[libc++] Implement P2505R5(Monadic operations for std::expected).

Implement P2505R5(https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2022/p2505r5.html)

Reviewed By: #libc, philnik, ldionne

Differential Revision: https://reviews.llvm.org/D140911

29 files changed, 3113 insertions, 35 deletions

diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 0f5ee6c24485..48c2d0ddfae1 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -320,7 +320,7 @@ Status
     ------------------------------------------------- -----------------
     ``__cpp_lib_constexpr_typeinfo``                  ``202106L``
     ------------------------------------------------- -----------------
-    ``__cpp_lib_expected``                            ``202202L``
+    ``__cpp_lib_expected``                            ``202211L``
     ------------------------------------------------- -----------------
     ``__cpp_lib_format_ranges``                       ``202207L``
     ------------------------------------------------- -----------------
diff --git a/libcxx/docs/ReleaseNotes.rst b/libcxx/docs/ReleaseNotes.rst
index 6e6cdc25ce63..d2db69e67b98 100644
--- a/libcxx/docs/ReleaseNotes.rst
+++ b/libcxx/docs/ReleaseNotes.rst
@@ -41,6 +41,7 @@ Implemented Papers
 - P1328R1 - ``constexpr type_info::operator==()``
 - P1413R3 - Formatting ``thread::id`` (the ``stacktrace`` is not done yet)
 - P2675R1 - ``format``'s width estimation is too approximate and not forward compatible
+- P2505R5 - Monadic operations for ``std::expected``
 
 Improvements and New Features
 -----------------------------
diff --git a/libcxx/docs/Status/Cxx2bIssues.csv b/libcxx/docs/Status/Cxx2bIssues.csv
index 95cc327b0d01..d658c18a6489 100644
--- a/libcxx/docs/Status/Cxx2bIssues.csv
+++ b/libcxx/docs/Status/Cxx2bIssues.csv
@@ -274,7 +274,7 @@
 "`3853 <https://wg21.link/LWG3853>`__","``basic_const_iterator<volatile int*>::operator->`` is ill-formed","February 2023","","",""
 "`3857 <https://wg21.link/LWG3857>`__","``basic_string_view`` should allow explicit conversion when only traits vary","February 2023","|Complete|","17.0",""
 "`3860 <https://wg21.link/LWG3860>`__","``range_common_reference_t`` is missing","February 2023","|Complete|","17.0","|ranges|"
-"`3866 <https://wg21.link/LWG3866>`__","Bad Mandates for ``expected::transform_error`` overloads","February 2023","","",""
+"`3866 <https://wg21.link/LWG3866>`__","Bad Mandates for ``expected::transform_error`` overloads","February 2023","|Complete|","17.0",""
 "`3867 <https://wg21.link/LWG3867>`__","Should ``std::basic_osyncstream``'s move assignment operator be ``noexcept``?","February 2023","","",""
 "`3441 <https://wg21.link/LWG3441>`__","Misleading note about calls to customization points","February 2023","","",""
 "`3622 <https://wg21.link/LWG3622>`__","Misspecified transitivity of equivalence in §[unord.req.general]","February 2023","","",""
@@ -301,7 +301,7 @@
 "`3872 <https://wg21.link/LWG3872>`__","``basic_const_iterator`` should have custom ``iter_move``","February 2023","","",""
 "`3875 <https://wg21.link/LWG3875>`__","``std::ranges::repeat_view<T, IntegerClass>::iterator`` may be ill-formed","February 2023","","","|ranges|"
 "`3876 <https://wg21.link/LWG3876>`__","Default constructor of ``std::layout_XX::mapping`` misses precondition","February 2023","","",""
-"`3877 <https://wg21.link/LWG3877>`__","Incorrect constraints on ``const``-qualified monadic overloads for ``std::expected``","February 2023","","",""
+"`3877 <https://wg21.link/LWG3877>`__","Incorrect constraints on ``const``-qualified monadic overloads for ``std::expected``","February 2023","|Complete|","17.0",""
 "`3878 <https://wg21.link/LWG3878>`__","import ``std;`` should guarantee initialization of standard iostreams objects","February 2023","","",""
 "`3879 <https://wg21.link/LWG3879>`__","``erase_if`` for ``flat_{,multi}set`` is incorrectly specified","February 2023","","",""
 "`3880 <https://wg21.link/LWG3880>`__","Clarify ``operator+=`` complexity for ``{chunk,stride}_view::iterator``","February 2023","","","|ranges|"
diff --git a/libcxx/docs/Status/Cxx2bPapers.csv b/libcxx/docs/Status/Cxx2bPapers.csv
index 550fb34d4b34..a49dc627a7fa 100644
--- a/libcxx/docs/Status/Cxx2bPapers.csv
+++ b/libcxx/docs/Status/Cxx2bPapers.csv
@@ -100,7 +100,7 @@
 "`P1478R8 <https://wg21.link/P1478R8>`__","LWG", "``Byte-wise`` ``atomic`` ``memcpy``", "November 2022","","","|concurrency TS|"
 "`P2167R3 <https://wg21.link/P2167R3>`__","LWG", "Improved Proposed Wording for LWG 2114", "November 2022","","",""
 "`P2396R1 <https://wg21.link/P2396R1>`__","LWG", "Concurrency TS 2 fixes ", "November 2022","","","|concurrency TS|"
-"`P2505R5 <https://wg21.link/P2505R5>`__","LWG", "Monadic Functions for ``std::expected``", "November 2022","","",""
+"`P2505R5 <https://wg21.link/P2505R5>`__","LWG", "Monadic Functions for ``std::expected``", "November 2022","|Complete|","17.0",""
 "`P2539R4 <https://wg21.link/P2539R4>`__","LWG", "Should the output of ``std::print`` to a terminal be synchronized with the underlying stream?", "November 2022","","","|format|"
 "`P2602R2 <https://wg21.link/P2602R2>`__","LWG", "Poison Pills are Too Toxic", "November 2022","","","|ranges|"
 "`P2708R1 <https://wg21.link/P2708R1>`__","LWG", "No Further Fundamentals TSes", "November 2022","|Nothing to do|","",""
diff --git a/libcxx/include/__expected/expected.h b/libcxx/include/__expected/expected.h
index 3ff8fbc7b211..668e23f21c71 100644
--- a/libcxx/include/__expected/expected.h
+++ b/libcxx/include/__expected/expected.h
@@ -14,10 +14,12 @@
 #include <__expected/bad_expected_access.h>
 #include <__expected/unexpect.h>
 #include <__expected/unexpected.h>
+#include <__functional/invoke.h>
 #include <__memory/addressof.h>
 #include <__memory/construct_at.h>
 #include <__type_traits/conjunction.h>
 #include <__type_traits/disjunction.h>
+#include <__type_traits/integral_constant.h>
 #include <__type_traits/is_assignable.h>
 #include <__type_traits/is_constructible.h>
 #include <__type_traits/is_convertible.h>
@@ -60,7 +62,17 @@
 
 _LIBCPP_BEGIN_NAMESPACE_STD
 
-namespace __expected {
+template <class _Tp, class _Err>
+class expected;
+
+template <class _Tp>
+struct __is_std_expected : false_type {};
+
+template <class _Tp, class _Err>
+struct __is_std_expected<expected<_Tp, _Err>> : true_type {};
+
+struct __expected_construct_in_place_from_invoke_tag {};
+struct __expected_construct_unexpected_from_invoke_tag {};
 
 template <class _Err, class _Arg>
 _LIBCPP_HIDE_FROM_ABI void __throw_bad_expected_access(_Arg&& __arg) {
@@ -72,8 +84,6 @@ _LIBCPP_HIDE_FROM_ABI void __throw_bad_expected_access(_Arg&& __arg) {
 #  endif
 }
 
-} // namespace __expected
-
 template <class _Tp, class _Err>
 class expected {
   static_assert(
@@ -166,6 +176,15 @@ private:
             _Not<is_constructible<unexpected<_Err>, const expected<_Up, _OtherErr>&>>,
             _Not<is_constructible<unexpected<_Err>, const expected<_Up, _OtherErr>>> >;
 
+  template <class _Func, class... _Args>
+  _LIBCPP_HIDE_FROM_ABI constexpr explicit expected(
+      std::__expected_construct_in_place_from_invoke_tag __tag, _Func&& __f, _Args&&... __args)
+      : __union_(__tag, std::forward<_Func>(__f), std::forward<_Args>(__args)...), __has_val_(true) {}
+
+  template <class _Func, class... _Args>
+  _LIBCPP_HIDE_FROM_ABI constexpr explicit expected(
+      std::__expected_construct_unexpected_from_invoke_tag __tag, _Func&& __f, _Args&&... __args)
+      : __union_(__tag, std::forward<_Func>(__f), std::forward<_Args>(__args)...), __has_val_(false) {}
 
 public:
   template <class _Up, class _OtherErr>
@@ -538,28 +557,28 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI constexpr const _Tp& value() const& {
     if (!__has_val_) {
-      __expected::__throw_bad_expected_access<_Err>(__union_.__unex_);
+      std::__throw_bad_expected_access<_Err>(__union_.__unex_);
     }
     return __union_.__val_;
   }
 
   _LIBCPP_HIDE_FROM_ABI constexpr _Tp& value() & {
     if (!__has_val_) {
-      __expected::__throw_bad_expected_access<_Err>(__union_.__unex_);
+      std::__throw_bad_expected_access<_Err>(__union_.__unex_);
     }
     return __union_.__val_;
   }
 
   _LIBCPP_HIDE_FROM_ABI constexpr const _Tp&& value() const&& {
     if (!__has_val_) {
-      __expected::__throw_bad_expected_access<_Err>(std::move(__union_.__unex_));
+      std::__throw_bad_expected_access<_Err>(std::move(__union_.__unex_));
     }
     return std::move(__union_.__val_);
   }
 
   _LIBCPP_HIDE_FROM_ABI constexpr _Tp&& value() && {
     if (!__has_val_) {
-      __expected::__throw_bad_expected_access<_Err>(std::move(__union_.__unex_));
+      std::__throw_bad_expected_access<_Err>(std::move(__union_.__unex_));
     }
     return std::move(__union_.__val_);
   }
@@ -598,6 +617,245 @@ public:
     return __has_val_ ? std::move(__union_.__val_) : static_cast<_Tp>(std::forward<_Up>(__v));
   }
 
