[libcxx-commits] [libcxx] 8afa6cf - [libc++][functional] P2944R3 (partial): Comparisons for `reference_wrapper` (`reference_wrapper` operators only) (#88384)
via libcxx-commits
libcxx-commits at lists.llvm.org
Thu May 9 02:48:41 PDT 2024
Author: Hristo Hristov
Date: 2024-05-09T12:48:37+03:00
New Revision: 8afa6cf510608079e24d07423782c4db20de7498
URL: https://github.com/llvm/llvm-project/commit/8afa6cf510608079e24d07423782c4db20de7498
DIFF: https://github.com/llvm/llvm-project/commit/8afa6cf510608079e24d07423782c4db20de7498.diff
LOG: [libc++][functional] P2944R3 (partial): Comparisons for `reference_wrapper` (`reference_wrapper` operators only) (#88384)
Implements https://wg21.link/P2944R3 (partially)
Implements https://wg21.link/LWG4071 /
https://cplusplus.github.io/LWG/issue4071 (fixes build failures in the
test suite)
- https://eel.is/c++draft/refwrap.comparisons
Added:
libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.const_ref.pass.cpp
libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.refwrap.pass.cpp
libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.refwrap_const.pass.cpp
libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.const_ref.pass.cpp
libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.refwrap.pass.cpp
libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.refwrap_const.pass.cpp
libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/helper_concepts.h
libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/helper_types.h
Modified:
libcxx/docs/FeatureTestMacroTable.rst
libcxx/docs/ReleaseNotes/19.rst
libcxx/docs/Status/Cxx2c.rst
libcxx/docs/Status/Cxx2cIssues.csv
libcxx/docs/Status/Cxx2cPapers.csv
libcxx/include/__functional/reference_wrapper.h
libcxx/include/functional
libcxx/include/version
libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.compile.pass.cpp
libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp
libcxx/utils/generate_feature_test_macro_components.py
Removed:
################################################################################
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 1032a9c338f45..17b3476d2c869 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -446,7 +446,7 @@ Status
---------------------------------------------------------- -----------------
``__cpp_lib_rcu`` *unimplemented*
---------------------------------------------------------- -----------------
- ``__cpp_lib_reference_wrapper`` *unimplemented*
+ ``__cpp_lib_reference_wrapper`` ``202403L``
---------------------------------------------------------- -----------------
``__cpp_lib_saturation_arithmetic`` ``202311L``
---------------------------------------------------------- -----------------
diff --git a/libcxx/docs/ReleaseNotes/19.rst b/libcxx/docs/ReleaseNotes/19.rst
index 5a07b11cbcd50..3fc007f459857 100644
--- a/libcxx/docs/ReleaseNotes/19.rst
+++ b/libcxx/docs/ReleaseNotes/19.rst
@@ -46,6 +46,7 @@ Implemented Papers
- P2869R4 - Remove Deprecated ``shared_ptr`` Atomic Access APIs from C++26
- P2872R3 - Remove ``wstring_convert`` From C++26
- P3142R0 - Printing Blank Lines with ``println`` (as DR against C++23)
+- P2944R3 - Comparisons for ``reference_wrapper`` (comparison operators for ``reference_wrapper`` only)
- P2302R4 - ``std::ranges::contains``
- P1659R3 - ``std::ranges::starts_with`` and ``std::ranges::ends_with``
- P3029R1 - Better ``mdspan``'s CTAD
diff --git a/libcxx/docs/Status/Cxx2c.rst b/libcxx/docs/Status/Cxx2c.rst
index e3d9cbb551ff6..5f459b4b3e4e6 100644
--- a/libcxx/docs/Status/Cxx2c.rst
+++ b/libcxx/docs/Status/Cxx2c.rst
@@ -41,6 +41,7 @@ Paper Status
.. [#note-P2510R3] This paper is applied as DR against C++20. (MSVC STL and libstdc++ will do the same.)
.. [#note-P3142R0] This paper is applied as DR against C++23. (MSVC STL and libstdc++ will do the same.)
+ .. [#note-P2944R3] Implemented comparisons for ``reference_wrapper`` only.
