Hui d7a24d30f6
[libc++] Implement ranges::shift_right (#177847)
Implement the `ranges::shift_right` algorithm from
[P2440R1](https://wg21.link/P2440R1).

Fixes #134062
Fixes #105184
2026-02-14 17:34:44 +00:00

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2.8 KiB
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===========================================
Libc++ 23.0.0 (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++ 23.0.0 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 23.0.0. 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++ 23.0.0?
==============================
Implemented Papers
------------------
- P2440R1: ``ranges::iota``, ``ranges::shift_left`` and ``ranges::shift_right`` (`Github <https://llvm.org/PR105184>`__)
Improvements and New Features
-----------------------------
- The ``std::ranges::fold_left_with_iter`` algorithm has been optimized for
segmented iterators, resulting in a performance improvement of up to 1.38x
for ``std::deque<int>`` iterators.
Deprecations and Removals
-------------------------
- The ``std::launch::any`` enumerator that was accidentally provided as an extension is now deprecated.
It will be removed in LLVM 25.
Potentially breaking changes
----------------------------
Announcements About Future Releases
-----------------------------------
ABI Affecting Changes
---------------------
- ``std::allocator`` is trivially default constructible since LLVM 22. The behaviour can be reverted by defining
``_LIBCPP_DEPRECATED_ABI_NON_TRIVIAL_ALLOCATOR``. Please inform the libc++ team if you need this flag, since it will
be removed in LLVM 24 if there is no evidence that it's required.
- ``bitset::operator[]`` returns ``bool`` since LLVM 22, making libc++ conforming. The behaviour can be reverted by
defining ``_LIBCPP_DEPRECATED_ABI_BITSET_CONST_SUBSCRIPT_RETURN_REF``. Please inform the libc++ team if you need this
flag, since it will be removed in LLVM 24 if there is no evidence that it's required.
Build System Changes
--------------------