+  template <class _Up = _Err>
+  _LIBCPP_HIDE_FROM_ABI constexpr _Err error_or(_Up&& __error) const& {
+    static_assert(is_copy_constructible_v<_Err>, "error_type has to be copy constructible");
+    static_assert(is_convertible_v<_Up, _Err>, "argument has to be convertible to error_type");
+    if (has_value())
+      return std::forward<_Up>(__error);
+    return error();
+  }
+
+  template <class _Up = _Err>
+  _LIBCPP_HIDE_FROM_ABI constexpr _Err error_or(_Up&& __error) && {
+    static_assert(is_move_constructible_v<_Err>, "error_type has to be move constructible");
+    static_assert(is_convertible_v<_Up, _Err>, "argument has to be convertible to error_type");
+    if (has_value())
+      return std::forward<_Up>(__error);
+    return std::move(error());
+  }
+
+  // [expected.void.monadic], monadic
+  template <class _Func>
+    requires is_constructible_v<_Err, _Err&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto and_then(_Func&& __f) & {
+    using _Up = remove_cvref_t<invoke_result_t<_Func, _Tp&>>;
+    static_assert(__is_std_expected<_Up>::value, "The result of f(value()) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Up::error_type, _Err>,
+                  "The result of f(value()) must have the same error_type as this expected");
+    if (has_value()) {
+      return std::invoke(std::forward<_Func>(__f), value());
+    }
+    return _Up(unexpect, error());
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, const _Err&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto and_then(_Func&& __f) const& {
+    using _Up = remove_cvref_t<invoke_result_t<_Func, const _Tp&>>;
+    static_assert(__is_std_expected<_Up>::value, "The result of f(value()) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Up::error_type, _Err>,
+                  "The result of f(value()) must have the same error_type as this expected");
+    if (has_value()) {
+      return std::invoke(std::forward<_Func>(__f), value());
+    }
+    return _Up(unexpect, error());
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, _Err&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto and_then(_Func&& __f) && {
+    using _Up = remove_cvref_t<invoke_result_t<_Func, _Tp&&>>;
+    static_assert(
+        __is_std_expected<_Up>::value, "The result of f(std::move(value())) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Up::error_type, _Err>,
+                  "The result of f(std::move(value())) must have the same error_type as this expected");
+    if (has_value()) {
+      return std::invoke(std::forward<_Func>(__f), std::move(value()));
+    }
+    return _Up(unexpect, std::move(error()));
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, const _Err&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto and_then(_Func&& __f) const&& {
+    using _Up = remove_cvref_t<invoke_result_t<_Func, const _Tp&&>>;
+    static_assert(
+        __is_std_expected<_Up>::value, "The result of f(std::move(value())) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Up::error_type, _Err>,
+                  "The result of f(std::move(value())) must have the same error_type as this expected");
+    if (has_value()) {
+      return std::invoke(std::forward<_Func>(__f), std::move(value()));
+    }
+    return _Up(unexpect, std::move(error()));
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Tp, _Tp&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto or_else(_Func&& __f) & {
+    using _Gp = remove_cvref_t<invoke_result_t<_Func, _Err&>>;
+    static_assert(__is_std_expected<_Gp>::value, "The result of f(error()) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Gp::value_type, _Tp>,
+                  "The result of f(error()) must have the same value_type as this expected");
+    if (has_value()) {
+      return _Gp(in_place, value());
+    }
+    return std::invoke(std::forward<_Func>(__f), error());
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Tp, const _Tp&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto or_else(_Func&& __f) const& {
+    using _Gp = remove_cvref_t<invoke_result_t<_Func, const _Err&>>;
+    static_assert(__is_std_expected<_Gp>::value, "The result of f(error()) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Gp::value_type, _Tp>,
+                  "The result of f(error()) must have the same value_type as this expected");
+    if (has_value()) {
+      return _Gp(in_place, value());
+    }
+    return std::invoke(std::forward<_Func>(__f), error());
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Tp, _Tp&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto or_else(_Func&& __f) && {
+    using _Gp = remove_cvref_t<invoke_result_t<_Func, _Err&&>>;
+    static_assert(
+        __is_std_expected<_Gp>::value, "The result of f(std::move(error())) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Gp::value_type, _Tp>,
+                  "The result of f(std::move(error())) must have the same value_type as this expected");
+    if (has_value()) {
+      return _Gp(in_place, std::move(value()));
+    }
+    return std::invoke(std::forward<_Func>(__f), std::move(error()));
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Tp, const _Tp&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto or_else(_Func&& __f) const&& {
+    using _Gp = remove_cvref_t<invoke_result_t<_Func, const _Err&&>>;
+    static_assert(
+        __is_std_expected<_Gp>::value, "The result of f(std::move(error())) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Gp::value_type, _Tp>,
+                  "The result of f(std::move(error())) must have the same value_type as this expected");
+    if (has_value()) {
+      return _Gp(in_place, std::move(value()));
+    }
+    return std::invoke(std::forward<_Func>(__f), std::move(error()));
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, _Err&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform(_Func&& __f) & {
+    using _Up = remove_cv_t<invoke_result_t<_Func, _Tp&>>;
+    if (!has_value()) {
+      return expected<_Up, _Err>(unexpect, error());
+    }
+    if constexpr (!is_void_v<_Up>) {
+      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), value());
+    } else {
+      std::invoke(std::forward<_Func>(__f), value());
+      return expected<_Up, _Err>();
+    }
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, const _Err&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform(_Func&& __f) const& {
+    using _Up = remove_cv_t<invoke_result_t<_Func, const _Tp&>>;
+    if (!has_value()) {
+      return expected<_Up, _Err>(unexpect, error());
+    }
+    if constexpr (!is_void_v<_Up>) {
+      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), value());
+    } else {
+      std::invoke(std::forward<_Func>(__f), value());
+      return expected<_Up, _Err>();
+    }
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, _Err&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform(_Func&& __f) && {
+    using _Up = remove_cv_t<invoke_result_t<_Func, _Tp&&>>;
+    if (!has_value()) {
+      return expected<_Up, _Err>(unexpect, std::move(error()));
+    }
+    if constexpr (!is_void_v<_Up>) {
+      return expected<_Up, _Err>(
+          __expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), std::move(value()));
+    } else {
+      std::invoke(std::forward<_Func>(__f), std::move(value()));
+      return expected<_Up, _Err>();
+    }
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, const _Err&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform(_Func&& __f) const&& {
+    using _Up = remove_cv_t<invoke_result_t<_Func, const _Tp&&>>;
+    if (!has_value()) {
+      return expected<_Up, _Err>(unexpect, std::move(error()));
+    }
+    if constexpr (!is_void_v<_Up>) {
+      return expected<_Up, _Err>(
+          __expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f), std::move(value()));
+    } else {
+      std::invoke(std::forward<_Func>(__f), std::move(value()));
+      return expected<_Up, _Err>();
+    }
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Tp, _Tp&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform_error(_Func&& __f) & {
+    using _Gp = remove_cv_t<invoke_result_t<_Func, _Err&>>;
+    static_assert(__valid_std_unexpected<_Gp>::value,
+                  "The result of f(error()) must be a valid template argument for unexpected");
+    if (has_value()) {
+      return expected<_Tp, _Gp>(in_place, value());
+    }
+    return expected<_Tp, _Gp>(__expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), error());
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Tp, const _Tp&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform_error(_Func&& __f) const& {
+    using _Gp = remove_cv_t<invoke_result_t<_Func, const _Err&>>;
+    static_assert(__valid_std_unexpected<_Gp>::value,
+                  "The result of f(error()) must be a valid template argument for unexpected");
+    if (has_value()) {
+      return expected<_Tp, _Gp>(in_place, value());
+    }
+    return expected<_Tp, _Gp>(__expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), error());
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Tp, _Tp&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform_error(_Func&& __f) && {
+    using _Gp = remove_cv_t<invoke_result_t<_Func, _Err&&>>;
+    static_assert(__valid_std_unexpected<_Gp>::value,
+                  "The result of f(std::move(error())) must be a valid template argument for unexpected");
+    if (has_value()) {
+      return expected<_Tp, _Gp>(in_place, std::move(value()));
+    }
+    return expected<_Tp, _Gp>(
+        __expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), std::move(error()));
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Tp, const _Tp&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform_error(_Func&& __f) const&& {
+    using _Gp = remove_cv_t<invoke_result_t<_Func, const _Err&&>>;
+    static_assert(__valid_std_unexpected<_Gp>::value,
+                  "The result of f(std::move(error())) must be a valid template argument for unexpected");
+    if (has_value()) {
+      return expected<_Tp, _Gp>(in_place, std::move(value()));
+    }
+    return expected<_Tp, _Gp>(
+        __expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), std::move(error()));
+  }
+
   // [expected.object.eq], equality operators
   template <class _T2, class _E2>
     requires(!is_void_v<_T2>)
@@ -625,24 +883,66 @@ public:
 
 private:
   struct __empty_t {};
-  // use named union because [[no_unique_address]] cannot be applied to an unnamed union
-  _LIBCPP_NO_UNIQUE_ADDRESS union __union_t {
+
+  template <class _ValueType, class _ErrorType>
+  union __union_t {
+    _LIBCPP_HIDE_FROM_ABI constexpr __union_t() {}
+
+    template <class _Func, class... _Args>
+    _LIBCPP_HIDE_FROM_ABI constexpr explicit __union_t(
+        std::__expected_construct_in_place_from_invoke_tag, _Func&& __f, _Args&&... __args)
+        : __val_(std::invoke(std::forward<_Func>(__f), std::forward<_Args>(__args)...)) {}
+
+    template <class _Func, class... _Args>
+    _LIBCPP_HIDE_FROM_ABI constexpr explicit __union_t(
+        std::__expected_construct_unexpected_from_invoke_tag, _Func&& __f, _Args&&... __args)
+        : __unex_(std::invoke(std::forward<_Func>(__f), std::forward<_Args>(__args)...)) {}
+
+    _LIBCPP_HIDE_FROM_ABI constexpr ~__union_t()
+      requires(is_trivially_destructible_v<_ValueType> && is_trivially_destructible_v<_ErrorType>)
+    = default;
+
+    // the expected's destructor handles this
+    _LIBCPP_HIDE_FROM_ABI constexpr ~__union_t() {}
+
+    _ValueType __val_;
+    _ErrorType __unex_;
+  };
+
+  // use named union because [[no_unique_address]] cannot be applied to an unnamed union,
+  // also guaranteed elision into a potentially-overlapping subobject is unsettled (and
+  // it's not clear that it's implementable, given that the function is allowed to clobber
+  // the tail padding) - see https://github.com/itanium-cxx-abi/cxx-abi/issues/107.
+  template <class _ValueType, class _ErrorType>
+    requires(is_trivially_move_constructible_v<_ValueType> && is_trivially_move_constructible_v<_ErrorType>)
+  union __union_t<_ValueType, _ErrorType> {
     _LIBCPP_HIDE_FROM_ABI constexpr __union_t() : __empty_() {}
 
+    template <class _Func, class... _Args>
+    _LIBCPP_HIDE_FROM_ABI constexpr explicit __union_t(
+        std::__expected_construct_in_place_from_invoke_tag, _Func&& __f, _Args&&... __args)
+        : __val_(std::invoke(std::forward<_Func>(__f), std::forward<_Args>(__args)...)) {}
+
+    template <class _Func, class... _Args>
+    _LIBCPP_HIDE_FROM_ABI constexpr explicit __union_t(
+        std::__expected_construct_unexpected_from_invoke_tag, _Func&& __f, _Args&&... __args)
+        : __unex_(std::invoke(std::forward<_Func>(__f), std::forward<_Args>(__args)...)) {}
+
     _LIBCPP_HIDE_FROM_ABI constexpr ~__union_t()
-      requires(is_trivially_destructible_v<_Tp> && is_trivially_destructible_v<_Err>)
+      requires(is_trivially_destructible_v<_ValueType> && is_trivially_destructible_v<_ErrorType>)
     = default;
 
     // the expected's destructor handles this
     _LIBCPP_HIDE_FROM_ABI constexpr ~__union_t()
-      requires(!is_trivially_destructible_v<_Tp> || !is_trivially_destructible_v<_Err>)
+      requires(!is_trivially_destructible_v<_ValueType> || !is_trivially_destructible_v<_ErrorType>)
     {}
 
     _LIBCPP_NO_UNIQUE_ADDRESS __empty_t __empty_;
-    _LIBCPP_NO_UNIQUE_ADDRESS _Tp __val_;
-    _LIBCPP_NO_UNIQUE_ADDRESS _Err __unex_;
-  } __union_;
+    _LIBCPP_NO_UNIQUE_ADDRESS _ValueType __val_;
+    _LIBCPP_NO_UNIQUE_ADDRESS _ErrorType __unex_;
+  };
 
+  _LIBCPP_NO_UNIQUE_ADDRESS __union_t<_Tp, _Err> __union_;
   bool __has_val_;
 };
 
@@ -762,6 +1062,19 @@ public:
     std::construct_at(std::addressof(__union_.__unex_), __il, std::forward<_Args>(__args)...);
   }
 
+private:
+  template <class _Func>
+  _LIBCPP_HIDE_FROM_ABI constexpr explicit expected(__expected_construct_in_place_from_invoke_tag, _Func&& __f)
+      : __has_val_(true) {
+    std::invoke(std::forward<_Func>(__f));
+  }
+
+  template <class _Func, class... _Args>
+  _LIBCPP_HIDE_FROM_ABI constexpr explicit expected(
+      __expected_construct_unexpected_from_invoke_tag __tag, _Func&& __f, _Args&&... __args)
+      : __union_(__tag, std::forward<_Func>(__f), std::forward<_Args>(__args)...), __has_val_(false) {}
+
+public:
   // [expected.void.dtor], destructor
 
   _LIBCPP_HIDE_FROM_ABI constexpr ~expected()
@@ -899,13 +1212,13 @@ public:
 
   _LIBCPP_HIDE_FROM_ABI constexpr void value() const& {
     if (!__has_val_) {
-      __expected::__throw_bad_expected_access<_Err>(__union_.__unex_);
+      std::__throw_bad_expected_access<_Err>(__union_.__unex_);
     }
   }
 
   _LIBCPP_HIDE_FROM_ABI constexpr void value() && {
     if (!__has_val_) {
-      __expected::__throw_bad_expected_access<_Err>(std::move(__union_.__unex_));
+      std::__throw_bad_expected_access<_Err>(std::move(__union_.__unex_));
     }
   }
 