.. _issues-status-cxx2c:
diff --git a/libcxx/docs/Status/Cxx2cIssues.csv b/libcxx/docs/Status/Cxx2cIssues.csv
index 30a059f8a3df2..76717e1d3448a 100644
--- a/libcxx/docs/Status/Cxx2cIssues.csv
+++ b/libcxx/docs/Status/Cxx2cIssues.csv
@@ -64,4 +64,5 @@
"","","","","",""
"`3343 <https://wg21.link/LWG3343>`__","Ordering of calls to ``unlock()`` and ``notify_all()`` in Effects element of ``notify_all_at_thread_exit()`` should be reversed","Not Yet Adopted","|Complete|","16.0",""
"XXXX","","The sys_info range should be affected by save","Not Yet Adopted","|Complete|","19.0"
+"`4071 <https://wg21.link/LWG4071>`__","","``reference_wrapper`` comparisons are not SFINAE-friendly","Not Yet Adopted","|Complete|","19.0"
"","","","","",""
diff --git a/libcxx/docs/Status/Cxx2cPapers.csv b/libcxx/docs/Status/Cxx2cPapers.csv
index 409278db1e87d..30a601858b63a 100644
--- a/libcxx/docs/Status/Cxx2cPapers.csv
+++ b/libcxx/docs/Status/Cxx2cPapers.csv
@@ -59,7 +59,7 @@
"`P2248R8 <https://wg21.link/P2248R8>`__","LWG","Enabling list-initialization for algorithms","Tokyo March 2024","","",""
"`P2810R4 <https://wg21.link/P2810R4>`__","LWG","``is_debugger_present`` ``is_replaceable``","Tokyo March 2024","","",""
"`P1068R11 <https://wg21.link/P1068R11>`__","LWG","Vector API for random number generation","Tokyo March 2024","","",""
-"`P2944R3 <https://wg21.link/P2944R3>`__","LWG","Comparisons for ``reference_wrapper``","Tokyo March 2024","","",""
+"`P2944R3 <https://wg21.link/P2944R3>`__","LWG","Comparisons for ``reference_wrapper``","Tokyo March 2024","|Partial| [#note-P2944R3]_","19.0",""
"`P2642R6 <https://wg21.link/P2642R6>`__","LWG","Padded ``mdspan`` layouts","Tokyo March 2024","","",""
"`P3029R1 <https://wg21.link/P3029R1>`__","LWG","Better ``mdspan``'s CTAD","Tokyo March 2024","|Complete|","19.0",""
"","","","","","",""
diff --git a/libcxx/include/__functional/reference_wrapper.h b/libcxx/include/__functional/reference_wrapper.h
index 94b39e3bc7861..ab5d7c7cee115 100644
--- a/libcxx/include/__functional/reference_wrapper.h
+++ b/libcxx/include/__functional/reference_wrapper.h
@@ -10,11 +10,14 @@
#ifndef _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H
#define _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H
+#include <__compare/synth_three_way.h>
+#include <__concepts/boolean_testable.h>
#include <__config>
#include <__functional/invoke.h>
#include <__functional/weak_result_type.h>
#include <__memory/addressof.h>
#include <__type_traits/enable_if.h>
+#include <__type_traits/is_const.h>
#include <__type_traits/remove_cvref.h>
#include <__type_traits/void_t.h>
#include <__utility/declval.h>
@@ -64,6 +67,54 @@ class _LIBCPP_TEMPLATE_VIS reference_wrapper : public __weak_result_type<_Tp> {
{
return std::__invoke(get(), std::forward<_ArgTypes>(__args)...);
}
+
+#if _LIBCPP_STD_VER >= 26
+
+ // [refwrap.comparisons], comparisons
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(reference_wrapper __x, reference_wrapper __y)
+ requires requires {
+ { __x.get() == __y.get() } -> __boolean_testable;
+ }
+ {
+ return __x.get() == __y.get();
+ }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(reference_wrapper __x, const _Tp& __y)
+ requires requires {
+ { __x.get() == __y } -> __boolean_testable;
+ }
+ {
+ return __x.get() == __y;
+ }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(reference_wrapper __x, reference_wrapper<const _Tp> __y)
+ requires(!is_const_v<_Tp>) && requires {
+ { __x.get() == __y.get() } -> __boolean_testable;
+ }
+ {
+ return __x.get() == __y.get();
+ }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(reference_wrapper __x, reference_wrapper __y)
+ requires requires { std::__synth_three_way(__x.get(), __y.get()); }
+ {
+ return std::__synth_three_way(__x.get(), __y.get());
+ }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(reference_wrapper __x, const _Tp& __y)
+ requires requires { std::__synth_three_way(__x.get(), __y); }
