[libcxx] Adds [concept.same]
Patch from Christopher Di Bella (cjdb@google.com)
Reviewed as https://reviews.llvm.org/D74291
Adds `std::same_as` to libc++. Since there aren't clang-format rules for
//requires-expressions//, I'll need to disable the formatter in certain areas.
Cr-Mirrored-From: https://chromium.googlesource.com/external/github.com/llvm/llvm-project
Cr-Mirrored-Commit: 601f7631827ae6ac08117a282c83a62b67dedf48
diff --git a/include/concepts b/include/concepts
new file mode 100644
index 0000000..047e2c2
--- /dev/null
+++ b/include/concepts
@@ -0,0 +1,166 @@
+// -*- C++ -*-
+//===-------------------------- concepts ----------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef _LIBCPP_CONCEPTS
+#define _LIBCPP_CONCEPTS
+
+/*
+ concepts synopsis
+namespace std {
+ // [concepts.lang], language-related concepts
+ // [concept.same], concept same_as
+ template<class T, class U>
+ concept same_as = see below;
+
+ // [concept.derived], concept derived_from
+ template<class Derived, class Base>
+ concept derived_from = see below;
+
+ // [concept.convertible], concept convertible_to
+ template<class From, class To>
+ concept convertible_to = see below;
+
+ // [concept.commonref], concept common_reference_with
+ template<class T, class U>
+ concept common_reference_with = see below;
+
+ // [concept.common], concept common_with
+ template<class T, class U>
+ concept common_with = see below;
+
+ // [concepts.arithmetic], arithmetic concepts
+ template<class T>
+ concept integral = see below;
+ template<class T>
+ concept signed_integral = see below;
+ template<class T>
+ concept unsigned_integral = see below;
+ template<class T>
+ concept floating_point = see below;
+
+ // [concept.assignable], concept assignable_from
+ template<class LHS, class RHS>
+ concept assignable_from = see below;
+
+ // [concept.swappable], concept swappable
+ namespace ranges {
+ inline namespace unspecified {
+ inline constexpr unspecified swap = unspecified;
+ }
+ }
+ template<class T>
+ concept swappable = see below;
+ template<class T, class U>
+ concept swappable_with = see below;
+
+ // [concept.destructible], concept destructible
+ template<class T>
+ concept destructible = see below;
+
+ // [concept.constructible], concept constructible_from
+ template<class T, class... Args>
+ concept constructible_from = see below;
+
+ // [concept.defaultconstructible], concept default_constructible
+ template<class T>
+ concept default_constructible = see below;
+
+ // [concept.moveconstructible], concept move_constructible
+ template<class T>
+ concept move_constructible = see below;
+
+ // [concept.copyconstructible], concept copy_constructible
+ template<class T>
+ concept copy_constructible = see below;
+
+ // [concepts.compare], comparison concepts
+ // [concept.boolean], concept boolean
+ template<class B>
+ concept boolean = see below;
+
+ // [concept.equalitycomparable], concept equality_comparable
+ template<class T>
+ concept equality_comparable = see below;
+ template<class T, class U>
+ concept equality_comparable_with = see below;
+
+ // [concept.totallyordered], concept totally_ordered
+ template<class T>
+ concept totally_ordered = see below;
+ template<class T, class U>
+ concept totally_ordered_with = see below;
+
+ // [concepts.object], object concepts
+ template<class T>
+ concept movable = see below;
+ template<class T>
+ concept copyable = see below;
+ template<class T>
+ concept semiregular = see below;
+ template<class T>
+ concept regular = see below;
+
+ // [concepts.callable], callable concepts
+ // [concept.invocable], concept invocable
+ template<class F, class... Args>
+ concept invocable = see below;
+
+ // [concept.regularinvocable], concept regular_invocable
+ template<class F, class... Args>
+ concept regular_invocable = see below;
+
+ // [concept.predicate], concept predicate
+ template<class F, class... Args>
+ concept predicate = see below;
+
+ // [concept.relation], concept relation
+ template<class R, class T, class U>
+ concept relation = see below;
+
+ // [concept.equiv], concept equivalence_relation
+ template<class R, class T, class U>
+ concept equivalence_relation = see below;
+
+ // [concept.strictweakorder], concept strict_weak_order
+ template<class R, class T, class U>
+ concept strict_weak_order = see below;
+}
+
+*/
+
+#include <__config>
+#include <type_traits>
+#include <version>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#pragma GCC system_header
+#endif
+
+_LIBCPP_PUSH_MACROS
+#include <__undef_macros>
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#if _LIBCPP_STD_VER > 17 && defined(__cpp_concepts) && __cpp_concepts >= 201811L
+
+// [concept.same]
+
+template<class _Tp, class _Up>
+concept __same_as_impl = _VSTD::_IsSame<_Tp, _Up>::value;
+
+template<class _Tp, class _Up>
+concept same_as = __same_as_impl<_Tp, _Up> && __same_as_impl<_Up, _Tp>;
+
+#endif //_LIBCPP_STD_VER > 17 && defined(__cpp_concepts) && __cpp_concepts >= 201811L
+
+_LIBCPP_END_NAMESPACE_STD
+
+_LIBCPP_POP_MACROS
+
+#endif // _LIBCPP_CONCEPTS