[libc++] P2944R3: Constrained comparisons - update reference_wrapper implementation

libcxx/docs/Status/Cxx2cPapers.csv

@@ -59,7 +59,7 @@
 "`P2248R8 <https://wg21.link/P2248R8>`__","Enabling list-initialization for algorithms","2024-03 (Tokyo)","","",""
 "`P2810R4 <https://wg21.link/P2810R4>`__","``is_debugger_present`` ``is_replaceable``","2024-03 (Tokyo)","","",""
 "`P1068R11 <https://wg21.link/P1068R11>`__","Vector API for random number generation","2024-03 (Tokyo)","","",""
-"`P2944R3 <https://wg21.link/P2944R3>`__","Comparisons for ``reference_wrapper``","2024-03 (Tokyo)","|Partial|","","Implemented changes to ``reference_wrapper`` and ``pair``"
+"`P2944R3 <https://wg21.link/P2944R3>`__","Comparisons for ``reference_wrapper``","2024-03 (Tokyo)","|Partial|","","Not implemented ``tuple`` and ``variant``"
 "`P2642R6 <https://wg21.link/P2642R6>`__","Padded ``mdspan`` layouts","2024-03 (Tokyo)","","",""
 "`P3029R1 <https://wg21.link/P3029R1>`__","Better ``mdspan``'s CTAD","2024-03 (Tokyo)","|Complete|","19",""
 "","","","","",""

libcxx/include/__functional/reference_wrapper.h

@@ -11,14 +11,14 @@
 #define _LIBCPP___FUNCTIONAL_REFERENCE_WRAPPER_H
 
 #include <__compare/synth_three_way.h>
-#include <__concepts/boolean_testable.h>
 #include <__config>
 #include <__functional/weak_result_type.h>
 #include <__memory/addressof.h>
 #include <__type_traits/desugars_to.h>
 #include <__type_traits/enable_if.h>
 #include <__type_traits/invoke.h>
 #include <__type_traits/is_const.h>
+#include <__type_traits/is_core_convertible.h>
 #include <__type_traits/remove_cvref.h>
 #include <__type_traits/void_t.h>
 #include <__utility/declval.h>
@@ -75,23 +75,23 @@ class reference_wrapper : public __weak_result_type<_Tp> {
 
   _LIBCPP_HIDE_FROM_ABI friend constexpr bool operator==(reference_wrapper __x, reference_wrapper __y)
     requires requires {
-      { __x.get() == __y.get() } -> __boolean_testable;
+      { __x.get() == __y.get() } -> __core_convertible_to<bool>;
     }
   {
     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;
+      { __x.get() == __y } -> __core_convertible_to<bool>;
     }
   {
     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;
+      { __x.get() == __y.get() } -> __core_convertible_to<bool>;
     }
   {
     return __x.get() == __y.get();

libcxx/include/version

@@ -80,8 +80,8 @@ __cpp_lib_constexpr_tuple                               201811L <tuple>
 __cpp_lib_constexpr_typeinfo                            202106L <typeinfo>
 __cpp_lib_constexpr_utility                             201811L <utility>
 __cpp_lib_constexpr_vector                              201907L <vector>
-__cpp_lib_constrained_equality                          202403L <optional> <tuple> <utility>
-                                                                <variant>
+__cpp_lib_constrained_equality                          202411L <expected> <optional> <tuple>
+                                                                <utility> <variant>
 __cpp_lib_containers_ranges                             202202L <deque> <forward_list> <list>
                                                                 <map> <queue> <set>
                                                                 <stack> <string> <unordered_map>
@@ -545,7 +545,7 @@ __cpp_lib_void_t                                        201411L <type_traits>
 # if !defined(_LIBCPP_ABI_VCRUNTIME)
 #   define __cpp_lib_constexpr_new                      202406L
 # endif
-// # define __cpp_lib_constrained_equality                 202403L
+// # define __cpp_lib_constrained_equality                 202411L
 // # define __cpp_lib_copyable_function                    202306L
 // # define __cpp_lib_debugging                            202311L
 // # define __cpp_lib_default_template_type_for_algorithm_values 202403L

libcxx/test/std/containers/sequences/array/compare.three_way.pass.cpp

@@ -26,7 +26,6 @@ constexpr std::size_t N{1};
 static_assert(std::three_way_comparable<std::array<int, N>>);
 