+ {
+ return std::__synth_three_way(__x.get(), __y);
+ }
+
+ _LIBCPP_HIDE_FROM_ABI friend constexpr auto operator<=>(reference_wrapper __x, reference_wrapper<const _Tp> __y)
+ requires(!is_const_v<_Tp>) && requires { std::__synth_three_way(__x.get(), __y.get()); }
+ {
+ return std::__synth_three_way(__x.get(), __y.get());
+ }
+
+#endif // _LIBCPP_STD_VER >= 26
};
#if _LIBCPP_STD_VER >= 17
diff --git a/libcxx/include/functional b/libcxx/include/functional
index a2476c93ad1b4..27cf21e1a4c8b 100644
--- a/libcxx/include/functional
+++ b/libcxx/include/functional
@@ -77,6 +77,15 @@ template <class T> struct unwrap_ref_decay : unwrap_reference<decay_t<T>> { };
template <class T> using unwrap_reference_t = typename unwrap_reference<T>::type; // since C++20
template <class T> using unwrap_ref_decay_t = typename unwrap_ref_decay<T>::type; // since C++20
+// [refwrap.comparisons], comparisons
+friend constexpr bool operator==(reference_wrapper, reference_wrapper); // Since C++26
+friend constexpr bool operator==(reference_wrapper, const T&); // Since C++26
+friend constexpr bool operator==(reference_wrapper, reference_wrapper<const T>); // Since C++26
+
+friend constexpr auto operator<=>(reference_wrapper, reference_wrapper); // Since C++26
+friend constexpr auto operator<=>(reference_wrapper, const T&); // Since C++26
+friend constexpr auto operator<=>(reference_wrapper, reference_wrapper<const T>); // Since C++26
+
template <class T> // <class T=void> in C++14
struct plus {
T operator()(const T& x, const T& y) const;
diff --git a/libcxx/include/version b/libcxx/include/version
index eb5fd5c805784..ba116957b033f 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -526,7 +526,7 @@ __cpp_lib_within_lifetime 202306L <type_traits>
// # define __cpp_lib_ranges_concat 202403L
# define __cpp_lib_ratio 202306L
// # define __cpp_lib_rcu 202306L
-// # define __cpp_lib_reference_wrapper 202403L
+# define __cpp_lib_reference_wrapper 202403L
# define __cpp_lib_saturation_arithmetic 202311L
// # define __cpp_lib_smart_ptr_owner_equality 202306L
# define __cpp_lib_span_at 202311L
diff --git a/libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.compile.pass.cpp b/libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.compile.pass.cpp
index aeb09a30b4259..27e76e5b2b05a 100644
--- a/libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.compile.pass.cpp
+++ b/libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.compile.pass.cpp
@@ -535,17 +535,11 @@
# error "__cpp_lib_ranges should have the value 202207L in c++26"
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_reference_wrapper
-# error "__cpp_lib_reference_wrapper should be defined in c++26"
-# endif
-# if __cpp_lib_reference_wrapper != 202403L
-# error "__cpp_lib_reference_wrapper should have the value 202403L in c++26"
-# endif
-# else // _LIBCPP_VERSION
-# ifdef __cpp_lib_reference_wrapper
-# error "__cpp_lib_reference_wrapper should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_reference_wrapper
+# error "__cpp_lib_reference_wrapper should be defined in c++26"
+# endif
+# if __cpp_lib_reference_wrapper != 202403L
+# error "__cpp_lib_reference_wrapper should have the value 202403L in c++26"
# endif
# ifndef __cpp_lib_result_of_sfinae
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 da7a780528c7a..d7035d7e5e3ad 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
@@ -7464,17 +7464,11 @@
# endif
# endif
-# if !defined(_LIBCPP_VERSION)
-# ifndef __cpp_lib_reference_wrapper
-# error "__cpp_lib_reference_wrapper should be defined in c++26"
-# endif
-# if __cpp_lib_reference_wrapper != 202403L
-# error "__cpp_lib_reference_wrapper should have the value 202403L in c++26"
-# endif
-# else // _LIBCPP_VERSION
-# ifdef __cpp_lib_reference_wrapper
-# error "__cpp_lib_reference_wrapper should not be defined because it is unimplemented in libc++!"