@@ -929,6 +1242,235 @@ public:
     return std::move(__union_.__unex_);
   }
 
+  template <class _Up = _Err>
+  _LIBCPP_HIDE_FROM_ABI constexpr _Err error_or(_Up&& __error) const& {
+    static_assert(is_copy_constructible_v<_Err>, "error_type has to be copy constructible");
+    static_assert(is_convertible_v<_Up, _Err>, "argument has to be convertible to error_type");
+    if (has_value()) {
+      return std::forward<_Up>(__error);
+    }
+    return error();
+  }
+
+  template <class _Up = _Err>
+  _LIBCPP_HIDE_FROM_ABI constexpr _Err error_or(_Up&& __error) && {
+    static_assert(is_move_constructible_v<_Err>, "error_type has to be move constructible");
+    static_assert(is_convertible_v<_Up, _Err>, "argument has to be convertible to error_type");
+    if (has_value()) {
+      return std::forward<_Up>(__error);
+    }
+    return std::move(error());
+  }
+
+  // [expected.void.monadic], monadic
+  template <class _Func>
+    requires is_constructible_v<_Err, _Err&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto and_then(_Func&& __f) & {
+    using _Up = remove_cvref_t<invoke_result_t<_Func>>;
+    static_assert(__is_std_expected<_Up>::value, "The result of f() must be a specialization of std::expected");
+    static_assert(
+        is_same_v<typename _Up::error_type, _Err>, "The result of f() must have the same error_type as this expected");
+    if (has_value()) {
+      return std::invoke(std::forward<_Func>(__f));
+    }
+    return _Up(unexpect, error());
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, const _Err&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto and_then(_Func&& __f) const& {
+    using _Up = remove_cvref_t<invoke_result_t<_Func>>;
+    static_assert(__is_std_expected<_Up>::value, "The result of f() must be a specialization of std::expected");
+    static_assert(
+        is_same_v<typename _Up::error_type, _Err>, "The result of f() must have the same error_type as this expected");
+    if (has_value()) {
+      return std::invoke(std::forward<_Func>(__f));
+    }
+    return _Up(unexpect, error());
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, _Err&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto and_then(_Func&& __f) && {
+    using _Up = remove_cvref_t<invoke_result_t<_Func>>;
+    static_assert(__is_std_expected<_Up>::value, "The result of f() must be a specialization of std::expected");
+    static_assert(
+        is_same_v<typename _Up::error_type, _Err>, "The result of f() must have the same error_type as this expected");
+    if (has_value()) {
+      return std::invoke(std::forward<_Func>(__f));
+    }
+    return _Up(unexpect, std::move(error()));
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, const _Err&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto and_then(_Func&& __f) const&& {
+    using _Up = remove_cvref_t<invoke_result_t<_Func>>;
+    static_assert(__is_std_expected<_Up>::value, "The result of f() must be a specialization of std::expected");
+    static_assert(
+        is_same_v<typename _Up::error_type, _Err>, "The result of f() must have the same error_type as this expected");
+    if (has_value()) {
+      return std::invoke(std::forward<_Func>(__f));
+    }
+    return _Up(unexpect, std::move(error()));
+  }
+
+  template <class _Func>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto or_else(_Func&& __f) & {
+    using _Gp = remove_cvref_t<invoke_result_t<_Func, _Err&>>;
+    static_assert(__is_std_expected<_Gp>::value, "The result of f(error()) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Gp::value_type, _Tp>,
+                  "The result of f(error()) must have the same value_type as this expected");
+    if (has_value()) {
+      return _Gp();
+    }
+    return std::invoke(std::forward<_Func>(__f), error());
+  }
+
+  template <class _Func>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto or_else(_Func&& __f) const& {
+    using _Gp = remove_cvref_t<invoke_result_t<_Func, const _Err&>>;
+    static_assert(__is_std_expected<_Gp>::value, "The result of f(error()) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Gp::value_type, _Tp>,
+                  "The result of f(error()) must have the same value_type as this expected");
+    if (has_value()) {
+      return _Gp();
+    }
+    return std::invoke(std::forward<_Func>(__f), error());
+  }
+
+  template <class _Func>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto or_else(_Func&& __f) && {
+    using _Gp = remove_cvref_t<invoke_result_t<_Func, _Err&&>>;
+    static_assert(__is_std_expected<_Gp>::value,
+                  "The result of f(std::move(error())) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Gp::value_type, _Tp>,
+                  "The result of f(std::move(error())) must have the same value_type as this expected");
+    if (has_value()) {
+      return _Gp();
+    }
+    return std::invoke(std::forward<_Func>(__f), std::move(error()));
+  }
+
+  template <class _Func>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto or_else(_Func&& __f) const&& {
+    using _Gp = remove_cvref_t<invoke_result_t<_Func, const _Err&&>>;
+    static_assert(__is_std_expected<_Gp>::value,
+                  "The result of f(std::move(error())) must be a specialization of std::expected");
+    static_assert(is_same_v<typename _Gp::value_type, _Tp>,
+                  "The result of f(std::move(error())) must have the same value_type as this expected");
+    if (has_value()) {
+      return _Gp();
+    }
+    return std::invoke(std::forward<_Func>(__f), std::move(error()));
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, _Err&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform(_Func&& __f) & {
+    using _Up = remove_cv_t<invoke_result_t<_Func>>;
+    if (!has_value()) {
+      return expected<_Up, _Err>(unexpect, error());
+    }
+    if constexpr (!is_void_v<_Up>) {
+      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f));
+    } else {
+      std::invoke(std::forward<_Func>(__f));
+      return expected<_Up, _Err>();
+    }
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, const _Err&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform(_Func&& __f) const& {
+    using _Up = remove_cv_t<invoke_result_t<_Func>>;
+    if (!has_value()) {
+      return expected<_Up, _Err>(unexpect, error());
+    }
+    if constexpr (!is_void_v<_Up>) {
+      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f));
+    } else {
+      std::invoke(std::forward<_Func>(__f));
+      return expected<_Up, _Err>();
+    }
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, _Err&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform(_Func&& __f) && {
+    using _Up = remove_cv_t<invoke_result_t<_Func>>;
+    if (!has_value()) {
+      return expected<_Up, _Err>(unexpect, std::move(error()));
+    }
+    if constexpr (!is_void_v<_Up>) {
+      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f));
+    } else {
+      std::invoke(std::forward<_Func>(__f));
+      return expected<_Up, _Err>();
+    }
+  }
+
+  template <class _Func>
+    requires is_constructible_v<_Err, const _Err&&>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform(_Func&& __f) const&& {
+    using _Up = remove_cv_t<invoke_result_t<_Func>>;
+    if (!has_value()) {
+      return expected<_Up, _Err>(unexpect, std::move(error()));
+    }
+    if constexpr (!is_void_v<_Up>) {
+      return expected<_Up, _Err>(__expected_construct_in_place_from_invoke_tag{}, std::forward<_Func>(__f));
+    } else {
+      std::invoke(std::forward<_Func>(__f));
+      return expected<_Up, _Err>();
+    }
+  }
+
+  template <class _Func>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform_error(_Func&& __f) & {
+    using _Gp = remove_cv_t<invoke_result_t<_Func, _Err&>>;
+    static_assert(__valid_std_unexpected<_Gp>::value,
+                  "The result of f(error()) must be a valid template argument for unexpected");
+    if (has_value()) {
+      return expected<_Tp, _Gp>();
+    }
+    return expected<_Tp, _Gp>(__expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), error());
+  }
+
+  template <class _Func>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform_error(_Func&& __f) const& {
+    using _Gp = remove_cv_t<invoke_result_t<_Func, const _Err&>>;
+    static_assert(__valid_std_unexpected<_Gp>::value,
+                  "The result of f(error()) must be a valid template argument for unexpected");
+    if (has_value()) {
+      return expected<_Tp, _Gp>();
+    }
+    return expected<_Tp, _Gp>(__expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), error());
+  }
+
+  template <class _Func>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform_error(_Func&& __f) && {
+    using _Gp = remove_cv_t<invoke_result_t<_Func, _Err&&>>;
+    static_assert(__valid_std_unexpected<_Gp>::value,
+                  "The result of f(std::move(error())) must be a valid template argument for unexpected");
+    if (has_value()) {
+      return expected<_Tp, _Gp>();
+    }
+    return expected<_Tp, _Gp>(
+        __expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), std::move(error()));
+  }
+
+  template <class _Func>
+  _LIBCPP_HIDE_FROM_ABI constexpr auto transform_error(_Func&& __f) const&& {
+    using _Gp = remove_cv_t<invoke_result_t<_Func, const _Err&&>>;
+    static_assert(__valid_std_unexpected<_Gp>::value,
+                  "The result of f(std::move(error())) must be a valid template argument for unexpected");
+    if (has_value()) {
+      return expected<_Tp, _Gp>();
+    }
+    return expected<_Tp, _Gp>(
+        __expected_construct_unexpected_from_invoke_tag{}, std::forward<_Func>(__f), std::move(error()));
+  }
+
   // [expected.void.eq], equality operators
   template <class _T2, class _E2>
     requires is_void_v<_T2>
@@ -947,23 +1489,55 @@ public:
 
 private:
   struct __empty_t {};
-  // use named union because [[no_unique_address]] cannot be applied to an unnamed union
-  _LIBCPP_NO_UNIQUE_ADDRESS union __union_t {
+
+  template <class _ErrorType>
+  union __union_t {
     _LIBCPP_HIDE_FROM_ABI constexpr __union_t() : __empty_() {}
 
+    template <class _Func, class... _Args>
+    _LIBCPP_HIDE_FROM_ABI constexpr explicit __union_t(
+        __expected_construct_unexpected_from_invoke_tag, _Func&& __f, _Args&&... __args)
+        : __unex_(std::invoke(std::forward<_Func>(__f), std::forward<_Args>(__args)...)) {}
+
+    _LIBCPP_HIDE_FROM_ABI constexpr ~__union_t()
+      requires(is_trivially_destructible_v<_ErrorType>)
+    = default;
+
+    // the expected's destructor handles this
+    _LIBCPP_HIDE_FROM_ABI constexpr ~__union_t() {}
+
+    __empty_t __empty_;
+    _ErrorType __unex_;
+  };
+
+  // use named union because [[no_unique_address]] cannot be applied to an unnamed union,
+  // also guaranteed elision into a potentially-overlapping subobject is unsettled (and
+  // it's not clear that it's implementable, given that the function is allowed to clobber
+  // the tail padding) - see https://github.com/itanium-cxx-abi/cxx-abi/issues/107.
+  template <class _ErrorType>
+    requires is_trivially_move_constructible_v<_ErrorType>
+  union __union_t<_ErrorType> {
+    _LIBCPP_HIDE_FROM_ABI constexpr __union_t() : __empty_() {}
+
+    template <class _Func, class... _Args>
+    _LIBCPP_HIDE_FROM_ABI constexpr explicit __union_t(
+        __expected_construct_unexpected_from_invoke_tag, _Func&& __f, _Args&&... __args)
+        : __unex_(std::invoke(std::forward<_Func>(__f), std::forward<_Args>(__args)...)) {}
+
     _LIBCPP_HIDE_FROM_ABI constexpr ~__union_t()
-      requires(is_trivially_destructible_v<_Err>)
+      requires(is_trivially_destructible_v<_ErrorType>)
     = default;
 
     // the expected's destructor handles this
     _LIBCPP_HIDE_FROM_ABI constexpr ~__union_t()
-      requires(!is_trivially_destructible_v<_Err>)
+      requires(!is_trivially_destructible_v<_ErrorType>)
     {}
 
     _LIBCPP_NO_UNIQUE_ADDRESS __empty_t __empty_;
-    _LIBCPP_NO_UNIQUE_ADDRESS _Err __unex_;
-  } __union_;
+    _LIBCPP_NO_UNIQUE_ADDRESS _ErrorType __unex_;
+  };
 
+  _LIBCPP_NO_UNIQUE_ADDRESS __union_t<_Err> __union_;
   bool __has_val_;
 };
 
diff --git a/libcxx/include/version b/libcxx/include/version
index b87abdfce522..4cb74e29cbf2 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -82,7 +82,7 @@ __cpp_lib_erase_if                                      202002L <deque> <forward
 __cpp_lib_exchange_function                             201304L <utility>
 __cpp_lib_execution                                     201902L <execution>
                                                         201603L // C++17
-__cpp_lib_expected                                      202202L <expected>
+__cpp_lib_expected                                      202211L <expected>
 __cpp_lib_filesystem                                    201703L <filesystem>
 __cpp_lib_format                                        202106L <format>
 __cpp_lib_format_ranges                                 202207L <format>
@@ -399,7 +399,7 @@ __cpp_lib_void_t                                        201411L <type_traits>
 # undef  __cpp_lib_constexpr_memory
 # define __cpp_lib_constexpr_memory                     202202L
 # define __cpp_lib_constexpr_typeinfo                   202106L
-# define __cpp_lib_expected                             202202L
+# define __cpp_lib_expected                             202211L
 # if !defined(_LIBCPP_HAS_NO_INCOMPLETE_FORMAT)
 #   define __cpp_lib_format_ranges                      202207L
 # endif
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp
new file mode 100644
index 000000000000..692ac60d0738
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/and_then.mandates.verify.cpp
@@ -0,0 +1,126 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// Test the mandates
+// template<class F> constexpr auto and_then(F&& f) &;
+// Mandates:
+//  Let U be std::remove_cvref_t<std::invoke_result<F, decltype(value())>>
+//  U is a specialization of std::expected and std::is_same_v<U:error_type, E> is true
+
+// template<class F> constexpr auto and_then(F&& f) const &;
+// Mandates:
+//  Let U be std::remove_cvref_t<std::invoke_result<F, decltype(value())>>
+//  U is a specialization of std::expected and std::is_same_v<U:error_type, E> is true
+
+// template<class F> constexpr auto and_then(F&& f) &&;
+// Mandates:
+//  Let U be std::remove_cvref_t<std::invoke_result<F, decltype(value())>>
+//  U is a specialization of std::expected and std::is_same_v<U:error_type, E> is true
+
+// template<class F> constexpr auto and_then(F&& f) const &&;
+// Mandates:
+//  Let U be std::remove_cvref_t<std::invoke_result<F, decltype(value())>>
+//  U is a specialization of std::expected and std::is_same_v<U:error_type, E> is true
+
+#include <expected>
+#include <utility>
+
+struct NotSameAsInt {};
+
+int lval_return_not_std_expected(int&) { return 0; }
+int clval_return_not_std_expected(const int&) { return 0; }
+int rval_return_not_std_expected(int&&) { return 0; }
+int crval_return_not_std_expected(const int&&) { return 0; }
+
+std::expected<int, NotSameAsInt> lval_error_type_not_same_as_int(int&) { return {}; }
+std::expected<int, NotSameAsInt> clval_error_type_not_same_as_int(const int&) { return {}; }
+std::expected<int, NotSameAsInt> rval_error_type_not_same_as_int(int&&) { return {}; }
+std::expected<int, NotSameAsInt> crval_error_type_not_same_as_int(const int&&) { return {}; }
+
+// clang-format off
+void test() {
+  // Test & overload
+  {
+    // U is not a specialization of std::expected
+    {
+      std::expected<int, int> f1(1);
+      f1.and_then(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(value()) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<U:error_type, E>
+    {
+      std::expected<int, int> f1(1);
+      f1.and_then(lval_error_type_not_same_as_int);  // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(value()) must have the same error_type as this expected}}
+    }
+  }
+
+  // Test const& overload
+  {
+    // U is not a specialization of std::expected
+    {
+      const std::expected<int, int> f1(1);
+      f1.and_then(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(const int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(value()) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<U:error_type, E>
+    {
+      const std::expected<int, int> f1(1);
+      f1.and_then(clval_error_type_not_same_as_int);  // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(const int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(value()) must have the same error_type as this expected}}
+
+    }
+  }
+
+  // Test && overload
+  {
+    // U is not a specialization of std::expected
+    {
+      std::expected<int, int> f1(1);
+      std::move(f1).and_then(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(value())) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<U:error_type, E>
+    {
+      std::expected<int, int> f1(1);
+      std::move(f1).and_then(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(value())) must have the same error_type as this expected}}
+    }
+  }
+
+  // Test const&& overload
+  {
+    // U is not a specialization of std::expected
+    {
+      const std::expected<int, int> f1(1);
+      std::move(f1).and_then(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<int (&)(const int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(value())) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<U:error_type, E>
+    {
+      const std::expected<int, int> f1(1);
+      std::move(f1).and_then(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::and_then<std::expected<int, NotSameAsInt> (&)(const int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(value())) must have the same error_type as this expected}}
+    }
+  }
+}
+// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/error_or.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/error_or.mandates.verify.cpp
new file mode 100644
index 000000000000..f0ab5c495517
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/error_or.mandates.verify.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
+
+// Test the mandates
+// template<class G = E> constexpr E error_or(G&&) const &;
+// Mandates: is_copy_constructible_v<G> is true and is_convertible_v<U, E> is true.
+
+// template<class G = E> constexpr E error_or(G&&) &&;
+// Mandates: is_move_constructible_v<G> is true and is_convertible_v<U, E> is true.
+
+#include <expected>
+#include <utility>
+
+struct NonCopyable {
+  NonCopyable(int) {}
+  NonCopyable(const NonCopyable&) = delete;
+};
+
+struct NonMovable {
+  NonMovable(int) {}
+  NonMovable(NonMovable&&) = delete;
+};
+
+struct NotConvertibleFromInt {};
+
+// clang-format off
+void test() {
+  // const & overload
+  // !is_copy_constructible_v<G>,
+  {
+    const std::expected<int, NonCopyable> f1(std::unexpect, 0);
+    f1.error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NonCopyable>::error_or<int>' requested here}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}error_type has to be copy constructible}}
+    // expected-error-re@*:* {{call to deleted constructor of{{.*}}}}
+  }
+
+  // const & overload
+  // !is_convertible_v<U, T>
+  {
+    const std::expected<int, NotConvertibleFromInt> f1(std::unexpect, NotConvertibleFromInt{});
+    f1.error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NotConvertibleFromInt>::error_or<int>' requested here}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}argument has to be convertible to error_type}}
+    // expected-error-re@*:* {{no viable conversion from returned value of type{{.*}}}}
+
+  }
+
+  // && overload
+  // !is_move_constructible_v<T>,
+  {
+    std::expected<int, NonMovable> f1(std::unexpect, 0);
+    std::move(f1).error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NonMovable>::error_or<int>' requested here}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}error_type has to be move constructible}}
+    // expected-error-re@*:* {{call to deleted constructor of{{.*}}}}
+  }
+
+  // && overload
+  // !is_convertible_v<U, T>
+  {
+    std::expected<int, NotConvertibleFromInt> f1(std::unexpect, NotConvertibleFromInt{});
+    std::move(f1).error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<int, NotConvertibleFromInt>::error_or<int>' requested here}}
+    //expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}argument has to be convertible to error_type}}
+    // expected-error-re@*:* {{no viable conversion from returned value of type{{.*}}}}
+  }
+}
+// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/no_unique_address.compile.pass.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/no_unique_address.compile.pass.cpp
index 3fd047df7134..c8c217054ae6 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.expected/no_unique_address.compile.pass.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/no_unique_address.compile.pass.cpp
@@ -16,4 +16,20 @@
 
 struct Empty {};
 
