Upgrade to 2022-era LLVM LIBCXX

third_party/libcxx/__memory/construct_at.h

@@ -0,0 +1,130 @@
+// -*- C++ -*-
+//===----------------------------------------------------------------------===//
+//
+// 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___MEMORY_CONSTRUCT_AT_H
+#define _LIBCPP___MEMORY_CONSTRUCT_AT_H
+
+#include <__assert>
+#include <__config>
+#include <__iterator/access.h>
+#include <__memory/addressof.h>
+#include <__memory/voidify.h>
+#include <__type_traits/enable_if.h>
+#include <__type_traits/is_array.h>
+#include <__utility/declval.h>
+#include <__utility/forward.h>
+#include <__utility/move.h>
+#include <new>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// construct_at
+
+#if _LIBCPP_STD_VER >= 20
+
+template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
+_LIBCPP_HIDE_FROM_ABI constexpr _Tp* construct_at(_Tp* __location, _Args&&... __args) {
+  _LIBCPP_ASSERT(__location != nullptr, "null pointer given to construct_at");
+  return ::new (std::__voidify(*__location)) _Tp(std::forward<_Args>(__args)...);
+}
+
+#endif
+
+template <class _Tp, class... _Args, class = decltype(::new(std::declval<void*>()) _Tp(std::declval<_Args>()...))>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR _Tp* __construct_at(_Tp* __location, _Args&&... __args) {
+#if _LIBCPP_STD_VER >= 20
+  return std::construct_at(__location, std::forward<_Args>(__args)...);
+#else
+  return _LIBCPP_ASSERT(__location != nullptr, "null pointer given to construct_at"),
+         ::new (std::__voidify(*__location)) _Tp(std::forward<_Args>(__args)...);
+#endif
+}
+
+// destroy_at
+
+// The internal functions are available regardless of the language version (with the exception of the `__destroy_at`
+// taking an array).
+
+template <class _ForwardIterator>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
+_ForwardIterator __destroy(_ForwardIterator, _ForwardIterator);
+
+template <class _Tp, typename enable_if<!is_array<_Tp>::value, int>::type = 0>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
+void __destroy_at(_Tp* __loc) {
+    _LIBCPP_ASSERT(__loc != nullptr, "null pointer given to destroy_at");
+    __loc->~_Tp();
+}
+
+#if _LIBCPP_STD_VER >= 20
+template <class _Tp, typename enable_if<is_array<_Tp>::value, int>::type = 0>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
+void __destroy_at(_Tp* __loc) {
+    _LIBCPP_ASSERT(__loc != nullptr, "null pointer given to destroy_at");
+    std::__destroy(std::begin(*__loc), std::end(*__loc));
+}
+#endif
+
+template <class _ForwardIterator>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
+_ForwardIterator __destroy(_ForwardIterator __first, _ForwardIterator __last) {
+    for (; __first != __last; ++__first)
+        std::__destroy_at(std::addressof(*__first));
+    return __first;
+}
+
+template <class _BidirectionalIterator>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
+_BidirectionalIterator __reverse_destroy(_BidirectionalIterator __first, _BidirectionalIterator __last) {
+    while (__last != __first) {
+        --__last;
+        std::__destroy_at(std::addressof(*__last));
+    }
+    return __last;
+}
+
+#if _LIBCPP_STD_VER >= 17
+
+template <class _Tp, enable_if_t<!is_array_v<_Tp>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
+void destroy_at(_Tp* __loc) {
+    std::__destroy_at(__loc);
+}
+
+#if _LIBCPP_STD_VER >= 20
+template <class _Tp, enable_if_t<is_array_v<_Tp>, int> = 0>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
+void destroy_at(_Tp* __loc) {
+  std::__destroy_at(__loc);
+}
+#endif
+
+template <class _ForwardIterator>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
+void destroy(_ForwardIterator __first, _ForwardIterator __last) {
+  (void)std::__destroy(std::move(__first), std::move(__last));
+}
+
+template <class _ForwardIterator, class _Size>
+_LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20
+_ForwardIterator destroy_n(_ForwardIterator __first, _Size __n) {
+    for (; __n > 0; (void)++__first, --__n)
+        std::__destroy_at(std::addressof(*__first));
+    return __first;
+}
+
+#endif // _LIBCPP_STD_VER >= 17
+
+_LIBCPP_END_NAMESPACE_STD
+
+#endif // _LIBCPP___MEMORY_CONSTRUCT_AT_H