[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.
diff --git a/libcxx/test/std/concepts/lang/same_as.pass.cpp b/libcxx/test/std/concepts/lang/same_as.pass.cpp
new file mode 100644
index 0000000..c41d6c4
--- /dev/null
+++ b/libcxx/test/std/concepts/lang/same_as.pass.cpp
@@ -0,0 +1,295 @@
+//===----------------------------------------------------------------------===//
+//
+// 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++98, c++03, c++11, c++14, c++17
+
+// template<class T, class U>
+// concept same_as;
+
+#include <concepts>
+#include <type_traits>
+
+struct S1 {};
+struct S2 {
+ int i;
+
+ int& f();
+ double g(int x) const;
+};
+struct S3 {
+ int& r;
+};
+struct S4 {
+ int&& r;
+};
+struct S5 {
+ int* p;
+};
+
+class C1 {};
+class C2 {
+ [[maybe_unused]] int i;
+};
+
+class C3 {
+public:
+ int i;
+};
+
+template <class T1, class T2 = T1>
+class C4 {
+ int t1;
+ int t2;
+};
+
+template <class T1, class T2 = T1>
+class C5 {
+ [[maybe_unused]] T1 t1;
+
+public:
+ T2 t2;
+};
+
+template <class T1, class T2 = T1>
+class C6 {
+public:
+ [[maybe_unused]] T1 t1;
+ [[maybe_unused]] T2 t2;
+};
+
+template <class T>
+struct identity {
+ using type = T;
+};
+
+template <template <typename> class Modifier = identity>
+void CheckSameAs() {
+ static_assert(
+ std::same_as<typename Modifier<int>::type, typename Modifier<int>::type>);
+ static_assert(
+ std::same_as<typename Modifier<S1>::type, typename Modifier<S1>::type>);
+ static_assert(
+ std::same_as<typename Modifier<S2>::type, typename Modifier<S2>::type>);
+ static_assert(
+ std::same_as<typename Modifier<S3>::type, typename Modifier<S3>::type>);
+ static_assert(
+ std::same_as<typename Modifier<S4>::type, typename Modifier<S4>::type>);
+ static_assert(
+ std::same_as<typename Modifier<S5>::type, typename Modifier<S5>::type>);
+ static_assert(
+ std::same_as<typename Modifier<C1>::type, typename Modifier<C1>::type>);
+ static_assert(
+ std::same_as<typename Modifier<C2>::type, typename Modifier<C2>::type>);
+ static_assert(
+ std::same_as<typename Modifier<C3>::type, typename Modifier<C3>::type>);
+ static_assert(std::same_as<typename Modifier<C4<int> >::type,
+ typename Modifier<C4<int> >::type>);
+ static_assert(std::same_as<typename Modifier<C4<int&> >::type,
+ typename Modifier<C4<int&> >::type>);
+ static_assert(std::same_as<typename Modifier<C4<int&&> >::type,
+ typename Modifier<C4<int&&> >::type>);
+ static_assert(std::same_as<typename Modifier<C5<int> >::type,
+ typename Modifier<C5<int> >::type>);
+ static_assert(std::same_as<typename Modifier<C5<int&> >::type,
+ typename Modifier<C5<int&> >::type>);
+ static_assert(std::same_as<typename Modifier<C5<int&&> >::type,
+ typename Modifier<C5<int&&> >::type>);
+ static_assert(std::same_as<typename Modifier<C6<int> >::type,
+ typename Modifier<C6<int> >::type>);
+ static_assert(std::same_as<typename Modifier<C6<int&> >::type,
+ typename Modifier<C6<int&> >::type>);
+ static_assert(std::same_as<typename Modifier<C6<int&&> >::type,
+ typename Modifier<C6<int&&> >::type>);
+
+ static_assert(std::same_as<typename Modifier<void>::type,
+ typename Modifier<void>::type>);
+}
+
+template <template <typename> class Modifier1,
+ template <typename> class Modifier2>
+void CheckNotSameAs() {
+ static_assert(!std::same_as<typename Modifier1<int>::type,
+ typename Modifier2<int>::type>);
+ static_assert(!std::same_as<typename Modifier1<S1>::type,