+struct A {
+  int x_;
+  int y_;
+};
+
+struct B : public A {
+  int z_;
+  virtual ~B() = default;
+};
+
 static_assert(sizeof(std::expected<Empty, Empty>) == sizeof(bool));
+static_assert(sizeof(std::expected<Empty, A>) == 2 * sizeof(int) + alignof(std::expected<Empty, A>));
+static_assert(sizeof(std::expected<Empty, B>) == sizeof(B) + alignof(std::expected<Empty, B>));
+static_assert(sizeof(std::expected<A, Empty>) == 2 * sizeof(int) + alignof(std::expected<A, Empty>));
+static_assert(sizeof(std::expected<A, A>) == 2 * sizeof(int) + alignof(std::expected<A, A>));
+static_assert(sizeof(std::expected<B, Empty>) == sizeof(B) + alignof(std::expected<B, Empty>));
+static_assert(sizeof(std::expected<B, B>) == sizeof(B) + alignof(std::expected<B, B>));
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp
new file mode 100644
index 000000000000..1264cc06b48c
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/or_else.mandates.verify.cpp
@@ -0,0 +1,125 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// Test the mandates
+// template<class F> constexpr auto or_else(F&& f) &;
+// Mandates:
+//  Let G be std::remove_cvref_t<std::invoke_result<F, decltype(error())>>
+//  G is a specialization of std::expected and std::is_same_v<G:value_type, T> is true
+
+// template<class F> constexpr auto or_else(F&& f) const &;
+// Mandates:
+//  Let G be std::remove_cvref_t<std::invoke_result<F, decltype(error())>>
+//  G is a specialization of std::expected and std::is_same_v<G:value_type, T> is true
+
+// template<class F> constexpr auto or_else(F&& f) &&;
+// Mandates:
+//  Let G be std::remove_cvref_t<std::invoke_result<F, decltype(error())>>
+//  G is a specialization of std::expected and std::is_same_v<G:value_type, T> is true
+
+// template<class F> constexpr auto or_else(F&& f) const &&;
+// Mandates:
+//  Let G be std::remove_cvref_t<std::invoke_result<F, decltype(error())>>
+//  G is a specialization of std::expected and std::is_same_v<G:value_type, T> is true
+
+#include <expected>
+#include <utility>
+
+struct NotSameAsInt {};
+
+int lval_return_not_std_expected(int&) { return 0; }
+int clval_return_not_std_expected(const int&) { return 0; }
+int rval_return_not_std_expected(int&&) { return 0; }
+int crval_return_not_std_expected(const int&&) { return 0; }
+
+std::expected<NotSameAsInt, int> lval_error_type_not_same_as_int(int&) { return {}; }
+std::expected<NotSameAsInt, int> clval_error_type_not_same_as_int(const int&) { return {}; }
+std::expected<NotSameAsInt, int> rval_error_type_not_same_as_int(int&&) { return {}; }
+std::expected<NotSameAsInt, int> crval_error_type_not_same_as_int(const int&&) { return {}; }
+
+// clang-format off
+void test() {
+  // Test & overload
+  {
+    // G is not a specialization of std::expected
+    {
+      std::expected<int, int> f1(std::unexpected<int>(1));
+      f1.or_else(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(error()) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<G:value_type, T>
+    {
+      std::expected<int, int> f1(std::unexpected<int>(1));
+      f1.or_else(lval_error_type_not_same_as_int);  // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(error()) must have the same value_type as this expected}}
+    }
+  }
+
+  // Test const& overload
+  {
+    // G is not a specialization of std::expected
+    {
+      const std::expected<int, int> f1(std::unexpected<int>(1));
+      f1.or_else(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(const int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(error()) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<G:value_type, T>
+    {
+      const std::expected<int, int> f1(std::unexpected<int>(1));
+      f1.or_else(clval_error_type_not_same_as_int);  // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(const int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(error()) must have the same value_type as this expected}}
+    }
+  }
+
+  // Test && overload
+  {
+    // G is not a specialization of std::expected
+    {
+      std::expected<int, int> f1(std::unexpected<int>(1));
+      std::move(f1).or_else(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(error())) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<G:value_type, T>
+    {
+      std::expected<int, int> f1(std::unexpected<int>(1));
+      std::move(f1).or_else(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(error())) must have the same value_type as this expected}}
+    }
+  }
+
+  // Test const&& overload
+  {
+    // G is not a specialization of std::expected
+    {
+      const std::expected<int, int> f1(std::unexpected<int>(1));
+      std::move(f1).or_else(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<int (&)(const int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(error())) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<G:value_type, T>
+    {
+      const std::expected<int, int> f1(std::unexpected<int>(1));
+      std::move(f1).or_else(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<int, int>::or_else<std::expected<NotSameAsInt, int> (&)(const int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(error())) must have the same value_type as this expected}}
+    }
+  }
+}
+// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.expected/transform_error.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.expected/transform_error.mandates.verify.cpp
new file mode 100644
index 000000000000..32b82fdaa255
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/expected/expected.expected/transform_error.mandates.verify.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
+
+// Test the mandates
+
+// template<class F> constexpr auto transform_error(F&& f) &;
+// template<class F> constexpr auto transform_error(F&& f) const &;
+//
+// Let G be remove_cv_t<invoke_result_t<F, decltype(error())>>
+// G is a valid template argument for unexpected ([expected.un.general]) and the declaration
+// G g(invoke(std::forward<F>(f), error())); is well-formed.
+
+// template<class F> constexpr auto transform_error(F&& f) &&;
+// template<class F> constexpr auto transform_error(F&& f) const &&;
+//
+// Let G be remove_cv_t<invoke_result_t<F, decltype(std::move(error()))>>.
+// G is a valid template argument for unexpected ([expected.un.general]) and the declaration
+// G g(invoke(std::forward<F>(f), std::move(error()))); is well-formed.
+
+#include <expected>
+#include <utility>
+
+static int val;
+
+template <class T>
+std::unexpected<int> return_unexpected(T) {
+  return std::unexpected<int>(1);
+}
+
+template <class T>
+int& return_no_object(T) {
+  return val;
+}
+
+// clang-format off
+void test() {
+
+  // Test & overload
+  {
+    std::expected<int, int> e;
+    e.transform_error(return_unexpected<int&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}[expected.object.general] A program that instantiates the definition of template expected<T, E> for {{.*}} is ill-formed.}}
+
+    e.transform_error(return_no_object<int&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}[expected.object.general] A program that instantiates the definition of template expected<T, E> for {{.*}} is ill-formed.}}
+  }
+
+  // Test const& overload
+  {
+    const std::expected<int, int> e;
+    e.transform_error(return_unexpected<const int &>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    e.transform_error(return_no_object<const int &>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+  }
+
+  // Test && overload
+  {
+    std::expected<int, int> e;
+    std::move(e).transform_error(return_unexpected<int&&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    std::move(e).transform_error(return_no_object<int&&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+  }
+
+  // Test const&& overload
+  {
+    const std::expected<int, int> e;
+    std::move(e).transform_error(return_unexpected<const int&&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    std::move(e).transform_error(return_no_object<const int&&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* 2 {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+  }
+}
+// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp
new file mode 100644
index 000000000000..615d5347fcc0
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/and_then.mandates.verify.cpp
@@ -0,0 +1,125 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// Test the mandates
+// template<class F> constexpr auto and_then(F&& f) &;
+// Mandates:
+//  Let U be std::remove_cvref_t<std::invoke_result<F>>
+//  U is a specialization of std::expected and std::is_same_v<U:error_type, E> is true
+
+// template<class F> constexpr auto and_then(F&& f) const &;
+// Mandates:
+//  Let U be std::remove_cvref_t<std::invoke_result<F>>
+//  U is a specialization of std::expected and std::is_same_v<U:error_type, E> is true
+
+// template<class F> constexpr auto and_then(F&& f) &&;
+// Mandates:
+//  Let U be std::remove_cvref_t<std::invoke_result<F>>
+//  U is a specialization of std::expected and std::is_same_v<U:error_type, E> is true
+
+// template<class F> constexpr auto and_then(F&& f) const &&;
+// Mandates:
+//  Let U be std::remove_cvref_t<std::invoke_result<F>>
+//  U is a specialization of std::expected and std::is_same_v<U:error_type, E> is true
+
+#include <expected>
+#include <utility>
+
+struct NotSameAsInt {};
+
+int lval_return_not_std_expected(void) { return 0; }
+int clval_return_not_std_expected(void) { return 0; }
+int rval_return_not_std_expected(void) { return 0; }
+int crval_return_not_std_expected(void) { return 0; }
+
+std::expected<int, NotSameAsInt> lval_error_type_not_same_as_int(void) { return {}; }
+std::expected<int, NotSameAsInt> clval_error_type_not_same_as_int(void) { return {}; }
+std::expected<int, NotSameAsInt> rval_error_type_not_same_as_int(void) { return {}; }
+std::expected<int, NotSameAsInt> crval_error_type_not_same_as_int(void) { return {}; }
+
+// clang-format off
+void test() {
+  // Test & overload
+  {
+    // U is not a specialization of std::expected
+    {
+      std::expected<void, int> f1;
+      f1.and_then(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f() must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<U:error_type, E>
+    {
+      std::expected<void, int> f1;
+      f1.and_then(lval_error_type_not_same_as_int);  // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f() must have the same error_type as this expected}}
+    }
+  }
+
+  // Test const& overload
+  {
+    // U is not a specialization of std::expected
+    {
+      const std::expected<void, int> f1;
+      f1.and_then(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f() must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<U:error_type, E>
+    {
+      const std::expected<void, int> f1;
+      f1.and_then(clval_error_type_not_same_as_int);  // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f() must have the same error_type as this expected}}
+    }
+  }
+
+  // Test && overload
+  {
+    // U is not a specialization of std::expected
+    {
+      std::expected<void, int> f1;
+      std::move(f1).and_then(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f() must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<U:error_type, E>
+    {
+      std::expected<void, int> f1;
+      std::move(f1).and_then(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f() must have the same error_type as this expected}}
+    }
+  }
+
+  // Test const&& overload
+  {
+    // U is not a specialization of std::expected
+    {
+      const std::expected<void, int> f1;
+      std::move(f1).and_then(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<int (&)()>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f() must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+      // expected-error-re@*:* {{no matching constructor for initialization of{{.*}}}}
+    }
+
+    // !std::is_same_v<U:error_type, E>
+    {
+      const std::expected<void, int> f1;
+      std::move(f1).and_then(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::and_then<std::expected<int, NotSameAsInt> (&)()>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f() must have the same error_type as this expected}}
+    }
+  }
+}
+// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/error_or.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/error_or.mandates.verify.cpp
new file mode 100644
index 000000000000..a36665b25c87
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/error_or.mandates.verify.cpp
@@ -0,0 +1,71 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// Test the mandates
+// template<class G = E> constexpr E error_or(G&&) const &;
+// Mandates: is_copy_constructible_v<G> is true and is_convertible_v<U, E> is true.
+
+// template<class G = E> constexpr E error_or(G&&) &&;
+// Mandates: is_move_constructible_v<G> is true and is_convertible_v<U, E> is true.
+
+#include <expected>
+#include <utility>
+
+struct NonCopyable {
+  NonCopyable(int) {}
+  NonCopyable(const NonCopyable&) = delete;
+};
+
+struct NonMovable {
+  NonMovable(int) {}
+  NonMovable(NonMovable&&) = delete;
+};
+
+struct NotConvertibleFromInt {};
+
+// clang-format off
+void test() {
+  // const & overload
+  // !is_copy_constructible_v<G>,
+  {
+    const std::expected<void, NonCopyable> f1(std::unexpect, 0);
+    f1.error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<void, NonCopyable>::error_or<int>' requested here}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}error_type has to be copy constructible}}
+    // expected-error-re@*:* {{call to deleted constructor of{{.*}}}}
+  }
+
+  // const & overload
+  // !is_convertible_v<U, T>
+  {
+    const std::expected<void, NotConvertibleFromInt> f1(std::unexpect, NotConvertibleFromInt{});
+    f1.error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<void, NotConvertibleFromInt>::error_or<int>' requested here}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}argument has to be convertible to error_type}}
+    // expected-error-re@*:* {{no viable conversion from returned value of type{{.*}}}}
+  }
+
+  // && overload
+  // !is_move_constructible_v<T>,
+  {
+    std::expected<void, NonMovable> f1(std::unexpect, 0);
+    std::move(f1).error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<void, NonMovable>::error_or<int>' requested here}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}error_type has to be move constructible}}
+    // expected-error-re@*:* {{call to deleted constructor of{{.*}}}}
+  }
+
+  // && overload
+  // !is_convertible_v<U, T>
+  {
+    std::expected<void, NotConvertibleFromInt> f1(std::unexpect, NotConvertibleFromInt{});
+    std::move(f1).error_or(5); // expected-note{{in instantiation of function template specialization 'std::expected<void, NotConvertibleFromInt>::error_or<int>' requested here}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}argument has to be convertible to error_type}}
+    // expected-error-re@*:* {{no viable conversion from returned value of type{{.*}}}}
+  }
+}
+// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/no_unique_address.compile.pass.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/no_unique_address.compile.pass.cpp
index 1ad2aa125c29..dc59a6228386 100644
--- a/libcxx/test/libcxx/utilities/expected/expected.void/no_unique_address.compile.pass.cpp
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/no_unique_address.compile.pass.cpp
@@ -16,4 +16,16 @@
 
 struct Empty {};
 
