[libcxx-commits] [libcxx] [libc++] Remove old release notes (PR #234169)
Nikolas Klauser via libcxx-commits
libcxx-commits at lists.llvm.org
Wed Oct 21 04:51:07 PDT 2026
https://github.com/philnik777 created https://github.com/llvm/llvm-project/pull/234169
The current release is 23, so we don't need any earlier release notes anymore. There is nothing to back-port that could benefit from them.
>From 889ac00d897c6363c3c2ff47f0746705990cca90 Mon Sep 17 00:00:00 2001
From: Nikolas Klauser <nikolasklauser at berlin.de>
Date: Wed, 21 Oct 2026 13:50:17 +0200
Subject: [PATCH] [libc++] Remove old release notes
---
libcxx/docs/ReleaseNotes/20.rst | 217 --------------------------------
libcxx/docs/ReleaseNotes/21.rst | 169 -------------------------
libcxx/docs/ReleaseNotes/22.rst | 158 -----------------------
3 files changed, 544 deletions(-)
delete mode 100644 libcxx/docs/ReleaseNotes/20.rst
delete mode 100644 libcxx/docs/ReleaseNotes/21.rst
delete mode 100644 libcxx/docs/ReleaseNotes/22.rst
diff --git a/libcxx/docs/ReleaseNotes/20.rst b/libcxx/docs/ReleaseNotes/20.rst
deleted file mode 100644
index 541d8048b1cd2..0000000000000
--- a/libcxx/docs/ReleaseNotes/20.rst
+++ /dev/null
@@ -1,217 +0,0 @@
-===========================================
-Libc++ 20.0.0 (In-Progress) Release Notes
-===========================================
-
-.. contents::
- :local:
- :depth: 2
-
-Written by the :doc:`Libc++ Team </index>`
-
-.. warning::
-
- These are in-progress notes for the upcoming libc++ 20.0.0 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 20.0.0. 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 :doc:`Libc++ Web Site
-</index>` 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++ 20.0.0?
-==============================
-
-The main focus of the libc++ team has been to implement new C++20, C++23, and C++26 features.
-
-Implemented Papers
-------------------
-
-- P0619R4: Reviewing Deprecated Facilities of C++17 for C++20 (`Github <https://github.com/llvm/llvm-project/issues/99985>`__)
-- P2747R2: ``constexpr`` placement new (`Github <https://github.com/llvm/llvm-project/issues/105427>`__)
-- P2609R3: Relaxing Ranges Just A Smidge (`Github <https://github.com/llvm/llvm-project/issues/105253>`__)
-- P2985R0: A type trait for detecting virtual base classes (`Github <https://github.com/llvm/llvm-project/issues/105432>`__)
-- ``std::jthread`` and ``<stop_token>`` are not guarded behind ``-fexperimental-library`` anymore
-- P2674R1: A trait for implicit lifetime types (`Github <https://github.com/llvm/llvm-project/issues/105259>`__)
-- P0429R9: A Standard ``flat_map`` (`Github <https://github.com/llvm/llvm-project/issues/105190>`__)
-
-Improvements and New Features
------------------------------
-
-- The ``lexicographical_compare`` and ``ranges::lexicographical_compare`` algorithms have been optimized for trivially
- equality comparable types, resulting in a performance improvement of up to 40x.
-
-- The ``_LIBCPP_ENABLE_CXX20_REMOVED_TEMPORARY_BUFFER`` macro has been added to make ``std::get_temporary_buffer`` and
- ``std::return_temporary_buffer`` available.
-
-- The ``std::uncaught_exception`` function was marked as deprecated since C++17 and removed since C++20. The
- ``_LIBCPP_ENABLE_CXX20_REMOVED_UNCAUGHT_EXCEPTION`` macro has been added to make ``std::uncaught_exception``
- available in C++20 and later modes.
-
-- The internal structure ``__compressed_pair`` has been replaced with ``[[no_unique_address]]``, resulting in reduced
- compile times and smaller debug information as well as better code generation if optimizations are disabled.
