1 files changed, 54 insertions, 0 deletions
diff --git a/contrib/llvm-project/libcxx/include/__utility/no_destroy.h b/contrib/llvm-project/libcxx/include/__utility/no_destroy.h
new file mode 100644
index 000000000000..8edd194577d7
--- /dev/null
+++ b/contrib/llvm-project/libcxx/include/__utility/no_destroy.h
@@ -0,0 +1,54 @@
+//===----------------------------------------------------------------------===//
+//
+// 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___UTILITY_NO_DESTROY_H
+#define _LIBCPP___UTILITY_NO_DESTROY_H
+
+#include <__config>
+#include <__type_traits/is_constant_evaluated.h>
+#include <__utility/forward.h>
+#include <new>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+struct __uninitialized_tag {};
+
+// This class stores an object of type _Tp but never destroys it.
+//
+// This is akin to using __attribute__((no_destroy)), except that it is possible
+// to control the lifetime of the object with more flexibility by deciding e.g.
+// whether to initialize the object at construction or to defer to a later
+// initialization using __emplace.
+template <class _Tp>
+struct __no_destroy {
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR explicit __no_destroy(__uninitialized_tag) : __obj_() {}
+
+  template <class... _Args>
+  _LIBCPP_HIDE_FROM_ABI explicit __no_destroy(_Args&&... __args) {
+    ::new ((void*)__obj_) _Tp(std::forward<_Args>(__args)...);
+  }
+
+  template <class... _Args>
+  _LIBCPP_HIDE_FROM_ABI _Tp& __emplace(_Args&&... __args) {
+    return *(::new ((void*)__obj_) _Tp(std::forward<_Args>(__args)...));
+  }
+
+  _LIBCPP_HIDE_FROM_ABI _Tp& __get() { return *reinterpret_cast<_Tp*>(__obj_); }
+  _LIBCPP_HIDE_FROM_ABI _Tp const& __get() const { return *reinterpret_cast<const _Tp*>(__obj_); }
+
+private:
+  _ALIGNAS_TYPE(_Tp) char __obj_[sizeof(_Tp)];
+};
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___UTILITY_NO_DESTROY_H