+struct A {
+  int x_;
+  int y_;
+};
+
+struct B : public A {
+  int z_;
+  virtual ~B() = default;
+};
+
 static_assert(sizeof(std::expected<void, Empty>) == sizeof(bool));
+static_assert(sizeof(std::expected<void, A>) == 2 * sizeof(int) + alignof(std::expected<void, A>));
+static_assert(sizeof(std::expected<void, B>) == sizeof(B) + alignof(std::expected<void, B>));
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp
new file mode 100644
index 000000000000..9ebf6f586de2
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/or_else.mandates.verify.cpp
@@ -0,0 +1,121 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// Test the mandates
+// template<class F> constexpr auto or_else(F&& f) &;
+// Mandates:
+//  Let G be std::remove_cvref_t<std::invoke_result<F, decltype(error())>>
+//  G is a specialization of std::expected and std::is_same_v<G:value_type, T> is true
+
+// template<class F> constexpr auto or_else(F&& f) const &;
+// Mandates:
+//  Let G be std::remove_cvref_t<std::invoke_result<F, decltype(error())>>
+//  G is a specialization of std::expected and std::is_same_v<G:value_type, T> is true
+
+// template<class F> constexpr auto or_else(F&& f) &&;
+// Mandates:
+//  Let G be std::remove_cvref_t<std::invoke_result<F, decltype(error())>>
+//  G is a specialization of std::expected and std::is_same_v<G:value_type, T> is true
+
+// template<class F> constexpr auto or_else(F&& f) const &&;
+// Mandates:
+//  Let G be std::remove_cvref_t<std::invoke_result<F, decltype(error())>>
+//  G is a specialization of std::expected and std::is_same_v<G:value_type, T> is true
+
+#include <expected>
+#include <utility>
+
+struct NotSameAsInt {};
+
+int lval_return_not_std_expected(int&) { return 0; }
+int clval_return_not_std_expected(const int&) { return 0; }
+int rval_return_not_std_expected(int&&) { return 0; }
+int crval_return_not_std_expected(const int&&) { return 0; }
+
+std::expected<NotSameAsInt, int> lval_error_type_not_same_as_int(int&) { return {}; }
+std::expected<NotSameAsInt, int> clval_error_type_not_same_as_int(const int&) { return {}; }
+std::expected<NotSameAsInt, int> rval_error_type_not_same_as_int(int&&) { return {}; }
+std::expected<NotSameAsInt, int> crval_error_type_not_same_as_int(const int&&) { return {}; }
+
+// clang-format off
+void test() {
+  // Test & overload
+  {
+    // G is not a specialization of std::expected
+    {
+      std::expected<void, int> f1(std::unexpected<int>(1));
+      f1.or_else(lval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<int (&)(int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(error()) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+    }
+
+    // !std::is_same_v<G:value_type, T>
+    {
+      std::expected<void, int> f1(std::unexpected<int>(1));
+      f1.or_else(lval_error_type_not_same_as_int);  // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<std::expected<NotSameAsInt, int> (&)(int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(error()) must have the same value_type as this expected}}
+    }
+  }
+
+  // Test const& overload
+  {
+    // G is not a specialization of std::expected
+    {
+      const std::expected<void, int> f1(std::unexpected<int>(1));
+      f1.or_else(clval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<int (&)(const int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(error()) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+    }
+
+    // !std::is_same_v<G:value_type, T>
+    {
+      const std::expected<void, int> f1(std::unexpected<int>(1));
+      f1.or_else(clval_error_type_not_same_as_int);  // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<std::expected<NotSameAsInt, int> (&)(const int &)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(error()) must have the same value_type as this expected}}
+    }
+  }
+
+  // Test && overload
+  {
+    // G is not a specialization of std::expected
+    {
+      std::expected<void, int> f1(std::unexpected<int>(1));
+      std::move(f1).or_else(rval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<int (&)(int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(error())) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+    }
+
+    // !std::is_same_v<G:value_type, T>
+    {
+      std::expected<void, int> f1(std::unexpected<int>(1));
+      std::move(f1).or_else(rval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<std::expected<NotSameAsInt, int> (&)(int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(error())) must have the same value_type as this expected}}
+    }
+  }
+
+  // Test const&& overload
+  {
+    // G is not a specialization of std::expected
+    {
+      const std::expected<void, int> f1(std::unexpected<int>(1));
+      std::move(f1).or_else(crval_return_not_std_expected); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<int (&)(const int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(error())) must be a specialization of std::expected}}
+      // expected-error-re@*:* {{{{.*}}cannot be used prior to '::' because it has no members}}
+    }
+
+    // !std::is_same_v<G:value_type, T>
+    {
+      const std::expected<void, int> f1(std::unexpected<int>(1));
+      std::move(f1).or_else(crval_error_type_not_same_as_int); // expected-note{{in instantiation of function template specialization 'std::expected<void, int>::or_else<std::expected<NotSameAsInt, int> (&)(const int &&)>' requested here}}
+      // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of f(std::move(error())) must have the same value_type as this expected}}
+    }
+  }
+}
+// clang-format on
diff --git a/libcxx/test/libcxx/utilities/expected/expected.void/transform_error.mandates.verify.cpp b/libcxx/test/libcxx/utilities/expected/expected.void/transform_error.mandates.verify.cpp
new file mode 100644
index 000000000000..cdae36733a33
--- /dev/null
+++ b/libcxx/test/libcxx/utilities/expected/expected.void/transform_error.mandates.verify.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
+
+// Test the mandates
+
+// template<class F> constexpr auto transform_error(F&& f) &;
+// template<class F> constexpr auto transform_error(F&& f) const &;
+//
+// Let G be remove_cv_t<invoke_result_t<F, decltype(error())>>
+// G is a valid template argument for unexpected ([expected.un.general]) and the declaration
+// G g(invoke(std::forward<F>(f), error())); is well-formed.
+
+// template<class F> constexpr auto transform_error(F&& f) &&;
+// template<class F> constexpr auto transform_error(F&& f) const &&;
+//
+// Let G be remove_cv_t<invoke_result_t<F, decltype(std::move(error()))>>.
+// G is a valid template argument for unexpected ([expected.un.general]) and the declaration
+// G g(invoke(std::forward<F>(f), std::move(error()))); is well-formed.
+
+#include <expected>
+#include <utility>
+
+static int val;
+
+template <class T>
+std::unexpected<int> return_unexpected(T) {
+  return std::unexpected<int>(1);
+}
+
+template <class T>
+int& return_no_object(T) {
+  return val;
+}
+
+// clang-format off
+void test() {
+
+  // Test & overload
+  {
+    std::expected<void, int> e;
+    e.transform_error(return_unexpected<int&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}A program that instantiates expected<T, E> with a E that is not a valid argument for unexpected<E> is ill-formed}}
+
+    e.transform_error(return_no_object<int&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}A program that instantiates expected<T, E> with a E that is not a valid argument for unexpected<E> is ill-formed}}
+  }
+
+  // Test const& overload
+  {
+    const std::expected<void, int> e;
+    e.transform_error(return_unexpected<const int &>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    e.transform_error(return_no_object<const int &>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+  }
+
+  // Test && overload
+  {
+    std::expected<void, int> e;
+    std::move(e).transform_error(return_unexpected<int&&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    std::move(e).transform_error(return_no_object<int&&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+  }
+
+  // Test const&& overload
+  {
+    const std::expected<void, int> e;
+    std::move(e).transform_error(return_unexpected<const int&&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+    std::move(e).transform_error(return_no_object<const int&&>); // expected-error-re@*:* {{{{(static_assert|static assertion)}} failed {{.*}}The result of {{.*}} must be a valid template argument for unexpected}}
+    // expected-error-re@*:* {{{{(excess elements in struct initializer|no matching constructor for initialization of)}}{{.*}}}}
+  }
+}
+// clang-format on
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/expected.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/expected.version.compile.pass.cpp
index 4872981be89e..289609838a13 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/expected.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/expected.version.compile.pass.cpp
@@ -16,7 +16,7 @@
 // Test the feature test macros defined by <expected>
 
 /*  Constant              Value
-    __cpp_lib_expected    202202L [C++2b]
+    __cpp_lib_expected    202211L [C++2b]
 */
 
 #include <expected>
@@ -51,8 +51,8 @@
 # ifndef __cpp_lib_expected
 #   error "__cpp_lib_expected should be defined in c++2b"
 # endif
-# if __cpp_lib_expected != 202202L
-#   error "__cpp_lib_expected should have the value 202202L in c++2b"
+# if __cpp_lib_expected != 202211L
+#   error "__cpp_lib_expected should have the value 202211L in c++2b"
 # endif
 
 #endif // TEST_STD_VER > 20
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
index e1bdde4551a7..74073cfcf1c1 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
@@ -76,7 +76,7 @@
     __cpp_lib_exchange_function                    201304L [C++14]
     __cpp_lib_execution                            201603L [C++17]
                                                    201902L [C++20]
-    __cpp_lib_expected                             202202L [C++2b]
+    __cpp_lib_expected                             202211L [C++2b]
     __cpp_lib_filesystem                           201703L [C++17]
     __cpp_lib_format                               202106L [C++20]
     __cpp_lib_format_ranges                        202207L [C++2b]
@@ -4161,8 +4161,8 @@
 # ifndef __cpp_lib_expected
 #   error "__cpp_lib_expected should be defined in c++2b"
 # endif
-# if __cpp_lib_expected != 202202L
-#   error "__cpp_lib_expected should have the value 202202L in c++2b"
+# if __cpp_lib_expected != 202211L
+#   error "__cpp_lib_expected should have the value 202211L in c++2b"
 # endif
 