- The Chromium project measured a 5% reduction in object file and debug information size.
-
-- The ``_LIBCPP_ABI_BOUNDED_UNIQUE_PTR`` ABI configuration was added, which allows ``std::unique_ptr<T[]>`` to
- detect out-of-bounds accesses in certain circumstances. ``std::unique_ptr<T[]>`` can now also detect out-of-bounds
- accesses for a limited set of types (non-trivially destructible types) when the ABI configuration is disabled.
-
-- The ``_LIBCPP_ABI_BOUNDED_ITERATORS_IN_STD_ARRAY`` ABI configuration was added, which allows storing valid bounds
- in ``std::array::iterator`` and detecting OOB accesses when the appropriate hardening mode is enabled.
-
-- The ``input_iterator``-pair overload of ``void assign(InputIt, InputIt)`` has been optimized for ``std::vector``,
- resulting in a performance improvement of up to 2x for trivial element types (e.g., ``std::vector<int>``), and up
- to 3.4x for non-trivial element types (e.g., ``std::vector<std::vector<int>>``).
-
-- The ``input_iterator``-pair overload of ``iterator insert(const_iterator, InputIt, InputIt)`` has been optimized
- for ``std::vector``, resulting in a performance improvement of up to 10x for ``std::vector<int>``, and up to 2.3x
- for ``std::vector<std::vector<int>>``.
-
-- On Windows, ``<system_error>``'s ``std::system_category`` is now distinct from ``std::generic_category``. The behavior
- on other operating systems is unchanged.
-
- On Windows -- unlike on Unix systems -- the libc and system APIs use distinct error codes. The libc functions return
- ``errno.h`` error codes via the ``errno`` global, while Win32 API functions return ``winerror.h`` error codes via
- ``GetLastError()``.
-
- The C++ standard's ``std::error_code`` and ``std::error_category`` functionality was designed to support multiple
- error domains, precisely in order to handle situations such as this. However, libc++ formerly treated
- ``generic_category()`` and ``system_category()`` as equivalent, even on Windows. It now implements the intended split,
- where ``system_category`` represents native ``winerror.h`` error codes, and ``generic_category`` represents libc error
- codes (and, equivalently, ``std::errc::*`` errors).
-
- This change enables code like ``std::error_code(GetLastError(), std::system_category()) ==
- std::errc::invalid_argument`` to function as desired: constructing an ``error_code`` with the Windows error number in
- the "system" category, and then mapping it to a generic code with ``error_condition``, for comparison with the
- ``std::errc`` constant.
-
- This is an incompatible change: ``std::error_code(ENOSYS, std::system_category()) ==
- std::errc::function_not_supported`` would formerly have returned true, but now returns false on Windows. Code
- providing a number from the ``errno.h`` domain should be migrated to construct a ``generic_category`` error_code,
- instead. (E.g., use ``std::error_code(ENOSYS, std::generic_category())``). The new behavior matches MSVC.
-
-- On Windows, the ``std::filesystem`` library now returns the Win32 ``system_category`` error codes, where it's feasible
- to do so. This allows interrogation and reporting of the original error code, which is useful if multiple Windows
- errors map to a single generic error (such as with ``std::errc::no_such_file_or_directory``).
-
- This is also a slightly-incompatible API change: code inspecting the raw integer value from the returned error_code
- expecting an integer from ``generic_category`` (e.g. ``err.value() == ENOTDIR``) will not work as desired. Instead,
- such code should use the comparison operators which implicitly handle eror mappings, ``err ==
- std::errc::not_a_directory``, or use ``err.default_error_condition()`` to map to an ``error_condition``, and then test
- its ``value()`` and ``category()``.
-
-- ``std::stable_sort`` uses radix sort for integral types now, which can improve the performance up to 10 times, depending
- on type of sorted elements and the initial state of the sorted array.
-
-- Reduced the amount of debug information generated for internal typedefs. This reduces the size of debug builds.
-
-- Added :ref:`hardening mode <hardening>` support for ``forward_list`` and ``bitset``.
