[libcxx-commits] [libcxx] [llvm] [libc++] Remove `get_temporary_buffer`/`return_temporary_buffer` (PR #100914)

[Louis Dionne via libcxx-commits]

================
@@ -0,0 +1,122 @@
+// -*- 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_SCOPED_TEMPORARY_BUFFER_H
+#define _LIBCPP___MEMORY_SCOPED_TEMPORARY_BUFFER_H
+
+#include <__config>
+#include <__memory/allocator.h>
+#include <__type_traits/is_constant_evaluated.h>
+#include <cstddef>
+#include <new>
+
+#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+#  pragma GCC system_header
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+template <class _Tp>
+struct __temporary_allocation_result {
+  _Tp* __ptr;
+  ptrdiff_t __count;
+};
+
+template <class _Tp>
+class __scoped_temporary_buffer {
+public:
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __scoped_temporary_buffer() _NOEXCEPT
+      : __ptr_(NULL),
+        __count_(0) {}
+
+  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 explicit __scoped_temporary_buffer(ptrdiff_t __count) _NOEXCEPT
+      : __ptr_(NULL),
+        __count_(0) {
+    __try_allocate(__count);
+  }
+
+#if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_TEMPORARY_BUFFER)
----------------
ldionne wrote:

Since this is an internal utility, I would provide this constructor at all times. You could add a comment like `// This constructor is only needed to implement get_temporary_buffer()`, though.

https://github.com/llvm/llvm-project/pull/100914