[libcxx-commits] [libcxx] [libc++] Implement `views::join_with` (PR #65536)

Jakub Mazurkiewicz via libcxx-commits libcxx-commits at lists.llvm.org
Thu Apr 11 06:14:55 PDT 2024


https://github.com/JMazurkiewicz updated https://github.com/llvm/llvm-project/pull/65536

>From f1433c59ed2423eb85652ab90dbf4bcbf1bd5904 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:42:52 +0100
Subject: [PATCH 01/24] [libc++] Implement `views::join_with`

* Add **experimental** implementation of P2441R2: `views::join_with` (https://wg21.link/P2441R2):
  * `views::join_with` cannot be used in constant expression because P2231R1 hasn't been implemented
  * There are some issues with current implementation, see LWG-3971 for example
  * Feature test macro `__cpp_lib_ranges_join_with` is not defined
* Complete implementation of P2711R1: "Making multi-param constructors of views explicit" (https://wg21.link/P2711R1)
* Complete implementation of P2770R0: "Stashing stashing iterators for proper flattening" (https://wg21.link/P2770R0)
---
 libcxx/include/CMakeLists.txt            |   1 +
 libcxx/include/__ranges/join_with_view.h | 457 +++++++++++++++++++++++
 libcxx/include/module.modulemap.in       |   4 +
 libcxx/include/ranges                    |  13 +
 libcxx/modules/std/ranges.inc            |  14 +-
 5 files changed, 483 insertions(+), 6 deletions(-)
 create mode 100644 libcxx/include/__ranges/join_with_view.h

diff --git a/libcxx/include/CMakeLists.txt b/libcxx/include/CMakeLists.txt
index 6a845c813dc33a..17acb327d4f1c3 100644
--- a/libcxx/include/CMakeLists.txt
+++ b/libcxx/include/CMakeLists.txt
@@ -632,6 +632,7 @@ 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/join_with_view.h b/libcxx/include/__ranges/join_with_view.h
new file mode 100644
index 00000000000000..fbab49c4efe992
--- /dev/null
+++ b/libcxx/include/__ranges/join_with_view.h
@@ -0,0 +1,457 @@
+// -*- 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 <__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 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
+
+namespace ranges {
+template <class _Range, class _Pattern>
+concept __compatible_joinable_ranges =
+    common_with<range_value_t<_Range>, range_value_t<_Pattern>> &&
+    common_reference_with<range_reference_t<_Range>, range_reference_t<_Pattern>> &&
+    common_reference_with<range_rvalue_reference_t<_Range>, range_rvalue_reference_t<_Pattern>>;
+
+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> &&
+           __compatible_joinable_ranges<range_reference_t<_View>, _Pattern>
+class join_with_view : public view_interface<join_with_view<_View, _Pattern>> {
+  using _InnerRng = range_reference_t<_View>;
+
+  _LIBCPP_NO_UNIQUE_ADDRESS _View __base_ = _View();
+
+  static constexpr bool _UseOuterItCache = !forward_range<_View>;
+  using _OuterItCache = _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 = _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))) {}
+
+  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr _View base() const&
+    requires copy_constructible<_View>
+  {
+    return __base_;
+  }
+
+  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr _View base() && { return std::move(__base_); }
+
+  _LIBCPP_NODISCARD_EXT _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};
+    }
+  }
+
+  _LIBCPP_NODISCARD_EXT _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>>
+  {
+    return __iterator<true>{*this, ranges::begin(__base_)};
+  }
+
+  _LIBCPP_NODISCARD_EXT _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};
+  }
+
+  _LIBCPP_NODISCARD_EXT _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>>
+  {
+    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>
+struct __join_with_view_iterator_category {};
+
+template <class _Base, class _PatternBase>
+  requires is_reference_v<range_reference_t<_Base>> && forward_range<_Base> && forward_range<range_reference_t<_Base>>
+struct __join_with_view_iterator_category<_Base, _PatternBase> {
+private:
+  static consteval auto __get_iterator_category() noexcept {
+    using _OuterC   = iterator_traits<iterator_t<_Base>>::iterator_category;
+    using _InnerC   = iterator_traits<iterator_t<range_reference_t<_Base>>>::iterator_category;
+    using _PatternC = iterator_traits<iterator_t<_PatternBase>>::iterator_category;
+
+    if constexpr (!is_reference_v<common_reference_t<iter_reference_t<iterator_t<range_reference_t<_Base>>>,
+                                                     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<range_reference_t<_Base>> &&
+                       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> &&
+           __compatible_joinable_ranges<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      = __maybe_const<_Const, join_with_view>;
+  using _Base        = __maybe_const<_Const, _View>;
+  using _InnerBase   = range_reference_t<_Base>;
+  using _PatternBase = __maybe_const<_Const, _Pattern>;
+
+  using _OuterIter   = iterator_t<_Base>;
+  using _InnerIter   = iterator_t<_InnerBase>;
+  using _PatternIter = 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                                 = _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();
+    }
+  }
+
+  _LIBCPP_HIDE_FROM_ABI constexpr _OuterIter& __get_outer() {
+    if constexpr (forward_range<_Base>)
+      return __outer_it_;
+    else
+      return *__parent_->__outer_it_;
+  }
+
+  _LIBCPP_HIDE_FROM_ABI constexpr const _OuterIter& __get_outer() const {
+    if constexpr (forward_range<_Base>)
+      return __outer_it_;
+    else
+      return *__parent_->__outer_it_;
+  }
+
+  _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([&]() -> decltype(auto) { return *__get_outer(); });
+  }
+
+  _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_));
+      }
+    }
+  }
+
+  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 difference_type =
+      common_type_t<iter_difference_t<_OuterIter>, iter_difference_t<_InnerIter>, iter_difference_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_)));
+    }
+  }
+
+  _LIBCPP_NODISCARD_EXT _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;
+  }
+
+  _LIBCPP_NODISCARD_EXT _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_;
+  }
+
+  _LIBCPP_NODISCARD_EXT _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> &&
+           __compatible_joinable_ranges<range_reference_t<_View>, _Pattern>
+template <bool _Const>
+struct join_with_view<_View, _Pattern>::__sentinel {
+private:
+  friend join_with_view;
+
+  using _Parent = __maybe_const<_Const, join_with_view>;
+  using _Base   = __maybe_const<_Const, _View>;
+
+  sentinel_t<_Base> __end_ = sentinel_t<_Base>();
+
+  _LIBCPP_HIDE_FROM_ABI constexpr explicit __sentinel(_Parent& __parent) : __end_(ranges::end(__parent.__base_)) {}
+
+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>>>
+  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI friend constexpr bool
+  operator==(const __iterator<_OtherConst>& __x, const __sentinel& __y) {
+    return __x.__get_outer() == __y.__end_;
+  }
+};
+
+namespace views {
+namespace __join_with_view {
+struct __fn {
+  template <class _Range, class _Pattern>
+  _LIBCPP_NODISCARD_EXT _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>
+  _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI constexpr auto operator()(_Pattern&& __pattern) const
+      noexcept(is_nothrow_constructible_v<decay_t<_Pattern>, _Pattern>) {
+    return __range_adaptor_closure_t(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 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
+
+_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 03f71290b66036..66b292af9d884b 100644
--- a/libcxx/include/module.modulemap.in
+++ b/libcxx/include/module.modulemap.in
@@ -1671,6 +1671,10 @@ module std_private_ranges_join_view                  [system] {
   export std_private_iterator_iterator_with_data
   export std_private_iterator_segmented_iterator
 }
+module std_private_ranges_join_with_view             [system] {
+  header "__ranges/join_with_view.h"
+  export std_variant
+}
 module std_private_ranges_lazy_split_view            [system] {
   header "__ranges/lazy_split_view.h"
   export std_private_ranges_non_propagating_cache
diff --git a/libcxx/include/ranges b/libcxx/include/ranges
index 660d533b2a7830..892e11de89725d 100644
--- a/libcxx/include/ranges
+++ b/libcxx/include/ranges
@@ -280,6 +280,18 @@ namespace std::ranges {
     requires view<V> && input_range<range_reference_t<V>>
   class join_view;
 