-
-- The performance of ``std::getline`` has been improved, resulting in a performance uplift of up to 10x.
-
-Deprecations and Removals
--------------------------
-
-- The ``LIBCXX_ENABLE_ASSERTIONS`` CMake variable and the ``_LIBCPP_ENABLE_ASSERTIONS`` macro that were used to
- enable the safe mode have been removed in LLVM 20. Please use :ref:`support for hardening <using-hardening-modes>`
- instead.
-
-- Support for the C++20 synchronization library (``<barrier>``, ``<latch>``, ``atomic::wait``, etc.) has been
- removed in language modes prior to C++20. If you are using these features prior to C++20, you will need to
- update to ``-std=c++20``.
-
-- The relational operators for ``std::chrono::weekday`` has been removed entirely, and the
- ``_LIBCPP_ENABLE_REMOVED_WEEKDAY_RELATIONAL_OPERATORS`` macro is now ignored.
-
-- The ``_LIBCPP_ENABLE_REMOVED_ALLOCATOR_CONST`` macro no longer has any effect. ``std::allocator<const T>`` is not
- supported as an extension anymore, please migrate any code that uses e.g. ``std::vector<const T>`` to be
- standards conforming.
-
-- Non-conforming member typedefs ``base``, ``iterator``, ``const_iterator``, ``size_type``, ``difference_type``, and
- ``const_reference`` of ``std::bitset``, and member typedef ``base`` of ``std::forward_list`` and ``std::list`` are
- removed. Previously, these member typedefs (except ``const_reference``) were private but could cause ambiguity in name
- lookup. Code that expects such ambiguity will possibly not compile in LLVM 20.
-
-- The function ``__libcpp_verbose_abort()`` is now ``noexcept``, to match ``std::terminate()``. (The combination of
- ``noexcept`` and ``[[noreturn]]`` has special significance for function effects analysis.) For backwards compatibility,
- the ``_LIBCPP_VERBOSE_ABORT_NOT_NOEXCEPT`` macro can be defined to make the function non-``noexcept``. That macro
- will be removed in LLVM 21.
-
-- ``<ccomplex>``, ``<cstdalign>`` (previously missing), ``<cstdbool>``, and ``<ctgmath>`` are deprecated since C++17 as
- specified by the standard. They, together with ``<ciso646>``, are removed in C++20, but libc++ still provides these
- headers as an extension and only deprecates them. The ``_LIBCPP_DISABLE_DEPRECATION_WARNINGS`` macro can be defined to
- suppress deprecation for these headers.
-
-- The pointer safety functions ``declare_reachable``, ``declare_no_pointers``, ``undeclare_no_pointers`` and
- ``__undeclare_reachable`` have been removed from the library. These functions were never implemented in a non-trivial
- way, making it very unlikely that any binary depends on them.
-
-- Non-conforming extension ``packaged_task::result_type`` is deprecated. It will be removed in LLVM 21.
-
-- The changes for ``ranges::zip_view`` from `P2165R4 <https://wg21.link/P2165R4>`_ have been implemented. This can
- lead to code assuming that ``zip_view`` produces ``std::pair`` to stop compiling now that it produces ``std::tuple``.
- The cases are rare since ``tuple`` and ``pair`` are compatible for the most part, but this can lead to code that
- was previously accepted now being rejected. This is necessary for libc++ to be conforming, so we don't provide any
- way to opt-out of that behavior.
-
-Upcoming Deprecations and Removals
-----------------------------------
-
-LLVM 21
-~~~~~~~
-
-- The status of the C++03 implementation will be frozen after the LLVM 21 release. This means that starting in LLVM 22,
- non-critical bug fixes may not be back-ported to C++03, including LWG issues. C++03 is a legacy platform, where most
- projects are no longer actively maintained. To reduce the amount of fixes required to keep such legacy projects
- compiling with up-to-date toolchains, libc++ will aim to freeze the status of the headers in C++03 mode to avoid
- unintended breaking changes. See https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc for more details.
-
- If you are using C++03 in your project, you should consider moving to a newer version of the Standard to get the most
- out of libc++.
