[libcxx-commits] [libcxx] WIP - [libc++][functional] P2944R3 (partial): Comparisons for ``reference_wrapper`` (``reference_wrapper`` operators only) (PR #88384)
via libcxx-commits
libcxx-commits at lists.llvm.org
Thu Apr 11 06:14:33 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libcxx
Author: Hristo Hristov (H-G-Hristov)
<details>
<summary>Changes</summary>
Implements https://wg21.link/P2944R3 (partially)
- https://eel.is/c++draft/refwrap.comparisons
---
Full diff: https://github.com/llvm/llvm-project/pull/88384.diff
12 Files Affected:
- (modified) libcxx/docs/FeatureTestMacroTable.rst (+1-1)
- (modified) libcxx/docs/ReleaseNotes/19.rst (+1)
- (modified) libcxx/docs/Status/Cxx2c.rst (+1)
- (modified) libcxx/docs/Status/Cxx2cPapers.csv (+1-1)
- (modified) libcxx/include/__functional/reference_wrapper.h (+43)
- (modified) libcxx/include/functional (+9)
- (modified) libcxx/include/version (+1-1)
- (modified) libcxx/test/std/language.support/support.limits/support.limits.general/functional.version.compile.pass.cpp (+5-11)
- (modified) libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp (+5-11)
- (added) libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.pass.cpp (+33)
- (added) libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.pass.cpp (+68)
- (modified) libcxx/utils/generate_feature_test_macro_components.py (-1)
``````````diff
diff --git a/libcxx/docs/FeatureTestMacroTable.rst b/libcxx/docs/FeatureTestMacroTable.rst
index 3197d2cd1b271c..83d8213ec29f9e 100644
--- a/libcxx/docs/FeatureTestMacroTable.rst
+++ b/libcxx/docs/FeatureTestMacroTable.rst
@@ -444,7 +444,7 @@ 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 81c05b9112bd26..a4c6975764cd73 100644
--- a/libcxx/docs/ReleaseNotes/19.rst
+++ b/libcxx/docs/ReleaseNotes/19.rst
@@ -45,6 +45,7 @@ Implemented Papers
- P2867R2 - Remove Deprecated ``strstream``\s 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``
diff --git a/libcxx/docs/Status/Cxx2c.rst b/libcxx/docs/Status/Cxx2c.rst
index a7ebc4662f517c..b6f1714a182a6c 100644
--- a/libcxx/docs/Status/Cxx2c.rst
+++ b/libcxx/docs/Status/Cxx2c.rst
@@ -40,6 +40,7 @@ Paper Status
.. note::
.. [#note-P2510R3] This paper is applied as DR against C++20. (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/Cxx2cPapers.csv b/libcxx/docs/Status/Cxx2cPapers.csv
index fa11da62bc080e..333d8fe824039f 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|","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","","",""
"","","","","","",""
diff --git a/libcxx/include/__functional/reference_wrapper.h b/libcxx/include/__functional/reference_wrapper.h
index 94b39e3bc78616..6c6643882886d7 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 <__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/is_convertible.h>
#include <__type_traits/remove_cvref.h>
#include <__type_traits/void_t.h>
#include <__utility/declval.h>
@@ -64,6 +67,46 @@ 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
+
+ friend constexpr bool operator==(reference_wrapper __x, reference_wrapper __y) {
+ static_assert(is_convertible_v<decltype(__x.get() == __y.get()), bool>);
+
+ return __x.get() == __y.get();
+ }
+
+ friend constexpr bool operator==(reference_wrapper __x, const _Tp& __y) {
+ static_assert(is_convertible_v<decltype(__x.get() == __y), bool>);
+
+ return __x.get() == __y;
+ }
+
+ friend constexpr bool operator==(reference_wrapper __x, reference_wrapper<const _Tp> __y)
+ requires(!is_const_v<_Tp>)
+ {
+ static_assert(is_convertible_v<decltype(__x.get() == __y.get()), bool>);
+
+ return __x.get() == __y.get();
+ }
+
+ friend constexpr __synth_three_way_result<_Tp> operator<=>(reference_wrapper __x, reference_wrapper __y) {
+ return std::__synth_three_way(__x.get(), __y.get());
+ }
+