+  // [range.join.with], join with view
+  template<class R, class P>
+    concept compatible-joinable-ranges = see below; // exposition only
+
+  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;                                                     // 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
@@ -397,6 +409,7 @@ namespace std {
 #include <__ranges/from_range.h>
 #include <__ranges/iota_view.h>
 #include <__ranges/join_view.h>
+#include <__ranges/join_with_view.h>
 #include <__ranges/lazy_split_view.h>
 #include <__ranges/rbegin.h>
 #include <__ranges/ref_view.h>
diff --git a/libcxx/modules/std/ranges.inc b/libcxx/modules/std/ranges.inc
index 82c7d99f8979a8..399d8983b4d086 100644
--- a/libcxx/modules/std/ranges.inc
+++ b/libcxx/modules/std/ranges.inc
@@ -122,7 +122,7 @@ export namespace std {
 
     namespace views {
       using std::ranges::views::repeat;
-    } // namespace views
+    }  // namespace views
 #endif // _LIBCPP_STD_VER >= 23
 
 #ifndef _LIBCPP_HAS_NO_LOCALIZATION
@@ -159,7 +159,7 @@ export namespace std {
 
     namespace views {
       using std::ranges::views::as_rvalue;
-    } // namespace views
+    }  // namespace views
 #endif // _LIBCPP_STD_VER >= 23
 
     // [range.filter], filter view
@@ -209,13 +209,15 @@ export namespace std {
     namespace views {
       using std::ranges::views::join;
     } // namespace views
-#if 0
+
+#if _LIBCPP_STD_VER >= 23 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
     using std::ranges::join_with_view;
 
     namespace views {
       using std::ranges::views::join_with;
-    } // namespace views
-#endif
+    }  // namespace views
+#endif // _LIBCPP_STD_VER >= 23 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
+
     using std::ranges::lazy_split_view;
 
     // [range.split], split view
@@ -271,7 +273,7 @@ export namespace std {
 
     namespace views {
       using std::ranges::views::zip;
-    } // namespace views
+    }  // namespace views
 #endif // _LIBCPP_STD_VER >= 23
 
 #if 0

>From d8a6690d26e9ad0a2082068b12f8126c0c77914a Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:45:40 +0100
Subject: [PATCH 02/24] Update `transitive_includes` files

---
 libcxx/test/libcxx/transitive_includes/cxx03.csv | 1 +
 libcxx/test/libcxx/transitive_includes/cxx11.csv | 1 +
 libcxx/test/libcxx/transitive_includes/cxx14.csv | 1 +
 libcxx/test/libcxx/transitive_includes/cxx17.csv | 1 +
 libcxx/test/libcxx/transitive_includes/cxx20.csv | 1 +
 5 files changed, 5 insertions(+)

diff --git a/libcxx/test/libcxx/transitive_includes/cxx03.csv b/libcxx/test/libcxx/transitive_includes/cxx03.csv
index d4c22023db7a06..36394c7cca31d0 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx03.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx03.csv
@@ -648,6 +648,7 @@ ranges optional
 ranges span
 ranges tuple
 ranges type_traits
+ranges variant
 ranges version
 ratio climits
 ratio cstdint
diff --git a/libcxx/test/libcxx/transitive_includes/cxx11.csv b/libcxx/test/libcxx/transitive_includes/cxx11.csv
index 5eb839a3aa7a66..3da979ccb3d24d 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx11.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx11.csv
@@ -653,6 +653,7 @@ ranges optional
 ranges span
 ranges tuple
 ranges type_traits
+ranges variant
 ranges version
 ratio climits
 ratio cstdint
diff --git a/libcxx/test/libcxx/transitive_includes/cxx14.csv b/libcxx/test/libcxx/transitive_includes/cxx14.csv
index 7b372fb37dcd58..1aee85a6741594 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx14.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx14.csv
@@ -655,6 +655,7 @@ ranges optional
 ranges span
 ranges tuple
 ranges type_traits
+ranges variant
 ranges version
 ratio climits
 ratio cstdint
diff --git a/libcxx/test/libcxx/transitive_includes/cxx17.csv b/libcxx/test/libcxx/transitive_includes/cxx17.csv
index 7b372fb37dcd58..1aee85a6741594 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx17.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx17.csv
@@ -655,6 +655,7 @@ ranges optional
 ranges span
 ranges tuple
 ranges type_traits
+ranges variant
 ranges version
 ratio climits
 ratio cstdint
diff --git a/libcxx/test/libcxx/transitive_includes/cxx20.csv b/libcxx/test/libcxx/transitive_includes/cxx20.csv
index 9b4915a468d1cf..ca4637c3525a51 100644
--- a/libcxx/test/libcxx/transitive_includes/cxx20.csv
+++ b/libcxx/test/libcxx/transitive_includes/cxx20.csv
@@ -660,6 +660,7 @@ ranges optional
 ranges span
 ranges tuple
 ranges type_traits
+ranges variant
 ranges version
 ratio climits
 ratio cstdint

>From 4ae6585871576644974ed19adf86f4b38d5615ed Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:48:12 +0100
Subject: [PATCH 03/24] Add helper types

---
 .../range.adaptors/range.join.with/types.h    | 268 ++++++++++++++++++
 1 file changed, 268 insertions(+)
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/types.h

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 00000000000000..cdbc404bfd789e
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/types.h
@@ -0,0 +1,268 @@
+//===----------------------------------------------------------------------===//
+//
+// 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 <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 difference_type = std::iter_difference_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 {
+  using Self = ForwardIteratorWithInputCategory;
+  It it_     = It();
+
+public:
+  using value_type        = std::iter_value_t<It>;
+  using difference_type   = std::iter_difference_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;
+  Self& operator++();
+  Self operator++(int);
+  friend bool operator==(const Self&, const Self&);
+};
+
+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 difference_type = std::iter_difference_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 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>>);
+} // namespace selftest
+
+#endif // TEST_STD_RANGES_RANGE_ADAPTORS_RANGE_JOIN_WITH_TYPES_H

>From 4e157cb6af4efe9f4b7a2945d59c539a34002d59 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:49:29 +0100
Subject: [PATCH 04/24] Test `[range.join.with.view]`

---
 .../range.join.with.view/base.pass.cpp        | 149 ++++++++++
 .../range.join.with.view/begin.pass.cpp       | 260 +++++++++++++++++
 .../constraints.compile.pass.cpp              | 267 ++++++++++++++++++
 .../ctad.compile.pass.cpp                     | 231 +++++++++++++++
 .../ctor.default.pass.cpp                     |  76 +++++
 .../ctor.range.element.pass.cpp               | 247 ++++++++++++++++
 .../ctor.range.pattern.pass.cpp               | 114 ++++++++
 .../range.join.with.view/end.pass.cpp         | 245 ++++++++++++++++
 .../inheritance.compile.pass.cpp              |  39 +++
 9 files changed, 1628 insertions(+)
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/base.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/begin.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/constraints.compile.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctad.compile.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.default.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.element.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.pattern.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/end.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/inheritance.compile.pass.cpp