-
-- The ``_LIBCPP_VERBOSE_ABORT_NOT_NOEXCEPT`` macro will be removed in LLVM 21, making ``std::__libcpp_verbose_abort``
- unconditionally ``noexcept``.
-
-- Non-conforming extension ``packaged_task::result_type`` will be removed in LLVM 21.
-
-
-ABI Affecting Changes
----------------------
-
-- The ABI breaks for removing undefined behaviour in ``std::forward_list``, ``std::list``, ``std::map``, ``std::set``,
- ``std::multimap``, ``std::multiset``, ``std::unordered_map``, ``std::unordered_set``, ``std::unordered_multimap`` and
- ``std::unordered_multiset`` are now applied unconditionally. This only affects fancy pointers which have a different
- value representation when pointing at the base of an internal node type instead of the type itself. A size or
- alignment difference is diagnosed, but more subtle ABI breaks may result in unexpected behaviour.
-
-- The internal structure ``__compressed_pair`` has been replaced with ``[[no_unique_address]]``. The ABI impact is:
-
- - When using the Itanium ABI (most non-MSVC platforms), empty types are now placed at the beginning of the enclosing
- object instead of where the beginning of the ``__compressed_pair`` subobject was. This is only observable by
- checking the address of the empty allocator, equality comparator or hasher.
- - Additionally, using an overaligned empty type as an allocator, comparator or hasher in the associative containers
- (and only those containers) may result in the container's object object size and data layout changing beyond only
- the address of the empty member.
- - When using the MSVC ABI, this change results in some classes having a completely different memory layout, so this is
- a genuine ABI break. However, the library does not currently guarantee ABI stability on MSVC platforms.
-
-- The localization support base API has been reimplemented, leading to different functions being exported from the
- libc++ built library on Windows and Windows-like platforms.
-
-- The changes for ``ranges::zip_view`` from `P2165R4 <https://wg21.link/P2165R4>`_ have been implemented. This changes
- the element type of ``zip_view`` from a ``std::pair`` to a ``std::tuple`` in some cases. This is technically an ABI
- break, however since ``zip_view`` is generally not an ABI sensitive type, we don't expect users to encounter any
- issues and we don't provide a way to change this behavior, which would make libc++ non-conforming.
diff --git a/libcxx/docs/ReleaseNotes/21.rst b/libcxx/docs/ReleaseNotes/21.rst
deleted file mode 100644
index 716971e546982..0000000000000
--- a/libcxx/docs/ReleaseNotes/21.rst
+++ /dev/null
@@ -1,169 +0,0 @@
-===========================================
-Libc++ 21.0.0 (In-Progress) Release Notes
-===========================================
-
-.. contents::
- :local:
- :depth: 2
-
-Written by the :doc:`Libc++ Team </index>`
-
-.. warning::
-
- These are in-progress notes for the upcoming libc++ 21.0.0 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 21.0.0. 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 :doc:`Libc++ Web Site
-</index>` 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++ 21.0.0?