-# endif
+# ifndef __cpp_lib_reference_wrapper
+# error "__cpp_lib_reference_wrapper should be defined in c++26"
+# endif
+# if __cpp_lib_reference_wrapper != 202403L
+# error "__cpp_lib_reference_wrapper should have the value 202403L in c++26"
# endif
# ifndef __cpp_lib_remove_cvref
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.const_ref.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.const_ref.pass.cpp
new file mode 100644
index 0000000000000..85106c18ec35a
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.const_ref.pass.cpp
@@ -0,0 +1,89 @@
+//===----------------------------------------------------------------------===//
+//
+// 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, c++23
+
+// <functional>
+
+// class reference_wrapper
+
+// [refwrap.comparisons], comparisons
+
+// friend constexpr auto operator<=>(reference_wrapper, const T&); // Since C++26
+
+#include <cassert>
+#include <concepts>
+#include <functional>
+
+#include "test_comparisons.h"
+#include "test_macros.h"
+
+#include "helper_concepts.h"
+#include "helper_types.h"
+
+// Test SFINAE.
+
+static_assert(HasSpaceshipOperatorWithInt<std::reference_wrapper<StrongOrder>>);
+static_assert(HasSpaceshipOperatorWithInt<std::reference_wrapper<WeakOrder>>);
+static_assert(HasSpaceshipOperatorWithInt<std::reference_wrapper<PartialOrder>>);
+
+static_assert(!HasSpaceshipOperatorWithInt<std::reference_wrapper<NonComparable>>);
+
+// Test comparisons.
+
+template <typename T, typename Order>
+constexpr void test() {
+ T t{47};
+
+ T bigger{94};
+ T smaller{82};
+
+ T unordered{std::numeric_limits<int>::min()};
+
+ // Identical contents
+ {
+ std::reference_wrapper<T> rw1{t};
+ assert(testOrder(rw1, t, Order::equivalent));
+ }
+ // Less
+ {
+ std::reference_wrapper<T> rw1{smaller};
+ assert(testOrder(rw1, bigger, Order::less));
+ }
+ // Greater
+ {
+ std::reference_wrapper<T> rw1{bigger};
+ assert(testOrder(rw1, smaller, Order::greater));
+ }
+ // Unordered
+ if constexpr (std::same_as<T, PartialOrder>) {
+ std::reference_wrapper<T> rw1{bigger};
+ assert(testOrder(rw1, unordered, Order::unordered));
+ }
+}
+
+constexpr bool test() {
+ test<int, std::strong_ordering>();
+ test<StrongOrder, std::strong_ordering>();
+ test<int, std::weak_ordering>();
+ test<WeakOrder, std::weak_ordering>();
+ test<int, std::partial_ordering>();
+ test<PartialOrder, std::partial_ordering>();
+
+ // `LessAndEqComp` does not have `operator<=>`. Ordering is synthesized based on `operator<`
+ test<LessAndEqComp, std::weak_ordering>();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.refwrap.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.refwrap.pass.cpp
new file mode 100644
index 0000000000000..794fac00de8a6
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.refwrap.pass.cpp
@@ -0,0 +1,93 @@
+//===----------------------------------------------------------------------===//
+//
+// 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, c++23
+
+// <functional>
+
+// class reference_wrapper
+
+// [refwrap.comparisons], comparisons
+
+// friend constexpr auto operator<=>(reference_wrapper, reference_wrapper); // Since C++26
+
+#include <cassert>
+#include <concepts>
+#include <functional>
+
+#include "test_comparisons.h"
+#include "test_macros.h"
+
+#include "helper_concepts.h"
+#include "helper_types.h"
+
+// Test SFINAE.