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 00000000000000..1a72ac200f869e
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/base.pass.cpp
@@ -0,0 +1,149 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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);
+  }
+
+  // Check the && 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 = std::move(view).base();
+    assert(result.was_copy_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 00000000000000..1d347e3fca09d3
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/begin.pass.cpp
@@ -0,0 +1,260 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <ranges>
+
+// constexpr auto begin() {
+//   if constexpr (forward_range<V>) {
+//     constexpr bool use_const =
+//       simple-view<V> && is_reference_v<InnerRng> && simple-view<Pattern>;
+//     return iterator<use_const>{*this, ranges::begin(base_)};
+//   }
+//   else {
+//     outer_it_ = ranges::begin(base_);
+//     return iterator<false>{*this};
+//   }
+// }
+// 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>> {
+//   return iterator<true>{*this, ranges::begin(base_)};
+// }
+
+#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>;
+
+class DifferentWhenConstV {
+  using Arr                      = std::array<std::array<int, 2>, 2>;
+  static constexpr Arr regular_v = {{{1, 2}, {3, 4}}};
+  static constexpr Arr const_v   = {{{5, 6}, {7, 8}}};
+
+public:
+  auto begin() { return regular_v.begin(); }
+  auto end() { return regular_v.end(); }
+  auto begin() const { return const_v.begin(); }
+  auto end() const { return const_v.end(); }
+};
+
+class DifferentWhenConstPattern {
+  using Pat                            = std::array<int, 2>;
+  static constexpr Pat regular_pattern = {0, 0};
+  static constexpr Pat const_pattern   = {1, 1};
+
+public:
+  auto begin() { return regular_pattern.begin(); }
+  auto end() { return regular_pattern.end(); }
+  auto begin() const { return const_pattern.begin(); }
+  auto end() const { return const_pattern.end(); }
+};
+
+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() {
+  { // `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<DifferentWhenConstV, ViewProperties{}, forward_iterator>;
+    using Pattern = BasicView<DifferentWhenConstPattern, ViewProperties{}, forward_iterator>;
+
+    const std::ranges::join_with_view<V, Pattern> jwv;
+    auto it = jwv.begin();
+    assert(std::ranges::equal(std::views::counted(it, 6), std::array{5, 6, 1, 1, 7, 8}));
+  }
+
+  using Vec = std::vector<std::array<int, 2>>;
+  using Pat = std::array<int, 2>;
+
+  { // `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>>);
+  }
+
+  { // 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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..683d36417d1a3c
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/constraints.compile.pass.cpp
@@ -0,0 +1,267 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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"
+
+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_compatible_joinable_ranges {
+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_common_range_value_type {
+struct InnerRange {
+  struct It {
+    using difference_type = ptrdiff_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_with<range_value_t<InnerRange>, range_value_t<Pattern>>);
+static_assert(std::common_reference_with<range_reference_t<InnerRange>, range_reference_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_common_range_value_type
+
+namespace no_common_range_reference_type {
+struct ValueType {};
+
+struct InnerRange {
+  struct It {
+    using difference_type = ptrdiff_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 difference_type = ptrdiff_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_with<range_value_t<InnerRange>, range_value_t<Pattern>>);
+static_assert(!std::common_reference_with<range_reference_t<InnerRange>, range_reference_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_common_range_reference_type
+
+namespace no_common_range_rvalue_reference_type {
+struct InnerRange {
+  using It = cpp20_input_iterator<int*>;
+  It begin();
+  sentinel_wrapper<It> end();
+};
+
+struct Pattern : std::ranges::view_base {
+  struct It {
+    using difference_type = ptrdiff_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_with<range_value_t<InnerRange>, range_value_t<Pattern>>);
+static_assert(std::common_reference_with<range_reference_t<InnerRange>, range_reference_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_common_range_rvalue_reference_type
+} // namespace test_when_used_ranges_are_not_compatible_joinable_ranges
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 00000000000000..c9b4de49bbf1d5
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctad.compile.pass.cpp
@@ -0,0 +1,231 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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 00000000000000..f6aca6530f9573
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.default.pass.cpp
@@ -0,0 +1,76 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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_trivial_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_trivial_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}));
+  }
+
+  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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..c62cf0f58ecebc
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.element.pass.cpp
@@ -0,0 +1,247 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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 Pattern = 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<Pattern, std::ranges::single_view<int>>);
+    static_assert(!std::constructible_from<std::ranges::join_with_view<View, Pattern>, 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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..26e9b338f77a01
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/ctor.range.pattern.pass.cpp
@@ -0,0 +1,114 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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;
+  }
+
+  auto begin() { return r_->begin(); }
+  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;
+  }
+
+  auto begin() { return val_->begin(); }
+  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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..8f883f34d0c6e1
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/end.pass.cpp
@@ -0,0 +1,245 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <ranges>
+
+// constexpr auto end() {
+//   if constexpr (forward_range<V> &&
+//                 is_reference_v<InnerRng> && forward_range<InnerRng> &&
+//                 common_range<V> && common_range<InnerRng>)
+//     return iterator<simple-view<V> && simple-view<Pattern>>{*this, ranges::end(base_)};
+//   else
+//     return sentinel<simple-view<V> && simple-view<Pattern>>{*this};
+// }
+// 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>> {
+//   using InnerConstRng = range_reference_t<const V>;
+//   if constexpr (forward_range<InnerConstRng> &&
+//                 common_range<const V> && common_range<InnerConstRng>)
+//     return iterator<true>{*this, ranges::end(base_)};
+//   else
+//     return sentinel<true>{*this};
+// }
+
+#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           = Bits & (1 << 0);
+  constexpr bool inner_range_is_reference         = Bits & (1 << 1);
+  constexpr bool inner_range_models_forward_range = Bits & (1 << 2);
+  constexpr bool v_models_common_range            = Bits & (1 << 3);
+  constexpr bool inner_range_models_common_range  = Bits & (1 << 4);
+  constexpr bool v_models_simple_range            = Bits & (1 << 5);
+  constexpr bool pattern_models_simple_range      = 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);
+  }
+}
+
+constexpr void test_end() {}
+
+template <std::size_t Bits>
+  requires(Bits < (1 << 7))
+constexpr void test_const_end() {
+  constexpr bool const_v_models_forward_range           = Bits & (1 << 0);
+  constexpr bool const_pattern_models_forward_range     = Bits & (1 << 1);
+  constexpr bool inner_const_range_is_reference         = Bits & (1 << 2);
+  constexpr bool inner_const_range_models_input_range   = Bits & (1 << 3);
+  constexpr bool inner_const_range_models_forward_range = Bits & (1 << 4);
+  constexpr bool const_v_models_common_range            = Bits & (1 << 5);
+  constexpr bool inner_const_range_models_common_range  = 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>);
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..ef9522a448a219
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.view/inheritance.compile.pass.cpp
@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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>>>);

>From 6444d0450f74e9fd6b2e95a8bcfce1e81c85488c Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:49:48 +0100
Subject: [PATCH 05/24] Test `[range.join.with.sentinel]`

---
 .../ctor.default.pass.cpp                     |  38 ++++++
 .../ctor.non_const.pass.cpp                   |  72 +++++++++++
 .../range.join.with.sentinel/eq.pass.cpp      | 112 ++++++++++++++++++
 3 files changed, 222 insertions(+)
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.default.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.non_const.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.pass.cpp

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 00000000000000..55f6603e349608
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.default.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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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 00000000000000..e47dc66d5d639d
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/ctor.non_const.pass.cpp
@@ -0,0 +1,72 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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 CSent = std::ranges::sentinel_t<const JWV>;
+
+    auto 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 00000000000000..30a4aa058842ea
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.pass.cpp
@@ -0,0 +1,112 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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>);
+
+template <class T, class U>
+concept weakly_equality_comparable_with = requires(const T& t, const U& u) {
+  t == u;
+  t != u;
+  u == t;
+  u != t;
+};
+
+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>);
+
+  {   // Compare iterator<Const> with sentinel<Const>
+    { // Const == true
+      AssertEqualityReturnBool<std::ranges::iterator_t<const JWV>, std::ranges::sentinel_t<const JWV>>();
+      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<std::ranges::iterator_t<JWV>, std::ranges::sentinel_t<JWV>>();
+      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<std::ranges::iterator_t<const JWV>, std::ranges::sentinel_t<JWV>>();
+      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<std::ranges::iterator_t<JWV>, std::ranges::sentinel_t<const JWV>>();
+      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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  return 0;
+}

>From 634d9b47986b42a5cb1e0b3513ef25c0931994d1 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:50:18 +0100
Subject: [PATCH 06/24] Test `[range.join.with.iterator]`

---
 .../ctor.default.pass.cpp                     |  80 +++
 .../ctor.not_const.pass.cpp                   | 107 ++++
 .../decrement.pass.cpp                        | 284 +++++++++++
 .../range.join.with.iterator/deref.pass.cpp   | 147 ++++++
 .../range.join.with.iterator/eq.pass.cpp      | 259 ++++++++++
 .../increment.pass.cpp                        | 317 ++++++++++++
 .../iter_move.pass.cpp                        | 343 +++++++++++++
 .../iter_swap.pass.cpp                        |  84 ++++
 .../types.compile.pass.cpp                    | 457 ++++++++++++++++++
 9 files changed, 2078 insertions(+)
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.default.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.not_const.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/decrement.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/increment.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_swap.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/types.compile.pass.cpp

