional_iterator>,
+ MaybeCommonPattern<false, bidirectional_iterator>,
+ std::forward_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<MaybeCommonView<false, forward_iterator, false, forward_iterator>,
+ MaybeCommonPattern<false, forward_iterator>,
+ std::forward_iterator_tag>);
+static_assert(
+ ConstIteratorCategoryIs<
+ BasicVectorView<BasicVectorView<float, ViewProperties{}, ForwardIteratorWithInputCategory, forward_iterator>,
+ ViewProperties{},
+ ForwardIteratorWithInputCategory,
+ forward_iterator>,
+ BasicVectorView<float, ViewProperties{}, ForwardIteratorWithInputCategory, forward_iterator>,
+ std::forward_iterator_tag>);
+
+// When `iterator<true>::iterator_category` is `input_iterator_tag`
+static_assert(ConstIteratorCategoryIs<View<ForwardIteratorWithInputCategory, forward_iterator>,
+ Pattern<forward_iterator>,
+ std::input_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<View<forward_iterator, ForwardIteratorWithInputCategory>,
+ Pattern<forward_iterator>,
+ std::input_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<View<forward_iterator, forward_iterator>,
+ Pattern<ForwardIteratorWithInputCategory>,
+ std::input_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<View<ForwardIteratorWithInputCategory, ForwardIteratorWithInputCategory>,
+ Pattern<ForwardIteratorWithInputCategory>,
+ std::input_iterator_tag>);
+static_assert(ConstIteratorCategoryIs<
+ BasicVectorView<
+ BasicVectorView<float, ViewProperties{}, DefaultCtorInputIter, ForwardIteratorWithInputCategory>,
+ ViewProperties{},
+ DefaultCtorInputIter,
+ ForwardIteratorWithInputCategory>,
+ BasicVectorView<float, ViewProperties{}, ForwardIteratorWithInputCategory>,
+ std::input_iterator_tag>);
+} // namespace test_iterator_category
+
+namespace test_value_type {
+template <class ValueType, class ConstValueType = ValueType>
+struct View : std::ranges::view_base {
+ struct InnerRange : std::ranges::view_base {
+ ValueType* begin();
+ ValueType* end();
+ ConstValueType* begin() const;
+ ConstValueType* end() const;
+ };
+
+ InnerRange* begin();
+ InnerRange* end();
+ const InnerRange* begin() const;
+ const InnerRange* end() const;
+};
+
+template <class ValueType, class ConstValueType = ValueType>
+using Pattern = View<ValueType, ConstValueType>::InnerRange;
+
+template <class V, class Pat>
+using IteratorValueType = std::ranges::iterator_t<std::ranges::join_with_view<V, Pat>>::value_type;
+
+template <class V, class Pat, class ValueType>
+concept IteratorValueTypeIs = std::same_as<IteratorValueType<V, Pat>, ValueType>;
+
+// Test that `iterator<false>::value_type` is equal to
+// common_type_t<iter_value_t<InnerIter>, iter_value_t<PatternIter>>
+static_assert(IteratorValueTypeIs<View<int>, Pattern<int>, int>);
+static_assert(IteratorValueTypeIs<View<int>, Pattern<long>, long>);
+static_assert(IteratorValueTypeIs<View<long>, Pattern<int>, long>);
+static_assert(IteratorValueTypeIs<View<std::nullptr_t>, Pattern<void*>, void*>);
+static_assert(IteratorValueTypeIs<View<std::tuple<long, int>>, Pattern<std::tuple<int, long>>, std::tuple<long, long>>);
+
+template <class V, class Pat>
+using ConstIteratorValueType = std::ranges::iterator_t<const std::ranges::join_with_view<V, Pat>>::value_type;
+
+template <class V, class Pat, class ValueType>
+concept ConstIteratorValueTypeIs = std::same_as<ConstIteratorValueType<V, Pat>, ValueType>;
+
+// Test that `iterator<true>::value_type` is equal to
+// common_type_t<iter_value_t<InnerIter>, iter_value_t<PatternIter>>
+static_assert(ConstIteratorValueTypeIs<View<int>, Pattern<int>, int>);
+static_assert(ConstIteratorValueTypeIs<View<int>, Pattern<long>, long>);
+static_assert(ConstIteratorValueTypeIs<View<long>, Pattern<int>, long>);
+static_assert(ConstIteratorValueTypeIs<View<std::nullptr_t>, Pattern<void*>, void*>);
+static_assert(
+ ConstIteratorValueTypeIs<View<std::tuple<long, int>>, Pattern<std::tuple<int, long>>, std::tuple<long, long>>);
+
+// Test value types of non-simple const ranges
+static_assert(ConstIteratorValueTypeIs<View<short, int>, Pattern<short, int>, int>);
+static_assert(ConstIteratorValueTypeIs<View<short, int>, Pattern<int, long>, long>);
+static_assert(ConstIteratorValueTypeIs<View<int, long>, Pattern<short, int>, long>);
+static_assert(ConstIteratorValueTypeIs<View<int, std::nullptr_t>, Pattern<int, void*>, void*>);
+static_assert(ConstIteratorValueTypeIs<View<std::tuple<long, int>, std::pair<long, int>>,
+ Pattern<std::tuple<int, long>, std::pair<int, long>>,
+ std::pair<long, long>>);
+} // namespace test_value_type
+
+namespace test_
diff erence_type {
+template <class DifferenceType, class ValueType>
+struct Iter {
+ using value_type = std::remove_const_t<ValueType>;
+ using
diff erence_type = DifferenceType;
+
+ ValueType& operator*() const;
+ Iter& operator++();
+ Iter operator++(int);
+ bool operator==(const Iter&) const;
+};
+
+static_assert(std::forward_iterator<Iter<int, void*>>);
+
+template <class DifferenceType,
+ class InnerDifferenceType,
+ class ConstDifferenceType = DifferenceType,
+ class InnerConstDifferenceType = InnerDifferenceType>
+struct View : std::ranges::view_base {
+ struct InnerRange : std::ranges::view_base {
+ Iter<InnerDifferenceType, float> begin();
+ Iter<InnerDifferenceType, float> end();
+ Iter<InnerConstDifferenceType, double> begin() const;
+ Iter<InnerConstDifferenceType, double> end() const;
+ };
+
+ Iter<DifferenceType, InnerRange> begin();
+ Iter<DifferenceType, InnerRange> end();
+ Iter<ConstDifferenceType, const InnerRange> begin() const;
+ Iter<ConstDifferenceType, const InnerRange> end() const;
+};
+
+template <class DifferenceType, class ConstDifferenceType = DifferenceType>
+struct Pattern : std::ranges::view_base {
+ Iter<DifferenceType, float> begin();
+ Iter<DifferenceType, float> end();
+ Iter<ConstDifferenceType, double> begin() const;
+ Iter<ConstDifferenceType, double> end() const;
+};
+
+template <class V, class Pat>
+using IteratorDifferenceType = std::ranges::iterator_t<std::ranges::join_with_view<V, Pat>>::
diff erence_type;
+
+template <class V, class Pat, class DifferenceType>
+concept IteratorDifferenceTypeIs = std::same_as<IteratorDifferenceType<V, Pat>, DifferenceType>;
+
+// Test that `iterator<false>::
diff erence_type` is equal to
+// common_type_t<
+// iter_
diff erence_t<OuterIter>,
+// iter_
diff erence_t<InnerIter>,
+// iter_
diff erence_t<PatternIter>>
+static_assert(IteratorDifferenceTypeIs<View<int, int>, Pattern<int>, int>);
+static_assert(IteratorDifferenceTypeIs<View<signed char, signed char>, Pattern<signed char>, signed char>);
+static_assert(IteratorDifferenceTypeIs<View<short, short>, Pattern<short>, short>);
+static_assert(IteratorDifferenceTypeIs<View<signed char, short>, Pattern<short>, int>);
+static_assert(IteratorDifferenceTypeIs<View<signed char, short>, Pattern<int>, int>);
+static_assert(IteratorDifferenceTypeIs<View<long long, long>, Pattern<int>, long long>);
+static_assert(IteratorDifferenceTypeIs<View<long, long long>, Pattern<int>, long long>);
+
+template <class V, class Pat>
+using ConstIteratorDifferenceType = std::ranges::iterator_t<const std::ranges::join_with_view<V, Pat>>::
diff erence_type;
+
+template <class V, class Pat, class DifferenceType>
+concept ConstIteratorDifferenceTypeIs = std::same_as<ConstIteratorDifferenceType<V, Pat>, DifferenceType>;
+
+// Test that `iterator<true>::
diff erence_type` is equal to
+// common_type_t<
+// iter_
diff erence_t<OuterIter>,
+// iter_
diff erence_t<InnerIter>,
+// iter_
diff erence_t<PatternIter>>
+static_assert(ConstIteratorDifferenceTypeIs<View<int, int>, Pattern<int>, int>);
+static_assert(ConstIteratorDifferenceTypeIs<View<signed char, signed char>, Pattern<signed char>, signed char>);
+static_assert(ConstIteratorDifferenceTypeIs<View<short, short>, Pattern<short>, short>);
+static_assert(ConstIteratorDifferenceTypeIs<View<signed char, short>, Pattern<short>, int>);
+static_assert(ConstIteratorDifferenceTypeIs<View<signed char, short>, Pattern<int>, int>);
+static_assert(ConstIteratorDifferenceTypeIs<View<long long, long>, Pattern<int>, long long>);
+static_assert(ConstIteratorDifferenceTypeIs<View<long, long long>, Pattern<int>, long long>);
+
+// Test
diff erence types of non-simple const ranges
+static_assert(ConstIteratorDifferenceTypeIs<View<short, short, int, int>, Pattern<short, int>, int>);
+static_assert(
+ ConstIteratorDifferenceTypeIs<View<int, short, signed char, signed char>, Pattern<long, signed char>, signed char>);
+static_assert(ConstIteratorDifferenceTypeIs<View<long, long long, signed char, short>, Pattern<long, short>, int>);
+static_assert(ConstIteratorDifferenceTypeIs<View<short, short, long long, long>, Pattern<short, int>, long long>);
+static_assert(ConstIteratorDifferenceTypeIs<View<signed char, signed char, long, long long>,
+ Pattern<signed char, int>,
+ long long>);
+} // namespace test_
diff erence_type
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.pass.cpp
new file mode 100644
index 0000000000000..da53bfaaa5a52
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.pass.cpp
@@ -0,0 +1,360 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// std::views::join_with_view
+
+#include <ranges>
+
+#include <memory>
+#include <span>
+#include <string_view>
+#include <utility>
+
+#include "test_iterators.h"
+
+template <class View, class T>
+concept CanBePiped = requires(View&& view, T&& t) {
+ { std::forward<View>(view) | std::forward<T>(t) };
+};
+
+struct Range : std::ranges::view_base {
+ using Iterator = forward_iterator<std::string_view*>;
+ using Sentinel = sentinel_wrapper<Iterator>;
+ constexpr explicit Range(std::string_view* b, std::string_view* e) : begin_(b), end_(e) {}
+ constexpr Iterator begin() const { return Iterator(begin_); }
+ constexpr Sentinel end() const { return Sentinel(Iterator(end_)); }
+
+private:
+ std::string_view* begin_;
+ std::string_view* end_;
+};
+
+struct Pattern : std::ranges::view_base {
+ using Iterator = forward_iterator<const char*>;
+ using Sentinel = sentinel_wrapper<Iterator>;
+ static constexpr std::string_view pat{", "};
+
+ constexpr Pattern() = default;
+ constexpr Iterator begin() const { return Iterator(pat.data()); }
+ constexpr Sentinel end() const { return Sentinel(Iterator(pat.data() + pat.size())); }
+};
+
+struct NonCopyablePattern : Pattern {
+ NonCopyablePattern(const NonCopyablePattern&) = delete;
+};
+
+template <typename View>
+constexpr void compareViews(View v, std::string_view list) {
+ auto b1 = v.begin();
+ auto e1 = v.end();
+ auto b2 = list.begin();
+ auto e2 = list.end();
+ for (; b1 != e1 && b2 != e2; ++b1, ++b2) {
+ assert(*b1 == *b2);
+ }
+ assert(b1 == e1);
+ assert(b2 == e2);
+}
+
+constexpr int absoluteValue(int x) { return x < 0 ? -x : x; }
+
+template <class T>
+constexpr const T&& asConstRvalue(T&& t) {
+ return static_cast<const T&&>(t);
+}
+
+constexpr void test_adaptor_with_pattern(std::span<std::string_view> buff) {
+ // Test `views::join_with(pattern)(v)`
+ {
+ using Result = std::ranges::join_with_view<Range, Pattern>;
+ const Range range(buff.data(), buff.data() + buff.size());
+ Pattern pattern;
+
+ {
+ // 'views::join_with(pattern)' - &&
+ std::same_as<Result> decltype(auto) result = std::views::join_with(pattern)(range);
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ {
+ // 'views::join_with(pattern)' - const&&
+ std::same_as<Result> decltype(auto) result = asConstRvalue(std::views::join_with(pattern))(range);
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ {
+ // 'views::join_with(pattern)' - &
+ auto partial = std::views::join_with(pattern);
+ std::same_as<Result> decltype(auto) result = partial(range);
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ {
+ // 'views::join_with(pattern)' - const&
+ auto const partial = std::views::join_with(pattern);
+ std::same_as<Result> decltype(auto) result = partial(range);
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ }
+
+ // Test `v | views::join_with(pattern)`
+ {
+ using Result = std::ranges::join_with_view<Range, Pattern>;
+ const Range range(buff.data(), buff.data() + buff.size());
+ Pattern pattern;
+
+ {
+ // 'views::join_with(pattern)' - &&
+ std::same_as<Result> decltype(auto) result = range | std::views::join_with(pattern);
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ {
+ // 'views::join_with(pattern)' - const&&
+ std::same_as<Result> decltype(auto) result = range | asConstRvalue(std::views::join_with(pattern));
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ {
+ // 'views::join_with(pattern)' - &
+ auto partial = std::views::join_with(pattern);
+ std::same_as<Result> decltype(auto) result = range | partial;
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ {
+ // 'views::join_with(pattern)' - const&
+ auto const partial = std::views::join_with(pattern);
+ std::same_as<Result> decltype(auto) result = range | partial;
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ }
+
+ // Test `views::join_with(v, pattern)` range adaptor object
+ {
+ using Result = std::ranges::join_with_view<Range, Pattern>;
+ const Range range(buff.data(), buff.data() + buff.size());
+ Pattern pattern;
+
+ {
+ // 'views::join_with' - &&
+ auto range_adaptor = std::views::join_with;
+ std::same_as<Result> decltype(auto) result = std::move(range_adaptor)(range, pattern);
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ {
+ // 'views::join_with' - const&&
+ const auto range_adaptor = std::views::join_with;
+ std::same_as<Result> decltype(auto) result = std::move(range_adaptor)(range, pattern);
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ {
+ // 'views::join_with' - &
+ auto range_adaptor = std::views::join_with;
+ std::same_as<Result> decltype(auto) result = range_adaptor(range, pattern);
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ {
+ // 'views::join_with' - const&
+ const auto range_adaptor = std::views::join_with;
+ std::same_as<Result> decltype(auto) result = range_adaptor(range, pattern);
+ compareViews(result, "abcd, ef, ghij, kl");
+ }
+ }
+
+ // Test `adaptor | views::join_with(pattern)`
+ {
+ auto pred = [](std::string_view s) { return s.size() >= 3; };
+ using Result = std::ranges::join_with_view<std::ranges::filter_view<Range, decltype(pred)>, Pattern>;
+ const Range range(buff.data(), buff.data() + buff.size());
+ Pattern pattern;
+
+ {
+ std::same_as<Result> decltype(auto) result = range | std::views::filter(pred) | std::views::join_with(pattern);
+ compareViews(result, "abcd, ghij");
+ }
+ {
+ const auto partial = std::views::filter(pred) | std::views::join_with(pattern);
+ std::same_as<Result> decltype(auto) result = range | partial;
+ compareViews(result, "abcd, ghij");
+ }
+ }
+}
+
+constexpr void test_adaptor_with_single_element(std::span<std::string_view> buff) {
+ // Test `views::join_with(element)(v)`
+ {
+ using Result = std::ranges::join_with_view<Range, std::ranges::single_view<char>>;
+ const Range range(buff.data(), buff.data() + buff.size());
+ const char element = '.';
+
+ {
+ // 'views::join_with(element)' - &&
+ std::same_as<Result> decltype(auto) result = std::views::join_with(element)(range);
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ {
+ // 'views::join_with(element)' - const&&
+ std::same_as<Result> decltype(auto) result = asConstRvalue(std::views::join_with(element))(range);
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ {
+ // 'views::join_with(element)' - &
+ auto partial = std::views::join_with(element);
+ std::same_as<Result> decltype(auto) result = partial(range);
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ {
+ // 'views::join_with(element)' - const&
+ const auto partial = std::views::join_with(element);
+ std::same_as<Result> decltype(auto) result = partial(range);
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ }
+
+ // Test `v | views::join_with(element)`
+ {
+ using Result = std::ranges::join_with_view<Range, std::ranges::single_view<char>>;
+ const Range range(buff.data(), buff.data() + buff.size());
+ const char element = '.';
+
+ {
+ // 'views::join_with(element)' - &&
+ std::same_as<Result> decltype(auto) result = range | std::views::join_with(element);
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ {
+ // 'views::join_with(element)' - const&&
+ std::same_as<Result> decltype(auto) result = range | asConstRvalue(std::views::join_with(element));
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ {
+ // 'views::join_with(element)' - &
+ auto partial = std::views::join_with(element);
+ std::same_as<Result> decltype(auto) result = range | partial;
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ {
+ // 'views::join_with(element)' - const&
+ const auto partial = std::views::join_with(element);
+ std::same_as<Result> decltype(auto) result = range | partial;
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ }
+
+ // Test `views::join_with(v, element)` range adaptor object
+ {
+ using Result = std::ranges::join_with_view<Range, std::ranges::single_view<char>>;
+ const Range range(buff.data(), buff.data() + buff.size());
+ const char element = '.';
+
+ {
+ // 'views::join_with' - &&
+ auto range_adaptor = std::views::join_with;
+ std::same_as<Result> decltype(auto) result = std::move(range_adaptor)(range, element);
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ {
+ // 'views::join_with' - const&&
+ const auto range_adaptor = std::views::join_with;
+ std::same_as<Result> decltype(auto) result = std::move(range_adaptor)(range, element);
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ {
+ // 'views::join_with' - &
+ auto range_adaptor = std::views::join_with;
+ std::same_as<Result> decltype(auto) result = range_adaptor(range, element);
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ {
+ // 'views::join_with' - const&
+ const auto range_adaptor = std::views::join_with;
+ std::same_as<Result> decltype(auto) result = range_adaptor(range, element);
+ compareViews(result, "abcd.ef.ghij.kl");
+ }
+ }
+
+ // Test `adaptor | views::join_with(element)`
+ {
+ auto pred = [](std::string_view s) { return s.size() >= 3; };
+ using Result =
+ std::ranges::join_with_view<std::ranges::filter_view<Range, decltype(pred)>, std::ranges::single_view<char>>;
+ const Range range(buff.data(), buff.data() + buff.size());
+ const char element = '.';
+
+ {
+ std::same_as<Result> decltype(auto) result = range | std::views::filter(pred) | std::views::join_with(element);
+ compareViews(result, "abcd.ghij");
+ }
+ {
+ const auto partial = std::views::filter(pred) | std::views::join_with(element);
+ std::same_as<Result> decltype(auto) result = range | partial;
+ compareViews(result, "abcd.ghij");
+ }
+ }
+}
+
+constexpr bool test() {
+ std::string_view buff[] = {"abcd", "ef", "ghij", "kl"};
+
+ // Test range adaptor object
+ {
+ using RangeAdaptorObject = decltype(std::views::join_with);
+ static_assert(std::is_const_v<RangeAdaptorObject>);
+
+ // The type of a customization point object, ignoring cv-qualifiers, shall model semiregular
+ static_assert(std::semiregular<std::remove_const<RangeAdaptorObject>>);
+ }
+
+ test_adaptor_with_pattern(buff);
+ test_adaptor_with_single_element(buff);
+
+ // Test that one can call std::views::join_with with arbitrary stuff, as long as we
+ // don't try to actually complete the call by passing it a range.
+ //
+ // That makes no sense and we can't do anything with the result, but it's valid.
+ {
+ long array[3] = {1, 2, 3};
+ [[maybe_unused]] auto partial = std::views::join_with(std::move(array));
+ }
+
+ // Test SFINAE friendliness
+ {
+ struct NotAView {};
+
+ static_assert(!CanBePiped<Range, decltype(std::views::join_with)>);
+ static_assert(CanBePiped<Range, decltype(std::views::join_with(Pattern{}))>);
+ static_assert(CanBePiped<Range, decltype(std::views::join_with('.'))>);
+ static_assert(!CanBePiped<NotAView, decltype(std::views::join_with(Pattern{}))>);
+ static_assert(!CanBePiped<NotAView, decltype(std::views::join_with('.'))>);
+ static_assert(!CanBePiped<std::initializer_list<char>, decltype(std::views::join_with(Pattern{}))>);
+ static_assert(!CanBePiped<std::initializer_list<char>, decltype(std::views::join_with('.'))>);
+ static_assert(!CanBePiped<Range, decltype(std::views::join_with(NotAView{}))>);
+
+ static_assert(!std::is_invocable_v<decltype(std::views::join_with)>);
+ static_assert(!std::is_invocable_v<decltype(std::views::join_with), Pattern, Range>);
+ static_assert(!std::is_invocable_v<decltype(std::views::join_with), char, Range>);
+ static_assert(std::is_invocable_v<decltype(std::views::join_with), Range, Pattern>);
+ static_assert(std::is_invocable_v<decltype(std::views::join_with), Range, char>);
+ static_assert(!std::is_invocable_v<decltype(std::views::join_with), Range, Pattern, Pattern>);
+ static_assert(!std::is_invocable_v<decltype(std::views::join_with), Range, char, char>);
+ static_assert(!std::is_invocable_v<decltype(std::views::join_with), NonCopyablePattern>);
+ }
+
+ {
+ static_assert(std::is_same_v<decltype(std::ranges::views::join_with), decltype(std::views::join_with)>);
+ assert(std::addressof(std::ranges::views::join_with) == std::addressof(std::views::join_with));
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/example.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/example.pass.cpp
new file mode 100644
index 0000000000000..1f7b889e2602e
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/example.pass.cpp
@@ -0,0 +1,42 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// [Example 1:
+// vector<string> vs = {"the", "quick", "brown", "fox"};
+// for (char c : vs | views::join_with('-')) {
+// cout << c;
+// }
+// // The above prints the-quick-brown-fox
+// - end example]
+
+#include <ranges>
+
+#include <cassert>
+#include <string>
+#include <vector>
+
+constexpr bool test() {
+ std::vector<std::string> vs = {"the", "quick", "brown", "fox"};
+ std::string result;
+ for (char c : vs | std::views::join_with('-')) {
+ result += c;
+ }
+
+ return result == "the-quick-brown-fox";
+}
+
+int main(int, char**) {
+ assert(test());
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.default.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.default.pass.cpp
new file mode 100644
index 0000000000000..634db24e02f28
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.default.pass.cpp
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// sentinel() = default;
+
+#include <ranges>
+
+#include "../types.h"
+
+constexpr bool test() {
+ using Inner = BasicVectorView<char, ViewProperties{.common = false}, forward_iterator>;
+ using V = BasicVectorView<Inner, ViewProperties{}, forward_iterator>;
+ using Pattern = Inner;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ static_assert(!std::ranges::common_range<JWV>);
+
+ [[maybe_unused]] std::ranges::sentinel_t<JWV> se;
+ [[maybe_unused]] std::ranges::sentinel_t<const JWV> cse;
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.non_const.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.non_const.pass.cpp
new file mode 100644
