[libcxx-commits] [libcxx] [libc++][test] Add backported `destroy({_at, _n})` for tests (PR #199185)

[A. Jiang via libcxx-commits]

https://github.com/frederick-vs-ja created https://github.com/llvm/llvm-project/pull/199185

It would be convenient to use `destroy_at`, `destroy`, and `destroy_n` in tests for pre-C++17 uninitialized memory algorithms. So this PR add backported versions of them for tests.

>From d519e62b182a87e9917131e0e01655cb81b65487 Mon Sep 17 00:00:00 2001
From: "A. Jiang" <de34 at live.cn>
Date: Fri, 22 May 2026 16:33:29 +0800
Subject: [PATCH] [libc++][test] Add backported `destroy({_at,_n})` for tests

It would be convenient to use `destroy_at`, `destroy`, and `destroy_n`
in tests for pre-C++17 uninitialized memory algorithms. So this PR add
backported versions of them for tests.
---
 .../memory/specialized.algorithms/destroy.h   | 47 +++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 libcxx/test/std/utilities/memory/specialized.algorithms/destroy.h

diff --git a/libcxx/test/std/utilities/memory/specialized.algorithms/destroy.h b/libcxx/test/std/utilities/memory/specialized.algorithms/destroy.h
new file mode 100644
index 0000000000000..e6af0008757c6
--- /dev/null
+++ b/libcxx/test/std/utilities/memory/specialized.algorithms/destroy.h
@@ -0,0 +1,47 @@
+// -*- 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_TEST_STD_UTILITIES_MEMORY_SPECIALIZED_ALGORITHMS_DESTROY_H
+#define LIBCPP_TEST_STD_UTILITIES_MEMORY_SPECIALIZED_ALGORITHMS_DESTROY_H
+
+#include <cstddef>
+#include <memory>
+#include <type_traits>
+
+#include "test_macros.h"
+
+namespace backport {
+
+template <class T, typename std::enable_if<!std::is_array<T>::value, int>::type = 0>
+TEST_CONSTEXPR_CXX20 void destroy_at(T* p) {
+  p->~T();
+}
+template <class T, typename std::enable_if<std::is_array<T>::value, int>::type = 0>
+TEST_CONSTEXPR_CXX20 void destroy_at(T* p) {
+  static_assert(std::extent<T>::value > 0, "must destroy a bounded array");
+  for (std::size_t i = 0; i != std::extent<T>::value; ++i)
+    backport::destroy_at(i + *p);
+}
+
+template <class Iterator>
+TEST_CONSTEXPR_CXX20 void destroy(Iterator first, Iterator last) {
+  for (; first != last; ++first)
+    backport::destroy_at(std::addressof(*first));
+}
+
+template <class Iterator, class Size>
+TEST_CONSTEXPR_CXX20 Iterator destroy_n(Iterator first, Size n) {
+  for (; n > 0; ++first, (void)--n)
+    backport::destroy_at(std::addressof(*first));
+  return first;
+}
+
+} // namespace backport
+
+#endif // LIBCPP_TEST_STD_UTILITIES_MEMORY_SPECIALIZED_ALGORITHMS_DESTROY_H