-==============================
-
-Implemented Papers
-------------------
-
-- N4258: Cleaning-up noexcept in the Library (`Github <https://github.com/llvm/llvm-project/issues/99937>`__)
-- P0767R1: Deprecate POD (`Github <https://github.com/llvm/llvm-project/issues/104013>`__)
-- P1361R2: Integration of chrono with text formatting (`Github <https://github.com/llvm/llvm-project/issues/100014>`__)
-- P2255R2: A type trait to detect reference binding to temporary (implemented the type traits only) (`Github <https://github.com/llvm/llvm-project/issues/105180>`__)
-- P2372R3: Fixing locale handling in chrono formatters (`Github <https://github.com/llvm/llvm-project/issues/100043>`__)
-- P2562R1: ``constexpr`` Stable Sorting (`Github <https://github.com/llvm/llvm-project/issues/105360>`__)
-- P0472R3: Put std::monostate in <utility> (`Github <https://github.com/llvm/llvm-project/issues/127874>`__)
-- P1222R4: A Standard ``flat_set`` (`Github <https://github.com/llvm/llvm-project/issues/105193>`__)
-- P2897R7: ``aligned_accessor``: An mdspan accessor expressing pointer over-alignment (`Github <https://github.com/llvm/llvm-project/issues/118372>`__)
-- P3247R2: Deprecate the notion of trivial types (`Github <https://github.com/llvm/llvm-project/issues/118387>`__)
-- P3372R3: ``constexpr`` containers and adaptors (`Github <https://github.com/llvm/llvm-project/issues/127876>`__) (``forward_list``, ``list``, ``priority_queue``, ``flat_map``, and ``flat_set`` are implemented)
-- P2441R2: ``views::join_with`` (`Github <https://github.com/llvm/llvm-project/issues/105185>`__)
-- P2711R1: Making multi-param constructors of ``views`` ``explicit`` (`Github <https://github.com/llvm/llvm-project/issues/105252>`__)
-- P2770R0: Stashing stashing ``iterators`` for proper flattening (`Github <https://github.com/llvm/llvm-project/issues/105250>`__)
-- P2655R3: ``common_reference_t`` of ``reference_wrapper`` Should Be a Reference Type (`Github <https://github.com/llvm/llvm-project/issues/105260>`__)
-- P3379R0: Constrain ``std::expected`` equality operators (`Github <https://github.com/llvm/llvm-project/issues/118135>`__)
-
-Improvements and New Features
------------------------------
-
-- The ``std::ranges::{copy, copy_n, copy_backward, move, move_backward, rotate}`` algorithms have been optimized for
- ``std::vector<bool>::iterator``, resulting in a performance improvement of up to 2000x.
-
-- The ``std::ranges::equal`` algorithm has been optimized for ``std::vector<bool>::iterator``, resulting in a performance
- improvement of up to 188x.
-
-- The ``std::ranges::swap_ranges`` algorithm has been optimized for ``std::vector<bool>::iterator``, resulting in a
- performance improvement of up to 611x.
-
-- Updated formatting library to Unicode 16.0.0.
-
-- The ``num_put::do_put`` integral overloads have been optimized, resulting in a performance improvement of up to 2.4x.
-
-- The ``std::stable_sort`` algorithm uses radix sort for floating-point types now, which can improve the performance
- up to 10x, depending on type of sorted elements and the initial state of the sorted array.
-
-- The segmented iterator optimization for ``std::for_each`` has been backported to C++11. Previously it was only available
- in C++23 and later.
-
-- The ``std::for_each_n``, ``std::ranges::for_each`` and ``std::ranges::for_each_n`` algorithms have been optimized for
- segmented iterators, resulting in a performance improvement of up to 17.7x for ``std::deque<short>`` iterators, and up
- to 13.9x for ``std::join_view<vector<vector<short>>>`` iterators.
-
-- The ``bitset::to_string`` function has been optimized, resulting in a performance improvement of up to 8.3x for bitsets
- with uniformly distributed zeros and ones, and up to 13.5x and 16.1x for sparse and dense bitsets, respectively.
-
-- The ``flat_map::insert`` and ``flat_set::insert_range`` have been optimized, resulting in a performance improvement of up
- to 10x for inserting elements into a ``flat_map`` when the input range is a ``flat_map`` or a ``zip_view``.
-
-- ``ctype::tolower`` and ``ctype::toupper`` have been optimized, resulting in a 2x performance improvement.
-
-- As an experimental feature, Hardening now supports assertion semantics that allow customizing how a hardening
- assertion failure is handled. The four available semantics, modeled on C++26 Contracts, are ``ignore``, ``observe``,
- ``quick-enforce`` and ``enforce``. The ``observe`` semantic is intended to make it easier to adopt Hardening in
- production but should not be used outside of this scenario. Please refer to the :ref:`Hardening documentation
- <hardening>` for details.
-
-Deprecations and Removals
--------------------------
-
-- ``std::is_pod`` and ``std::is_pod_v`` are deprecated in C++20 and later.
-
-- ``std::is_trivial`` and ``std::is_trivial_v`` are deprecated in C++26 and later.