index 0000000000000..14688ba7c538f
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.non_const.pass.cpp
@@ -0,0 +1,74 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// constexpr sentinel(sentinel<!Const> s)
+// requires Const && convertible_to<sentinel_t<V>, sentinel_t<Base>>;
+
+#include <ranges>
+
+#include <type_traits>
+#include <vector>
+
+#include "../types.h"
+#include "test_iterators.h"
+
+constexpr bool test() {
+ { // Regular conversion from `!Const` to `Const` sentinel
+ using Inner = BasicVectorView<int, ViewProperties{.common = false}, forward_iterator>;
+ std::vector<Inner> vec = {Inner{11, 12}, Inner{13, 14}};
+
+ std::ranges::join_with_view jwv(vec, 0);
+ using JWV = decltype(jwv);
+ static_assert(!std::ranges::common_range<JWV>);
+
+ using Sent = std::ranges::sentinel_t<JWV>;
+ using CSent = std::ranges::sentinel_t<const JWV>;
+ static_assert(!std::same_as<Sent, CSent>);
+
+ Sent se = jwv.end();
+ [[maybe_unused]] CSent cse = se;
+ }
+
+ { // Test conversion from `Const` to `!Const` (should be invalid)
+ using Inner = BasicVectorView<int, ViewProperties{.common = false}, forward_iterator>;
+ using V = std::vector<Inner>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<std::views::all_t<V>, Pattern>;
+ static_assert(!std::ranges::common_range<JWV>);
+
+ using Sent = std::ranges::sentinel_t<JWV>;
+ using CSent = std::ranges::sentinel_t<const JWV>;
+ static_assert(!std::convertible_to<CSent, Sent>);
+ static_assert(!std::constructible_from<Sent, CSent>);
+ }
+
+ { // When `convertible_to<sentinel_t<V>, sentinel_t<Base>>` is not modeled
+ using V = ConstOppositeView<std::vector<long>>;
+ using Pattern = std::ranges::single_view<long>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ static_assert(!std::ranges::common_range<JWV>);
+
+ using Sent = std::ranges::sentinel_t<JWV>;
+ using CSent = std::ranges::sentinel_t<const JWV>;
+ static_assert(!std::convertible_to<CSent, Sent>);
+ static_assert(!std::constructible_from<Sent, CSent>);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.pass.cpp
new file mode 100644
index 0000000000000..44fb25b403ba1
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.pass.cpp
@@ -0,0 +1,109 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// template<bool OtherConst>
+// requires sentinel_for<sentinel_t<Base>, iterator_t<maybe-const<OtherConst, V>>>
+// friend constexpr bool operator==(const iterator<OtherConst>& x, const sentinel& y);
+
+#include <ranges>
+
+#include <cassert>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+#include "../types.h"
+#include "test_comparisons.h"
+#include "test_iterators.h"
+
+struct NonCrossConstComparableView : std::ranges::view_base {
+ using NonConstRange = std::vector<int>;
+ NonConstRange* begin();
+ sentinel_wrapper<NonConstRange*> end();
+
+ using ConstRange = BasicVectorView<int, ViewProperties{}, forward_iterator>;
+ ConstRange* begin() const;
+ sentinel_wrapper<ConstRange*> end() const;
+};
+
+static_assert(std::ranges::range<NonCrossConstComparableView>);
+static_assert(std::ranges::range<const NonCrossConstComparableView>);
+
+constexpr bool test() {
+ using Inner = BasicVectorView<int, ViewProperties{.common = false}, cpp20_input_iterator>;
+ using V = std::vector<Inner>;
+ using Pattern = std::ranges::single_view<int>;
+ using JWV = std::ranges::join_with_view<std::ranges::owning_view<V>, Pattern>;
+ static_assert(!std::ranges::common_range<JWV>);
+
+ using Iter = std::ranges::iterator_t<JWV>;
+ using CIter = std::ranges::iterator_t<const JWV>;
+ static_assert(!std::same_as<Iter, CIter>);
+
+ using Sent = std::ranges::sentinel_t<JWV>;
+ using CSent = std::ranges::sentinel_t<const JWV>;
+ static_assert(!std::same_as<Sent, CSent>);
+
+ { // Compare iterator<Const> with sentinel<Const>
+ { // Const == true
+ AssertEqualityReturnBool<CIter, CSent>();
+ const JWV jwv(V{Inner{1, 2}, Inner{4}}, 3);
+ assert(testEquality(std::ranges::next(jwv.begin(), 4), jwv.end(), true));
+ assert(testEquality(jwv.begin(), jwv.end(), false));
+ }
+
+ { // Const == false
+ AssertEqualityReturnBool<Iter, Sent>();
+ JWV jwv(V{Inner{5}, Inner{7, 8}}, 6);
+ assert(testEquality(std::ranges::next(jwv.begin(), 4), jwv.end(), true));
+ assert(testEquality(std::ranges::next(jwv.begin(), 2), jwv.end(), false));
+ }
+ }
+
+ { // Compare iterator<Const> with sentinel<!Const>
+ { // Const == true
+ AssertEqualityReturnBool<CIter, Sent>();
+ JWV jwv(V{Inner{9, 10}, Inner{12}}, 11);
+ assert(testEquality(std::ranges::next(std::as_const(jwv).begin(), 4), jwv.end(), true));
+ assert(testEquality(std::ranges::next(std::as_const(jwv).begin(), 2), jwv.end(), false));
+ }
+
+ { // Const == false
+ AssertEqualityReturnBool<Iter, CSent>();
+ JWV jwv(V{Inner{13}, Inner{15, 16}}, 14);
+ assert(testEquality(std::ranges::next(jwv.begin(), 4), std::as_const(jwv).end(), true));
+ assert(testEquality(std::ranges::next(jwv.begin(), 3), std::as_const(jwv).end(), false));
+ }
+ }
+
+ { // Check invalid comparisons between iterator<Const> and sentinel<!Const>
+ using JWV2 = std::ranges::join_with_view<NonCrossConstComparableView, Pattern>;
+ static_assert(!std::ranges::common_range<JWV2>);
+
+ static_assert(!weakly_equality_comparable_with<std::ranges::iterator_t<const JWV2>, std::ranges::sentinel_t<JWV2>>);
+ static_assert(!weakly_equality_comparable_with<std::ranges::iterator_t<JWV2>, std::ranges::sentinel_t<const JWV2>>);
+
+ // Those should be valid
+ static_assert(weakly_equality_comparable_with<std::ranges::iterator_t<JWV2>, std::ranges::sentinel_t<JWV2>>);
+ static_assert(
+ weakly_equality_comparable_with<std::ranges::iterator_t<const JWV2>, std::ranges::sentinel_t<const JWV2>>);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/base.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/base.pass.cpp
new file mode 100644
index 0000000000000..4e79b0fadfce4
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/base.pass.cpp
@@ -0,0 +1,132 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// constexpr View base() const& requires copy_constructible<View>;
+// constexpr View base() &&;
+
+#include <ranges>
+
+#include <cassert>
+#include <utility>
+#include <vector>
+
+using InnerRange = std::vector<int>;
+
+struct Range : std::ranges::view_base {
+ constexpr explicit Range(InnerRange* b, InnerRange* e) : begin_(b), end_(e) {}
+ constexpr Range(const Range& other) : begin_(other.begin_), end_(other.end_), was_copy_initialized_(true) {}
+ constexpr Range(Range&& other) : begin_(other.begin_), end_(other.end_), was_move_initialized_(true) {}
+ Range& operator=(const Range&) = default;
+ Range& operator=(Range&&) = default;
+ constexpr InnerRange* begin() const { return begin_; }
+ constexpr InnerRange* end() const { return end_; }
+
+ InnerRange* begin_;
+ InnerRange* end_;
+ bool was_copy_initialized_ = false;
+ bool was_move_initialized_ = false;
+};
+
+static_assert(std::ranges::view<Range>);
+static_assert(std::ranges::input_range<Range>);
+
+struct Pattern : std::ranges::view_base {
+ static constexpr int pat[2] = {0, 0};
+ constexpr const int* begin() const { return pat; }
+ constexpr const int* end() const { return pat + 2; }
+};
+
+static_assert(std::ranges::view<Pattern>);
+static_assert(std::ranges::forward_range<Pattern>);
+
+template <class Tp>
+struct NonCopyableRange : std::ranges::view_base {
+ NonCopyableRange(const NonCopyableRange&) = delete;
+ NonCopyableRange(NonCopyableRange&&) = default;
+ NonCopyableRange& operator=(const NonCopyableRange&) = default;
+ NonCopyableRange& operator=(NonCopyableRange&&) = default;
+ Tp* begin() const;
+ Tp* end() const;
+};
+
+static_assert(!std::copy_constructible<NonCopyableRange<InnerRange>>);
+static_assert(!std::copy_constructible<NonCopyableRange<int>>);
+
+template <typename T>
+concept CanCallBaseOn = requires(T&& t) { std::forward<T>(t).base(); };
+
+constexpr bool test() {
+ InnerRange buff[3] = {{1, 2, 3}, {4, 5, 6}, {7, 8, 9}};
+ Pattern pattern;
+
+ { // Check the const& overload
+ Range range(buff, buff + 3);
+ std::ranges::join_with_view<Range, Pattern> view(range, pattern);
+ std::same_as<Range> decltype(auto) result = view.base();
+ assert(result.was_copy_initialized_);
+ assert(result.begin() == buff);
+ assert(result.end() == buff + 3);
+ }
+
+ { // Check the const& overload on const `view`
+ Range range(buff, buff + 3);
+ const std::ranges::join_with_view<Range, Pattern> view(range, pattern);
+ std::same_as<Range> decltype(auto) result = view.base();
+ assert(result.was_copy_initialized_);
+ assert(result.begin() == buff);
+ assert(result.end() == buff + 3);
+ }
+
+ { // Check the && overload
+ Range range(buff, buff + 3);
+ std::ranges::join_with_view<Range, Pattern> view(range, pattern);
+ std::same_as<Range> decltype(auto) result = std::move(view).base();
+ assert(result.was_move_initialized_);
+ assert(result.begin() == buff);
+ assert(result.end() == buff + 3);
+ }
+
+ { // Ensure the const& overload is not considered when the base is not copy-constructible
+ static_assert(!CanCallBaseOn<const std::ranges::join_with_view<NonCopyableRange<InnerRange>, Pattern>&>);
+ static_assert(!CanCallBaseOn<std::ranges::join_with_view<NonCopyableRange<InnerRange>, Pattern>&>);
+ static_assert(!CanCallBaseOn<const std::ranges::join_with_view<NonCopyableRange<InnerRange>, Pattern>&&>);
+ static_assert(CanCallBaseOn<std::ranges::join_with_view<NonCopyableRange<InnerRange>, Pattern>&&>);
+ static_assert(CanCallBaseOn<std::ranges::join_with_view<NonCopyableRange<InnerRange>, Pattern>>);
+ }
+
+ { // Ensure the const& overload does not depend on Pattern's copy-constructability
+ static_assert(CanCallBaseOn<const std::ranges::join_with_view<Range, NonCopyableRange<int>>&>);
+ static_assert(CanCallBaseOn<std::ranges::join_with_view<Range, NonCopyableRange<int>>&>);
+ static_assert(CanCallBaseOn<const std::ranges::join_with_view<Range, NonCopyableRange<int>>&&>);
+ static_assert(CanCallBaseOn<std::ranges::join_with_view<Range, NonCopyableRange<int>>&&>);
+ static_assert(CanCallBaseOn<std::ranges::join_with_view<Range, NonCopyableRange<int>>>);
+ }
+
+ { // Check above two at the same time
+ static_assert(
+ !CanCallBaseOn<const std::ranges::join_with_view<NonCopyableRange<InnerRange>, NonCopyableRange<int>>&>);
+ static_assert(!CanCallBaseOn<std::ranges::join_with_view<NonCopyableRange<InnerRange>, NonCopyableRange<int>>&>);
+ static_assert(
+ !CanCallBaseOn<const std::ranges::join_with_view< NonCopyableRange<InnerRange>, NonCopyableRange<int>>&&>);
+ static_assert(CanCallBaseOn<std::ranges::join_with_view<NonCopyableRange<InnerRange>, NonCopyableRange<int>>&&>);
+ static_assert(CanCallBaseOn<std::ranges::join_with_view<NonCopyableRange<InnerRange>, NonCopyableRange<int>>>);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/begin.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/begin.pass.cpp
new file mode 100644
index 0000000000000..22872c20773a4
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/begin.pass.cpp
@@ -0,0 +1,221 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// constexpr auto begin();
+// constexpr auto begin() const
+// requires forward_range<const V> &&
+// forward_range<const Pattern> &&
+// is_reference_v<range_reference_t<const V>> &&
+// input_range<range_reference_t<const V>>;
+
+#include <ranges>
+
+#include <algorithm>
+#include <array>
+#include <string>
+#include <vector>
+
+#include "../types.h"
+#include "test_iterators.h"
+
+template <bool Simple>
+using MaybeSimpleForwardView = BasicView<std::vector<std::string>, ViewProperties{.simple = Simple}, forward_iterator>;
