[libcxx-commits] [libcxx] [libc++][tuple][utility] P2968R2 Make `std::ignore` a first-class object (PR #97401)

[A. Jiang via libcxx-commits]

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@@ -0,0 +1,35 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___TUPLE_IGNORE_H
+#define _LIBCPP___TUPLE_IGNORE_H
+
+#include <__config>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+#ifndef _LIBCPP_CXX03_LANG
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+struct __ignore_type {
+  template <class _Tp>
+  _LIBCPP_HIDE_FROM_ABI constexpr const __ignore_type& operator=(const _Tp&) const noexcept {
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frederick-vs-ja wrote:

Previously this was `_LIBCPP_CONSTEXPR_SINCE_CXX14`, which was synchonized with `constexpr` additions to `tuple` (via [N3471](https://wg21.link/n3471) in C++14). Not sure further (?) backport of `constexpr` is desired...

https://github.com/llvm/llvm-project/pull/97401