docs/ReleaseNotes/18.rst

===========================================
Libc++ 18.0.0 (In-Progress) Release Notes
===========================================

.. contents::
   :local:
   :depth: 2

Written by the `Libc++ Team <https://libcxx.llvm.org>`_

.. warning::

   These are in-progress notes for the upcoming libc++ 18.0.0 release.
   Release notes for previous releases can be found on
   `the Download Page <https://releases.llvm.org/download.html>`_.

Introduction
============

This document contains the release notes for the libc++ C++ Standard Library,
part of the LLVM Compiler Infrastructure, release 18.0.0. Here we describe the
status of libc++ in some detail, including major improvements from the previous
release and new feature work. For the general LLVM release notes, see `the LLVM
documentation <https://llvm.org/docs/ReleaseNotes.html>`_. All LLVM releases may
be downloaded from the `LLVM releases web site <https://llvm.org/releases/>`_.

For more information about libc++, please see the `Libc++ Web Site
<https://libcxx.llvm.org>`_ or the `LLVM Web Site <https://llvm.org>`_.

Note that if you are reading this file from a Git checkout or the
main Libc++ web page, this document applies to the *next* release, not
the current one. To see the release notes for a specific release, please
see the `releases page <https://llvm.org/releases/>`_.

What's New in Libc++ 18.0.0?
==============================


Implemented Papers
------------------


Improvements and New Features
-----------------------------


Deprecations and Removals
-------------------------


Upcoming Deprecations and Removals
----------------------------------

LLVM 18
~~~~~~~

- The base template for ``std::char_traits`` has been marked as deprecated and
  will be removed in LLVM 18. If you are using ``std::char_traits`` with types
  other than ``char``, ``wchar_t``, ``char8_t``, ``char16_t``, ``char32_t`` or
  a custom character type for which you specialized ``std::char_traits``, your code
  will stop working when we remove the base template. The Standard does not
  mandate that a base template is provided, and such a base template is bound
  to be incorrect for some types, which could currently cause unexpected
  behavior while going undetected.

- The ``_LIBCPP_AVAILABILITY_CUSTOM_VERBOSE_ABORT_PROVIDED`` macro will not be honored anymore in LLVM 18.
  Please see the updated documentation about the safe libc++ mode and in particular the ``_LIBCPP_VERBOSE_ABORT``
  macro for details.

- The headers ``<experimental/deque>``, ``<experimental/forward_list>``, ``<experimental/list>``,
  ``<experimental/map>``, ``<experimental/memory_resource>``, ``<experimental/regex>``, ``<experimental/set>``,
  ``<experimental/string>``, ``<experimental/unordered_map>``, ``<experimental/unordered_set>``,
  and ``<experimental/vector>`` will be removed in LLVM 18, as all their contents will have been implemented in
  namespace ``std`` for at least two releases.

ABI Affecting Changes
---------------------


Build System Changes
--------------------