+
+template <bool Simple>
+using MaybeSimpleForwardRvalueView =
+ BasicView<RvalueVector<std::string>, ViewProperties{.simple = Simple}, forward_iterator>;
+
+template <bool Simple>
+using MaybeSimplePattern = BasicView<std::string, ViewProperties{.simple = Simple}, forward_iterator>;
+
+template <class V, class Pattern>
+concept JoinWithViewHasConstBegin = requires(const std::ranges::join_with_view<V, Pattern> jwv) {
+ { jwv.begin() } -> std::input_iterator;
+};
+
+constexpr void test_begin() {
+ using Str = std::string;
+ using Vec = std::vector<Str>;
+
+ { // `V` models simple-view
+ // `is_reference_v<InnerRng>` is true
+ // `Pattern` models simple-view
+ // `V` and `Pattern` contain some elements
+ using V = MaybeSimpleForwardView<true>;
+ using Pattern = MaybeSimplePattern<true>;
+ std::ranges::join_with_view<V, Pattern> jwv(V(Vec{"A", "B", "C"}), Pattern(Str{">>"}));
+ auto it = jwv.begin();
+ assert(std::ranges::equal(std::views::counted(it, 7), Str{"A>>B>>C"}));
+ }
+
+ { // `V` does not model simple-view
+ // `is_reference_v<InnerRng>` is true
+ // `Pattern` models simple-view
+ // `V` and `Pattern` are empty
+ using V = MaybeSimpleForwardView<false>;
+ using Pattern = MaybeSimplePattern<true>;
+ std::ranges::join_with_view<V, Pattern> jwv(V(Vec{}), Pattern(Str{}));
+ auto it = jwv.begin();
+ assert(it == jwv.end());
+ }
+
+ { // `V` models simple-view
+ // `is_reference_v<InnerRng>` is false
+ // `Pattern` models simple-view
+ // `V` contains two elements, `Pattern` is empty
+ using V = MaybeSimpleForwardRvalueView<true>;
+ using Pattern = MaybeSimplePattern<true>;
+ std::ranges::join_with_view<V, Pattern> jwv(V(Vec{"1", "2"}), Pattern(Str{""}));
+ auto it = jwv.begin();
+ assert(*it == '1');
+ assert(*++it == '2');
+ }
+
+ { // `V` models simple-view
+ // `is_reference_v<InnerRng>` is true
+ // `Pattern` does not model simple-view
+ // `V` contains one element, `Pattern` is empty
+ using V = MaybeSimpleForwardView<true>;
+ using Pattern = MaybeSimplePattern<false>;
+ std::ranges::join_with_view<V, Pattern> jwv(V(Vec{"07"}), Pattern(Str{}));
+ auto it = jwv.begin();
+ assert(*it++ == '0');
+ assert(*it == '7');
+ }
+
+ { // `V` does not model simple-view
+ // `is_reference_v<InnerRng>` is false
+ // `Pattern` models simple-view
+ // `V` contains three elements (2nd is empty), `Pattern` is not empty
+ using V = MaybeSimpleForwardRvalueView<false>;
+ using Pattern = MaybeSimplePattern<true>;
+ std::ranges::join_with_view<V, Pattern> jwv(V(Vec{"A", "", "C"}), Pattern(Str{"--"}));
+ auto it = jwv.begin();
+ assert(std::ranges::equal(std::views::counted(it, 6), Str("A----C")));
+ }
+
+ { // `V` does not model simple-view
+ // `is_reference_v<InnerRng>` is true
+ // `Pattern` does not model simple-view
+ // `V` contains some empty elements, `Pattern` is not empty
+ using V = MaybeSimpleForwardView<false>;
+ using Pattern = MaybeSimplePattern<false>;
+ std::ranges::join_with_view<V, Pattern> jwv(V(Vec{"", "", ""}), Pattern(Str{"-"}));
+ auto it = jwv.begin();
+ assert(*it++ == '-');
+ assert(*it == '-');
+ }
+
+ { // `V` models simple-view
+ // `is_reference_v<InnerRng>` is false
+ // `Pattern` does not model simple-view
+ // `V` contains two elements, `Pattern` is not empty
+ using V = MaybeSimpleForwardRvalueView<true>;
+ using Pattern = MaybeSimplePattern<false>;
+ std::ranges::join_with_view<V, Pattern> jwv(V(Vec{"X", "Z"}), Pattern(Str{"Y"}));
+ auto it = jwv.begin();
+ assert(*it == 'X');
+ assert(*++it == 'Y');
+ assert(*++it == 'Z');
+ }
+
+ { // `V` does not model simple-view
+ // `is_reference_v<InnerRng>` is false
+ // `Pattern` does not model simple-view
+ // `V` contains two empty elements, `Pattern` is not empty
+ using V = MaybeSimpleForwardRvalueView<false>;
+ using Pattern = MaybeSimplePattern<false>;
+ std::ranges::join_with_view<V, Pattern> jwv(V(Vec{"", ""}), Pattern(Str{"?"}));
+ auto it = jwv.begin();
+ assert(*it == '?');
+ assert(++it == jwv.end());
+ }
+
+ { // `V` does not model forward range
+ // `V` contains some empty elements, `Pattern` is empty
+ using V = BasicView<Vec, ViewProperties{.common = false}, cpp20_input_iterator>;
+ using Pattern = MaybeSimplePattern<false>;
+ std::ranges::join_with_view<V, Pattern> jwv(V(Vec{"", "", ""}), Pattern(Str{""}));
+ auto it = jwv.begin();
+ assert(it == jwv.end());
+ }
+}
+
+constexpr void test_const_begin() {
+ using Vec = std::vector<std::array<int, 2>>;
+ using Pat = std::array<int, 2>;
+
+ { // `const V` models forward range
+ // `const Pattern` models forward range
+ // `is_reference_v<range_reference_t<const V>>` is true
+ // `range_reference_t<const V>` models input range
+ using V = BasicView<Vec, ViewProperties{}, forward_iterator>;
+ using Pattern = BasicView<Pat, ViewProperties{}, forward_iterator>;
+
+ const std::ranges::join_with_view<V, Pattern> jwv{V{Vec{std::array{1, 2}, std::array{3, 4}}}, Pattern{Pat{0, 0}}};
+ auto it = jwv.begin();
+ assert(std::ranges::equal(std::views::counted(it, 6), std::array{1, 2, 0, 0, 3, 4}));
+ }
+
+ // `const V` does not model forward range
+ // `const Pattern` models forward range
+ // `is_reference_v<range_reference_t<const V>>` is true
+ // `range_reference_t<const V>` models input range
+ static_assert(!JoinWithViewHasConstBegin<BasicView<Vec, ViewProperties{.common = false}, cpp20_input_iterator>,
+ BasicView<Pat, ViewProperties{}, forward_iterator>>);
+
+ // `const V` models forward range
+ // `const Pattern` does not model forward range
+ // `is_reference_v<range_reference_t<const V>>` is true
+ // `range_reference_t<const V>` models input range
+ static_assert(!JoinWithViewHasConstBegin<BasicView<Vec, ViewProperties{}, forward_iterator>,
+ BasicView<Pat, ViewProperties{.common = false}, cpp20_input_iterator>>);
+
+ // `const V` models forward range
+ // `const Pattern` models forward range
+ // `is_reference_v<range_reference_t<const V>>` is false
+ // `range_reference_t<const V>` models input range
+ static_assert(
+ !JoinWithViewHasConstBegin<BasicView<RvalueVector<std::vector<int>>, ViewProperties{}, forward_iterator>,
+ BasicView<Pat, ViewProperties{}, forward_iterator>>);
+
+ // `const V` models forward range
+ // `const Pattern` models forward range
+ // `is_reference_v<range_reference_t<const V>>` is true
+ // `range_reference_t<const V>` does not model input range
+ static_assert(!JoinWithViewHasConstBegin<
+ BasicView<std::vector<InputRangeButOutputWhenConst<int>>, ViewProperties{}, forward_iterator>,
+ BasicView<Pat, ViewProperties{}, forward_iterator>>);
+
+ // `concatable<range_reference_t<const V>, const Pattern>` is not satisfied
+ // See also LWG-4074: compatible-joinable-ranges is underconstrained
+ static_assert(!JoinWithViewHasConstBegin<BasicVectorView<int, ViewProperties{}, forward_iterator>,
+ lwg4074::PatternWithProxyConstAccess>);
+
+ // Check situation when iterators returned by `begin()` and `begin() const` are the same
+ using JWV = std::ranges::join_with_view<MaybeSimpleForwardView<true>, MaybeSimplePattern<true>>;
+ static_assert(std::same_as<std::ranges::iterator_t<JWV&>, std::ranges::iterator_t<const JWV&>>);
+}
+
+constexpr bool test() {
+ test_begin();
+ test_const_begin();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/constraints.compile.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/constraints.compile.pass.cpp
new file mode 100644
index 0000000000000..86d624941d22f
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/constraints.compile.pass.cpp
@@ -0,0 +1,289 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// template <input_range V, forward_range Pattern>
+// requires view<V> && input_range<range_reference_t<V>> && view<Pattern> &&
+// compatible-joinable-ranges<range_reference_t<V>, Pattern>
+// class join_with_view;
+
+#include <ranges>
+
+#include <cstddef>
+#include <vector>
+
+#include "test_iterators.h"
+#include "../types.h"
+
+template <class View, class Pattern>
+concept CanFormJoinWithView = requires { typename std::ranges::join_with_view<View, Pattern>; };
+
+// join_with_view is not valid when `V` is not an input_range
+namespace test_when_view_is_not_an_input_range {
+struct View : std::ranges::view_base {
+ using It = cpp20_output_iterator<std::vector<int>*>;
+ It begin();
+ sentinel_wrapper<It> end();
+};
+
+struct Pattern : std::ranges::view_base {
+ int* begin();
+ int* end();
+};
+
+static_assert(std::ranges::range<View>);
+static_assert(!std::ranges::input_range<View>);
+static_assert(std::ranges::view<View>);
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::view<Pattern>);
+static_assert(!CanFormJoinWithView<View, Pattern>);
+} // namespace test_when_view_is_not_an_input_range
+
+// join_with_view is not valid when `Pattern` is not a forward_range
+namespace test_when_pattern_is_not_a_forward_range {
+struct View : std::ranges::view_base {
+ std::vector<float>* begin();
+ std::vector<float>* end();
+};
+
+struct Pattern : std::ranges::view_base {
+ using It = cpp20_input_iterator<float*>;
+ It begin();
+ sentinel_wrapper<It> end();
+};
+
+static_assert(std::ranges::input_range<View>);
+static_assert(std::ranges::view<View>);
+static_assert(!std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::view<Pattern>);
+static_assert(!CanFormJoinWithView<View, Pattern>);
+} // namespace test_when_pattern_is_not_a_forward_range
+
+// join_with_view is not valid when `V` does not model std::ranges::view
+namespace test_when_view_does_not_model_view {
+struct View {
+ std::vector<double>* begin();
+ std::vector<double>* end();
+};
+
+struct Pattern : std::ranges::view_base {
+ double* begin();
+ double* end();
+};
+
+static_assert(std::ranges::input_range<View>);
+static_assert(!std::ranges::view<View>);
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::view<Pattern>);
+static_assert(!CanFormJoinWithView<View, Pattern>);
+} // namespace test_when_view_does_not_model_view
+
+// join_with_view is not valid when `range_reference_t` of `V` is not an input_range
+namespace test_when_range_reference_t_of_view_is_not_an_input_range {
+struct InnerRange {
+ using It = cpp20_output_iterator<long*>;
+ It begin();
+ sentinel_wrapper<It> end();
+};
+
+struct View : std::ranges::view_base {
+ InnerRange* begin();
+ InnerRange* end();
+};
+
+struct Pattern : std::ranges::view_base {
+ long* begin();
+ long* end();
+};
+
+static_assert(std::ranges::range<InnerRange>);
+static_assert(!std::ranges::input_range<InnerRange>);
+static_assert(std::ranges::input_range<View>);
+static_assert(std::ranges::view<View>);
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::view<Pattern>);
+static_assert(!CanFormJoinWithView<View, Pattern>);
+} // namespace test_when_range_reference_t_of_view_is_not_an_input_range
+
+// join_with_view is not valid when `Pattern` does not model std::ranges::view
+namespace test_when_pattern_does_not_model_view {
+struct View : std::ranges::view_base {
+ std::vector<short>* begin();
+ std::vector<short>* end();
+};
+
+struct Pattern {
+ short* begin();
+ short* end();
+};
+
+static_assert(std::ranges::input_range<View>);
+static_assert(std::ranges::view<View>);
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(!std::ranges::view<Pattern>);
+static_assert(!CanFormJoinWithView<View, Pattern>);
+} // namespace test_when_pattern_does_not_model_view
+
+// join_with_view is not valid when `range_reference_t<View>` and pattern
+// does not model together compatible-joinable-ranges
+namespace test_when_used_ranges_are_not_concatable {