 # if !defined(_LIBCPP_AVAILABILITY_HAS_NO_FILESYSTEM)
diff --git a/libcxx/test/std/utilities/expected/expected.expected/monadic/and_then.pass.cpp b/libcxx/test/std/utilities/expected/expected.expected/monadic/and_then.pass.cpp
new file mode 100644
index 000000000000..1630931d4a85
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.expected/monadic/and_then.pass.cpp
@@ -0,0 +1,288 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// <expected>
+
+// template<class F> constexpr auto and_then(F&& f) &;
+// template<class F> constexpr auto and_then(F&& f) const &;
+// template<class F> constexpr auto and_then(F&& f) &&;
+// template<class F> constexpr auto and_then(F&& f) const &&;
+
+#include <cassert>
+#include <concepts>
+#include <expected>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+struct LVal {
+  constexpr std::expected<int, int> operator()(int&) { return 1; }
+  std::expected<int, int> operator()(const int&)  = delete;
+  std::expected<int, int> operator()(int&&)       = delete;
+  std::expected<int, int> operator()(const int&&) = delete;
+};
+
+struct CLVal {
+  std::expected<int, int> operator()(int&) = delete;
+  constexpr std::expected<int, int> operator()(const int&) { return 1; }
+  std::expected<int, int> operator()(int&&)       = delete;
+  std::expected<int, int> operator()(const int&&) = delete;
+};
+
+struct RVal {
+  std::expected<int, int> operator()(int&)       = delete;
+  std::expected<int, int> operator()(const int&) = delete;
+  constexpr std::expected<int, int> operator()(int&&) { return 1; }
+  std::expected<int, int> operator()(const int&&) = delete;
+};
+
+struct CRVal {
+  std::expected<int, int> operator()(int&)       = delete;
+  std::expected<int, int> operator()(const int&) = delete;
+  std::expected<int, int> operator()(int&&)      = delete;
+  constexpr std::expected<int, int> operator()(const int&&) { return 1; }
+};
+
+struct RefQual {
+  constexpr std::expected<int, int> operator()(int) & { return 1; }
+  std::expected<int, int> operator()(int) const&  = delete;
+  std::expected<int, int> operator()(int) &&      = delete;
+  std::expected<int, int> operator()(int) const&& = delete;
+};
+
+struct CRefQual {
+  std::expected<int, int> operator()(int) & = delete;
+  constexpr std::expected<int, int> operator()(int) const& { return 1; }
+  std::expected<int, int> operator()(int) &&      = delete;
+  std::expected<int, int> operator()(int) const&& = delete;
+};
+
+struct RVRefQual {
+  std::expected<int, int> operator()(int) &      = delete;
+  std::expected<int, int> operator()(int) const& = delete;
+  constexpr std::expected<int, int> operator()(int) && { return 1; }
+  std::expected<int, int> operator()(int) const&& = delete;
+};
+
+struct RVCRefQual {
+  std::expected<int, int> operator()(int) &      = delete;
+  std::expected<int, int> operator()(int) const& = delete;
+  std::expected<int, int> operator()(int) &&     = delete;
+  constexpr std::expected<int, int> operator()(int) const&& { return 1; }
+};
+
+struct UnexpectedLVal {
+  constexpr std::expected<int, int> operator()(int&) { return std::expected<int, int>(std::unexpected<int>(5)); }
+  std::expected<int, int> operator()(const int&)  = delete;
+  std::expected<int, int> operator()(int&&)       = delete;
+  std::expected<int, int> operator()(const int&&) = delete;
+};
+
+struct UnexpectedCLVal {
+  std::expected<int, int> operator()(int&) = delete;
+  constexpr std::expected<int, int> operator()(const int&) { return std::expected<int, int>(std::unexpected<int>(5)); }
+  std::expected<int, int> operator()(int&&)       = delete;
+  std::expected<int, int> operator()(const int&&) = delete;
+};
+
+struct UnexpectedRVal {
+  std::expected<int, int> operator()(int&)       = delete;
+  std::expected<int, int> operator()(const int&) = delete;
+  constexpr std::expected<int, int> operator()(int&&) { return std::expected<int, int>(std::unexpected<int>(5)); }
+  std::expected<int, int> operator()(const int&&) = delete;
+};
+
+struct UnexpectedCRVal {
+  std::expected<int, int> operator()(int&)       = delete;
+  std::expected<int, int> operator()(const int&) = delete;
+  std::expected<int, int> operator()(int&&)      = delete;
+  constexpr std::expected<int, int> operator()(const int&&) { return std::expected<int, int>(std::unexpected<int>(5)); }
+};
+
+struct UnexpectedRefQual {
+  constexpr std::expected<int, int> operator()(int) & { return std::expected<int, int>(std::unexpected<int>(5)); }
+  std::expected<int, int> operator()(int) const&  = delete;
+  std::expected<int, int> operator()(int) &&      = delete;
+  std::expected<int, int> operator()(int) const&& = delete;
+};
+
+struct UnexpectedCRefQual {
+  std::expected<int, int> operator()(int) & = delete;
+  constexpr std::expected<int, int> operator()(int) const& { return std::expected<int, int>(std::unexpected<int>(5)); }
+  std::expected<int, int> operator()(int) &&      = delete;
+  std::expected<int, int> operator()(int) const&& = delete;
+};
+
+struct UnexpectedRVRefQual {
+  std::expected<int, int> operator()(int) &      = delete;
+  std::expected<int, int> operator()(int) const& = delete;
+  constexpr std::expected<int, int> operator()(int) && { return std::expected<int, int>(std::unexpected<int>(5)); }
+  std::expected<int, int> operator()(int) const&& = delete;
+};
+
+struct UnexpectedRVCRefQual {
+  std::expected<int, int> operator()(int) &      = delete;
+  std::expected<int, int> operator()(int) const& = delete;
+  std::expected<int, int> operator()(int) &&     = delete;
+  constexpr std::expected<int, int> operator()(int) const&& { return std::expected<int, int>(std::unexpected<int>(5)); }
+};
+
+struct NonCopyable {
+  constexpr NonCopyable(int) {}
+  NonCopyable(const NonCopyable&) = delete;
+};
+
+struct NonMovable {
+  constexpr NonMovable(int) {}
+  NonMovable(NonMovable&&) = delete;
+};
+
+struct NonConst {
+  std::expected<int, int> non_const() { return 1; }
+};
+
+template <class E, class F>
+concept has_and_then = requires(E&& e, F&& f) {
+  {std::forward<E>(e).and_then(std::forward<F>(f))};
+};
+
+static_assert( has_and_then<std::expected<int, int>&, std::expected<int, int>(int&)>);
+static_assert(!has_and_then<std::expected<int, NonCopyable>&, std::expected<int, NonCopyable>(int&)>);
+static_assert( has_and_then<const std::expected<int, int>&, std::expected<int, int>(const int&)>);
+static_assert(!has_and_then<const std::expected<int, NonCopyable>&, std::expected<int, NonCopyable>(const int&)>);
+static_assert( has_and_then<std::expected<int, int>&&, std::expected<int, int>(int)>);
+static_assert(!has_and_then<std::expected<int, NonMovable>&&, std::expected<int, NonMovable>(int)>);
+static_assert( has_and_then<const std::expected<int, int>&&, std::expected<int, int>(const int)>);
+static_assert(!has_and_then<const std::expected<int, NonMovable>&&, std::expected<int, NonMovable>(const int)>);
+
+// [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
+static_assert(!has_and_then<const std::expected<int, std::unique_ptr<int>>&, int()>);
+static_assert(!has_and_then<const std::expected<int, std::unique_ptr<int>>&&, int()>);
+
+// clang-format off
+constexpr void test_val_types() {
+  // Test & overload
+  {
+    // Without &qualifier on F'soperator()
+    {
+      std::expected<int, int> e{0};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.and_then(LVal{});
+      assert(val == 1);
+      assert(e.and_then(UnexpectedLVal{}).error() == 5);
+    }
+
+    // With & qualifier on F's operator()
+    {
+      std::expected<int, int> e{0};
+      RefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.and_then(l);
+      assert(val == 1);
+      UnexpectedRefQual nl{};
+      assert(e.and_then(nl).error() == 5);
+    }
+  }
+
+  // Test const& overload
+  {
+    // Without & qualifier on F's operator()
+    {
+      const std::expected<int, int> e{0};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.and_then(CLVal{});
+      assert(val == 1);
+      assert(e.and_then(UnexpectedCLVal{}).error() == 5);
+    }
+
+    // With & qualifier on F's operator()
+    {
+      const std::expected<int, int> e{0};
+      const CRefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.and_then(l);
+      assert(val == 1);
+      const UnexpectedCRefQual nl{};
+      assert(e.and_then(nl).error() == 5);
+    }
+  }
+
+  // Test && overload
+  {
+    // Without & qualifier on F's operator()
+    {
+      std::expected<int, int> e{0};
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).and_then(RVal{});
+      assert(val == 1);
+      assert(std::move(e).and_then(UnexpectedRVal{}).error() == 5);
+    }
+
+    // With & qualifier on F's operator()
+    {
+      std::expected<int, int> e{0};
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).and_then(RVRefQual{});
+      assert(val == 1);
+      assert(e.and_then(UnexpectedRVRefQual{}).error() == 5);
+    }
+  }
+
+  // Test const&& overload
+  {
+    // Without & qualifier on F's operator()
+    {
+      const std::expected<int, int> e{0};
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).and_then(CRVal{});
+      assert(val == 1);
+      assert(std::move(e).and_then(UnexpectedCRVal{}).error() == 5);
+    }
+
+    // With & qualifier on F's operator()
+    {
+      const std::expected<int, int> e{0};
+      const RVCRefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).and_then(std::move(l));
+      assert(val == 1);
+      const UnexpectedRVCRefQual nl{};
+      assert(std::move(e).and_then(std::move(nl)).error() == 5);
+    }
+  }
+}
+// clang-format on
+
+// check that the lambda body is not instantiated during overload resolution
+constexpr void test_sfinae() {
+  std::expected<NonConst, int> e(std::unexpected<int>(2));
+  auto l = [](auto&& x) { return x.non_const(); };
+  e.and_then(l);
+  std::move(e).and_then(l);
+}
+
+constexpr bool test() {
+  test_sfinae();
+  test_val_types();
+
+  std::expected<int, int> e(std::unexpected<int>(1));
+  const auto& ce = e;
+
+  const auto never_called = [](int) {
+    assert(false);
+    return std::expected<int, int>();
+  };
+
+  e.and_then(never_called);
+  std::move(e).and_then(never_called);
+  ce.and_then(never_called);
+  std::move(ce).and_then(never_called);
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/expected/expected.expected/monadic/or_else.pass.cpp b/libcxx/test/std/utilities/expected/expected.expected/monadic/or_else.pass.cpp
new file mode 100644
index 000000000000..bf5b481a158a
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.expected/monadic/or_else.pass.cpp
@@ -0,0 +1,202 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// <expected>
+
+// template<class F> constexpr auto or_else(F&& f) &;
+// template<class F> constexpr auto or_else(F&& f) const &;
+// template<class F> constexpr auto or_else(F&& f) &&;
+// template<class F> constexpr auto or_else(F&& f) const &&;
+
+#include <cassert>
+#include <concepts>
+#include <expected>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+struct LVal {
+  constexpr std::expected<int, int> operator()(int&) { return 1; }
+  std::expected<int, int> operator()(const int&)  = delete;
+  std::expected<int, int> operator()(int&&)       = delete;
+  std::expected<int, int> operator()(const int&&) = delete;
+};
+
+struct CLVal {
+  std::expected<int, int> operator()(int&) = delete;
+  constexpr std::expected<int, int> operator()(const int&) { return 1; }
+  std::expected<int, int> operator()(int&&)       = delete;
+  std::expected<int, int> operator()(const int&&) = delete;
+};
+
+struct RVal {
+  std::expected<int, int> operator()(int&)       = delete;
+  std::expected<int, int> operator()(const int&) = delete;
+  constexpr std::expected<int, int> operator()(int&&) { return 1; }
+  std::expected<int, int> operator()(const int&&) = delete;
+};
+
+struct CRVal {
+  std::expected<int, int> operator()(int&)       = delete;
+  std::expected<int, int> operator()(const int&) = delete;
+  std::expected<int, int> operator()(int&&)      = delete;
+  constexpr std::expected<int, int> operator()(const int&&) { return 1; }
+};
+
+struct RefQual {
+  constexpr std::expected<int, int> operator()(int) & { return 1; }
+  std::expected<int, int> operator()(int) const&  = delete;
+  std::expected<int, int> operator()(int) &&      = delete;
+  std::expected<int, int> operator()(int) const&& = delete;
+};
+
+struct CRefQual {
+  std::expected<int, int> operator()(int) & = delete;
+  constexpr std::expected<int, int> operator()(int) const& { return 1; }
+  std::expected<int, int> operator()(int) &&      = delete;
+  std::expected<int, int> operator()(int) const&& = delete;
+};
+
+struct RVRefQual {
+  std::expected<int, int> operator()(int) &      = delete;
+  std::expected<int, int> operator()(int) const& = delete;
+  constexpr std::expected<int, int> operator()(int) && { return 1; }
+  std::expected<int, int> operator()(int) const&& = delete;
+};
+
+struct RVCRefQual {
+  std::expected<int, int> operator()(int) &      = delete;
+  std::expected<int, int> operator()(int) const& = delete;
+  std::expected<int, int> operator()(int) &&     = delete;
+  constexpr std::expected<int, int> operator()(int) const&& { return 1; }
+};
+
+template <class E, class F>
+concept has_or_else =
+    requires(E&& e, F&& f) {
+      { std::forward<E>(e).or_else(std::forward<F>(f)) };
+    };
+
+// [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
+static_assert(!has_or_else<const std::expected<std::unique_ptr<int>, int>&, int()>);
+static_assert(!has_or_else<const std::expected<std::unique_ptr<int>, int>&&, int()>);
+
+// clang-format off
+constexpr void test_val_types() {
+  // Test & overload
+  {
+    // Without & qualifier on F's operator()
+    {
+      std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.or_else(LVal{});
+      assert(val == 1);
+    }
+
+    // With & qualifier on F's operator
+    {
+      std::expected<int, int> e(std::unexpected<int>(0));
+      RefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.or_else(l);
+      assert(val == 1);
+    }
+  }
+
+  // Test const& overload
+  {
+    // Without const& qualifier on F's operator()
+    {
+      const std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.or_else(CLVal{});
+      assert(val == 1);
+    }
+
+    // With const& qualifier on F's operator()
+    {
+      const std::expected<int, int> e(std::unexpected<int>(0));
+      const CRefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.or_else(l);
+      assert(val == 1);
+    }
+  }
+
+  // Test && overload
+  {
+    // Without && qualifier on F's operator()
+    {
+      std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).or_else(RVal{});
+      assert(val == 1);
+    }
+
+    // With && qualifier on F's operator()
+    {
+      std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).or_else(RVRefQual{});
+      assert(val == 1);
+    }
+  }
+
+  // Test const&& overload
+  {
+    // Without const&& qualifier on F's operator()
+    {
+      const std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).or_else(CRVal{});
+      assert(val == 1);
+    }
+
+    // With const&& qualifier on F's operator()
+    {
+      const std::expected<int, int> e(std::unexpected<int>(0));
+      const RVCRefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).or_else(std::move(l));
+      assert(val == 1);
+    }
+  }
+}
+// clang-format on
+
+struct NonConst {
+  std::expected<int, int> non_const() { return std::expected<int, int>(std::unexpect, 1); }
+};
+
+// check that the lambda body is not instantiated during overload resolution
+constexpr void test_sfinae() {
+  std::expected<int, NonConst> e{1};
+  auto l = [](auto&& x) { return x.non_const(); };
+  e.or_else(l);
+  std::move(e).or_else(l);
+}
+
+constexpr bool test() {
+  test_sfinae();
+  test_val_types();
+
+  std::expected<int, int> e(1);
+  const auto& ce = e;
+
+  const auto never_called = [](int) {
+    assert(false);
+    return std::expected<int, int>();
+  };
+
+  e.or_else(never_called);
+  std::move(e).or_else(never_called);
+  ce.or_else(never_called);
+  std::move(ce).or_else(never_called);
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/expected/expected.expected/monadic/transform.pass.cpp b/libcxx/test/std/utilities/expected/expected.expected/monadic/transform.pass.cpp
new file mode 100644
index 000000000000..b72055fb2523
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.expected/monadic/transform.pass.cpp