+
+static_assert(std::three_way_comparable<std::reference_wrapper<StrongOrder>>);
+static_assert(std::three_way_comparable<std::reference_wrapper<WeakOrder>>);
+static_assert(std::three_way_comparable<std::reference_wrapper<PartialOrder>>);
+
+static_assert(!std::three_way_comparable<std::reference_wrapper<NonComparable>>);
+
+// Test comparisons.
+
+template <typename T, typename Order>
+constexpr void test() {
+ T t{47};
+
+ T bigger{94};
+ T smaller{82};
+
+ T unordered{std::numeric_limits<int>::min()};
+
+ // Identical contents
+ {
+ std::reference_wrapper<T> rw1{t};
+ std::reference_wrapper<T> rw2{t};
+ assert(testOrder(rw1, rw2, Order::equivalent));
+ }
+ // Less
+ {
+ std::reference_wrapper<T> rw1{smaller};
+ std::reference_wrapper<T> rw2{bigger};
+ assert(testOrder(rw1, rw2, Order::less));
+ }
+ // Greater
+ {
+ std::reference_wrapper<T> rw1{bigger};
+ std::reference_wrapper<T> rw2{smaller};
+ assert(testOrder(rw1, rw2, Order::greater));
+ }
+ // Unordered
+ if constexpr (std::same_as<T, PartialOrder>) {
+ std::reference_wrapper<T> rw1{bigger};
+ std::reference_wrapper<T> rw2{unordered};
+ assert(testOrder(rw1, rw2, Order::unordered));
+ }
+}
+
+constexpr bool test() {
+ test<int, std::strong_ordering>();
+ test<StrongOrder, std::strong_ordering>();
+ test<int, std::weak_ordering>();
+ test<WeakOrder, std::weak_ordering>();
+ test<int, std::partial_ordering>();
+ test<PartialOrder, std::partial_ordering>();
+
+ // `LessAndEqComp` does not have `operator<=>`. Ordering is synthesized based on `operator<`
+ test<LessAndEqComp, std::weak_ordering>();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.refwrap_const.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.refwrap_const.pass.cpp
new file mode 100644
index 0000000000000..9b1302affa851
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.refwrap_const.pass.cpp
@@ -0,0 +1,95 @@
+//===----------------------------------------------------------------------===//
+//
+// 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, c++23
+
+// <functional>
+
+// class reference_wrapper
+
+// [refwrap.comparisons], comparisons
+
+// friend constexpr auto operator<=>(reference_wrapper, reference_wrapper<const T>); // Since C++26
+
+#include <cassert>
+#include <concepts>
+#include <functional>
+
+#include "test_comparisons.h"
+#include "test_macros.h"
+
+#include "helper_concepts.h"
+#include "helper_types.h"
+
+// Test SFINAE.
+
+static_assert(std::three_way_comparable_with<std::reference_wrapper<StrongOrder>, const StrongOrder>);
+static_assert(std::three_way_comparable_with<std::reference_wrapper<WeakOrder>, const WeakOrder>);
+static_assert(std::three_way_comparable_with<std::reference_wrapper<PartialOrder>, const PartialOrder>);
+
+static_assert(!std::three_way_comparable_with<std::reference_wrapper<StrongOrder>, const NonComparable>);
+static_assert(!std::three_way_comparable_with<std::reference_wrapper<WeakOrder>, const NonComparable>);
+static_assert(!std::three_way_comparable_with<std::reference_wrapper<PartialOrder>, const NonComparable>);
+
+// Test comparisons.