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 00000000000000..b1a9288abb5184
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.default.pass.cpp
@@ -0,0 +1,80 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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>;
+
+    Iter iter;
+    assert(testEquality(iter, Iter{}, true));
+
+    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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..0ffb43e4273321
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/ctor.not_const.pass.cpp
@@ -0,0 +1,107 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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);
+    auto it = jwv.begin();
+    assert(*it == 1);
+
+    using CIter      = std::ranges::iterator_t<const decltype(jwv)>;
+    const CIter cit1 = it; // `cit1` points to element of `V`
+    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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..0465ef8059a829
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/decrement.pass.cpp
@@ -0,0 +1,284 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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());
+    }
+  }
+
+  { // `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);
+    }
+  }
+
+  { // `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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..b78052d3f4305d
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.pass.cpp
@@ -0,0 +1,147 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <ranges>
+
+// constexpr decltype(auto) operator*() const;
+
+#include <ranges>
+
+#include <array>
+#include <cassert>
+#include <string>
+#include <string_view>
+#include <utility>
+#include <vector>
+
+#include "../types.h"
+
+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 == ' ');
+    }
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..e6930cfe624c9d
--- /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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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(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(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(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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..479eedf47e8778
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/increment.pass.cpp
@@ -0,0 +1,317 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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++; };
+
+constexpr void test_pre_increment() {
+  { // `V` and `Pattern` are not empty. Test return type too.
+    using V       = std::array<std::array<int, 2>, 3>;
+    using Pattern = std::array<int, 2>;
+    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(CanPreIncrement<Iter>);
+    static_assert(!CanPreIncrement<const Iter>);
+    static_assert(CanPreIncrement<CIter>);
+    static_assert(!CanPreIncrement<const CIter>);
+
+    JWV jwv(V{{{1, 1}, {2, 2}, {3, 3}}}, Pattern{0, 0});
+
+    {
+      auto it = jwv.begin();
+      assert(*it == 1);
+      std::same_as<Iter&> decltype(auto) it_ref = ++it;
+      assert(it_ref == it);
+      ++it;
+      assert(*it == 0);
+      ++it_ref;
+      ++it_ref;
+      assert(*it_ref == 2);
+      ++it;
+      ++it_ref;
+      assert(*it == 0);
+    }
+
+    {
+      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);
+    }
+  }
+
+  { // `Pattern` is empty, `V` is not.
+    using V       = std::array<std::vector<int>, 3>;
+    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());
+    }
+
+    {
+      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       = 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{{{1}, {}, {3}}}, Pattern{0});
+
+    {
+      auto it = jwv.begin();
+      assert(*it == 1);
+      ++it;
+      assert(*it == 0);
+      ++it;
+      assert(*it == 0);
+      ++it;
+      assert(*it == 3);
+    }
+
+    {
+      auto cit = std::as_const(jwv).begin();
+      assert(*cit == 1);
+      ++cit;
+      assert(*cit == 0);
+      ++cit;
+      assert(*cit == 0);
+      ++cit;
+      assert(*cit == 3);
+    }
+  }
+
+  { // Only first element of `V` is not empty. `Pattern` is empty.
+    using V       = std::array<std::vector<int>, 3>;
+    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());
+    }
+
+    {
+      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 and `ref-is-glvalue` is false.
+    using Inner   = RvalueVector<std::string>;
+    using V       = BasicView<Inner, 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 and `ref-is-glvalue` is false.
+    using Inner   = RvalueVector<std::string>;
+    using V       = BasicView<Inner, 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. Test return type too.
+    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. `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>>;
+
+    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.
+    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++)>);
+  }
+
+  { // Only first element of `V` is not empty. `Pattern` is empty. InnerIter does not model forward iterator.
+    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++)>);
+  }
+}
+
+constexpr bool test() {
+  test_pre_increment();
+  test_post_increment();
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..7021c58ba4b44e
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.pass.cpp
@@ -0,0 +1,343 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <ranges>
+
+// 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 visit<rvalue_reference>(ranges::iter_move, x.inner_it_);
+// }
+
+#include <ranges>
+
+#include <algorithm>
+#include <array>
+#include <cassert>
+#include <type_traits>
+#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 Status get_status() const { return status_; }
+
+  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>);
+
+template <class T>
+class ProxyRvalue {
+  T val_;
+
+public:
+  constexpr ProxyRvalue(T val) : val_(std::move(val)) {}
+
+  ProxyRvalue(ProxyRvalue&&)            = default;
+  ProxyRvalue& operator=(ProxyRvalue&&) = default;
+
+  constexpr explicit operator T&&() noexcept { return std::move(val_); }
+};
+
+static_assert(std::common_reference_with<ProxyRvalue<int>, int>);
+static_assert(std::common_reference_with<ProxyRvalue<MoveOnlyInt>, MoveOnlyInt>);
+
+template <std::bidirectional_iterator It>
+class ProxyOnIterMoveIter {
+  It it_ = It();
+
+public:
+  using value_type      = std::iter_value_t<It>;
+  using difference_type = std::iter_difference_t<It>;
+
+  ProxyOnIterMoveIter() = default;
+  constexpr ProxyOnIterMoveIter(It it) : it_(std::move(it)) {}
+
+  constexpr decltype(auto) operator*() const { return *it_; }
+
+  constexpr ProxyOnIterMoveIter& operator++() {
+    ++it_;
+    return *this;
+  }
+
+  constexpr ProxyOnIterMoveIter operator++(int) {
+    ProxyOnIterMoveIter copy = *this;
+    ++it_;
+    return copy;
+  }
+
+  constexpr ProxyOnIterMoveIter& operator--() {
+    --it_;
+    return *this;
+  }
+
+  constexpr ProxyOnIterMoveIter operator--(int) {
+    ProxyOnIterMoveIter copy = *this;
+    --it_;
+    return copy;
+  }
+
+  friend bool operator==(const ProxyOnIterMoveIter&, const ProxyOnIterMoveIter&) = default;
+
+  friend constexpr ProxyRvalue<value_type> iter_move(const ProxyOnIterMoveIter iter) {
+    return ProxyRvalue<value_type>{std::ranges::iter_move(iter.it_)};
+  }
+};
+
+template <class It>
+ProxyOnIterMoveIter(It) -> ProxyOnIterMoveIter<It>;
+
+static_assert(std::bidirectional_iterator<ProxyOnIterMoveIter<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, [](const MoveOnlyInt& i) { return i.get_status() == MoveOnlyInt::constructed; }));
+
+    {
+      using enum MoveOnlyInt::Status;
+      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, [](const MoveOnlyInt& i) { return i.get_status() == move_constructed; }));
+    }
+
+    {
+      using enum MoveOnlyInt::Status;
+      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, [](const MoveOnlyInt& i) { return i.get_status() == move_constructed; }));
+    }
+
+    assert(
+        std::ranges::all_of(jwv, [](const MoveOnlyInt& i) { return i.get_status() == MoveOnlyInt::moved_from_this; }));
+  }
+
+  { // Test `iter_move` when result is proxy rvalue reference. Test return types and moving.
+    using Inner   = std::vector<MoveOnlyInt>;
+    using V       = std::vector<Inner>;
+    using Pattern = BasicVectorView<MoveOnlyInt, ViewProperties{}, ProxyOnIterMoveIter>;
+    using JWV     = std::ranges::join_with_view<std::ranges::owning_view<V>, std::ranges::owning_view<Pattern>>;
+
+    using RRef = ProxyRvalue<MoveOnlyInt>;
+    static_assert(std::same_as<RRef, 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)));
+    JWV jwv(std::move(v), Pattern{std::ranges::to<std::vector<MoveOnlyInt>>(std::views::iota(4, 12))});
+    assert(std::ranges::all_of(jwv, [](const MoveOnlyInt& i) { return i.get_status() == MoveOnlyInt::constructed; }));
+
+    {
+      using enum MoveOnlyInt::Status;
+      std::vector<MoveOnlyInt> values;
+      values.reserve(8);
+
+      auto it                                 = jwv.begin();
+      std::same_as<RRef> decltype(auto) rref1 = iter_move(it);
+      values.emplace_back(std::move(rref1));
+      ++it;
+      std::same_as<RRef> decltype(auto) rref2 = iter_move(std::as_const(it));
+      values.emplace_back(rref2);
+      it++;
+      std::same_as<RRef> decltype(auto) rref3 = std::ranges::iter_move(it);
+      values.emplace_back(rref3);
+      ++it;
+      std::same_as<RRef> decltype(auto) rref4 = std::ranges::iter_move(std::as_const(it));
+      values.emplace_back(rref4);
+      it++; // `it` points to element of `Pattern` from here
+      std::same_as<RRef> decltype(auto) rref5 = iter_move(it);
+      values.emplace_back(rref5);
+      ++it;
+      std::same_as<RRef> decltype(auto) rref6 = iter_move(std::as_const(it));
+      values.emplace_back(rref6);
+      it++;
+      std::same_as<RRef> decltype(auto) rref7 = std::ranges::iter_move(it);
+      values.emplace_back(rref7);
+      ++it;
+      std::same_as<RRef> decltype(auto) rref8 = std::ranges::iter_move(std::as_const(it));
+      values.emplace_back(rref8);
+
+      assert(std::ranges::equal(values, std::views::iota(0, 8)));
+      assert(std::ranges::all_of(values, [](const MoveOnlyInt& i) { return i.get_status() == move_constructed; }));
+    }
+
+    {
+      using enum MoveOnlyInt::Status;
+      std::vector<MoveOnlyInt> values;
+      values.reserve(8);
+
+      auto cit                                = std::prev(std::as_const(jwv).end());
+      std::same_as<RRef> decltype(auto) rref1 = iter_move(cit);
+      values.emplace_back(rref1);
+      cit--;
+      std::same_as<RRef> decltype(auto) rref2 = iter_move(std::as_const(cit));
+      values.emplace_back(rref2);
+      --cit;
+      std::same_as<RRef> decltype(auto) rref3 = std::ranges::iter_move(cit);
+      values.emplace_back(rref3);
+      cit--;
+      std::same_as<RRef> decltype(auto) rref4 = std::ranges::iter_move(std::as_const(cit));
+      values.emplace_back(rref4);
+      --cit; // `it` points to element of `Pattern` from here
+      std::same_as<RRef> decltype(auto) rref5 = iter_move(cit);
+      values.emplace_back(rref5);
+      cit--;
+      std::same_as<RRef> decltype(auto) rref6 = iter_move(std::as_const(cit));
+      values.emplace_back(rref6);
+      --cit;
+      std::same_as<RRef> decltype(auto) rref7 = std::ranges::iter_move(cit);
+      values.emplace_back(rref7);
+      cit--;
+      std::same_as<RRef> decltype(auto) rref8 = std::ranges::iter_move(std::as_const(cit));
+      values.emplace_back(rref8);
+
+      assert(std::ranges::equal(std::views::reverse(values), std::views::iota(8, 16)));
+      assert(std::ranges::all_of(values, [](const MoveOnlyInt& i) { return i.get_status() == move_constructed; }));
+    }
+
+    assert(
+        std::ranges::all_of(jwv, [](const MoveOnlyInt& i) { return i.get_status() == MoveOnlyInt::moved_from_this; }));
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..caf11445810888
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_swap.pass.cpp
@@ -0,0 +1,84 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <ranges>
+
+// friend constexpr void iter_swap(const iterator& x, const iterator& y)
+//   requires indirectly_swappable<InnerIter, PatternIter> {
+//   visit(ranges::iter_swap, x.inner_it_, y.inner_it_);
+// }
+
+#include <ranges>
+
+#include <algorithm>
+#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); };
+
+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 different 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>>);
+  }
+
+  { // 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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..b4188f4d74df1b
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.iterator/types.compile.pass.cpp
@@ -0,0 +1,457 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <ranges>
+
+// using iterator_concept = see below;
+// using iterator_category = see below; // not always present
+// using value_type = see below;
+// using difference_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 different 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 different 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_difference_type {
+template <class DifferenceType, class ValueType>
+struct Iter {
+  using value_type      = std::remove_const_t<ValueType>;
+  using difference_type = DifferenceType;
+
+  ValueType& operator*() const;
+  Iter& operator++();
+  Iter operator++(int);
+  friend bool operator==(const Iter&, const Iter&);
+};
+
+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>>::difference_type;
+
+template <class V, class Pat, class DifferenceType>
+concept IteratorDifferenceTypeIs = std::same_as<IteratorDifferenceType<V, Pat>, DifferenceType>;
+
+// Test that `iterator<false>::difference_type` is equal to
+//   common_type_t<
+//       iter_difference_t<OuterIter>,
+//       iter_difference_t<InnerIter>,
+//       iter_difference_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>>::difference_type;
+
+template <class V, class Pat, class DifferenceType>
+concept ConstIteratorDifferenceTypeIs = std::same_as<ConstIteratorDifferenceType<V, Pat>, DifferenceType>;
+
+// Test that `iterator<true>::difference_type` is equal to
+//   common_type_t<
+//       iter_difference_t<OuterIter>,
+//       iter_difference_t<InnerIter>,
+//       iter_difference_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 difference 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_difference_type