 // Thanks to SFINAE, the following is not a compiler error but returns `false`
-struct NonComparable {};
 static_assert(!std::three_way_comparable<std::array<NonComparable, N>>);
 
 // Implementation detail of `test_sequence_container_array_spaceship`

libcxx/test/std/language.support/support.limits/support.limits.general/expected.version.compile.pass.cpp

@@ -20,6 +20,10 @@
 
 #if TEST_STD_VER < 14
 
+#  ifdef __cpp_lib_constrained_equality
+#    error "__cpp_lib_constrained_equality should not be defined before c++26"
+#  endif
+
 #  ifdef __cpp_lib_expected
 #    error "__cpp_lib_expected should not be defined before c++23"
 #  endif
@@ -30,6 +34,10 @@
 
 #elif TEST_STD_VER == 14
 
+#  ifdef __cpp_lib_constrained_equality
+#    error "__cpp_lib_constrained_equality should not be defined before c++26"
+#  endif
+
 #  ifdef __cpp_lib_expected
 #    error "__cpp_lib_expected should not be defined before c++23"
 #  endif
@@ -40,6 +48,10 @@
 
 #elif TEST_STD_VER == 17
 
+#  ifdef __cpp_lib_constrained_equality
+#    error "__cpp_lib_constrained_equality should not be defined before c++26"
+#  endif
+
 #  ifdef __cpp_lib_expected
 #    error "__cpp_lib_expected should not be defined before c++23"
 #  endif
@@ -50,6 +62,10 @@
 
 #elif TEST_STD_VER == 20
 
+#  ifdef __cpp_lib_constrained_equality
+#    error "__cpp_lib_constrained_equality should not be defined before c++26"
+#  endif
+
 #  ifdef __cpp_lib_expected
 #    error "__cpp_lib_expected should not be defined before c++23"
 #  endif
@@ -60,6 +76,10 @@
 
 #elif TEST_STD_VER == 23
 
+#  ifdef __cpp_lib_constrained_equality
+#    error "__cpp_lib_constrained_equality should not be defined before c++26"
+#  endif
+
 #  ifndef __cpp_lib_expected
 #    error "__cpp_lib_expected should be defined in c++23"
 #  endif
@@ -73,6 +93,19 @@
 
 #elif TEST_STD_VER > 23
 
+#  if !defined(_LIBCPP_VERSION)
+#    ifndef __cpp_lib_constrained_equality
+#      error "__cpp_lib_constrained_equality should be defined in c++26"
+#    endif
+#    if __cpp_lib_constrained_equality != 202411L
+#      error "__cpp_lib_constrained_equality should have the value 202411L in c++26"
+#    endif
+#  else
+#    ifdef __cpp_lib_constrained_equality
+#      error "__cpp_lib_constrained_equality should not be defined because it is unimplemented in libc++!"
+#    endif
+#  endif
+
 #  ifndef __cpp_lib_expected
 #    error "__cpp_lib_expected should be defined in c++26"
 #  endif

libcxx/test/std/language.support/support.limits/support.limits.general/optional.version.compile.pass.cpp

@@ -123,8 +123,8 @@
 #    ifndef __cpp_lib_constrained_equality
 #      error "__cpp_lib_constrained_equality should be defined in c++26"
 #    endif
-#    if __cpp_lib_constrained_equality != 202403L
-#      error "__cpp_lib_constrained_equality should have the value 202403L in c++26"
+#    if __cpp_lib_constrained_equality != 202411L
+#      error "__cpp_lib_constrained_equality should have the value 202411L in c++26"
 #    endif
 #  else
 #    ifdef __cpp_lib_constrained_equality

libcxx/test/std/language.support/support.limits/support.limits.general/tuple.version.compile.pass.cpp

