[libcxx-commits] [libcxx] [libc++][type_traits] P2674R1: A trait for implicit lifetime types (PR #106870)

[Nikolas Klauser via libcxx-commits]

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@@ -0,0 +1,32 @@
+//===----------------------------------------------------------------------===//
+//
+// 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
+
+// These compilers don't support __builtin_is_implicit_lifetime yet.
+// UNSUPPORTED: clang-17, clang-18, clang-19, gcc-14, apple-clang-15, apple-clang-16
+
+// <type_traits>
+
+// template<class T> struct is_implicit_lifetime;
+
+#include <type_traits>
+
+struct IncompleteStruct;
+
+// expected-error@*:* {{incomplete type 'IncompleteStruct' used in type trait expression}}
+static_assert(!std::is_implicit_lifetime<IncompleteStruct>::value);
+
+// expected-error@*:* {{incomplete type 'IncompleteStruct' used in type trait expression}}
+static_assert(!std::is_implicit_lifetime_v<IncompleteStruct>);
+
+// expected-error@*:* {{atomic types are not supported in '__builtin_is_implicit_lifetime'}}
+static_assert(!std::is_implicit_lifetime<_Atomic int>::value);
+
+// expected-error@*:* {{atomic types are not supported in '__builtin_is_implicit_lifetime'}}
+static_assert(!std::is_implicit_lifetime_v<_Atomic int>);
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philnik777 wrote:

We don't have any support for `_Atomic` AFAIK. It would be good to check what happens with `std::atomic` though.

https://github.com/llvm/llvm-project/pull/106870