-
-- The ``_LIBCPP_VERBOSE_ABORT_NOT_NOEXCEPT`` has been removed, making ``std::__libcpp_verbose_abort``
- unconditionally ``noexcept``.
-
-- libc++ no longer adds ``constexpr`` to ``std::hash<std::vector<bool, A>>::operator()``, as the ``constexpr`` addition
- since C++20 was an unintended extension.
-
-- The non-conforming extension ``packaged_task::result_type`` has been removed in LLVM 21.
-
-Potentially breaking changes
-----------------------------
-
-- The implementation of ``num_put::do_put`` has been replaced to improve the performance, which can lead to different
- output when printing pointers.
-
-- User-defined specializations of ``std::common_reference`` are diagnosed now. To customize the common reference type, ``std::basic_common_reference`` should be specialized instead.
-
-- ``std::function`` used to have allocator support, which was removed from the Standard by `http://wg21.link/p0302r1`
- due to issues with its design and inconsistent support from implementations. Previously, libc++ would provide
- allocator-aware APIs in ``std::function`` in C++11 and C++14, but ignores the allocator argument in all places but
- one. Starting in this release, the allocator argument is always ignored.
-
-Announcements About Future Releases
------------------------------------
-
-LLVM 22
-~~~~~~~
-
-- The status of the C++03 implementation will be frozen after the LLVM 21 release. This means that starting in LLVM 22,
- non-critical bug fixes may not be back-ported to C++03, including LWG issues. C++03 is a legacy platform, where most
- projects are no longer actively maintained. To reduce the amount of fixes required to keep such legacy projects
- compiling with up-to-date toolchains, libc++ will aim to freeze the status of the headers in C++03 mode to avoid
- unintended breaking changes. See https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc for more details.
-
- If you are using C++03 in your project, you should consider moving to a newer version of the Standard to get the most
- out of libc++.
-
-
-ABI Affecting Changes
----------------------
-
-- When using GCC, the ``std`` namespace is now annotated with ``[[gnu::visibility("default")]]``. This may cause more
- symbols to be exported from shared libraries when building with ``-fvisibility=hidden``. This also fixes RTTI
- comparison between shared libraries, since all RTTI has the correct visibility now. There is no behaviour change on
- Clang.
-
-- LLVM 20 contained an ABI break that can result in the size of ``std::unordered_{map,set,multimap,multiset}`` and ``std::deque`` changing when used with an allocator type that is empty and contains a base class that is the same across rebound allocator instantiations (e.g. ``Allocator<int>`` and ``Allocator<char>`` are both empty and contain the same base class).
- In addition, the layout of a user-defined type that:
-
- - contains one of the following containers: ``std::unordered_{map,set,multimap,multiset}``, ``std::deque``, ``std::map``, ``std::set``, ``std::multimap``, ``std::multiset``, ``std::list`` or ``std::vector``, and
- - passes an empty allocator, comparator or hasher type to that container, and
- - has a member of that same empty allocator, comparator or hasher type inside the enclosing struct, and
- - that member is either marked with ``[[no_unique_address]]`` or optimized out via the EBO (empty base optimization) technique
-
- saw its size increase from LLVM 19 to LLVM 20. This was caused by the usage of ``[[no_unique_address]]`` within some of libc++'s containers in a way that allowed subtle interactions with enclosing objects. This is fixed in LLVM 21 when using the Clang compiler (returning to the LLVM 19 ABI), however that implies an ABI break from LLVM 20 to LLVM 21.
-
- Furthermore, fixing this causes a slight regression to constant evaluation support in ``std::unique_ptr``. Specifically, constant evaluation will now fail when the deleter relies on being value-initialized for constant-evaluation admissibility. If a default-initialized deleter can be used during constant evaluation, or if the default constructor is non-trivial, the ``unique_ptr`` is not affected by this regression. In particular, this regression does not impact any ``unique_ptr`` using the default deleter.