@@ -0,0 +1,251 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// GCC has a issue for `Guaranteed copy elision for potentially-overlapping non-static data members`,
+// please refer to: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108333, but we have a workaround to
+// avoid this issue.
+
+// <expected>
+
+// template<class F> constexpr auto transform(F&& f) &;
+// template<class F> constexpr auto transform(F&& f) const &;
+// template<class F> constexpr auto transform(F&& f) &&;
+// template<class F> constexpr auto transform(F&& f) const &&;
+
+#include <expected>
+#include <concepts>
+#include <cassert>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+struct LVal {
+  constexpr int operator()(int&) { return 1; }
+  int operator()(const int&)  = delete;
+  int operator()(int&&)       = delete;
+  int operator()(const int&&) = delete;
+};
+
+struct CLVal {
+  int operator()(int&) = delete;
+  constexpr int operator()(const int&) { return 1; }
+  int operator()(int&&)       = delete;
+  int operator()(const int&&) = delete;
+};
+
+struct RVal {
+  int operator()(int&)       = delete;
+  int operator()(const int&) = delete;
+  constexpr int operator()(int&&) { return 1; }
+  int operator()(const int&&) = delete;
+};
+
+struct CRVal {
+  int operator()(int&)       = delete;
+  int operator()(const int&) = delete;
+  int operator()(int&&)      = delete;
+  constexpr int operator()(const int&&) { return 1; }
+};
+
+struct RefQual {
+  constexpr int operator()(int) & { return 1; }
+  int operator()(int) const&  = delete;
+  int operator()(int) &&      = delete;
+  int operator()(int) const&& = delete;
+};
+
+struct CRefQual {
+  int operator()(int) & = delete;
+  constexpr int operator()(int) const& { return 1; }
+  int operator()(int) &&      = delete;
+  int operator()(int) const&& = delete;
+};
+
+struct RVRefQual {
+  int operator()(int) &      = delete;
+  int operator()(int) const& = delete;
+  constexpr int operator()(int) && { return 1; }
+  int operator()(int) const&& = delete;
+};
+
+struct RVCRefQual {
+  int operator()(int) &      = delete;
+  int operator()(int) const& = delete;
+  int operator()(int) &&     = delete;
+  constexpr int operator()(int) const&& { return 1; }
+};
+
+struct NonCopy {
+  int value;
+  constexpr explicit NonCopy(int val) : value(val) {}
+  NonCopy(const NonCopy&) = delete;
+};
+
+struct NonConst {
+  int non_const() { return 1; }
+};
+
+template <class E, class F>
+concept has_transform =
+    requires(E&& e, F&& f) {
+      { std::forward<E>(e).transform(std::forward<F>(f)) };
+    };
+
+// [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
+static_assert(!has_transform<const std::expected<int, std::unique_ptr<int>>&, int()>);
+static_assert(!has_transform<const std::expected<int, std::unique_ptr<int>>&&, int()>);
+
+// clang-format off
+constexpr void test_val_types() {
+  // Test & overload
+  {
+    // Without &qualifier on F'soperator()
+    {
+      std::expected<int, int> e(0);
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.transform(LVal{});
+      assert(val == 1);
+    }
+
+    // With & qualifier on F's operator()
+    {
+      std::expected<int, int> e(0);
+      RefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.transform(l);
+      assert(val == 1);
+    }
+  }
+
+  // Test const& overload
+  {
+    // Without & qualifier on F's operator()
+    {
+      const std::expected<int, int> e(0);
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.transform(CLVal{});
+      assert(val == 1);
+    }
+
+    // With & qualifier on F's operator()
+    {
+      const std::expected<int, int> e(0);
+      const CRefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.transform(l);
+      assert(val == 1);
+    }
+  }
+
+  // Test && overload
+  {
+    // Without & qualifier on F's operator()
+    {
+      std::expected<int, int> e(0);
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).transform(RVal{});
+      assert(val == 1);
+    }
+
+    // With & qualifier on F's operator()
+    {
+      std::expected<int, int> e(0);
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).transform(RVRefQual{});
+      assert(val == 1);
+    }
+  }
+
+  // Test const&& overload
+  {
+    // Without & qualifier on F's operator()
+    {
+      const std::expected<int, int> e(0);
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).transform(CRVal{});
+      assert(val == 1);
+    }
+
+    // With & qualifier on F's operator()
+    {
+      const std::expected<int, int> e(0);
+      const RVCRefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.transform(std::move(l));
+      assert(val == 1);
+    }
+  }
+}
+// clang-format on
+
+constexpr void test_take_val_return_void() {
+  std::expected<int, int> e(1);
+  int val = 0;
+  e.transform([&val]<typename T>(T&&) -> void {
+    static_assert(std::is_same_v<T, int&>);
+    assert(val == 0);
+    val = 1;
+  });
+  assert(val == 1);
+  std::move(e).transform([&val]<typename T>(T&&) -> void {
+    static_assert(std::is_same_v<T, int>);
+    assert(val == 1);
+    val = 2;
+  });
+
+  const auto& ce = e;
+  assert(val == 2);
+  ce.transform([&val]<typename T>(T&&) -> void {
+    static_assert(std::is_same_v<T, const int&>);
+    assert(val == 2);
+    val = 3;
+  });
+  assert(val == 3);
+  std::move(ce).transform([&val]<typename T>(T&&) -> void {
+    static_assert(std::is_same_v<T, const int>);
+    assert(val == 3);
+    val = 4;
+  });
+  assert(val == 4);
+}
+
+// check val member is direct-non-list-initialized with invoke(std::forward<F>(f), value())
+constexpr void test_direct_non_list_init() {
+  auto xform = [](int i) { return NonCopy(i); };
+  std::expected<int, int> e(2);
+  std::expected<NonCopy, int> n = e.transform(xform);
+  assert(n.value().value == 2);
+}
+
+// check that the lambda body is not instantiated during overload resolution
+constexpr void test_sfinae() {
+  std::expected<NonConst, int> e(std::unexpected<int>(2));
+  auto l = [](auto&& x) { return x.non_const(); };
+  e.transform(l);
+  std::move(e).transform(l);
+
+  std::expected<int, int> e1(std::unexpected<int>(1));
+  const auto& ce1         = e1;
+  const auto never_called = [](int) {
+    assert(false);
+    return std::expected<int, int>();
+  };
+
+  e1.transform(never_called);
+  std::move(e1).transform(never_called);
+  ce1.and_then(never_called);
+  std::move(ce1).transform(never_called);
+}
+
+constexpr bool test() {
+  test_sfinae();
+  test_val_types();
+  test_direct_non_list_init();
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/expected/expected.expected/monadic/transform_error.pass.cpp b/libcxx/test/std/utilities/expected/expected.expected/monadic/transform_error.pass.cpp
new file mode 100644
index 000000000000..edcc56abc2f7
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.expected/monadic/transform_error.pass.cpp
@@ -0,0 +1,221 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20
+
+// GCC has a issue for `Guaranteed copy elision for potentially-overlapping non-static data members`,
+// please refer to: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108333, but we have a workaround to
+// avoid this issue.
+
+// <expected>
+
+// template<class F> constexpr auto transform_error(F&& f) &;
+// template<class F> constexpr auto transform_error(F&& f) const &;
+// template<class F> constexpr auto transform_error(F&& f) &&;
+// template<class F> constexpr auto transform_error(F&& f) const &&;
+
+#include <expected>
+#include <concepts>
+#include <cassert>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+struct LVal {
+  constexpr int operator()(int&) { return 1; }
+  int operator()(const int&)  = delete;
+  int operator()(int&&)       = delete;
+  int operator()(const int&&) = delete;
+};
+
+struct CLVal {
+  int operator()(int&) = delete;
+  constexpr int operator()(const int&) { return 1; }
+  int operator()(int&&)       = delete;
+  int operator()(const int&&) = delete;
+};
+
+struct RVal {
+  int operator()(int&)       = delete;
+  int operator()(const int&) = delete;
+  constexpr int operator()(int&&) { return 1; }
+  int operator()(const int&&) = delete;
+};
+
+struct CRVal {
+  int operator()(int&)       = delete;
+  int operator()(const int&) = delete;
+  int operator()(int&&)      = delete;
+  constexpr int operator()(const int&&) { return 1; }
+};
+
+struct RefQual {
+  constexpr int operator()(int) & { return 1; }
+  int operator()(int) const&  = delete;
+  int operator()(int) &&      = delete;
+  int operator()(int) const&& = delete;
+};
+
+struct CRefQual {
+  int operator()(int) & = delete;
+  constexpr int operator()(int) const& { return 1; }
+  int operator()(int) &&      = delete;
+  int operator()(int) const&& = delete;
+};
+
+struct RVRefQual {
+  int operator()(int) &      = delete;
+  int operator()(int) const& = delete;
+  constexpr int operator()(int) && { return 1; }
+  int operator()(int) const&& = delete;
+};
+
+struct RVCRefQual {
+  int operator()(int) &      = delete;
+  int operator()(int) const& = delete;
+  int operator()(int) &&     = delete;
+  constexpr int operator()(int) const&& { return 1; }
+};
+
+struct NonCopy {
+  int value;
+  constexpr explicit NonCopy(int val) : value(val) {}
+  NonCopy(const NonCopy&) = delete;
+};
+
+struct NonConst {
+  int non_const() { return 1; }
+};
+
+template <class E, class F>
+concept has_transform_error =
+    requires(E&& e, F&& f) {
+      { std::forward<E>(e).transform_error(std::forward<F>(f)) };
+    };
+
+// [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
+static_assert(!has_transform_error<const std::expected<std::unique_ptr<int>, int>&, int()>);
+static_assert(!has_transform_error<const std::expected<std::unique_ptr<int>, int>&&, int()>);
+
+// clang-format off
+constexpr void test_val_types() {
+  // Test & overload
+  {
+    // Without & qualifier on F's operator()
+    {
+      std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.transform_error(LVal{});
+      assert(val.error() == 1);
+    }
+
+    // With & qualifier on F's operator()
+    {
+      std::expected<int, int> e(std::unexpected<int>(0));
+      RefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.transform_error(l);
+      assert(val.error() == 1);
+    }
+  }
+
+  // Test const& overload
+  {
+    // Without const& qualifier on F's operator()
+    {
+      const std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.transform_error(CLVal{});
+      assert(val.error() == 1);
+    }
+
+    // With const& qualifier on F's operator()
+    {
+      const std::expected<int, int> e(std::unexpected<int>(0));
+      const CRefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = e.transform_error(l);
+      assert(val.error() == 1);
+    }
+  }
+
+  // Test && overload
+  {
+    // Without && qualifier on F's operator()
+    {
+      std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).transform_error(RVal{});
+      assert(val.error() == 1);
+    }
+
+    // With && qualifier on F's operator()
+    {
+      std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).transform_error(RVRefQual{});
+      assert(val.error() == 1);
+    }
+  }
+
+  // Test const&& overload
+  {
+    // Without const&& qualifier on F's operator()
+    {
+      const std::expected<int, int> e(std::unexpected<int>(0));
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).transform_error(CRVal{});
+      assert(val.error() == 1);
+    }
+
+    // With const&& qualifier on F's operator()
+    {
+      const std::expected<int, int> e(std::unexpected<int>(0));
+      const RVCRefQual l{};
+      std::same_as<std::expected<int, int>> decltype(auto) val = std::move(e).transform_error(std::move(l));
+      assert(val.error() == 1);
+    }
+  }
+}
+// clang-format on
+
+// check unex member is direct-non-list-initialized with invoke(std::forward<F>(f), error())
+constexpr void test_direct_non_list_init() {
+  auto xform = [](int i) { return NonCopy(i); };
+  std::expected<int, int> e(std::unexpected<int>(2));
+  std::expected<int, NonCopy> n = e.transform_error(xform);
+  assert(n.error().value == 2);
+}
+
+// check that the lambda body is not instantiated during overload resolution
+constexpr void test_sfinae() {
+  std::expected<int, NonConst> e(2);
+  auto l = [](auto&& x) { return x.non_const(); };
+  e.transform_error(l);
+  std::move(e).transform_error(l);
+
+  std::expected<int, int> e1;
+  const auto& ce1 = e1;
+
+  const auto never_called = [](int) {
+    assert(false);
+    return 0;
+  };
+
+  e1.transform_error(never_called);
+  std::move(e1).transform_error(never_called);
+  ce1.transform_error(never_called);
+  std::move(ce1).transform_error(never_called);
+}
+
+constexpr bool test() {
+  test_sfinae();
+  test_val_types();
+  test_direct_non_list_init();
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/expected/expected.expected/observers/error_or.pass.cpp b/libcxx/test/std/utilities/expected/expected.expected/observers/error_or.pass.cpp
new file mode 100644
index 000000000000..f698f44ba8f3
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.expected/observers/error_or.pass.cpp
@@ -0,0 +1,96 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// template<class G = E> constexpr E error_or(G&& e) const &;
+// template<class G = E> constexpr E error_or(G&& e) &&;
+
+#include <cassert>
+#include <concepts>
+#include <expected>
+#include <type_traits>
+#include <utility>
+
+struct ConstructFromInt {
+  int value;
+  constexpr ConstructFromInt(int v) : value(v) {}
+};
+
+constexpr bool test_default_template_arg() {
+  // const &, has_value()
+  {
+    const std::expected<int, ConstructFromInt> e(5);
+    std::same_as<ConstructFromInt> decltype(auto) x = e.error_or(10);
+    assert(x.value == 10);
+  }
+
+  // const &, !has_value()
+  {
+    const std::expected<int, ConstructFromInt> e(std::unexpect, 5);
+    std::same_as<ConstructFromInt> decltype(auto) x = e.error_or(10);
+    assert(x.value == 5);
+  }
+
+  // &&, has_value()
+  {
+    const std::expected<int, ConstructFromInt> e(5);
+    std::same_as<ConstructFromInt> decltype(auto) x = std::move(e).error_or(10);
+    assert(x.value == 10);
+  }
+
+  // &&, !has_value()
+  {
+    const std::expected<int, ConstructFromInt> e(std::unexpect, 5);
+    std::same_as<ConstructFromInt> decltype(auto) x = std::move(e).error_or(10);
+    assert(x.value == 5);
+  }
+
+  return true;
+}
+
+constexpr bool test() {
+  // const &, has_value()
+  {
+    const std::expected<int, int> e(5);
+    std::same_as<int> decltype(auto) x = e.error_or(10);
+    assert(x == 10);
+  }
+
+  // const &, !has_value()
+  {
+    const std::expected<int, int> e(std::unexpect, 5);
+    std::same_as<int> decltype(auto) x = e.error_or(10);
+    assert(x == 5);
+  }
+
+  // &&, has_value()
+  {
+    std::expected<int, int> e(5);
+    std::same_as<int> decltype(auto) x = std::move(e).error_or(10);
+    assert(x == 10);
+  }
+
+  // &&, !has_value()
+  {
+    std::expected<int, int> e(std::unexpect, 5);
+    std::same_as<int> decltype(auto) x = std::move(e).error_or(10);
+    assert(x == 5);
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+  test_default_template_arg();
+  static_assert(test_default_template_arg());
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/expected/expected.void/monadic/and_then.pass.cpp b/libcxx/test/std/utilities/expected/expected.void/monadic/and_then.pass.cpp
new file mode 100644
index 000000000000..f60002c67ebc
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.void/monadic/and_then.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
+
+// <expected>
+
+// template<class F> constexpr auto and_then(F&& f) &;
+// template<class F> constexpr auto and_then(F&& f) const &;
+// template<class F> constexpr auto and_then(F&& f) &&;
+// template<class F> constexpr auto and_then(F&& f) const &&;
+
+#include <expected>
+#include <concepts>
+#include <cassert>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+struct NonCopyable {
+  constexpr NonCopyable(int) {}
+  NonCopyable(const NonCopyable&) = delete;
+};
+
+struct NonMovable {
+  constexpr NonMovable(int) {}
+  NonMovable(NonMovable&&) = delete;
+};
+
+template <class E, class F>
+concept has_and_then =
+    requires(E&& e, F&& f) {
+      { std::forward<E>(e).and_then(std::forward<F>(f)) };
+    };
+
+std::expected<void, int> return_int() { return {}; }
+std::expected<void, NonCopyable> return_noncopyable() { return {}; }