>From 5b539d298449cab8cf96b6eb868eb76d01688825 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:51:11 +0100
Subject: [PATCH 07/24] Test `[range.join.with.overview]`

---
 .../range.join.with.overview/adaptor.pass.cpp | 362 ++++++++++++++++++
 .../range.join.with.overview/example.pass.cpp |  48 +++
 2 files changed, 410 insertions(+)
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.pass.cpp
 create mode 100644 libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/example.pass.cpp

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 00000000000000..ae7ccdd6671683
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.pass.cpp
@@ -0,0 +1,362 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <ranges>
+
+// std::views::join_with_view
+
+#include <ranges>
+
+#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();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  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 00000000000000..97d1c5667db1fb
--- /dev/null
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/range.join.with.overview/example.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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+
+// <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 <algorithm>
+#include <string>
+#include <string_view>
+#include <vector>
+
+using namespace std::string_view_literals;
+
+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 std::ranges::equal(result, "the-quick-brown-fox"sv);
+}
+
+int main(int, char**) {
+  test();
+#if __cpp_lib_variant >= 202106
+  static_assert(test());
+#endif
+
+  return 0;
+}

>From 575b46e7d15f10b6ad1c49cf11495923edb53f0c Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:51:32 +0100
Subject: [PATCH 08/24] Test `[[nodiscard]]` extensions

---
 .../deref.nodiscard.verify.cpp                | 28 +++++++++++++++
 .../eq.nodiscard.verify.cpp                   | 30 ++++++++++++++++
 .../iter_move.nodiscard.verify.cpp            | 28 +++++++++++++++
 .../adaptor.nodiscard.verify.cpp              | 33 +++++++++++++++++
 .../eq.nodiscard.verify.cpp                   | 35 +++++++++++++++++++
 .../base.nodiscard.verify.cpp                 | 30 ++++++++++++++++
 .../begin.nodiscard.verify.cpp                | 28 +++++++++++++++
 .../end.nodiscard.verify.cpp                  | 28 +++++++++++++++
 8 files changed, 240 insertions(+)
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/deref.nodiscard.verify.cpp
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/eq.nodiscard.verify.cpp
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/iter_move.nodiscard.verify.cpp
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.overview/adaptor.nodiscard.verify.cpp
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.sentinel/eq.nodiscard.verify.cpp
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/base.nodiscard.verify.cpp
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/begin.nodiscard.verify.cpp
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/end.nodiscard.verify.cpp

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 00000000000000..58abf717d7bbeb
--- /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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <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 00000000000000..78b6332f778e13
--- /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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <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 00000000000000..1e4a92f827572f
--- /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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <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.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 00000000000000..bd2972f938648c
--- /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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <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 00000000000000..8cd234b85ad1d0
--- /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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <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.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 00000000000000..b08b9f9b8bc0da
--- /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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <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 00000000000000..6d930d46be77ac
--- /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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <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 00000000000000..1d5f0e394d67f0
--- /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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// <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
+}

>From 1835f687f10e348221ea283e343a2bd38ababd2f Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:52:59 +0100
Subject: [PATCH 09/24] Update docs

---
 libcxx/docs/ReleaseNotes/19.rst    | 3 +++
 libcxx/docs/Status/Cxx23.rst       | 5 ++---
 libcxx/docs/Status/Cxx23Papers.csv | 6 +++---
 libcxx/docs/Status/RangesViews.csv | 2 +-
 libcxx/docs/UsingLibcxx.rst        | 1 +
 5 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/libcxx/docs/ReleaseNotes/19.rst b/libcxx/docs/ReleaseNotes/19.rst
index db731de2e43996..19a2a48669dd15 100644
--- a/libcxx/docs/ReleaseNotes/19.rst
+++ b/libcxx/docs/ReleaseNotes/19.rst
@@ -40,6 +40,9 @@ Implemented Papers
 
 - P2637R3 - Member ``visit``
 - P2652R2 - Disallow User Specialization of ``allocator_traits``
+- P2441R2 - ``views::join_with`` (in the experimental library)
+- P2711R1 - Making multi-param constructors of ``views`` ``explicit``
+- P2770R0 - Stashing stashing ``iterators`` for proper flattening
 