+
+template <typename T, typename Order>
+constexpr void test() {
+ T t{47};
+
+ T bigger{94};
+ T smaller{82};
+
+ T unordered{std::numeric_limits<int>::min()};
+
+ // Identical contents
+ {
+ std::reference_wrapper<T> rw1{t};
+ std::reference_wrapper<const T> rw2{t};
+ assert(testOrder(rw1, rw2, Order::equivalent));
+ }
+ // Less
+ {
+ std::reference_wrapper<T> rw1{smaller};
+ std::reference_wrapper<const T> rw2{bigger};
+ assert(testOrder(rw1, rw2, Order::less));
+ }
+ // Greater
+ {
+ std::reference_wrapper<T> rw1{bigger};
+ std::reference_wrapper<const T> rw2{smaller};
+ assert(testOrder(rw1, rw2, Order::greater));
+ }
+ // Unordered
+ if constexpr (std::same_as<T, PartialOrder>) {
+ std::reference_wrapper<T> rw1{bigger};
+ std::reference_wrapper<const T> rw2{unordered};
+ assert(testOrder(rw1, rw2, Order::unordered));
+ }
+}
+
+constexpr bool test() {
+ test<int, std::strong_ordering>();
+ test<StrongOrder, std::strong_ordering>();
+ test<int, std::weak_ordering>();
+ test<WeakOrder, std::weak_ordering>();
+ test<int, std::partial_ordering>();
+ test<PartialOrder, std::partial_ordering>();
+
+ // `LessAndEqComp` does not have `operator<=>`. Ordering is synthesized based on `operator<`
+ test<LessAndEqComp, std::weak_ordering>();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.const_ref.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.const_ref.pass.cpp
new file mode 100644
index 0000000000000..465326818f17c
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.const_ref.pass.cpp
@@ -0,0 +1,62 @@
+//===----------------------------------------------------------------------===//
+//
+// 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, c++23
+
+// <functional>
+
+// class reference_wrapper
+
+// [refwrap.comparisons], comparisons
+
+// friend constexpr bool operator==(reference_wrapper, const T&); // Since C++26
+
+#include <cassert>
+#include <concepts>
+#include <functional>
+
+#include "test_comparisons.h"
+#include "test_macros.h"
+
+#include "helper_concepts.h"
+#include "helper_types.h"
+
+// Test SFINAE.
+
+static_assert(HasEqualityOperatorWithInt<std::reference_wrapper<EqualityComparable>>);
+
+static_assert(!HasEqualityOperatorWithInt<std::reference_wrapper<NonComparable>>);
+
+// Test equality.
+
+template <typename T>
+constexpr void test() {
+ T i{92};
+ T j{84};
+
+ std::reference_wrapper<T> rw1{i};
+
+ // refwrap, const&
+ AssertEqualityReturnBool<decltype(rw1), decltype(i)>();
+ assert(testEquality(rw1, i, true));
+ assert(testEquality(rw1, j, false));
+}
+
+constexpr bool test() {
+ test<int>();
+ test<EqualityComparable>();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.refwrap.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.refwrap.pass.cpp
new file mode 100644
index 0000000000000..a50b530bbc6e1
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.refwrap.pass.cpp
@@ -0,0 +1,64 @@
+//===----------------------------------------------------------------------===//
+//
+// 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, c++23
+
+// <functional>
+
+// class reference_wrapper
+
+// [refwrap.comparisons], comparisons
+// friend constexpr bool operator==(reference_wrapper, reference_wrapper); // Since C++26
+
+#include <cassert>
+#include <concepts>
+#include <functional>
+
+#include "test_comparisons.h"
+#include "test_macros.h"
+
+#include "helper_concepts.h"
+#include "helper_types.h"
+
+// Test SFINAE.
+
+static_assert(std::equality_comparable<std::reference_wrapper<EqualityComparable>>);
+
+static_assert(!std::equality_comparable<std::reference_wrapper<NonComparable>>);
+
+// Test equality.
+
+template <typename T>
+constexpr void test() {
+ T i{92};
+ T j{84};
+
+ std::reference_wrapper<T> rw1{i};
+ std::reference_wrapper<T> rw2 = rw1;
+ std::reference_wrapper<T> rw3{j};
+ std::reference_wrapper<const T> crw1{i};
+ std::reference_wrapper<const T> crw3{j};
+
+ AssertEqualityReturnBool<decltype(rw1), decltype(rw2)>();
+ assert(testEquality(rw1, rw2, true));
+ assert(testEquality(rw1, rw3, false));
+}
+
+constexpr bool test() {
+ test<int>();
+ test<EqualityComparable>();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.refwrap_const.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.refwrap_const.pass.cpp
new file mode 100644
index 0000000000000..10f017742a87f
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.refwrap.refwrap_const.pass.cpp
@@ -0,0 +1,67 @@
+//===----------------------------------------------------------------------===//
+//
+// 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, c++23
+
+// <functional>
+
+// class reference_wrapper
+
+// [refwrap.comparisons], comparisons
+
+// friend constexpr bool operator==(reference_wrapper, reference_wrapper<const T>); // Since C++26
+
+#include <cassert>
+#include <concepts>
+#include <functional>
+
+#include "test_comparisons.h"
+#include "test_macros.h"
+
+#include "helper_concepts.h"
+#include "helper_types.h"
+
+// Test SFINAE.