+using std::ranges::range_reference_t;
+using std::ranges::range_rvalue_reference_t;
+using std::ranges::range_value_t;
+
+template <class InnerRange>
+struct View : std::ranges::view_base {
+ InnerRange* begin();
+ InnerRange* end();
+};
+
+namespace no_concat_reference_t {
+struct ValueType {};
+
+struct InnerRange {
+ struct It {
+ using
diff erence_type = std::ptr
diff _t;
+ using value_type = ValueType;
+ struct reference {
+ operator value_type();
+ };
+
+ It& operator++();
+ void operator++(int);
+ reference operator*() const;
+ };
+
+ It begin();
+ sentinel_wrapper<It> end();
+};
+
+struct Pattern : std::ranges::view_base {
+ struct It {
+ using
diff erence_type = std::ptr
diff _t;
+ using value_type = ValueType;
+ struct reference {
+ operator value_type();
+ };
+
+ It& operator++();
+ It operator++(int);
+ reference operator*() const;
+ bool operator==(const It&) const;
+ friend value_type&& iter_move(const It&);
+ };
+
+ It begin();
+ It end();
+};
+
+static_assert(std::ranges::input_range<InnerRange>);
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::view<Pattern>);
+static_assert(!std::common_reference_with<range_reference_t<InnerRange>, range_reference_t<Pattern>>);
+static_assert(std::common_with<range_value_t<InnerRange>, range_value_t<Pattern>>);
+static_assert(std::common_reference_with<range_rvalue_reference_t<InnerRange>, range_rvalue_reference_t<Pattern>>);
+static_assert(!CanFormJoinWithView<View<InnerRange>, Pattern>);
+} // namespace no_concat_reference_t
+
+namespace no_concat_value_t {
+struct InnerRange {
+ struct It {
+ using
diff erence_type = std::ptr
diff _t;
+ struct value_type {};
+
+ struct reference {
+ operator value_type();
+ operator float();
+ };
+
+ It& operator++();
+ void operator++(int);
+ reference operator*() const;
+ };
+
+ It begin();
+ sentinel_wrapper<It> end();
+};
+
+struct Pattern : std::ranges::view_base {
+ const float* begin();
+ const float* end();
+};
+
+static_assert(std::ranges::input_range<InnerRange>);
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::view<Pattern>);
+static_assert(std::common_reference_with<range_reference_t<InnerRange>, range_reference_t<Pattern>>);
+static_assert(!std::common_with<range_value_t<InnerRange>, range_value_t<Pattern>>);
+static_assert(std::common_reference_with<range_rvalue_reference_t<InnerRange>, range_rvalue_reference_t<Pattern>>);
+static_assert(!CanFormJoinWithView<View<InnerRange>, Pattern>);
+} // namespace no_concat_value_t
+
+namespace no_concat_rvalue_reference_t {
+struct InnerRange {
+ using It = cpp20_input_iterator<int*>;
+ It begin();
+ sentinel_wrapper<It> end();
+};
+
+struct Pattern : std::ranges::view_base {
+ struct It {
+ using
diff erence_type = std::ptr
diff _t;
+ struct value_type {
+ operator int() const;
+ };
+
+ struct rvalue_reference {
+ operator value_type();
+ };
+
+ It& operator++();
+ It operator++(int);
+ value_type& operator*() const;
+ bool operator==(const It&) const;
+ friend rvalue_reference iter_move(const It&);
+ };
+
+ It begin();
+ It end();
+};
+
+static_assert(std::ranges::input_range<InnerRange>);
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::view<Pattern>);
+static_assert(std::common_reference_with<range_reference_t<InnerRange>, range_reference_t<Pattern>>);
+static_assert(std::common_with<range_value_t<InnerRange>, range_value_t<Pattern>>);
+static_assert(!std::common_reference_with<range_rvalue_reference_t<InnerRange>, range_rvalue_reference_t<Pattern>>);
+static_assert(!CanFormJoinWithView<View<InnerRange>, Pattern>);
+} // namespace no_concat_rvalue_reference_t
+
+namespace not_concat_indirectly_readable { // Required after LWG-4074 ("compatible-joinable-ranges is underconstrained")
+struct InnerRange {
+ using It = cpp20_input_iterator<int*>;
+ It begin();
+ sentinel_wrapper<It> end();
+};
+
+struct Pattern : std::ranges::view_base {
+ lwg4074::Iter begin();
+ lwg4074::Iter end();
+};
+
+static_assert(std::ranges::input_range<InnerRange>);
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::view<Pattern>);
+static_assert(std::common_reference_with<range_reference_t<InnerRange>, range_reference_t<Pattern>>);
+static_assert(std::common_with<range_value_t<InnerRange>, range_value_t<Pattern>>);
+static_assert(std::common_reference_with<range_rvalue_reference_t<InnerRange>, range_rvalue_reference_t<Pattern>>);
+LIBCPP_STATIC_ASSERT(!std::ranges::__concat_indirectly_readable<InnerRange, Pattern>);
+static_assert(!CanFormJoinWithView<View<InnerRange>, Pattern>);
+} // namespace not_concat_indirectly_readable
+} // namespace test_when_used_ranges_are_not_concatable
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctad.compile.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctad.compile.pass.cpp
new file mode 100644
index 0000000000000..07b70bc39cda4
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctad.compile.pass.cpp
@@ -0,0 +1,230 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// template<class R, class P>
+// join_with_view(R&&, P&&) -> join_with_view<views::all_t<R>, views::all_t<P>>;
+//
+// template<input_range R>
+// join_with_view(R&&, range_value_t<range_reference_t<R>>)
+// -> join_with_view<views::all_t<R>, single_view<range_value_t<range_reference_t<R>>>>;
+
+#include <ranges>
+
+#include <deque>
+#include <type_traits>
+
+#include "test_iterators.h"
+
+struct View : std::ranges::view_base {
+ using It = cpp20_input_iterator<std::deque<int>*>;
+
+ View() = default;
+ It begin() const;
+ sentinel_wrapper<It> end() const;
+};
+
+static_assert(std::ranges::input_range<View>);
+static_assert(std::ranges::view<View>);
+
+struct Pattern : std::ranges::view_base {
+ Pattern() = default;
+ forward_iterator<int*> begin();
+ forward_iterator<int*> end();
+};
+
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::view<Pattern>);
+
+// A range that is not a view
+struct Range {
+ using It = cpp20_input_iterator<std::deque<int>*>;
+
+ Range() = default;
+ It begin() const;
+ sentinel_wrapper<It> end() const;
+};
+
+static_assert(std::ranges::input_range<Range>);
+static_assert(!std::ranges::view<Range>);
+
+// A pattern that is not a view
+struct RangePattern {
+ RangePattern() = default;
+ forward_iterator<int*> begin();
+ forward_iterator<int*> end();
+};
+
+static_assert(std::ranges::forward_range<RangePattern>);
+static_assert(!std::ranges::view<RangePattern>);
+
+void test_range_and_pattern_deduction_guide() {
+ { // Both `v` and `pat` model `std::ranges::view`.
+ {
+ View v;
+ Pattern pat;
+ std::ranges::join_with_view view(v, pat);
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<View, Pattern>>);
+ }
+ {
+ View v;
+ std::ranges::join_with_view view(v, Pattern{});
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<View, Pattern>>);
+ }
+ {
+ Pattern pat;
+ std::ranges::join_with_view view(View{}, pat);
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<View, Pattern>>);
+ }
+ {
+ std::ranges::join_with_view view(View{}, Pattern{});
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<View, Pattern>>);
+ }
+ }
+
+ { // Only `pat` models `std::ranges::view`.
+ {
+ Range v;
+ Pattern pat;
+ std::ranges::join_with_view view(v, pat);
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<std::ranges::ref_view<Range>, Pattern>>);
+ }
+ {
+ Range v;
+ std::ranges::join_with_view view(v, Pattern{});
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<std::ranges::ref_view<Range>, Pattern>>);
+ }
+ {
+ Pattern pat;
+ std::ranges::join_with_view view(Range{}, pat);
+ static_assert(
+ std::is_same_v<decltype(view), std::ranges::join_with_view<std::ranges::owning_view<Range>, Pattern>>);
+ }
+ {
+ std::ranges::join_with_view view(Range{}, Pattern{});
+ static_assert(
+ std::is_same_v<decltype(view), std::ranges::join_with_view<std::ranges::owning_view<Range>, Pattern>>);
+ }
+ }
+
+ { // Only `v` models `std::ranges::view`.
+ {
+ View v;
+ RangePattern pat;
+ std::ranges::join_with_view view(v, pat);
+ static_assert(
+ std::is_same_v<decltype(view), std::ranges::join_with_view<View, std::ranges::ref_view<RangePattern>>>);
+ }
+ {
+ View v;
+ std::ranges::join_with_view view(v, RangePattern{});
+ static_assert(
+ std::is_same_v<decltype(view), std::ranges::join_with_view<View, std::ranges::owning_view<RangePattern>>>);
+ }
+ {
+ RangePattern pat;
+ std::ranges::join_with_view view(View{}, pat);
+ static_assert(
+ std::is_same_v<decltype(view), std::ranges::join_with_view<View, std::ranges::ref_view<RangePattern>>>);
+ }
+ {
+ std::ranges::join_with_view view(View{}, RangePattern{});
+ static_assert(
+ std::is_same_v<decltype(view), std::ranges::join_with_view<View, std::ranges::owning_view<RangePattern>>>);
+ }
+ }
+
+ { // Both `v` and `pat` don't model `std::ranges::view`.
+ {
+ Range r;
+ RangePattern pat;
+ std::ranges::join_with_view view(r, pat);
+ static_assert(std::is_same_v<
+ decltype(view),
+ std::ranges::join_with_view<std::ranges::ref_view<Range>, std::ranges::ref_view<RangePattern>>>);
+ }
+ {
+ Range r;
+ std::ranges::join_with_view view(r, RangePattern{});
+ static_assert(std::is_same_v<
+ decltype(view),
+ std::ranges::join_with_view<std::ranges::ref_view<Range>, std::ranges::owning_view<RangePattern>>>);
+ }
+ {
+ RangePattern pat;
+ std::ranges::join_with_view view(Range{}, pat);
+ static_assert(std::is_same_v<
+ decltype(view),
+ std::ranges::join_with_view<std::ranges::owning_view<Range>, std::ranges::ref_view<RangePattern>>>);
+ }
+ {
+ std::ranges::join_with_view view(Range{}, RangePattern{});
+ static_assert(
+ std::is_same_v<
+ decltype(view),
+ std::ranges::join_with_view<std::ranges::owning_view<Range>, std::ranges::owning_view<RangePattern>>>);
+ }
+ }
+}
+
+void test_range_and_element_deduction_guide() {
+ { // Element is lvalue
+ int elem = 0;
+
+ {
+ View v;
+ std::ranges::join_with_view view(v, elem);
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<View, std::ranges::single_view<int>>>);
+ }
+ {
+ std::ranges::join_with_view view(View{}, elem);
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<View, std::ranges::single_view<int>>>);
+ }
+ {
+ Range r;
+ std::ranges::join_with_view view(r, elem);
+ static_assert(
+ std::is_same_v<decltype(view),
+ std::ranges::join_with_view<std::ranges::ref_view<Range>, std::ranges::single_view<int>>>);
+ }
+ {
+ std::ranges::join_with_view view(Range{}, elem);
+ static_assert(
+ std::is_same_v<decltype(view),
+ std::ranges::join_with_view<std::ranges::owning_view<Range>, std::ranges::single_view<int>>>);
+ }
+ }
+
+ { // Element is rvalue
+ {
+ View v;
+ std::ranges::join_with_view view(v, 1);
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<View, std::ranges::single_view<int>>>);
+ }
+ {
+ std::ranges::join_with_view view(View{}, 1);
+ static_assert(std::is_same_v<decltype(view), std::ranges::join_with_view<View, std::ranges::single_view<int>>>);
+ }
+ {
+ Range r;
+ std::ranges::join_with_view view(r, 1);
+ static_assert(
+ std::is_same_v<decltype(view),
+ std::ranges::join_with_view<std::ranges::ref_view<Range>, std::ranges::single_view<int>>>);
+ }
+ {
+ std::ranges::join_with_view view(Range{}, 1);
+ static_assert(
+ std::is_same_v<decltype(view),
+ std::ranges::join_with_view<std::ranges::owning_view<Range>, std::ranges::single_view<int>>>);
+ }
+ }
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.default.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.default.pass.cpp
new file mode 100644
index 0000000000000..2177ea48ce851
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.default.pass.cpp