@@ -274,8 +274,8 @@
 #    ifndef __cpp_lib_constrained_equality
 #      error "__cpp_lib_constrained_equality should be defined in c++26"
 #    endif
-#    if __cpp_lib_constrained_equality != 202403L
-#      error "__cpp_lib_constrained_equality should have the value 202403L in c++26"
+#    if __cpp_lib_constrained_equality != 202411L
+#      error "__cpp_lib_constrained_equality should have the value 202411L in c++26"
 #    endif
 #  else
 #    ifdef __cpp_lib_constrained_equality

libcxx/test/std/language.support/support.limits/support.limits.general/utility.version.compile.pass.cpp

@@ -405,8 +405,8 @@
 #    ifndef __cpp_lib_constrained_equality
 #      error "__cpp_lib_constrained_equality should be defined in c++26"
 #    endif
-#    if __cpp_lib_constrained_equality != 202403L
-#      error "__cpp_lib_constrained_equality should have the value 202403L in c++26"
+#    if __cpp_lib_constrained_equality != 202411L
+#      error "__cpp_lib_constrained_equality should have the value 202411L in c++26"
 #    endif
 #  else
 #    ifdef __cpp_lib_constrained_equality

libcxx/test/std/language.support/support.limits/support.limits.general/variant.version.compile.pass.cpp

@@ -103,8 +103,8 @@
 #    ifndef __cpp_lib_constrained_equality
 #      error "__cpp_lib_constrained_equality should be defined in c++26"
 #    endif
-#    if __cpp_lib_constrained_equality != 202403L
-#      error "__cpp_lib_constrained_equality should have the value 202403L in c++26"
+#    if __cpp_lib_constrained_equality != 202411L
+#      error "__cpp_lib_constrained_equality should have the value 202411L in c++26"
 #    endif
 #  else
 #    ifdef __cpp_lib_constrained_equality

libcxx/test/std/language.support/support.limits/support.limits.general/version.version.compile.pass.cpp

@@ -6494,8 +6494,8 @@
 #    ifndef __cpp_lib_constrained_equality
 #      error "__cpp_lib_constrained_equality should be defined in c++26"
 #    endif
-#    if __cpp_lib_constrained_equality != 202403L
-#      error "__cpp_lib_constrained_equality should have the value 202403L in c++26"
+#    if __cpp_lib_constrained_equality != 202411L
+#      error "__cpp_lib_constrained_equality should have the value 202411L in c++26"
 #    endif
 #  else
 #    ifdef __cpp_lib_constrained_equality

libcxx/test/std/utilities/expected/expected.expected/equality/equality.T2.pass.cpp

@@ -16,14 +16,14 @@
 #include <type_traits>
 #include <utility>
 
+#include "test_comparisons.h"
 #include "test_macros.h"
-#include "../../types.h"
 
 #if TEST_STD_VER >= 26
 // https://wg21.link/P3379R0
-static_assert(CanCompare<std::expected<int, int>, int>);
-static_assert(CanCompare<std::expected<int, int>, EqualityComparable>);
-static_assert(!CanCompare<std::expected<int, int>, NonComparable>);
+static_assert(HasOperatorEqual<std::expected<int, int>, int>);
+static_assert(HasOperatorEqual<std::expected<int, int>, EqualityComparable>);
+static_assert(!HasOperatorEqual<std::expected<int, int>, NonComparable>);
 #endif
 
 constexpr bool test() {

libcxx/test/std/utilities/expected/expected.expected/equality/equality.other_expected.pass.cpp

@@ -17,26 +17,26 @@
 #include <type_traits>
 #include <utility>
 
+#include "test_comparisons.h"
 #include "test_macros.h"
-#include "../../types.h"
 
 // Test constraint
-static_assert(!CanCompare<NonComparable, NonComparable>);
+static_assert(!HasOperatorEqual<NonComparable, NonComparable>);
 