 
 Improvements and New Features
diff --git a/libcxx/docs/Status/Cxx23.rst b/libcxx/docs/Status/Cxx23.rst
index 3e6e33f08c7ccf..55fecdc7d0a5ac 100644
--- a/libcxx/docs/Status/Cxx23.rst
+++ b/libcxx/docs/Status/Cxx23.rst
@@ -44,8 +44,7 @@ Paper Status
    .. [#note-P1413R3] P1413R3: ``std::aligned_storage_t`` and ``std::aligned_union_t`` are marked deprecated, but
       clang doesn't issue a diagnostic for deprecated using template declarations.
    .. [#note-P2520R0] P2520R0: Libc++ implemented this paper as a DR in C++20 as well.
-   .. [#note-P2711R1] P2711R1: ``join_with_view`` hasn't been done yet since this type isn't implemented yet.
-   .. [#note-P2770R0] P2770R0: ``join_with_view`` hasn't been done yet since this type isn't implemented yet.
+   .. [#note-P2441R2] P2441R2: ``views::join_with`` cannot be used in constant expressions (depends on P2231R1).
    .. [#note-P2693R1] P2693R1: The formatter for ``std::thread::id`` is implemented.
       The formatter for ``stacktrace`` is not implemented, since ``stacktrace`` is
       not implemented yet.
@@ -63,4 +62,4 @@ Library Working Group Issues Status
 .. note::
 
    .. [#note-LWG3750] LWG3750 Only ``__cpp_lib_format_ranges`` is fully implemented.
-   .. [#note-LWG3798] LWG3798: ``join_with_view``, ``zip_transform_view``, and ``adjacent_transform_view`` haven't been done yet since these types aren't implemented yet.
+   .. [#note-LWG3798] LWG3798: ``zip_transform_view`` and ``adjacent_transform_view`` haven't been done yet since these types aren't implemented yet.
diff --git a/libcxx/docs/Status/Cxx23Papers.csv b/libcxx/docs/Status/Cxx23Papers.csv
index eb415ed8c031fa..91914b8ed2c753 100644
--- a/libcxx/docs/Status/Cxx23Papers.csv
+++ b/libcxx/docs/Status/Cxx23Papers.csv
@@ -47,7 +47,7 @@
 "`P2273R3 <https://wg21.link/P2273R3>`__","LWG","Making ``std::unique_ptr`` constexpr","February 2022","|Complete|","16.0"
 "`P2387R3 <https://wg21.link/P2387R3>`__","LWG","Pipe support for user-defined range adaptors","February 2022","","","|ranges|"
 "`P2440R1 <https://wg21.link/P2440R1>`__","LWG","``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right``","February 2022","","","|ranges|"
-"`P2441R2 <https://wg21.link/P2441R2>`__","LWG","``views::join_with``","February 2022","|In Progress|","","|ranges|"
+"`P2441R2 <https://wg21.link/P2441R2>`__","LWG","``views::join_with``","February 2022","|Partial| [#note-P2441R2]_","","|ranges|"
 "`P2442R1 <https://wg21.link/P2442R1>`__","LWG","Windowing range adaptors: ``views::chunk`` and ``views::slide``","February 2022","","","|ranges|"
 "`P2443R1 <https://wg21.link/P2443R1>`__","LWG","``views::chunk_by``","February 2022","|Complete|","18.0","|ranges|"
 "","","","","","",""
@@ -104,9 +104,9 @@
 "`P2708R1 <https://wg21.link/P2708R1>`__","LWG", "No Further Fundamentals TSes", "November 2022","|Nothing to do|","",""
 "","","","","","",""
 "`P0290R4 <https://wg21.link/P0290R4>`__","LWG", "``apply()`` for ``synchronized_value<T>``","February 2023","","","|concurrency TS|"
-"`P2770R0 <https://wg21.link/P2770R0>`__","LWG", "Stashing stashing ``iterators`` for proper flattening","February 2023","|Partial| [#note-P2770R0]_","","|ranges|"
+"`P2770R0 <https://wg21.link/P2770R0>`__","LWG", "Stashing stashing ``iterators`` for proper flattening","February 2023","|Complete|","19.0","|ranges|"
 "`P2164R9 <https://wg21.link/P2164R9>`__","LWG", "``views::enumerate``","February 2023","","","|ranges|"
-"`P2711R1 <https://wg21.link/P2711R1>`__","LWG", "Making multi-param constructors of ``views`` ``explicit``","February 2023","|In Progress| [#note-P2711R1]_","","|ranges|"
+"`P2711R1 <https://wg21.link/P2711R1>`__","LWG", "Making multi-param constructors of ``views`` ``explicit``","February 2023","|Complete|","19.0","|ranges|"
 "`P2609R3 <https://wg21.link/P2609R3>`__","LWG", "Relaxing Ranges Just A Smidge","February 2023","","","|ranges|"
 "`P2713R1 <https://wg21.link/P2713R1>`__","LWG", "Escaping improvements in ``std::format``","February 2023","","","|format|"
 "`P2675R1 <https://wg21.link/P2675R1>`__","LWG", "``format``'s width estimation is too approximate and not forward compatible","February 2023","|Complete|","17.0","|format|"
diff --git a/libcxx/docs/Status/RangesViews.csv b/libcxx/docs/Status/RangesViews.csv
index f141656eb131a2..610c5b76368e58 100644
--- a/libcxx/docs/Status/RangesViews.csv
+++ b/libcxx/docs/Status/RangesViews.csv
@@ -28,7 +28,7 @@ C++23,`zip <https://wg21.link/P2321R2>`_,Hui Xie,`D122806 <https://llvm.org/D122
 C++23,`zip_transform <https://wg21.link/P2321R2>`_,Hui Xie,No patch yet,Not started
 C++23,`adjacent <https://wg21.link/P2321R2>`_,Hui Xie,No patch yet,Not started
 C++23,`adjacent_transform <https://wg21.link/P2321R2>`_,Hui Xie,No patch yet,Not started
-C++23,`join_with <https://wg21.link/P2441R2>`_,Jakub Mazurkiewicz,`65536 <https://github.com/llvm/llvm-project/pull/65536>`_,In progress
+C++23,`join_with <https://wg21.link/P2441R2>`_,Jakub Mazurkiewicz,`65536 <https://github.com/llvm/llvm-project/pull/65536>`_,In Progress
 C++23,`slide <https://wg21.link/P2442R1>`_,Will Hawkins,`67146 <https://github.com/llvm/llvm-project/pull/67146>`_,In Progress
 C++23,`chunk <https://wg21.link/P2442R1>`_,Unassigned,No patch yet,Not started
 C++23,`chunk_by <https://wg21.link/P2443R1>`_,Jakub Mazurkiewicz,`D144767 <https://llvm.org/D144767>`_,✅
diff --git a/libcxx/docs/UsingLibcxx.rst b/libcxx/docs/UsingLibcxx.rst
index 3b1be286c16981..d7f7ae67347b84 100644
--- a/libcxx/docs/UsingLibcxx.rst
+++ b/libcxx/docs/UsingLibcxx.rst
@@ -50,6 +50,7 @@ when ``-fexperimental-library`` is passed:
 * ``std::stop_token``, ``std::stop_source`` and ``std::stop_callback``
 * ``std::jthread``
 * ``std::chrono::tzdb`` and related time zone functionality
+* ``std::ranges::join_with_view``
 
 .. warning::
   Experimental libraries are experimental.