@@ -0,0 +1,77 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// join_with_view()
+// requires default_initializable<V> && default_initializable<Pattern> = default;
+
+#include <ranges>
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <type_traits>
+
+static constexpr auto view = std::to_array<std::array<int, 2>>({{1, 2}, {3, 4}, {5, 6}});
+
+struct TrivialView : std::ranges::view_base {
+ int val_; // intentionally uninitialized
+
+ constexpr auto begin() { return view.data(); }
+ constexpr auto end() { return view.data() + view.size(); }
+};
+
+static_assert(std::is_trivially_copyable_v<TrivialView> && std::is_trivially_default_constructible_v<TrivialView>);
+
+struct NonDefaultConstructibleView : TrivialView {
+ NonDefaultConstructibleView(int);
+};
+
+struct TrivialPattern : std::ranges::view_base {
+ int val_; // intentionally uninitialized
+
+ constexpr int* begin() { return &val_; }
+ constexpr int* end() { return &val_ + 1; }
+};
+
+static_assert(std::is_trivially_copyable_v<TrivialPattern> &&
+ std::is_trivially_default_constructible_v<TrivialPattern>);
+
+struct NonDefaultConstructiblePattern : TrivialPattern {
+ NonDefaultConstructiblePattern(int);
+};
+
+constexpr bool test() {
+ { // Check if `base_` and `pattern_` are value initialised
+ std::ranges::join_with_view<TrivialView, TrivialPattern> v;
+ assert(std::move(v).base().val_ == 0);
+ assert(std::ranges::equal(v, std::array{1, 2, 0, 3, 4, 0, 5, 6}));
+ }
+
+ { // Default constructor should not be explicit
+ [[maybe_unused]] std::ranges::join_with_view<TrivialView, TrivialPattern> v = {};
+ }
+
+ static_assert(std::default_initializable<std::ranges::join_with_view<TrivialView, TrivialPattern>>);
+ static_assert(!std::default_initializable<std::ranges::join_with_view<TrivialView, NonDefaultConstructiblePattern>>);
+ static_assert(!std::default_initializable<std::ranges::join_with_view<NonDefaultConstructibleView, TrivialPattern>>);
+ static_assert(!std::default_initializable<
+ std::ranges::join_with_view<NonDefaultConstructibleView, NonDefaultConstructiblePattern>>);
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.element.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.element.pass.cpp
new file mode 100644
index 0000000000000..7266912e41fdf
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.element.pass.cpp
@@ -0,0 +1,244 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// template<input_range R>
+// requires constructible_from<V, views::all_t<R>> &&
+// constructible_from<Pattern, single_view<range_value_t<InnerRng>>>
+// constexpr explicit join_with_view(R&& r, range_value_t<InnerRng> e);
+
+#include <ranges>
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <type_traits>
+#include <utility>
+
+#include "../types.h"
+#include "test_iterators.h"
+#include "test_range.h"
+
+struct MoveOnlyInt {
+ MoveOnlyInt() = default;
+ MoveOnlyInt(MoveOnlyInt&&) = default;
+ MoveOnlyInt& operator=(MoveOnlyInt&&) = default;
+
+ constexpr MoveOnlyInt(int val) : val_(val) {}
+ constexpr operator int() const { return val_; }
+
+ int val_ = 0;
+};
+
+template <>
+struct std::common_type<MoveOnlyInt, int> {
+ using type = int;
+};
+
+template <>
+struct std::common_type<int, MoveOnlyInt> {
+ using type = int;
+};
+
+struct OutputView : std::ranges::view_base {
+ using It = cpp20_output_iterator<int*>;
+ It begin() const;
+ sentinel_wrapper<It> end() const;
+};
+
+static_assert(std::ranges::output_range<OutputView, int>);
+static_assert(std::ranges::view<OutputView>);
+
+struct InputRange {
+ using It = cpp20_input_iterator<int*>;
+ It begin() const;
+ sentinel_wrapper<It> end() const;
+};
+
+struct InputView : InputRange, std::ranges::view_base {};
+
+static_assert(std::ranges::input_range<InputRange>);
+static_assert(std::ranges::input_range<const InputRange>);
+static_assert(std::ranges::view<InputView>);
+static_assert(std::ranges::input_range<InputView>);
+static_assert(std::ranges::input_range<const InputView>);
+
+class View : public std::ranges::view_base {
+ using OuterRange = std::array<std::array<MoveOnlyInt, 2>, 3>;
+
+ static constexpr OuterRange range_on_input_view = {{{1, 1}, {1, 1}, {1, 1}}};
+ static constexpr OuterRange range_on_ref_input_range = {{{2, 2}, {2, 2}, {2, 2}}};
+ static constexpr OuterRange range_on_const_ref_input_range = {{{3, 3}, {3, 3}, {3, 3}}};
+ static constexpr OuterRange range_on_owning_input_range = {{{4, 4}, {4, 4}, {4, 4}}};
+
+ const OuterRange* r_;
+
+public:
+ // Those functions should never be called in this test.
+ View(View&&) { assert(false); }
+ View(OutputView) { assert(false); }
+ View& operator=(View&&) {
+ assert(false);
+ return *this;
+ }
+
+ constexpr explicit View(InputView) : r_(&range_on_input_view) {}
+ constexpr explicit View(InputRange) = delete;
+ constexpr explicit View(std::ranges::ref_view<InputRange>) : r_(&range_on_ref_input_range) {}
+ constexpr explicit View(std::ranges::ref_view<const InputRange>) : r_(&range_on_const_ref_input_range) {}
+ constexpr explicit View(std::ranges::owning_view<InputRange>) : r_(&range_on_owning_input_range) {}
+
+ constexpr auto begin() const { return r_->begin(); }
+ constexpr auto end() const { return r_->end(); }
+};
+
+static_assert(std::ranges::input_range<View>);
+static_assert(std::ranges::input_range<const View>);
+
+class Pattern : public std::ranges::view_base {
+ int val_;
+
+public:
+ // Those functions should never be called in this test.
+ Pattern(Pattern&&) { assert(false); }
+ template <class T>
+ Pattern(const std::ranges::single_view<T>&) {
+ assert(false);
+ }
+ Pattern& operator=(Pattern&&) {
+ assert(false);
+ return *this;
+ }
+
+ template <class T>
+ constexpr explicit Pattern(std::ranges::single_view<T>&& v) : val_(v[0]) {}
+
+ constexpr const int* begin() const { return &val_; }
+ constexpr const int* end() const { return &val_ + 1; }
+};
+
+static_assert(std::ranges::forward_range<Pattern>);
+static_assert(std::ranges::forward_range<const Pattern>);
+
+constexpr void test_ctor_with_view_and_element() {
+ // Check construction from `r` and `e`, when `r` models `std::ranges::view`
+
+ { // `r` and `e` are glvalues
+ InputView r;
+ int e = 0;
+ std::ranges::join_with_view<View, Pattern> jwv(r, e);
+ assert(std::ranges::equal(jwv, std::array{1, 1, 0, 1, 1, 0, 1, 1}));
+ }
+
+ { // `r` and `e` are const glvalues
+ const InputView r;
+ const int e = 1;
+ std::ranges::join_with_view<View, Pattern> jwv(r, e);
+ assert(std::ranges::equal(jwv, std::array{1, 1, 1, 1, 1, 1, 1, 1}));
+ }
+
+ { // `r` and `e` are prvalues
+ std::ranges::join_with_view<View, Pattern> jwv(InputView{}, MoveOnlyInt{2});
+ assert(std::ranges::equal(jwv, std::array{1, 1, 2, 1, 1, 2, 1, 1}));
+ }
+
+ { // `r` and `e` are xvalues
+ InputView r;
+ MoveOnlyInt e = 3;
+ std::ranges::join_with_view<View, Pattern> jwv(std::move(r), std::move(e));
+ assert(std::ranges::equal(jwv, std::array{1, 1, 3, 1, 1, 3, 1, 1}));
+ }
+
+ // Check explicitness
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, InputView, MoveOnlyInt>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, InputView, int>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, InputView&, int&>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, const InputView, const int>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, const InputView&, const int&>);
+}
+
+constexpr void test_ctor_with_non_view_and_element() {
+ // Check construction from `r` and `e`, when `r` does not model `std::ranges::view`
+
+ { // `r` and `e` are glvalues
+ InputRange r;
+ int e = 0;
+ std::ranges::join_with_view<View, Pattern> jwv(r, e);
+ assert(std::ranges::equal(jwv, std::array{2, 2, 0, 2, 2, 0, 2, 2}));
+ }
+
+ { // `r` and `e` are const glvalues
+ const InputRange r;
+ const int e = 1;
+ std::ranges::join_with_view<View, Pattern> jwv(r, e);
+ assert(std::ranges::equal(jwv, std::array{3, 3, 1, 3, 3, 1, 3, 3}));
+ }
+
+ { // `r` and `e` are prvalues
+ std::ranges::join_with_view<View, Pattern> jwv(InputRange{}, MoveOnlyInt{2});
+ assert(std::ranges::equal(jwv, std::array{4, 4, 2, 4, 4, 2, 4, 4}));
+ }
+
+ { // `r` and `e` are xvalues
+ InputRange r;
+ MoveOnlyInt e = 3;
+ std::ranges::join_with_view<View, Pattern> jwv(std::move(r), std::move(e));
+ assert(std::ranges::equal(jwv, std::array{4, 4, 3, 4, 4, 3, 4, 4}));
+ }
+
+ // Check explicitness
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, InputRange, MoveOnlyInt>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, InputRange, int>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, InputRange&, int&>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, const InputRange&, const int&>);
+}
+
+constexpr void test_constraints() {
+ { // `R` is not an input range
+ using R = OutputView;
+ static_assert(!std::ranges::input_range<R>);
+ static_assert(std::constructible_from<View, std::views::all_t<R>>);
+ static_assert(std::constructible_from<Pattern, std::ranges::single_view<int>>);
+ static_assert(!std::constructible_from<std::ranges::join_with_view<View, Pattern>, R, int>);
+ }
+
+ { // `V` is not constructible from `views::all_t<R>`
+ using R = test_range<cpp20_input_iterator>;
+ static_assert(std::ranges::input_range<R>);
+ static_assert(!std::constructible_from<View, std::views::all_t<R>>);
+ static_assert(std::constructible_from<Pattern, std::ranges::single_view<int>>);
+ static_assert(!std::constructible_from<std::ranges::join_with_view<View, Pattern>, R, int>);
+ }
+
+ { // `Pattern` is not constructible from `single_view<range_value_t<InnerRng>>`
+ using R = InputView;
+ using Pat = test_view<forward_iterator>;
+ static_assert(std::ranges::input_range<R>);
+ static_assert(std::constructible_from<View, std::views::all_t<R>>);
+ static_assert(!std::constructible_from<Pat, std::ranges::single_view<int>>);
+ static_assert(!std::constructible_from<std::ranges::join_with_view<View, Pat>, R, int>);
+ }
+}
+
+constexpr bool test() {
+ test_ctor_with_view_and_element();
+ test_ctor_with_non_view_and_element();
+ test_constraints();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.pattern.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.pattern.pass.cpp
new file mode 100644
index 0000000000000..d3ee228ab0eb8
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.pattern.pass.cpp
@@ -0,0 +1,111 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// constexpr explicit join_with_view(V base, Pattern pattern);
+
+#include <ranges>
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <utility>
+
+#include "../types.h"
+
+class View : public std::ranges::view_base {
+ using OuterRange = std::array<std::array<int, 2>, 3>;
+
+ static constexpr OuterRange default_range = {{{1, 2}, {3, 4}, {5, 6}}};
+ static constexpr OuterRange range_on_move = {{{6, 5}, {4, 3}, {2, 1}}};
+
+ const OuterRange* r_ = &default_range;
+
+public:
+ View() = default;
+ constexpr View(const View&) : r_(&default_range) {}
+ constexpr View(View&&) : r_(&range_on_move) {}
+
+ constexpr View& operator=(View) {
+ r_ = &default_range;
+ return *this;
+ }
+
+ constexpr auto begin() { return r_->begin(); }
+ constexpr auto end() { return r_->end(); }
+};
+
+class Pattern : public std::ranges::view_base {
+ using PatternRange = std::array<int, 2>;
+
+ static constexpr PatternRange default_range = {0, 0};
+ static constexpr PatternRange range_on_move = {7, 7};
+
+ const PatternRange* val_ = &default_range;
+
+public:
+ Pattern() = default;
+ constexpr Pattern(const Pattern&) : val_(&default_range) {}
+ constexpr Pattern(Pattern&&) : val_(&range_on_move) {}