+ friend constexpr __synth_three_way_result<_Tp> operator<=>(reference_wrapper __x, const _Tp& __y) {
+ return std::__synth_three_way(__x.get(), __y.get());
+ }
+
+ friend constexpr __synth_three_way_result<_Tp> operator<=>(reference_wrapper __x, reference_wrapper<const _Tp> __y)
+ requires(!is_const_v<_Tp>)
+ {
+ 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 a2476c93ad1b43..1da953f82241b5 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 synth-three-way-result<T> operator<=>(reference_wrapper, reference_wrapper); // Since C++26
+friend constexpr synth-three-way-result<T> operator<=>(reference_wrapper, const T&); // Since C++26
+friend constexpr synth-three-way-result<T> 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 0ed77345baa71d..0ce262462eb3ee 100644
--- a/libcxx/include/version
+++ b/libcxx/include/version
@@ -524,7 +524,7 @@ __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 aeb09a30b42591..27e76e5b2b05a3 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 3ec548f56cea1d..54fb538680ebad 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
@@ -7433,17 +7433,11 @@
# 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.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.pass.cpp
new file mode 100644
index 00000000000000..cbf5d8830200b5
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.pass.cpp
@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
+
+// <functional>
+
+// class reference_wrapper
+
+// // [refwrap.comparisons], comparisons
+
+// friend constexpr synth-three-way-result<T> operator<=>(reference_wrapper, reference_wrapper); // Since C++26
+// friend constexpr synth-three-way-result<T> operator<=>(reference_wrapper, const T&); // Since C++26
+// friend constexpr synth-three-way-result<T> operator<=>(reference_wrapper, reference_wrapper<const T>); // Since C++26
+
+#include <cassert>
+#include <functional>
+
+#include "test_macros.h"
+
+constexpr bool test() { 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.pass.cpp b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.pass.cpp
new file mode 100644
index 00000000000000..8012c0c40d5b8e
--- /dev/null
+++ b/libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/equal.pass.cpp
@@ -0,0 +1,68 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+// friend constexpr bool operator==(reference_wrapper, const T&); // Since C++26
+// friend constexpr bool operator==(reference_wrapper, reference_wrapper<const T>); // Since C++26
+
+#include <cassert>
+#include <functional>
+
+#include "test_macros.h"
+
+constexpr bool test() {
+ int i = 92;
+ int j = 84;
+
+ // ==
+ {
+ std::reference_wrapper<int> lhs{i};
+ std::reference_wrapper<int> rhs = lhs;
+ assert(lhs == rhs);
+ }
+ {
+ std::reference_wrapper<int> lhs{i};
+ assert(lhs == i);
+ }
+ {
+ std::reference_wrapper<int> lhs{i};
+ std::reference_wrapper<const int> rhs = lhs;
+ assert(lhs == rhs);
+ }
+ // !=
+ {
+ std::reference_wrapper<int> lhs{i};
+ std::reference_wrapper<int> rhs{j};
+ assert(lhs != rhs);
+ }
+ {
+ std::reference_wrapper<int> lhs{i};
+ assert(lhs != j);
+ }
+ {
+ std::reference_wrapper<int> lhs{i};
+ std::reference_wrapper<const int> rhs{j};
+ assert(lhs != rhs);
+ }
+
+ return true;
+}
+
+int main(int, char**) {
+ test();
+ static_assert(test());
+
+ return 0;
+}
diff --git a/libcxx/utils/generate_feature_test_macro_components.py b/libcxx/utils/generate_feature_test_macro_components.py
index f2b8d55c0e11b0..5f127bd1213c14 100755
--- a/libcxx/utils/generate_feature_test_macro_components.py
+++ b/libcxx/utils/generate_feature_test_macro_components.py
@@ -1040,7 +1040,6 @@ 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",
``````````
</details>
https://github.com/llvm/llvm-project/pull/88384
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