>From 07c91315c617b8749b04c048e8608815bcb6083d Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 00:59:58 +0100
Subject: [PATCH 10/24] Update `RangesMajorFeatures.csv`

---
 libcxx/docs/Status/RangesMajorFeatures.csv | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libcxx/docs/Status/RangesMajorFeatures.csv b/libcxx/docs/Status/RangesMajorFeatures.csv
index c0bec8d924e8a9..76cd564ff5ab21 100644
--- a/libcxx/docs/Status/RangesMajorFeatures.csv
+++ b/libcxx/docs/Status/RangesMajorFeatures.csv
@@ -2,4 +2,4 @@ Standard,Name,Assignee,CL,Status
 C++23,`ranges::to <https://wg21.link/P1206R7>`_,Konstantin Varlamov,`D142335 <https://reviews.llvm.org/D142335>`_,Complete
 C++23,`Pipe support for user-defined range adaptors <https://wg21.link/P2387R3>`_,Unassigned,No patch yet,Not started
 C++23,`Formatting Ranges <https://wg21.link/P2286R8>`_,Mark de Wever,Various,Complete
-C++20,`Stashing stashing iterators for proper flattening <https://wg21.link/P2770R0>`_,Jakub Mazurkiewicz,Various,In progress
+C++20,`Stashing stashing iterators for proper flattening <https://wg21.link/P2770R0>`_,Jakub Mazurkiewicz,Various,Complete

>From de59d3677f6bb4c851905705442a311fd899aace Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 01:04:37 +0100
Subject: [PATCH 11/24] Fix formatting

---
 libcxx/modules/std/ranges.inc | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libcxx/modules/std/ranges.inc b/libcxx/modules/std/ranges.inc
index 399d8983b4d086..c899d755a10b70 100644
--- a/libcxx/modules/std/ranges.inc
+++ b/libcxx/modules/std/ranges.inc
@@ -122,7 +122,7 @@ export namespace std {
 
     namespace views {
       using std::ranges::views::repeat;
-    }  // namespace views
+    } // namespace views
 #endif // _LIBCPP_STD_VER >= 23
 
 #ifndef _LIBCPP_HAS_NO_LOCALIZATION
@@ -273,7 +273,7 @@ export namespace std {
 
     namespace views {
       using std::ranges::views::zip;
-    }  // namespace views
+    } // namespace views
 #endif // _LIBCPP_STD_VER >= 23
 
 #if 0

>From 01ea1f811eb642e9e6d2ed87bec28145879c5aa1 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 01:05:28 +0100
Subject: [PATCH 12/24] Add `// [range.join.with]` in `ranges.inc`

---
 libcxx/modules/std/ranges.inc | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libcxx/modules/std/ranges.inc b/libcxx/modules/std/ranges.inc
index c899d755a10b70..cd67d0699569f5 100644
--- a/libcxx/modules/std/ranges.inc
+++ b/libcxx/modules/std/ranges.inc
@@ -211,6 +211,7 @@ export namespace std {
     } // namespace views
 
 #if _LIBCPP_STD_VER >= 23 && defined(_LIBCPP_ENABLE_EXPERIMENTAL)
+    // [range.join.with]
     using std::ranges::join_with_view;
 
     namespace views {

>From f90b842e727c1f6445dd3060d7337dcf1960f3df Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 01:09:48 +0100
Subject: [PATCH 13/24] Run `libcxx-generate-files`

---
 libcxx/include/libcxx.imp | 1 +
 1 file changed, 1 insertion(+)

diff --git a/libcxx/include/libcxx.imp b/libcxx/include/libcxx.imp
index 13c0dfeb2bc98f..4373a525dd2f4d 100644
--- a/libcxx/include/libcxx.imp
+++ b/libcxx/include/libcxx.imp
@@ -622,6 +622,7 @@
   { include: [ "<__ranges/iota_view.h>", "private", "<ranges>", "public" ] },
   { include: [ "<__ranges/istream_view.h>", "private", "<ranges>", "public" ] },
   { include: [ "<__ranges/join_view.h>", "private", "<ranges>", "public" ] },
+  { include: [ "<__ranges/join_with_view.h>", "private", "<ranges>", "public" ] },
   { include: [ "<__ranges/lazy_split_view.h>", "private", "<ranges>", "public" ] },
   { include: [ "<__ranges/movable_box.h>", "private", "<ranges>", "public" ] },
   { include: [ "<__ranges/non_propagating_cache.h>", "private", "<ranges>", "public" ] },

>From 95c99e454863f2e5eb1c00e675a86f8e9f75c205 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 01:16:43 +0100
Subject: [PATCH 14/24] Cleanup `ForwardIteratorWithInputCategory`

---
 .../std/ranges/range.adaptors/range.join.with/types.h    | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

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
index cdbc404bfd789e..0f5a36425c3354 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.join.with/types.h
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/types.h
@@ -149,8 +149,7 @@ using ForwardViewButInputWhenConst =
 
 template <class It>
 class ForwardIteratorWithInputCategory {
-  using Self = ForwardIteratorWithInputCategory;
-  It it_     = It();
+  It it_ = It();
 
 public:
   using value_type        = std::iter_value_t<It>;
@@ -162,9 +161,9 @@ class ForwardIteratorWithInputCategory {
   explicit ForwardIteratorWithInputCategory(It it);
 
   std::iter_reference_t<It> operator*() const;
-  Self& operator++();
-  Self operator++(int);
-  friend bool operator==(const Self&, const Self&);
+  ForwardIteratorWithInputCategory& operator++();
+  ForwardIteratorWithInputCategory operator++(int);
+  friend bool operator==(const ForwardIteratorWithInputCategory&, const ForwardIteratorWithInputCategory&);
 };
 
 template <class It>

>From ae39c5bf77d132874d749b87e675711de4614a72 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 01:33:54 +0100
Subject: [PATCH 15/24] =?UTF-8?q?Minor=20fix=20(`=E2=80=94`=20->=20`-`)?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 .../range.join.with/range.join.with.overview/example.pass.cpp   | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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
index 97d1c5667db1fb..8b261d8ba2d954 100644
--- 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
@@ -17,7 +17,7 @@
 //     cout << c;
 //   }
 //   // The above prints the-quick-brown-fox
-// — end example]
+// - end example]
 
 #include <ranges>
 

>From 7194c70a67ee15af312aac810b9c2d4ff35e27f7 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 01:35:40 +0100
Subject: [PATCH 16/24] GCC-13: Fix
 `ForwardIteratorWithInputCategory::operator==`

---
 libcxx/test/std/ranges/range.adaptors/range.join.with/types.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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
index 0f5a36425c3354..be551202966820 100644
--- a/libcxx/test/std/ranges/range.adaptors/range.join.with/types.h
+++ b/libcxx/test/std/ranges/range.adaptors/range.join.with/types.h
@@ -163,7 +163,7 @@ class ForwardIteratorWithInputCategory {
   std::iter_reference_t<It> operator*() const;
   ForwardIteratorWithInputCategory& operator++();
   ForwardIteratorWithInputCategory operator++(int);
-  friend bool operator==(const ForwardIteratorWithInputCategory&, const ForwardIteratorWithInputCategory&);
+  bool operator==(const ForwardIteratorWithInputCategory&) const;
 };
 
 template <class It>

>From ed3290ab1b49c798d25165f6956735c659627894 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 01:53:49 +0100
Subject: [PATCH 17/24] GCC-13: Fix `test_difference_type::Iter::operator==`

---
 .../range.join.with.iterator/types.compile.pass.cpp             | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

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
index b4188f4d74df1b..fcb57ce4180107 100644
--- 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
@@ -376,7 +376,7 @@ struct Iter {
   ValueType& operator*() const;
   Iter& operator++();
   Iter operator++(int);
-  friend bool operator==(const Iter&, const Iter&);
+  bool operator==(const Iter&) const;
 };
 
 static_assert(std::forward_iterator<Iter<int, void*>>);

>From f7d1c71f779b988494ecd760c7402ea0d44802e4 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 13:11:44 +0100
Subject: [PATCH 18/24] GCC-13: Fix `ctor.range.element.pass.cpp` test

---
 .../range.join.with.view/ctor.range.element.pass.cpp      | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

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
index c62cf0f58ecebc..44f690c75d5c17 100644
--- 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
@@ -220,12 +220,12 @@ constexpr void test_constraints() {
   }
 
   { // `Pattern` is not constructible from `single_view<range_value_t<InnerRng>>`
-    using R       = InputView;
-    using Pattern = test_view<forward_iterator>;
+    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<Pattern, std::ranges::single_view<int>>);
-    static_assert(!std::constructible_from<std::ranges::join_with_view<View, Pattern>, R, int>);
+    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>);
   }
 }
 

>From 7c0edf414642c7b0fe6104bad7b3d894561ac91f Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 15:38:12 +0100
Subject: [PATCH 19/24] Remove dead tests