-
- Note that there is currently no way to realistically fix this ABI break on GCC, therefore GCC will remain on the ABI introduced in LLVM 19. That also means that Clang and GCC will have a slightly different ABI for the small subset of types listed above until we are able to apply the same fix we did with Clang on GCC.
-
- For more details see https://llvm.org/PR154146.
-
-Build System Changes
---------------------
-
-- TODO
diff --git a/libcxx/docs/ReleaseNotes/22.rst b/libcxx/docs/ReleaseNotes/22.rst
deleted file mode 100644
index 9b1b91acca187..0000000000000
--- a/libcxx/docs/ReleaseNotes/22.rst
+++ /dev/null
@@ -1,158 +0,0 @@
-===========================================
-Libc++ 22.0.0 (In-Progress) Release Notes
-===========================================
-
-.. contents::
- :local:
- :depth: 2
-
-Written by the :doc:`Libc++ Team </index>`
-
-.. warning::
-
- These are in-progress notes for the upcoming libc++ 22.0.0 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 22.0.0. 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 :doc:`Libc++ Web Site
-</index>` 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++ 22.0.0?
-==============================
-
-Implemented Papers
-------------------
-
-- P2592R3: Hashing support for ``std::chrono`` value classes (`Github <https://llvm.org/PR105358>`__)
-- P2321R2: ``zip`` (`Github <https://llvm.org/PR105169>`__)
-- P2988R12: ``std::optional<T&>`` (`Github <https://llvm.org/PR148131>`__)
-- P3044R2: sub-``string_view`` from ``string`` (`Github <https://llvm.org/PR148140>`__)
-- P3223R2: Making ``std::istream::ignore`` less surprising (`Github <https://llvm.org/PR148178>`__)
-- P3060R3: Add ``std::views::indices(n)`` (`Github <https://llvm.org/PR148175>`__)
-- P2404R3: Move-only types for ``equality_comparable_with``, ``totally_ordered_with``, and ``three_way_comparable_with``
- (`Github <https://llvm.org/PR105210>`__)
-- P2641R4: Checking if a ``union`` alternative is active (``std::is_within_lifetime``)
- (`Github <https://llvm.org/PR105381>`__)
-- P2835R7: Expose ``std::atomic_ref``'s object address (`Github <https://llvm.org/PR118377>`__)
-- P2944R3: Comparisons for ``reference_wrapper`` (`Github <https://llvm.org/PR105424>`__)
-- P3168R2: Give ``std::optional`` Range Support
- (guarded by ``-fexperimental-library``, `Github <https://llvm.org/PR105430>`__)
-- P3567R2: ``flat_meow`` Fixes (`Github <https://llvm.org/PR162022>`__)
-- P3836R2: Make ``optional<T&>`` trivially copyable (`Github <https://llvm.org/PR171275>`__)
-- P1789R3: Library Support for Expansion Statements (`Github <https://llvm.org/PR167184>`__)
-
-Improvements and New Features
------------------------------
-
-- The performance of associative and unordered containers has been significantly improved. This is an overview of the
- different functions and by up to how much they have been improved:
-
- - ``map::map(const map&)``: 2.3x
- - ``map::operator=(const map&)``: 11x
- - ``unordered_set::unordered_set(const unordered_set&)``: 3.3x
- - ``unordered_set::operator=(const unordered_set&)``: 5x
- - ``erase`` of ``map`` and ``set``: 2x
- - ``find(key)`` of ``map``, ``set``, ``multimap`` and ``multiset``: 2.3x
- - ``(iterator, iterator)`` constructors of ``map``, ``set``, ``multimap`` and ``multiset``: 3x
- - ``insert(iterator, iterator)`` of ``map``, ``set``, ``multimap`` and ``multiset``: 2.5x
- - ``erase(iterator, iterator)`` of the unordered containers: 1.9x
- - ``map::insert_or_assign``: 2x
-
-- The performance of many algorithms has been improved. This is an overview of the different functions and by up to how
- much they have been improved:
-
- - ``std::find`` for integral types: 2x
- - ``std::for_each`` and ``ranges::for_each`` over the associative containers: 2x
- - ``std::rotate``: 3x
- - Some have been specifically optimized for segmented iterators:
-
- - ``std::distance`` and ``std::ranges::distance`` on non-random-access iterators: 1600x
- - ``{std,ranges}::{fill, fill_n}``: 10x
- - ``std::{generate, generate_n}`` and ``std::ranges::generate_n``: 1.8x
-
- - ``std::search_n`` for random access iterators now tries to skip elements.
