llvm-project/libcxx/docs/ReleaseNotes.rst

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Libc++ 17.0.0 (In-Progress) Release Notes
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Written by the `Libc++ Team <https://libcxx.llvm.org>`_

.. warning::

   These are in-progress notes for the upcoming libc++ 17 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 17.0.0. 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++ 17.0.0?
============================

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

- P1328R1 - ``constexpr type_info::operator==()``

Improvements and New Features
-----------------------------
- ``std::equal`` and ``std::ranges::equal`` are now forwarding to ``std::memcmp`` for integral types and pointers,
  which can lead up to 40x performance improvements.

- ``std::string_view`` now provides iterators that check for out-of-bounds accesses when the safe
  libc++ mode is enabled.

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

- The ``<experimental/coroutine>`` header has been removed in this release. The ``<coroutine>`` header
  has been shipping since LLVM 14, so the Coroutines TS implementation is being removed per our policy
  for removing TSes.

- Several incidental transitive includes have been removed from libc++. Those
  includes are removed based on the language version used. Incidental transitive
  inclusions of the following headers have been removed:

  - C++2b: ``bit``, ``cstring``, ``type_traits``

- The headers ``<experimental/algorithm>`` and ``<experimental/functional>`` have been removed, since all the contents
  have been implemented in namespace ``std`` for at least two releases.

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

- 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.

API Changes
-----------

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

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