[libcxx-commits] [libcxx] [libc++] Add the __is_replaceable type trait (PR #132408)

[Louis Dionne via libcxx-commits]

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@@ -0,0 +1,59 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___TYPE_TRAITS_IS_REPLACEABLE_H
+#define _LIBCPP___TYPE_TRAITS_IS_REPLACEABLE_H
+
+#include <__config>
+#include <__type_traits/enable_if.h>
+#include <__type_traits/integral_constant.h>
+#include <__type_traits/is_same.h>
+#include <__type_traits/is_trivially_copyable.h>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
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ldionne wrote:

I think we need to wait for proper compiler support, otherwise this trait will be non-conforming. It will report that some types that should be replaceable per the language rules are actually not in our implementation.

I think we should wait for the trivial relocation papers to settle a little bit before we start vending public names, but nothing stops us from getting started on actually using those concepts inside the library.

https://github.com/llvm/llvm-project/pull/132408