-static_assert(CanCompare<std::expected<int, int>, std::expected<int, int>>);
-static_assert(CanCompare<std::expected<int, int>, std::expected<short, short>>);
+static_assert(HasOperatorEqual<std::expected<int, int>, std::expected<int, int>>);
+static_assert(HasOperatorEqual<std::expected<int, int>, std::expected<short, short>>);
 
 #if TEST_STD_VER >= 26
 // https://wg21.link/P3379R0
-static_assert(!CanCompare<std::expected<int, int>, std::expected<void, int>>);
-static_assert(CanCompare<std::expected<int, int>, std::expected<int, int>>);
-static_assert(!CanCompare<std::expected<NonComparable, int>, std::expected<NonComparable, int>>);
-static_assert(!CanCompare<std::expected<int, NonComparable>, std::expected<int, NonComparable>>);
-static_assert(!CanCompare<std::expected<NonComparable, int>, std::expected<int, NonComparable>>);
-static_assert(!CanCompare<std::expected<int, NonComparable>, std::expected<NonComparable, int>>);
+static_assert(!HasOperatorEqual<std::expected<int, int>, std::expected<void, int>>);
+static_assert(HasOperatorEqual<std::expected<int, int>, std::expected<int, int>>);
+static_assert(!HasOperatorEqual<std::expected<NonComparable, int>, std::expected<NonComparable, int>>);
+static_assert(!HasOperatorEqual<std::expected<int, NonComparable>, std::expected<int, NonComparable>>);
+static_assert(!HasOperatorEqual<std::expected<NonComparable, int>, std::expected<int, NonComparable>>);
+static_assert(!HasOperatorEqual<std::expected<int, NonComparable>, std::expected<NonComparable, int>>);
 #else
 // Note this is true because other overloads in expected<non-void> are unconstrained
-static_assert(CanCompare<std::expected<void, int>, std::expected<int, int>>);
+static_assert(HasOperatorEqual<std::expected<void, int>, std::expected<int, int>>);
 #endif
 constexpr bool test() {
   // x.has_value() && y.has_value()

libcxx/test/std/utilities/expected/expected.expected/equality/equality.unexpected.pass.cpp

@@ -16,14 +16,14 @@
 #include <type_traits>
 #include <utility>
 
+#include "test_comparisons.h"
 #include "test_macros.h"
-#include "../../types.h"
 
 #if TEST_STD_VER >= 26
 // https://wg21.link/P3379R0
-static_assert(CanCompare<std::expected<EqualityComparable, EqualityComparable>, std::unexpected<int>>);
-static_assert(CanCompare<std::expected<EqualityComparable, int>, std::unexpected<EqualityComparable>>);
-static_assert(!CanCompare<std::expected<EqualityComparable, NonComparable>, std::unexpected<int>>);
+static_assert(HasOperatorEqual<std::expected<EqualityComparable, EqualityComparable>, std::unexpected<int>>);
+static_assert(HasOperatorEqual<std::expected<EqualityComparable, int>, std::unexpected<EqualityComparable>>);
+static_assert(!HasOperatorEqual<std::expected<EqualityComparable, NonComparable>, std::unexpected<int>>);
 #endif
 
 constexpr bool test() {

libcxx/test/std/utilities/expected/expected.void/equality/equality.other_expected.pass.cpp

@@ -17,26 +17,26 @@
 #include <type_traits>
 #include <utility>
 
+#include "test_comparisons.h"
 #include "test_macros.h"
-#include "../../types.h"
 
 struct Foo{};
-static_assert(!CanCompare<Foo, Foo>);
+static_assert(!HasOperatorEqual<Foo, Foo>);
 
-static_assert(CanCompare<std::expected<void, int>, std::expected<void, int>>);
-static_assert(CanCompare<std::expected<void, int>, std::expected<void, short>>);
+static_assert(HasOperatorEqual<std::expected<void, int>, std::expected<void, int>>);
+static_assert(HasOperatorEqual<std::expected<void, int>, std::expected<void, short>>);
 