+
+ constexpr Pattern& operator=(Pattern) {
+ val_ = &default_range;
+ return *this;
+ }
+
+ constexpr auto begin() { return val_->begin(); }
+ constexpr auto end() { return val_->end(); }
+};
+
+constexpr bool test() {
+ { // Check construction from `view` and `pattern`
+ { // `view` and `pattern` are glvalues
+ View v;
+ Pattern p;
+ std::ranges::join_with_view<View, Pattern> jwv(v, p);
+ assert(std::ranges::equal(jwv, std::array{6, 5, 7, 7, 4, 3, 7, 7, 2, 1}));
+ }
+
+ { // `view` and `pattern` are const glvalues
+ const View v;
+ const Pattern p;
+ std::ranges::join_with_view<View, Pattern> jwv(v, p);
+ assert(std::ranges::equal(jwv, std::array{6, 5, 7, 7, 4, 3, 7, 7, 2, 1}));
+ }
+
+ { // `view` and `pattern` are prvalues
+ std::ranges::join_with_view<View, Pattern> jwv(View{}, Pattern{});
+ assert(std::ranges::equal(jwv, std::array{6, 5, 7, 7, 4, 3, 7, 7, 2, 1}));
+ }
+
+ { // `view` and `pattern` are xvalues
+ View v;
+ Pattern p;
+ std::ranges::join_with_view<View, Pattern> jwv(std::move(v), std::move(p));
+ assert(std::ranges::equal(jwv, std::array{6, 5, 7, 7, 4, 3, 7, 7, 2, 1}));
+ }
+ }
+
+ // Check explicitness
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, View, Pattern>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, View&, Pattern&>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, const View, const Pattern>);
+ static_assert(ConstructionIsExplicit<std::ranges::join_with_view<View, Pattern>, const View&, const Pattern&>);
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/end.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/end.pass.cpp
new file mode 100644
index 0000000000000..c6e973abfface
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/end.pass.cpp
@@ -0,0 +1,232 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// constexpr auto end();
+// constexpr auto end() const
+// requires forward_range<const V> && forward_range<const Pattern> &&
+// is_reference_v<range_reference_t<const V>> &&
+// input_range<range_reference_t<const V>>;
+
+// ADDITIONAL_COMPILE_FLAGS(has-fconstexpr-steps): -fconstexpr-steps=10000000
+
+#include <ranges>
+
+#include <algorithm>
+#include <string>
+#include <vector>
+
+#include "../types.h"
+#include "test_iterators.h"
+
+template <class V, class Pattern>
+concept JoinWithViewHasConstEnd = requires(const std::ranges::join_with_view<V, Pattern> jwv) { jwv.end(); };
+
+template <size_t Bits>
+ requires(Bits < (1 << 7))
+constexpr void test_end() {
+ constexpr bool v_models_forward_range = static_cast<bool>(Bits & (1 << 0));
+ constexpr bool inner_range_is_reference = static_cast<bool>(Bits & (1 << 1));
+ constexpr bool inner_range_models_forward_range = static_cast<bool>(Bits & (1 << 2));
+ constexpr bool v_models_common_range = static_cast<bool>(Bits & (1 << 3));
+ constexpr bool inner_range_models_common_range = static_cast<bool>(Bits & (1 << 4));
+ constexpr bool v_models_simple_range = static_cast<bool>(Bits & (1 << 5));
+ constexpr bool pattern_models_simple_range = static_cast<bool>(Bits & (1 << 6));
+
+ constexpr ViewProperties inner_range_props{.common = inner_range_models_common_range};
+ using InnerRange =
+ std::conditional_t<inner_range_models_forward_range,
+ BasicView<std::vector<int>, inner_range_props, forward_iterator>,
+ BasicView<std::vector<int>, inner_range_props, DefaultCtorInputIter>>;
+
+ constexpr ViewProperties v_props{.simple = v_models_simple_range, .common = v_models_common_range};
+ using UnderlyingV = std::conditional_t<inner_range_is_reference, std::vector<InnerRange>, RvalueVector<InnerRange>>;
+ using V = std::conditional_t<v_models_forward_range,
+ BasicView<UnderlyingV, v_props, forward_iterator>,
+ BasicView<UnderlyingV, v_props, DefaultCtorInputIter>>;
+
+ using UnderlyingPattern = std::vector<int>;
+ using Pattern = BasicView<UnderlyingPattern, ViewProperties{.simple = pattern_models_simple_range}, forward_iterator>;
+
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Iter = std::ranges::iterator_t<JWV>;
+
+ // Test when `JWV` models common range
+ static_assert(std::same_as<Iter, std::ranges::sentinel_t<JWV>> ==
+ (v_models_forward_range && inner_range_is_reference && inner_range_models_forward_range &&
+ v_models_common_range && inner_range_models_common_range));
+
+ { // `V` and `Pattern` are empty
+ V v{};
+ Pattern pattern{};
+ JWV jwv(std::move(v), std::move(pattern));
+ Iter it = jwv.begin();
+ std::sentinel_for<Iter> decltype(auto) se = jwv.end();
+ assert(it == se);
+ }
+
+ { // `V` is empty, `Pattern` contains some elements
+ V v{};
+ Pattern pattern{std::vector<int>{0}};
+ JWV jwv(std::move(v), std::move(pattern));
+ Iter it = jwv.begin();
+ std::sentinel_for<Iter> decltype(auto) se = jwv.end();
+ assert(it == se);
+ }
+
+ { // `V` is not empty, `Pattern is empty`
+ V v{UnderlyingV{
+ std::vector<InnerRange>{InnerRange(std::vector<int>{1, 2, 3}), InnerRange(std::vector<int>{4, 5, 6})}}};
+ Pattern pattern{};
+ JWV jwv(std::move(v), std::move(pattern));
+ Iter it = jwv.begin();
+ std::sentinel_for<Iter> decltype(auto) se = jwv.end();
+ assert(std::ranges::next(it, 6) == se);
+ }
+
+ { // `V` and `Pattern` are not empty
+ V v{UnderlyingV{std::vector<InnerRange>{
+ InnerRange(std::vector<int>{6, 5}),
+ InnerRange(std::vector<int>{4, 3}),
+ InnerRange(std::vector<int>{2, 1, 0})}}};
+ Pattern pattern{std::vector<int>{-1, -1}};
+ JWV jwv(std::move(v), std::move(pattern));
+ Iter it = jwv.begin();
+ std::sentinel_for<Iter> decltype(auto) se = jwv.end();
+ assert(std::ranges::next(it, 11) == se);
+ }
+}
+
+template <std::size_t Bits>
+ requires(Bits < (1 << 7))
+constexpr void test_const_end() {
+ constexpr bool const_v_models_forward_range = static_cast<bool>(Bits & (1 << 0));
+ constexpr bool const_pattern_models_forward_range = static_cast<bool>(Bits & (1 << 1));
+ constexpr bool inner_const_range_is_reference = static_cast<bool>(Bits & (1 << 2));
+ constexpr bool inner_const_range_models_input_range = static_cast<bool>(Bits & (1 << 3));
+ constexpr bool inner_const_range_models_forward_range = static_cast<bool>(Bits & (1 << 4));
+ constexpr bool const_v_models_common_range = static_cast<bool>(Bits & (1 << 5));
+ constexpr bool inner_const_range_models_common_range = static_cast<bool>(Bits & (1 << 6));
+
+ constexpr ViewProperties inner_range_props{.common = inner_const_range_models_common_range};
+ using InnerRange =
+ std::conditional_t<inner_const_range_models_forward_range,
+ BasicView<std::vector<int>, inner_range_props, forward_iterator>,
+ std::conditional_t<inner_const_range_models_input_range,
+ BasicView<std::vector<int>, inner_range_props, DefaultCtorInputIter>,
+ InputRangeButOutputWhenConst<int>>>;
+
+ constexpr ViewProperties v_props{.common = const_v_models_common_range};
+ using UnderlyingV =
+ std::conditional_t<inner_const_range_is_reference, std::vector<InnerRange>, RvalueVector<InnerRange>>;
+ using V = std::conditional_t<const_v_models_forward_range,
+ BasicView<UnderlyingV, v_props, forward_iterator>,
+ BasicView<UnderlyingV, v_props, DefaultCtorInputIter>>;
+ using Pattern =
+ std::conditional_t<const_pattern_models_forward_range,
+ BasicView<std::vector<int>, ViewProperties{}, forward_iterator>,
+ ForwardViewButInputWhenConst<int>>;
+
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ static_assert(JoinWithViewHasConstEnd<V, Pattern> ==
+ (const_v_models_forward_range && const_pattern_models_forward_range && inner_const_range_is_reference &&
+ (inner_const_range_models_input_range || inner_const_range_models_forward_range)));
+ static_assert(JoinWithViewHasConstEnd<V, Pattern> == std::ranges::range<const JWV>);
+
+ if constexpr (std::ranges::range<const JWV>) {
+ using ConstIter = std::ranges::iterator_t<const JWV>;
+
+ // Test when `const JWV` models common range
+ static_assert(std::same_as<ConstIter, std::ranges::sentinel_t<const JWV>> ==
+ (inner_const_range_models_forward_range && const_v_models_common_range &&
+ inner_const_range_models_common_range));
+
+ { // `const V` and `const Pattern` are empty
+ V v{};
+ Pattern pattern{};
+ const JWV jwv(std::move(v), std::move(pattern));
+ ConstIter it = jwv.begin();
+ std::sentinel_for<ConstIter> decltype(auto) se = jwv.end();
+ assert(it == se);
+ }
+
+ { // `const V` is empty, `const Pattern` contains some elements
+ V v{};
+ Pattern pattern{std::vector<int>{1}};
+ const JWV jwv(std::move(v), std::move(pattern));
+ ConstIter it = jwv.begin();
+ std::sentinel_for<ConstIter> decltype(auto) se = jwv.end();
+ assert(it == se);
+ }
+
+ { // `const V` is not empty, `const Pattern is empty`
+ V v{UnderlyingV{
+ std::vector<InnerRange>{InnerRange(std::vector<int>{1, 2, 3}), InnerRange(std::vector<int>{4, 5, 6})}}};
+ Pattern pattern{};
+ const JWV jwv(std::move(v), std::move(pattern));
+ ConstIter it = jwv.begin();
+ std::sentinel_for<ConstIter> decltype(auto) se = jwv.end();
+ assert(std::ranges::next(it, 6) == se);
+ }
+
+ { // `const V` and `const Pattern` are not empty
+ V v{UnderlyingV{std::vector<InnerRange>{
+ InnerRange(std::vector<int>{1}), InnerRange(std::vector<int>{2, 2}), InnerRange(std::vector<int>{3, 3, 3})}}};
+ Pattern pattern{std::vector<int>{0}};
+ const JWV jwv(std::move(v), std::move(pattern));
+ ConstIter it = jwv.begin();
+ std::sentinel_for<ConstIter> decltype(auto) se = jwv.end();
+ assert(std::ranges::next(it, 8) == se);
+ }
+ }
+}
+
+constexpr bool test() {
+ []<std::size_t... Bits>(std::index_sequence<Bits...>) {
+ (test_end<Bits>(), ...);
+ (test_const_end<Bits>(), ...);
+ }(std::make_index_sequence<(1 << 7)>{});
+
+ { // Check situation when iterators returned by `end()` and `end() const` are of the same type
+ using V = BasicView<std::vector<std::string>, ViewProperties{.simple = true}, forward_iterator>;
+ using Pattern = BasicView<std::string, ViewProperties{.simple = true}, forward_iterator>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Sentinel = std::ranges::sentinel_t<JWV&>;
+ using ConstSentinel = std::ranges::sentinel_t<const JWV&>;
+ static_assert(std::input_iterator<Sentinel>);
+ static_assert(std::input_iterator<ConstSentinel>);
+ static_assert(std::same_as<Sentinel, ConstSentinel>);
+ }
+
+ { // Check situation when sentinels returned by `end()` and `end() const` are of the same type
+ using V = BasicView<std::vector<std::string>, ViewProperties{.simple = true, .common = false}, forward_iterator>;
+ using Pattern = BasicView<std::string, ViewProperties{.simple = true}, forward_iterator>;
+ using JWV = std::ranges::join_with_view<V, Pattern>;
+ using Sentinel = std::ranges::sentinel_t<JWV&>;
+ using ConstSentinel = std::ranges::sentinel_t<const JWV&>;
+ static_assert(!std::input_iterator<Sentinel>);
+ static_assert(!std::input_iterator<ConstSentinel>);
+ static_assert(std::same_as<Sentinel, ConstSentinel>);
+ }
+
+ // Check LWG-4074: compatible-joinable-ranges is underconstrained
+ static_assert(!JoinWithViewHasConstEnd<BasicVectorView<int, ViewProperties{}, forward_iterator>,
+ lwg4074::PatternWithProxyConstAccess>);
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/inheritance.compile.pass.cpp b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/inheritance.compile.pass.cpp
new file mode 100644
index 0000000000000..dff8817666531
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/inheritance.compile.pass.cpp
@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// REQUIRES: std-at-least-c++23
+
+// <ranges>
+
+// class join_with_view : public view_interface<join_with_view<V, Pattern>>
+
+#include <ranges>
+