---
 .../range.join.with.iterator/ctor.default.pass.cpp             | 3 ---
 .../range.join.with.iterator/ctor.not_const.pass.cpp           | 3 ---
 .../range.join.with.iterator/decrement.pass.cpp                | 3 ---
 .../range.join.with/range.join.with.iterator/deref.pass.cpp    | 3 ---
 .../range.join.with/range.join.with.iterator/eq.pass.cpp       | 3 ---
 .../range.join.with.iterator/increment.pass.cpp                | 3 ---
 .../range.join.with.iterator/iter_move.pass.cpp                | 3 ---
 .../range.join.with.iterator/iter_swap.pass.cpp                | 3 ---
 .../range.join.with/range.join.with.overview/adaptor.pass.cpp  | 3 ---
 .../range.join.with/range.join.with.overview/example.pass.cpp  | 3 ---
 .../range.join.with/range.join.with.sentinel/eq.pass.cpp       | 3 ---
 .../range.join.with/range.join.with.view/begin.pass.cpp        | 3 ---
 .../range.join.with/range.join.with.view/ctor.default.pass.cpp | 3 ---
 .../range.join.with.view/ctor.range.element.pass.cpp           | 3 ---
 .../range.join.with.view/ctor.range.pattern.pass.cpp           | 3 ---
 .../range.join.with/range.join.with.view/end.pass.cpp          | 3 ---
 16 files changed, 48 deletions(-)

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
index b1a9288abb5184..00f5853b47aef2 100644
--- 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
@@ -72,9 +72,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 0ffb43e4273321..b1c00d6b09a094 100644
--- 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
@@ -99,9 +99,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 0465ef8059a829..3ee150d6591a58 100644
--- 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
@@ -276,9 +276,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index b78052d3f4305d..3d8ceb68c33007 100644
--- 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
@@ -139,9 +139,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index e6930cfe624c9d..aa11d9e1e8fcd3 100644
--- 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
@@ -251,9 +251,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 479eedf47e8778..71016e0f0ac348 100644
--- 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
@@ -309,9 +309,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 7021c58ba4b44e..2127bc7a59c8de 100644
--- 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
@@ -335,9 +335,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index caf11445810888..c21387d49218c2 100644
--- 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
@@ -76,9 +76,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   return 0;
 }
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
index ae7ccdd6671683..491d595d9db971 100644
--- 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
@@ -354,9 +354,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 8b261d8ba2d954..fb11d84b551989 100644
--- 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
@@ -40,9 +40,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 30a4aa058842ea..a33f1d2214bf5d 100644
--- 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
@@ -104,9 +104,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 1d347e3fca09d3..748cad63423d23 100644
--- 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
@@ -252,9 +252,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   return 0;
 }
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
index f6aca6530f9573..fce1f1b4ac5e59 100644
--- 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
@@ -68,9 +68,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 44f690c75d5c17..9a8951b7e057ff 100644
--- 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
@@ -239,9 +239,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 26e9b338f77a01..409c8e65c3b447 100644
--- 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
@@ -106,9 +106,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   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
index 8f883f34d0c6e1..4464236a150d7c 100644
--- 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
@@ -237,9 +237,6 @@ constexpr bool test() {
 
 int main(int, char**) {
   test();
-#if __cpp_lib_variant >= 202106
-  static_assert(test());
-#endif
 
   return 0;
 }

>From c1dd0d6f94cbb0d9c0fe6bc619e8770a6dd82925 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 16:08:19 +0100
Subject: [PATCH 20/24] Test `[[no_unique_address]]` extensions

---
 .../no_unique_address.compile.pass.cpp        | 39 ++++++++++++++++++
 .../no_unique_address.compile.pass.cpp        | 40 +++++++++++++++++++
 2 files changed, 79 insertions(+)
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/no_unique_address.compile.pass.cpp
 create mode 100644 libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/no_unique_address.compile.pass.cpp

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 00000000000000..a934d6e07140d2
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.iterator/no_unique_address.compile.pass.cpp
@@ -0,0 +1,39 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+// XFAIL: msvc
+
+// <ranges>
+
+// This test ensures that we use `[[no_unique_address]]` in `join_with_view::iterator`.
+
+#include <ranges>
+
+#include "test_iterators.h"
+#include "test_range.h"
+
+struct InputView : std::ranges::view_base {
+  using Inner = test_range<forward_iterator>;
+
+  cpp20_input_iterator<Inner*> begin();
+  sentinel_wrapper<cpp20_input_iterator<Inner*>> end();
+};
+
+static_assert(std::ranges::input_range<InputView>);
+static_assert(!std::ranges::forward_range<InputView>);
+
+struct Pattern : std::ranges::view_base {
+  int* begin();
+  int* end();
+};
+
+static_assert(alignof(void*) == alignof(std::variant<int*, int*>)); // alignof(__parent_) == alignof(__inner_it_)
+static_assert(sizeof(std::ranges::iterator_t<std::ranges::join_with_view<InputView, Pattern>>) ==
+              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.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 00000000000000..dfd6e6ad4cd864
--- /dev/null
+++ b/libcxx/test/libcxx/ranges/range.adaptors/range.join.with/range.join.with.view/no_unique_address.compile.pass.cpp
@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
+// 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;
+  char c;
+};
+
+static_assert(sizeof(Test<std::ranges::join_with_view<ForwardView, Pattern>>) ==
+              sizeof(std::ranges::join_with_view<ForwardView, Pattern>));

>From ad713e6b6d4bc1591bc8046dd589d0faf13c9724 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 16:10:36 +0100
Subject: [PATCH 21/24] Fix tests in `no-experimental` mode

---
 .../range.join.with.iterator/deref.nodiscard.verify.cpp          | 1 +
 .../range.join.with.iterator/eq.nodiscard.verify.cpp             | 1 +
 .../range.join.with.iterator/iter_move.nodiscard.verify.cpp      | 1 +
 .../range.join.with.overview/adaptor.nodiscard.verify.cpp        | 1 +
 .../range.join.with.sentinel/eq.nodiscard.verify.cpp             | 1 +
 .../range.join.with.view/base.nodiscard.verify.cpp               | 1 +
 .../range.join.with.view/begin.nodiscard.verify.cpp              | 1 +
 .../range.join.with.view/end.nodiscard.verify.cpp                | 1 +
 8 files changed, 8 insertions(+)

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
index 58abf717d7bbeb..12827085930de5 100644
--- 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
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
 
 // <ranges>
 
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
index 78b6332f778e13..f619c0cebeb056 100644
--- 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
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
 
 // <ranges>
 
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
index 1e4a92f827572f..ac043d7a65e5b6 100644
--- 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
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
 
 // <ranges>
 
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
index bd2972f938648c..dd5f962109a46d 100644
--- 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
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
 
 // <ranges>
 
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
index 8cd234b85ad1d0..6cfc0ff732377c 100644
--- 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
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
 
 // <ranges>
 
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
index b08b9f9b8bc0da..0ff09f5fd2c1fb 100644
--- 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
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
 
 // <ranges>
 
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
index 6d930d46be77ac..b0bff7472ab86e 100644
--- 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
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
 
 // <ranges>
 
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
index 1d5f0e394d67f0..5792fa9d962fbd 100644
--- 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
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 // UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+// UNSUPPORTED: !c++experimental
 
 // <ranges>
 

>From f30cc75d07aa63e2225c84d8822119822664ff5a Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 20:52:20 +0100
Subject: [PATCH 22/24] Remove `views::join_with` from release notes

---
 libcxx/docs/ReleaseNotes/19.rst | 1 -
 1 file changed, 1 deletion(-)

diff --git a/libcxx/docs/ReleaseNotes/19.rst b/libcxx/docs/ReleaseNotes/19.rst
index 19a2a48669dd15..120964c8d29fa3 100644
--- a/libcxx/docs/ReleaseNotes/19.rst
+++ b/libcxx/docs/ReleaseNotes/19.rst
@@ -40,7 +40,6 @@ Implemented Papers
 
 - P2637R3 - Member ``visit``
 - P2652R2 - Disallow User Specialization of ``allocator_traits``
-- P2441R2 - ``views::join_with`` (in the experimental library)
 - P2711R1 - Making multi-param constructors of ``views`` ``explicit``
 - P2770R0 - Stashing stashing ``iterators`` for proper flattening
 

>From 9d671fea78c36ec40a65d38c66b4df95e304fd46 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 21:11:07 +0100
Subject: [PATCH 23/24] Poke CI


>From 2d1701e9cedd8025e23dd244779b4c4a86fdbb96 Mon Sep 17 00:00:00 2001
From: Jakub Mazurkiewicz <mazkuba3 at gmail.com>
Date: Sat, 3 Feb 2024 21:27:28 +0100
Subject: [PATCH 24/24] Poke CI (again)




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