+ typename Modifier2<S1>::type>);
+ static_assert(!std::same_as<typename Modifier1<S2>::type,
+ typename Modifier2<S2>::type>);
+ static_assert(!std::same_as<typename Modifier1<S3>::type,
+ typename Modifier2<S3>::type>);
+ static_assert(!std::same_as<typename Modifier1<S4>::type,
+ typename Modifier2<S4>::type>);
+ static_assert(!std::same_as<typename Modifier1<S5>::type,
+ typename Modifier2<S5>::type>);
+ static_assert(!std::same_as<typename Modifier1<C1>::type,
+ typename Modifier2<C1>::type>);
+ static_assert(!std::same_as<typename Modifier1<C2>::type,
+ typename Modifier2<C2>::type>);
+ static_assert(!std::same_as<typename Modifier1<C3>::type,
+ typename Modifier2<C3>::type>);
+ static_assert(!std::same_as<typename Modifier1<C4<int> >::type,
+ typename Modifier2<C4<int> >::type>);
+ static_assert(!std::same_as<typename Modifier1<C4<int&> >::type,
+ typename Modifier2<C4<int&> >::type>);
+ static_assert(!std::same_as<typename Modifier1<C4<int&&> >::type,
+ typename Modifier2<C4<int&&> >::type>);
+ static_assert(!std::same_as<typename Modifier1<C5<int> >::type,
+ typename Modifier2<C5<int> >::type>);
+ static_assert(!std::same_as<typename Modifier1<C5<int&> >::type,
+ typename Modifier2<C5<int&> >::type>);
+ static_assert(!std::same_as<typename Modifier1<C5<int&&> >::type,
+ typename Modifier2<C5<int&&> >::type>);
+ static_assert(!std::same_as<typename Modifier1<C6<int> >::type,
+ typename Modifier2<C6<int> >::type>);
+ static_assert(!std::same_as<typename Modifier1<C6<int&> >::type,
+ typename Modifier2<C6<int&> >::type>);
+ static_assert(!std::same_as<typename Modifier1<C6<int&&> >::type,
+ typename Modifier2<C6<int&&> >::type>);
+}
+
+// Checks subsumption works as intended
+template <class T, class U>
+requires std::same_as<T, U> void SubsumptionTest();
+
+// clang-format off
+template <class T, class U>
+requires std::same_as<U, T> && true // NOLINT(readability-simplify-boolean-expr)
+int SubsumptionTest();
+// clang-format on
+
+static_assert(std::same_as<int, decltype(SubsumptionTest<int, int>())>);
+static_assert(std::same_as<int, decltype(SubsumptionTest<void, void>())>);
+static_assert(
+ std::same_as<int, decltype(SubsumptionTest<int (*)(), int (*)()>())>);
+static_assert(
+ std::same_as<
+ int, decltype(SubsumptionTest<double (&)(int), double (&)(int)>())>);
+static_assert(
+ std::same_as<int, decltype(SubsumptionTest<int S2::*, int S2::*>())>);
+static_assert(
+ std::same_as<int,
+ decltype(SubsumptionTest<int& (S2::*)(), int& (S2::*)()>())>);
+
+int main(int, char**) {
+ { // Checks std::same_as<T, T> is true
+ CheckSameAs();
+
+ // Checks std::same_as<T&, T&> is true
+ CheckSameAs<std::add_lvalue_reference>();
+
+ // Checks std::same_as<T&&, T&&> is true
+ CheckSameAs<std::add_rvalue_reference>();
+
+ // Checks std::same_as<const T, const T> is true
+ CheckSameAs<std::add_const>();
+
+ // Checks std::same_as<volatile T, volatile T> is true
+ CheckSameAs<std::add_volatile>();
+
+ // Checks std::same_as<const volatile T, const volatile T> is true
+ CheckSameAs<std::add_cv>();
+
+ // Checks std::same_as<T*, T*> is true
+ CheckSameAs<std::add_pointer>();
+
+ // Checks concrete types are identical
+ static_assert(std::same_as<void, void>);
+
+ using Void = void;
+ static_assert(std::same_as<void, Void>);
+
+ static_assert(std::same_as<int[1], int[1]>);
+ static_assert(std::same_as<int[2], int[2]>);
+
+ static_assert(std::same_as<int (*)(), int (*)()>);