+#include <concepts>
+#include <string>
+#include <vector>
+
+template <class T>
+struct View : std::ranges::view_base {
+ std::vector<T>* begin();
+ std::vector<T>* end();
+};
+
+template <class T>
+struct Pattern : std::ranges::view_base {
+ T* begin();
+ T* end();
+};
+
+template <class T>
+using JoinWithView = std::ranges::join_with_view<View<T>, Pattern<T>>;
+
+static_assert(std::derived_from<JoinWithView<int>, std::ranges::view_interface<JoinWithView<int>>>);
+static_assert(std::derived_from<JoinWithView<void*>, std::ranges::view_interface<JoinWithView<void*>>>);
+static_assert(std::derived_from<JoinWithView<std::string>, std::ranges::view_interface<JoinWithView<std::string>>>);
diff --git a/libcxx/test/std/ranges/range.adaptors/range.join.with/types.h b/libcxx/test/std/ranges/range.adaptors/range.join.with/types.h
new file mode 100644
index 0000000000000..588c647cef23a
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/types.h
@@ -0,0 +1,319 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef TEST_STD_RANGES_RANGE_ADAPTORS_RANGE_JOIN_WITH_TYPES_H
+#define TEST_STD_RANGES_RANGE_ADAPTORS_RANGE_JOIN_WITH_TYPES_H
+
+#include <cstddef>
+#include <initializer_list>
+#include <ranges>
+#include <string>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+#include "test_iterators.h"
+#include "test_macros.h"
+#include "test_range.h"
+
+template <class Tp>
+void pass_value(Tp);
+
+template <class Tp, class... Args>
+concept ConstructionIsExplicit = std::constructible_from<Tp, Args...> && !requires(Args&&... args) {
+ pass_value<Tp>({std::forward<Args>(args)...});
+};
+
+struct ViewProperties {
+ bool simple = false;
+ bool common = true;
+};
+
+template <std::ranges::input_range Data,
+ ViewProperties Prop,
+ template <class...> class It,
+ template <class...> class ConstIt = It>
+class BasicView : public std::ranges::view_base {
+ Data data_;
+
+public:
+ constexpr BasicView()
+ requires std::default_initializable<Data>
+ = default;
+
+ template <class R>
+ constexpr explicit BasicView(R&& r)
+ requires requires { std::ranges::to<Data>(std::forward<R>(r)); }
+ /*******/ : data_(std::ranges::to<Data>(std::forward<R>(r))) {}
+
+ constexpr explicit BasicView(std::initializer_list<std::ranges::range_value_t<Data>> il)
+ : data_(std::ranges::to<Data>(il)) {}
+
+ constexpr auto begin()
+ requires(!Prop.simple)
+ {
+ return It(data_.begin());
+ }
+
+ constexpr auto end()
+ requires(!Prop.simple)
+ {
+ if constexpr (Prop.common)
+ return It(data_.end());
+ else
+ return sentinel_wrapper(It(data_.end()));
+ }
+
+ constexpr auto begin() const { return ConstIt(data_.begin()); }
+
+ constexpr auto end() const {
+ if constexpr (Prop.common)
+ return ConstIt(data_.end());
+ else
+ return sentinel_wrapper(ConstIt(data_.end()));
+ }
+};
+
+template <class Tp, ViewProperties Prop, template <class...> class It, template <class...> class ConstIt = It>
+using BasicVectorView = BasicView<std::vector<Tp>, Prop, It, ConstIt>;
+
+struct AsPrvalue {
+ template <class Tp>
+ constexpr auto operator()(Tp&& t) const {
+ return std::forward<Tp>(t);
+ }
+};
+
+template <class Tp>
+class RvalueVector {
+ using Vec = std::vector<Tp>;
+ std::ranges::transform_view<std::ranges::owning_view<Vec>, AsPrvalue> range_;
+
+public:
+ constexpr RvalueVector() = default;
+ constexpr explicit RvalueVector(Vec vec) : range_(std::move(vec), AsPrvalue{}) {}
+ constexpr explicit RvalueVector(std::initializer_list<Tp> il) : RvalueVector(Vec(il)) {}
+
+ constexpr auto begin() { return range_.begin(); }
+ constexpr auto end() { return range_.end(); }
+ constexpr auto begin() const { return range_.begin(); }
+ constexpr auto end() const { return range_.end(); }
+};
+
+template <class It>
+class DefaultCtorInputIter {
+ It it_ = It();
+
+public:
+ using value_type = std::iter_value_t<It>;
+ using
diff erence_type = std::iter_
diff erence_t<It>;
+
+ DefaultCtorInputIter() = default;
+ constexpr explicit DefaultCtorInputIter(It it) : it_(it) {}
+
+ constexpr DefaultCtorInputIter& operator++() {
+ ++it_;
+ return *this;
+ }
+
+ constexpr void operator++(int) { ++*this; }
+ constexpr decltype(auto) operator*() const { return *it_; }
+ constexpr bool operator==(const DefaultCtorInputIter&) const = default;
+};
+
+template <class It>
+DefaultCtorInputIter(It) -> DefaultCtorInputIter<It>;
+
+template <class Tp>
+class InputRangeButOutputWhenConst {
+ using Vec = std::vector<Tp>;
+ std::ranges::ref_view<Vec> range_;
+
+public:
+ constexpr explicit InputRangeButOutputWhenConst(Vec& vec) : range_(vec) {}
+
+ constexpr auto begin() { return cpp20_input_iterator(range_.begin()); }
+ constexpr auto end() { return sentinel_wrapper(cpp20_input_iterator(range_.end())); }
+ constexpr auto begin() const { return cpp20_output_iterator(range_.begin()); }
+ constexpr auto end() const { return sentinel_wrapper(cpp20_output_iterator(range_.end())); }
+};
+
+template <class Tp>
+using ForwardViewButInputWhenConst =
+ BasicVectorView<Tp, ViewProperties{.common = false}, forward_iterator, cpp20_input_iterator>;
+
+template <class It>
+class ForwardIteratorWithInputCategory {
+ It it_ = It();
+
+public:
+ using value_type = std::iter_value_t<It>;
+ using
diff erence_type = std::iter_
diff erence_t<It>;
+ using iterator_concept = std::forward_iterator_tag;
+ using iterator_category = std::input_iterator_tag;
+
+ ForwardIteratorWithInputCategory() = default;
+ explicit ForwardIteratorWithInputCategory(It it);
+
+ std::iter_reference_t<It> operator*() const;
+ ForwardIteratorWithInputCategory& operator++();
+ ForwardIteratorWithInputCategory operator++(int);
+ bool operator==(const ForwardIteratorWithInputCategory&) const;
+};
+
+template <class It>
+explicit ForwardIteratorWithInputCategory(It) -> ForwardIteratorWithInputCategory<It>;
+
+template <class It>
+class EqComparableInputIter {
+ It it_;
+
+public:
+ using value_type = std::iter_value_t<It>;
+ using
diff erence_type = std::iter_
diff erence_t<It>;
+
+ constexpr explicit EqComparableInputIter(It it) : it_(it) {}
+
+ constexpr decltype(auto) operator*() const { return *it_; }
+ constexpr EqComparableInputIter& operator++() {
+ ++it_;
+ return *this;
+ }
+ constexpr void operator++(int) { ++it_; }
+
+ friend constexpr It base(const EqComparableInputIter& i) { return i.it_; }
+
+ friend constexpr bool operator==(const EqComparableInputIter& left, const EqComparableInputIter& right) {
+ return left.it_ == right.it_;
+ }
+};
+
+template <class It>
+EqComparableInputIter(It) -> EqComparableInputIter<It>;
+
+template <class Val>
+struct ConstOppositeView : std::ranges::view_base {
+ const Val* begin();
+ sentinel_wrapper<const Val*> end();
+ Val* begin() const;
+ sentinel_wrapper<Val*> end() const;
+};
+
+namespace lwg4074 { // Helpers for LWG-4074 ("compatible-joinable-ranges is underconstrained")
+struct CommonReference;
+
+struct Value {
+ Value(int);
+};
+
+struct Reference {
+ operator Value() const;
+ operator CommonReference() const;
+};
+
+struct CommonReference {
+ CommonReference(int);
+};
+
+struct Iter {
+ using value_type = Value;
+ using
diff erence_type = std::ptr
diff _t;
+
+ Iter& operator++();
+ Iter operator++(int);
+ Reference operator*() const;
+ bool operator==(const Iter&) const;
+};
+
+struct PatternWithProxyConstAccess {
+ int* begin();
+ int* end();
+ Iter begin() const;
+ Iter end() const;
+};
+} // namespace lwg4074
+
+template <template <class> class TQual, template <class> class UQual>
+struct std::basic_common_reference<lwg4074::Reference, int, TQual, UQual> {
+ using type = lwg4074::CommonReference;
+};
+
+template <template <class> class TQual, template <class> class UQual>
+struct std::basic_common_reference<int, lwg4074::Reference, TQual, UQual> {
+ using type = lwg4074::CommonReference;
+};
+
+namespace selftest {
+using BV1 = BasicView<std::string, ViewProperties{.simple = true}, forward_iterator>;
+static_assert(std::ranges::forward_range<BV1>);
+static_assert(!std::ranges::bidirectional_range<BV1>);
+static_assert(std::ranges::common_range<BV1>);
+static_assert(simple_view<BV1>);
+
+using BV2 =
+ BasicView<RvalueVector<std::string>, ViewProperties{.simple = false, .common = false}, cpp20_input_iterator>;
+static_assert(std::ranges::input_range<BV2>);
+static_assert(!std::ranges::forward_range<BV2>);
+static_assert(!std::ranges::common_range<BV2>);
+static_assert(!std::is_reference_v<std::ranges::range_reference_t<BV2>>);
+static_assert(!simple_view<BV2>);
+
+using RV = RvalueVector<int>;
+static_assert(std::movable<RV>);
+static_assert(std::ranges::random_access_range<RV>);
+static_assert(std::ranges::random_access_range<const RV>);
+static_assert(!std::is_reference_v<std::ranges::range_reference_t<RV>>);
+static_assert(!std::is_reference_v<std::ranges::range_reference_t<const RV>>);
+
+using DCII = DefaultCtorInputIter<int*>;
+static_assert(std::default_initializable<DCII>);
+static_assert(std::sentinel_for<DCII, DCII>);
+static_assert(std::input_iterator<DCII>);
+static_assert(!std::forward_iterator<DCII>);
+
+using IRBOWC = InputRangeButOutputWhenConst<int>;
+static_assert(std::ranges::input_range<IRBOWC>);
+static_assert(std::ranges::output_range<const IRBOWC&, int>);
+
+using FVBIWC = ForwardViewButInputWhenConst<int>;
+static_assert(std::default_initializable<FVBIWC>);
+static_assert(std::ranges::view<FVBIWC>);
+static_assert(std::ranges::forward_range<FVBIWC>);
+static_assert(!std::ranges::common_range<FVBIWC>);
+static_assert(std::ranges::input_range<const FVBIWC&>);
+static_assert(!std::ranges::forward_range<const FVBIWC&>);
+static_assert(!std::ranges::common_range<const FVBIWC&>);
+
+using FIWIC = ForwardIteratorWithInputCategory<long*>;
+static_assert(std::forward_iterator<FIWIC>);
+static_assert(std::same_as<FIWIC::iterator_category, std::input_iterator_tag>);
+static_assert(std::same_as<FIWIC::iterator_category, std::iterator_traits<FIWIC>::iterator_category>);
+
+using ECII = EqComparableInputIter<int*>;
+static_assert(std::input_iterator<ECII>);
+static_assert(!std::forward_iterator<ECII>);
+static_assert(std::equality_comparable<ECII>);
+
+using COV = ConstOppositeView<int>;
+static_assert(std::ranges::view<COV>);
+static_assert(std::ranges::range<const COV>);
+static_assert(!std::ranges::common_range<COV>);
+static_assert(!std::ranges::common_range<const COV>);
+static_assert(std::convertible_to<std::ranges::iterator_t<const COV>, std::ranges::iterator_t<COV>>);
+static_assert(!std::convertible_to<std::ranges::iterator_t<COV>, std::ranges::iterator_t<const COV>>);
+
+static_assert(std::common_with<lwg4074::Value, int>);
+static_assert(std::common_with<lwg4074::Value, lwg4074::Reference>);
+static_assert(std::common_reference_with<lwg4074::Reference, int&>);
+static_assert(std::common_reference_with<lwg4074::Reference, lwg4074::CommonReference>);
+static_assert(std::forward_iterator<lwg4074::Iter>);
+static_assert(std::ranges::forward_range<lwg4074::PatternWithProxyConstAccess>);
+static_assert(std::ranges::forward_range<const lwg4074::PatternWithProxyConstAccess>);
+} // namespace selftest
+
+#endif // TEST_STD_RANGES_RANGE_ADAPTORS_RANGE_JOIN_WITH_TYPES_H
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index 849a96b9585b8..edd7b124a1fb3 100644
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -1115,7 +1115,6 @@ def add_version_header(tc):
"name": "__cpp_lib_ranges_join_with",
"values": {"c++23": 202202},
"headers": ["ranges"],
- "unimplemented": True,
},
{
"name": "__cpp_lib_ranges_repeat",
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