+
+static_assert(std::equality_comparable_with<std::reference_wrapper<EqualityComparable>,
+ std::reference_wrapper<const EqualityComparable>>);
+
+static_assert(!std::equality_comparable_with<std::reference_wrapper<EqualityComparable>,
+ std::reference_wrapper<const NonComparable>>);
+
+// Test equality.
+
+template <typename T>
+constexpr void test() {
+ T i{92};
+ T j{84};
+
+ std::reference_wrapper<T> rw1{i};
+
+ std::reference_wrapper<T> rw3{j};
+ std::reference_wrapper<const T> crw1{i};
+ std::reference_wrapper<const T> crw3{j};
+
+ AssertEqualityReturnBool<decltype(rw1), decltype(crw1)>();
+ assert(testEquality(rw1, crw1, true));
+ assert(testEquality(rw1, crw3, false));
+}
+
+constexpr bool test() {
+ test<int>();
+ test<EqualityComparable>();
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/helper_concepts.h b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/helper_concepts.h
new file mode 100644
index 0000000000000..2dbb304f8af63
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/helper_concepts.h
@@ -0,0 +1,38 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef TEST_STD_FUNCTIONOBJECTS_REFWRAP_HELPER_CONCEPTS_H
+#define TEST_STD_FUNCTIONOBJECTS_REFWRAP_HELPER_CONCEPTS_H
+
+#include <concepts>
+#include <utility>
+
+// Equality
+
+template <typename T>
+concept HasEqualityOperatorWithInt = requires(T t, int i) {
+ { t.get() == i } -> std::convertible_to<bool>;
+};
+
+// Spaceship
+
+template <class T>
+concept BooleanTestableImpl = std::convertible_to<T, bool>;
+
+template <class T>
+concept BooleanTestable = BooleanTestableImpl<T> && requires(T&& t) {
+ { !std::forward<T>(t) } -> BooleanTestableImpl;
+};
+
+template <typename T>
+concept HasSpaceshipOperatorWithInt = requires(T t, int i) {
+ { t < i } -> BooleanTestable;
+ { i < t } -> BooleanTestable;
+};
+
+#endif // TEST_STD_FUNCTIONOBJECTS_REFWRAP_HELPER_CONCEPTS_H
diff --git a/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/helper_types.h b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/helper_types.h
new file mode 100644
index 0000000000000..cf5e568dbf936
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/helper_types.h
@@ -0,0 +1,30 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef TEST_STD_FUNCTIONOBJECTS_REFWRAP_HELPER_TYPES_H
+#define TEST_STD_FUNCTIONOBJECTS_REFWRAP_HELPER_TYPES_H
+
+#include <concepts>
+
+struct EqualityComparable {
+ constexpr EqualityComparable(int value) : value_{value} {};
+
+ friend constexpr bool operator==(const EqualityComparable&, const EqualityComparable&) noexcept = default;
+
+ int value_;
+};
+
+static_assert(std::equality_comparable<EqualityComparable>);
+static_assert(EqualityComparable{94} == EqualityComparable{94});
+static_assert(EqualityComparable{94} != EqualityComparable{82});
+
+struct NonComparable {};
+
+static_assert(!std::three_way_comparable<NonComparable>);
+
+#endif // TEST_STD_FUNCTIONOBJECTS_REFWRAP_HELPER_TYPES_H
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index 29c8ceba0c7ef..d0171c84acbc3 100755
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -1044,7 +1044,6 @@ def add_version_header(tc):
"name": "__cpp_lib_reference_wrapper",
"values": {"c++26": 202403}, # P2944R3: Comparisons for reference_wrapper
"headers": ["functional"],
- "unimplemented": True,
},
{
"name": "__cpp_lib_remove_cvref",
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