 #if TEST_STD_VER >= 26
 // https://wg21.link/P3379R0
-static_assert(!CanCompare<std::expected<void, int>, std::expected<int, int>>);
-static_assert(CanCompare<std::expected<void, int>, std::expected<void, int>>);
-static_assert(CanCompare<std::expected<void, int>, std::expected<void, int>>);
-static_assert(!CanCompare<std::expected<void, NonComparable>, std::expected<void, NonComparable>>);
-static_assert(!CanCompare<std::expected<void, int>, std::expected<void, NonComparable>>);
-static_assert(!CanCompare<std::expected<void, NonComparable>, std::expected<void, int>>);
+static_assert(!HasOperatorEqual<std::expected<void, int>, std::expected<int, int>>);
+static_assert(HasOperatorEqual<std::expected<void, int>, std::expected<void, int>>);
+static_assert(HasOperatorEqual<std::expected<void, int>, std::expected<void, int>>);
+static_assert(!HasOperatorEqual<std::expected<void, NonComparable>, std::expected<void, NonComparable>>);
+static_assert(!HasOperatorEqual<std::expected<void, int>, std::expected<void, NonComparable>>);
+static_assert(!HasOperatorEqual<std::expected<void, NonComparable>, std::expected<void, int>>);
 #else
 // Note this is true because other overloads in expected<non-void> are unconstrained
-static_assert(CanCompare<std::expected<void, int>, std::expected<int, int>>);
+static_assert(HasOperatorEqual<std::expected<void, int>, std::expected<int, int>>);
 #endif
 
 constexpr bool test() {

libcxx/test/std/utilities/expected/expected.void/equality/equality.unexpected.pass.cpp

@@ -16,14 +16,14 @@
 #include <type_traits>
 #include <utility>
 
+#include "test_comparisons.h"
 #include "test_macros.h"
-#include "../../types.h"
 
 #if TEST_STD_VER >= 26
 // https://wg21.link/P3379R0
-static_assert(CanCompare<std::expected<void, EqualityComparable>, std::unexpected<int>>);
-static_assert(CanCompare<std::expected<void, int>, std::unexpected<EqualityComparable>>);
-static_assert(!CanCompare<std::expected<void, NonComparable>, std::unexpected<int>>);
+static_assert(HasOperatorEqual<std::expected<void, EqualityComparable>, std::unexpected<int>>);
+static_assert(HasOperatorEqual<std::expected<void, int>, std::unexpected<EqualityComparable>>);
+static_assert(!HasOperatorEqual<std::expected<void, NonComparable>, std::unexpected<int>>);
 #endif
 
 constexpr bool test() {

libcxx/test/std/utilities/expected/types.h

@@ -336,17 +336,4 @@ struct CheckForInvalidWrites : public CheckForInvalidWritesBase<WithPaddedExpect
   }
 };
 
-struct NonComparable {};
-
-struct EqualityComparable {
-  int i;
-  constexpr EqualityComparable(int ii) : i(ii) {}
-
-  friend constexpr bool operator==(const EqualityComparable& data, int ii) { return data.i == ii; }
-};
-
-// Test constraint
-template <class T1, class T2>
-concept CanCompare = requires(T1 t1, T2 t2) { t1 == t2; };
-
 #endif // TEST_STD_UTILITIES_EXPECTED_TYPES_H

libcxx/test/std/utilities/function.objects/refwrap/refwrap.comparissons/compare.three_way.refwrap.const_ref.pass.cpp

@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 
-// UNSUPPORTED: c++03, c++11, c++14, c++17, c++20, c++23
+// REQUIRES: std-at-least-c++26
 
 // <functional>
 
@@ -23,16 +23,13 @@
 #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(HasOperatorSpaceship<std::reference_wrapper<StrongOrder>, int>);
+static_assert(HasOperatorSpaceship<std::reference_wrapper<WeakOrder>, int>);
+static_assert(HasOperatorSpaceship<std::reference_wrapper<PartialOrder>, int>);
 
-static_assert(!HasSpaceshipOperatorWithInt<std::reference_wrapper<NonComparable>>);
+static_assert(!HasOperatorSpaceship<std::reference_wrapper<NonComparable>, int>);
 
 // Test comparisons.