- In contrived cases improvements of 70,000x have been observed.
-
-- There have also been performance improvements in other library facilities:
-
- - ``vector<bool>::reserve()``: 2x
- - ``deque::append_range``: 3.4x
- - ``num_get::do_get`` integral overloads: 2.8x
- - Some reallocations are now avoided in ``std::filesystem::path::lexically_relative``: 1.7x
- - ``ofstream::write`` passes large strings to system calls directly instead of copying them in chunks into a buffer
- - ``std::align`` is now an inline function, which allows the compiler to better optimize calls to it
-
-- ``std::atomic::wait`` has been refactored to accept more types to use platform native wait functions directly.
- This is guarded behind the ABI Macro ``_LIBCPP_ABI_ATOMIC_WAIT_NATIVE_BY_SIZE``.
-
-- Multiple internal types have been refactored to use ``[[no_unique_address]]``, resulting in faster compile times and
- reduced debug information.
-
-Deprecations and Removals
--------------------------
-
-- The minimally supported deployment target on macOS has been increased to 11.0.
-
-Potentially breaking changes
-----------------------------
-
-- The algorithm for ``multi{map,set}::find`` has been modified such that it doesn't necessarily return an iterator to
- the first equal element in the container. This was never guaranteed by the Standard, but libc++ previously happened to
- always return the first equal element, like other implementations do. Starting with this release, code relying on the
- first element being returned from ``find`` will be broken, and ``lower_bound`` or ``equal_range`` should be used
- instead.
-
-- The algorithms for ``std::{map,set}`` ``lower_bound`` and ``upper_bound`` operations were modified such that their
- result changed for comparators that are not a strict weak order. Being a strict weak order was always a requirement
- of the Standard and still is, however in this release libc++ changed the behavior of ``std::{map,set}`` for such
- comparators. Since this may be tricky to work around in some cases, an escape hatch is provided in this release:
- defining ``_LIBCPP_ENABLE_LEGACY_TREE_LOWER_UPPER_BOUND`` will revert to the historical implementation of
- these operations. That escape hatch will be removed in LLVM 23.
-
-- The ABI flag ``_LIBCPP_ABI_NO_REVERSE_ITERATOR_SECOND_MEMBER`` has been split off from
- ``_LIBCPP_ABI_NO_ITERATOR_BASES``. If you are using this flag and care about ABI stability, you should set
- ``_LIBCPP_ABI_NO_REVERSE_ITERATOR_SECOND_MEMBER`` as well.
-
-Announcements About Future Releases
------------------------------------
-
-ABI Affecting Changes
----------------------
-
-- The ABI flag ``_LIBCPP_ABI_NO_REVERSE_ITERATOR_SECOND_MEMBER`` has been split off from
- ``_LIBCPP_ABI_NO_ITERATOR_BASES``. If you are using this flag and care about ABI stability, you should set
- ``_LIBCPP_ABI_NO_REVERSE_ITERATOR_SECOND_MEMBER`` as well.
-
-- The internal types ``__map_value_compare``, ``__unordered_map_hasher``, ``__unordered_map_equal``,
- ``__hash_map_hasher`` and ``__hash_map_equal`` have been refactored to use ``_LIBCPP_COMPRESSED_ELEMENT`` instead of
- potentially inheriting from the types they wrap. At this point in time we are not aware of any ABI changes caused by
- this.
-
-- ``ranges::iota_view`` is now aware of ``__int128``. This causes ``iota_view::difference_type`` to change from
- ``long long`` to ``__int128`` in some cases.
-
-- ``std::allocator`` is now trivially default constructible. 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[]`` now returns ``bool``, 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
---------------------
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