+std::expected<void, NonMovable> return_nonmovable() { return {}; }
+
+static_assert(has_and_then<std::expected<void, int>&, decltype(return_int)>);
+static_assert(!has_and_then<std::expected<void, NonCopyable>&, decltype(return_noncopyable)>);
+static_assert(has_and_then<const std::expected<void, int>&, decltype(return_int)>);
+static_assert(!has_and_then<const std::expected<void, NonCopyable>&, decltype(return_noncopyable)>);
+static_assert(has_and_then<std::expected<void, int>&&, decltype(return_int)>);
+static_assert(!has_and_then<std::expected<void, NonMovable>&&, decltype(return_nonmovable)>);
+static_assert(has_and_then<const std::expected<void, int>&&, decltype(return_int)>);
+static_assert(!has_and_then<const std::expected<void, NonMovable>&&, decltype(return_nonmovable)>);
+
+// [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
+static_assert(!has_and_then<const std::expected<int, std::unique_ptr<int>>&, int()>);
+static_assert(!has_and_then<const std::expected<int, std::unique_ptr<int>>&&, int()>);
+
+constexpr void test_val_types() {
+  // Test & overload
+  {
+    auto l = [] -> std::expected<int, int> { return 2; };
+    std::expected<void, int> v;
+    std::same_as<std::expected<int, int>> decltype(auto) val = v.and_then(l);
+    assert(val == 2);
+  }
+
+  // Test const& overload
+  {
+    auto l = [] -> std::expected<int, int> { return 2; };
+    const std::expected<void, int> v;
+    assert(v.and_then(l).value() == 2);
+    static_assert(std::is_same_v< decltype(v.and_then(l)), std::expected<int, int>>);
+  }
+
+  // Test && overload
+  {
+    auto l = [] -> std::expected<int, int> { return 2; };
+    std::expected<void, int> v;
+    std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).and_then(l);
+    assert(val == 2);
+  }
+
+  // Test const&& overload
+  {
+    auto l = [] -> std::expected<int, int> { return 2; };
+    const std::expected<void, int> v;
+    std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).and_then(l);
+    assert(val == 2);
+  }
+}
+
+constexpr void test_fail() {
+  // Test & overload
+  {
+    auto f = [] -> std::expected<int, int> {
+      assert(false);
+      return 0;
+    };
+    std::expected<void, int> v(std::unexpected<int>(2));
+    std::same_as<std::expected<int, int>> decltype(auto) val = v.and_then(f);
+    assert(val.error() == 2);
+  }
+
+  // Test const& overload
+  {
+    auto f = [] -> std::expected<int, int> {
+      assert(false);
+      return 0;
+    };
+    const std::expected<void, int> v(std::unexpected<int>(2));
+    std::same_as<std::expected<int, int>> decltype(auto) val = v.and_then(f);
+    assert(val.error() == 2);
+  }
+
+  // Test && overload
+  {
+    auto f = [] -> std::expected<int, int> {
+      assert(false);
+      return 0;
+    };
+    std::expected<void, int> v(std::unexpected<int>(2));
+    std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).and_then(f);
+    assert(val.error() == 2);
+  }
+
+  // Test const&& overload
+  {
+    auto f = [] -> std::expected<int, int> {
+      assert(false);
+      return 0;
+    };
+    const std::expected<void, int> v(std::unexpected<int>(2));
+    std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).and_then(f);
+    assert(val.error() == 2);
+  }
+}
+
+constexpr bool test() {
+  test_fail();
+  test_val_types();
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/expected/expected.void/monadic/or_else.pass.cpp b/libcxx/test/std/utilities/expected/expected.void/monadic/or_else.pass.cpp
new file mode 100644
index 000000000000..13e341c6d20c
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.void/monadic/or_else.pass.cpp
@@ -0,0 +1,104 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// <expected>
+
+// template<class F> constexpr auto or_else(F&& f) &;
+// template<class F> constexpr auto or_else(F&& f) const &;
+// template<class F> constexpr auto or_else(F&& f) &&;
+// template<class F> constexpr auto or_else(F&& f) const &&;
+
+#include <expected>
+#include <concepts>
+#include <cassert>
+#include <type_traits>
+#include <utility>
+
+constexpr void test_val_types() {
+  // Test & overload
+  {
+    auto l = [](auto) -> std::expected<void, long> { return {}; };
+    std::expected<void, int> v(std::unexpected<int>(1));
+    std::same_as<std::expected<void, long>> decltype(auto) val = v.or_else(l);
+    assert(val.has_value());
+  }
+
+  // Test const& overload
+  {
+    auto l = [](auto) -> std::expected<void, long> { return {}; };
+    const std::expected<void, int> v(std::unexpected<int>(1));
+    std::same_as<std::expected<void, long>> decltype(auto) val = v.or_else(l);
+    assert(val.has_value());
+  }
+
+  // Test && overload
+  {
+    auto l = [](auto) -> std::expected<void, long> { return {}; };
+    std::expected<void, int> v(std::unexpected<int>(1));
+    std::same_as<std::expected<void, long>> decltype(auto) val = std::move(v).or_else(l);
+    assert(val.has_value());
+  }
+
+  // Test const&& overload
+  {
+    auto l = [](auto) -> std::expected<void, long> { return {}; };
+    const std::expected<void, int> v(std::unexpected<int>(1));
+    std::same_as<std::expected<void, long>> decltype(auto) val = std::move(v).or_else(l);
+    assert(val.has_value());
+  }
+}
+
+constexpr void test_fail() {
+  auto never_called = [](auto) -> std::expected<void, long> {
+    assert(false);
+    return std::expected<void, long>(std::unexpected<long>(5));
+  };
+
+  // Test & overload
+  {
+    std::expected<void, int> v;
+    std::same_as<std::expected<void, long>> decltype(auto) val = v.or_else(never_called);
+    assert(val.has_value());
+  }
+
+  // Test const& overload
+  {
+    const std::expected<void, int> v;
+    std::same_as<std::expected<void, long>> decltype(auto) val = v.or_else(never_called);
+    assert(val.has_value());
+  }
+
+  // Test && overload
+  {
+    std::expected<void, int> v;
+    std::same_as<std::expected<void, long>> decltype(auto) val = std::move(v).or_else(never_called);
+    assert(val.has_value());
+  }
+
+  // Test const&& overload
+  {
+    const std::expected<void, int> v;
+    std::same_as<std::expected<void, long>> decltype(auto) val = std::move(v).or_else(never_called);
+    assert(val.has_value());
+  }
+}
+
+constexpr bool test() {
+  test_fail();
+  test_val_types();
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/expected/expected.void/monadic/transform.pass.cpp b/libcxx/test/std/utilities/expected/expected.void/monadic/transform.pass.cpp
new file mode 100644
index 000000000000..ea90006e3199
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.void/monadic/transform.pass.cpp
@@ -0,0 +1,126 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// <expected>
+
+// template<class F> constexpr auto transform_error(F&& f) &;
+// template<class F> constexpr auto transform_error(F&& f) const &;
+// template<class F> constexpr auto transform_error(F&& f) &&;
+// template<class F> constexpr auto transform_error(F&& f) const &&;
+
+#include <expected>
+#include <concepts>
+#include <cassert>
+#include <memory>
+#include <type_traits>
+#include <utility>
+
+template <class E, class F>
+concept has_transform =
+    requires(E&& e, F&& f) {
+      { std::forward<E>(e).transform(std::forward<F>(f)) };
+    };
+
+// [LWG 3877] https://cplusplus.github.io/LWG/issue3877, check constraint failing but not compile error inside the function body.
+static_assert(!has_transform<const std::expected<int, std::unique_ptr<int>>&, int()>);
+static_assert(!has_transform<const std::expected<int, std::unique_ptr<int>>&&, int()>);
+
+constexpr void test_val_types() {
+  // Test & overload
+  {
+    auto l = [] -> int { return 1; };
+    std::expected<void, int> v;
+    std::same_as<std::expected<int, int>> decltype(auto) val = v.transform(l);
+    assert(val == 1);
+  }
+
+  // Test const& overload
+  {
+    auto l = [] -> int { return 1; };
+    const std::expected<void, int> v;
+    std::same_as<std::expected<int, int>> decltype(auto) val = v.transform(l);
+    assert(val == 1);
+  }
+
+  // Test && overload
+  {
+    auto l = [] -> int { return 1; };
+    std::expected<void, int> v;
+    std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).transform(l);
+    assert(val == 1);
+  }
+
+  // Test const&& overload
+  {
+    auto l = [] -> int { return 1; };
+    const std::expected<void, int> v;
+    std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).transform(l);
+    assert(val == 1);
+  }
+}
+
+constexpr void test_fail() {
+  // Test & overload
+  {
+    auto l = [] -> int {
+      assert(false);
+      return 0;
+    };
+    std::expected<void, int> v(std::unexpected<int>(5));
+    std::same_as<std::expected<int, int>> decltype(auto) val = v.transform(l);
+    assert(val.error() == 5);
+  }
+
+  // Test const& overload
+  {
+    auto l = [] -> int {
+      assert(false);
+      return 0;
+    };
+    const std::expected<void, int> v(std::unexpected<int>(5));
+    std::same_as<std::expected<int, int>> decltype(auto) val = v.transform(l);
+    assert(val.error() == 5);
+  }
+
+  // Test && overload
+  {
+    auto l = [] -> int {
+      assert(false);
+      return 0;
+    };
+    std::expected<void, int> v(std::unexpected<int>(5));
+    std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).transform(l);
+    assert(val.error() == 5);
+  }
+
+  // Test const&& overload
+  {
+    auto l = [] -> int {
+      assert(false);
+      return 0;
+    };
+    const std::expected<void, int> v(std::unexpected<int>(5));
+    std::same_as<std::expected<int, int>> decltype(auto) val = std::move(v).transform(l);
+    assert(val.error() == 5);
+  }
+}
+
+constexpr bool test() {
+  test_fail();
+  test_val_types();
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/expected/expected.void/monadic/transform_error.pass.cpp b/libcxx/test/std/utilities/expected/expected.void/monadic/transform_error.pass.cpp
new file mode 100644
index 000000000000..f0e19ac3c398
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.void/monadic/transform_error.pass.cpp
@@ -0,0 +1,134 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// GCC has a issue for `Guaranteed copy elision for potentially-overlapping non-static data members`,
+// please refer to: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108333, but we have a workaround to
+// avoid this issue.
+
+// <expected>
+
+// template<class F> constexpr auto transform_error(F&& f) &;
+// template<class F> constexpr auto transform_error(F&& f) const &;
+// template<class F> constexpr auto transform_error(F&& f) &&;
+// template<class F> constexpr auto transform_error(F&& f) const &&;
+
+#include <expected>
+#include <concepts>
+#include <cassert>
+#include <type_traits>
+#include <utility>
+
+struct NonCopy {
+  int value;
+  constexpr explicit NonCopy(int val) : value(val) {}
+  NonCopy(const NonCopy&) = delete;
+};
+
+constexpr void test_val_types() {
+  // Test & overload
+  {
+    auto l = [](auto) -> int { return 1; };
+    std::expected<void, int> v(std::unexpected<int>(2));
+    std::same_as<std::expected<void, int>> decltype(auto) val = v.transform_error(l);
+    assert(val.error() == 1);
+  }
+
+  // Test const& overload
+  {
+    auto l = [](auto) -> int { return 1; };
+    const std::expected<void, int> v(std::unexpected<int>(2));
+    std::same_as<std::expected<void, int>> decltype(auto) val = v.transform_error(l);
+    assert(val.error() == 1);
+  }
+
+  // Test && overload
+  {
+    auto l = [](auto) -> int { return 1; };
+    std::expected<void, int> v(std::unexpected<int>(2));
+    std::same_as<std::expected<void, int>> decltype(auto) val = std::move(v).transform_error(l);
+    assert(val.error() == 1);
+  }
+
+  // Test const&& overload
+  {
+    auto l = [](auto) -> int { return 1; };
+    const std::expected<void, int> v(std::unexpected<int>(2));
+    std::same_as<std::expected<void, int>> decltype(auto) val = std::move(v).transform_error(l);
+    assert(val.error() == 1);
+  }
+}
+
+constexpr void test_fail() {
+  // Test & overload
+  {
+    auto l = [](auto) -> int {
+      assert(false);
+      return 0;
+    };
+    std::expected<void, int> v;
+    std::same_as<std::expected<void, int>> decltype(auto) val = v.transform_error(l);
+    assert(val.has_value());
+  }
+
+  // Test const& overload
+  {
+    auto l = [](auto) -> int {
+      assert(false);
+      return 0;
+    };
+    const std::expected<void, int> v;
+    std::same_as<std::expected<void, int>> decltype(auto) val = v.transform_error(l);
+    assert(val.has_value());
+  }
+
+  // Test && overload
+  {
+    auto l = [](auto) -> int {
+      assert(false);
+      return 0;
+    };
+    std::expected<void, int> v;
+    std::same_as<std::expected<void, int>> decltype(auto) val = std::move(v).transform_error(l);
+    assert(val.has_value());
+  }
+
+  // Test const&& overload
+  {
+    auto l = [](auto) -> int {
+      assert(false);
+      return 0;
+    };
+    const std::expected<void, int> v;
+    std::same_as<std::expected<void, int>> decltype(auto) val = std::move(v).transform_error(l);
+    assert(val.has_value());
+  }
+}
+
+// check unex member is direct-non-list-initialized with invoke(std::forward<F>(f))
+constexpr void test_direct_non_list_init() {
+  auto x = [](int i) { return NonCopy(i); };
+  std::expected<void, int> v(std::unexpected<int>(2));
+  std::expected<void, NonCopy> nv = v.transform_error(x);
+  assert(nv.error().value == 2);
+}
+
+constexpr bool test() {
+  test_fail();
+  test_val_types();
+  test_direct_non_list_init();
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+
+  return 0;
+}
diff --git a/libcxx/test/std/utilities/expected/expected.void/observers/error_or.pass.cpp b/libcxx/test/std/utilities/expected/expected.void/observers/error_or.pass.cpp
new file mode 100644
index 000000000000..db2891f61c3c
--- /dev/null
+++ b/libcxx/test/std/utilities/expected/expected.void/observers/error_or.pass.cpp
@@ -0,0 +1,96 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// template<class G = E> constexpr E error_or(G&& e) const &;
+// template<class G = E> constexpr E error_or(G&& e) &&;
+
+#include <cassert>
+#include <concepts>
+#include <expected>
+#include <type_traits>
+#include <utility>
+
+struct ConstructFromInt {
+  int value;
+  constexpr ConstructFromInt(int v) : value(v) {}
+};
+
+constexpr bool test_default_template_arg() {
+  // const &, has_value()
+  {
+    const std::expected<void, ConstructFromInt> e;
+    std::same_as<ConstructFromInt> decltype(auto) x = e.error_or(10);
+    assert(x.value == 10);
+  }
+
+  // const &, !has_value()
+  {
+    const std::expected<void, ConstructFromInt> e(std::unexpect, 5);
+    std::same_as<ConstructFromInt> decltype(auto) x = e.error_or(10);
+    assert(x.value == 5);
+  }
+
+  // &&, has_value()
+  {
+    const std::expected<void, ConstructFromInt> e;
+    std::same_as<ConstructFromInt> decltype(auto) x = std::move(e).error_or(10);
+    assert(x.value == 10);
+  }
+
+  // &&, !has_value()
+  {
+    const std::expected<void, ConstructFromInt> e(std::unexpect, 5);
+    std::same_as<ConstructFromInt> decltype(auto) x = std::move(e).error_or(10);
+    assert(x.value == 5);
+  }
+
+  return true;
+}
+
+constexpr bool test() {
+  // const &, has_value()
+  {
+    const std::expected<void, int> e;
+    std::same_as<int> decltype(auto) x = e.error_or(10);
+    assert(x == 10);
+  }
+
+  // const &, !has_value()
+  {
+    const std::expected<void, int> e(std::unexpect, 5);
+    std::same_as<int> decltype(auto) x = e.error_or(10);
+    assert(x == 5);
+  }
+
+  // &&, has_value()
+  {
+    std::expected<void, int> e;
+    std::same_as<int> decltype(auto) x = std::move(e).error_or(10);
+    assert(x == 10);
+  }
+
+  // &&, !has_value()
+  {
+    std::expected<void, int> e(std::unexpect, 5);
+    std::same_as<int> decltype(auto) x = std::move(e).error_or(10);
+    assert(x == 5);
+  }
+
+  return true;
+}
+
+int main(int, char**) {
+  test();
+  static_assert(test());
+  test_default_template_arg();
+  static_assert(test_default_template_arg());
+
+  return 0;
+}
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index 5ace82348dcb..c23ebd5b7a03 100755
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -306,7 +306,7 @@ feature_test_macros = [ add_version_header(x) for x in [
     "unimplemented": True,
   }, {
     "name": "__cpp_lib_expected",
-    "values": { "c++2b": 202202 },
+    "values": { "c++2b": 202211 },
     "headers": ["expected"],
   }, {
     "name": "__cpp_lib_filesystem",