+ static_assert(std::same_as<void (&)(), void (&)()>);
+ static_assert(std::same_as<S1& (*)(S1), S1& (*)(S1)>);
+ static_assert(std::same_as<C1& (&)(S1, int), C1& (&)(S1, int)>);
+
+ static_assert(std::same_as<int S2::*, int S2::*>);
+ static_assert(std::same_as<double S2::*, double S2::*>);
+
+ static_assert(std::same_as<int& (S2::*)(), int& (S2::*)()>);
+ static_assert(std::same_as<double& (S2::*)(int), double& (S2::*)(int)>);
+ }
+
+ { // Checks that `T` and `T&` are distinct types
+ CheckNotSameAs<identity, std::add_lvalue_reference>();
+ CheckNotSameAs<std::add_lvalue_reference, identity>();
+
+ // Checks that `T` and `T&&` are distinct types
+ CheckNotSameAs<identity, std::add_rvalue_reference>();
+ CheckNotSameAs<std::add_rvalue_reference, identity>();
+
+ // Checks that `T` and `const T` are distinct types
+ CheckNotSameAs<identity, std::add_const>();
+ CheckNotSameAs<std::add_const, identity>();
+
+ // Checks that `T` and `volatile T` are distinct types
+ CheckNotSameAs<identity, std::add_volatile>();
+ CheckNotSameAs<std::add_volatile, identity>();
+
+ // Checks that `T` and `const volatile T` are distinct types
+ CheckNotSameAs<identity, std::add_cv>();
+ CheckNotSameAs<std::add_cv, identity>();
+
+ // Checks that `const T` and `volatile T` are distinct types
+ CheckNotSameAs<std::add_const, std::add_volatile>();
+ CheckNotSameAs<std::add_volatile, std::add_const>();
+
+ // Checks that `const T` and `const volatile T` are distinct types
+ CheckNotSameAs<std::add_const, std::add_cv>();
+ CheckNotSameAs<std::add_cv, std::add_const>();
+
+ // Checks that `volatile T` and `const volatile T` are distinct types
+ CheckNotSameAs<std::add_volatile, std::add_cv>();
+ CheckNotSameAs<std::add_cv, std::add_volatile>();
+
+ // Checks `T&` and `T&&` are distinct types
+ CheckNotSameAs<std::add_lvalue_reference, std::add_rvalue_reference>();
+ CheckNotSameAs<std::add_rvalue_reference, std::add_lvalue_reference>();
+ }
+
+ { // Checks different type names are distinct types
+ static_assert(!std::same_as<S1, C1>);
+ static_assert(!std::same_as<C4<int>, C5<int> >);
+ static_assert(!std::same_as<C4<int>, C5<int> >);
+ static_assert(!std::same_as<C5<int, double>, C5<double, int> >);
+
+ static_assert(!std::same_as<int&, const int&>);
+ static_assert(!std::same_as<int&, volatile int&>);
+ static_assert(!std::same_as<int&, const volatile int&>);
+
+ static_assert(!std::same_as<int&&, const int&>);
+ static_assert(!std::same_as<int&&, volatile int&>);
+ static_assert(!std::same_as<int&&, const volatile int&>);
+
+ static_assert(!std::same_as<int&, const int&&>);
+ static_assert(!std::same_as<int&, volatile int&&>);
+ static_assert(!std::same_as<int&, const volatile int&&>);
+
+ static_assert(!std::same_as<int&&, const int&&>);
+ static_assert(!std::same_as<int&&, volatile int&&>);
+ static_assert(!std::same_as<int&&, const volatile int&&>);
+
+ static_assert(!std::same_as<void, int>);
+
+ static_assert(!std::same_as<int[1], int[2]>);
+ static_assert(!std::same_as<double[1], int[2]>);
+
+ static_assert(!std::same_as<int* (*)(), const int* (*)()>);
+ static_assert(!std::same_as<void (&)(), void (&)(S1)>);
+ static_assert(!std::same_as<S1 (*)(S1), S1& (*)(S1)>);
+ static_assert(!std::same_as<C3 (&)(int), C1& (&)(S1, int)>);
+
+ static_assert(!std::same_as<int S2::*, double S2::*>);
+
+ static_assert(!std::same_as<int& (S2::*)(), double& (S2::*)(int)>);
+ }
+
+ return 0;
+}