[runtimes] Post-branch tasks for the LLVM 23 release (#176007)

This performs most of the post-branch tasks to start working on the LLVM
23 release. Things that are left to do:
- Update the unicode version
- Update CI versions and supported compiler versions

libcxx/docs/ReleaseNotes.rst

@@ -1,4 +1,4 @@
-.. include:: ReleaseNotes/22.rst
+.. include:: ReleaseNotes/23.rst
 
 .. Make sure to reference the non-live release notes in a toctree to avoid Sphinx errors.
 .. toctree::
@@ -6,6 +6,7 @@
 
     ReleaseNotes/20
     ReleaseNotes/21
+    ReleaseNotes/22
 
 .. The release notes are in versioned files, but we make sure to keep publishing
 .. them in an unversioned ReleaseNotes.html page for external sites to reference.

libcxx/docs/ReleaseNotes/23.rst

@@ -0,0 +1,65 @@
+===========================================
+Libc++ 23.0.0 (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++ 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
+------------------
+
+Improvements and New Features
+-----------------------------
+
+Deprecations and Removals
+-------------------------
+
+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
+--------------------

libcxx/docs/ReleaseProcedure.rst

@@ -64,8 +64,6 @@ backported to the release branch the oldest compiler is not removed yet.
 The section ``Upcoming Deprecations and Removals`` is cleared by the release
 managers. Copy back the items that were in this section.
 
-The items that need changing are marked with ``LLVM POST-BRANCH``.
-
 Post release
 ============
 

libcxx/docs/conf.py

@@ -48,9 +48,9 @@ copyright = "2011-%d, LLVM Project" % date.today().year
 # built documents.
 #
 # The short X.Y version.
-version = "17.0"
+version = "23.0"
 # The full version, including alpha/beta/rc tags.
-release = "17.0"
+release = "23.0"
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.

libcxxabi/include/cxxabi.h

@@ -19,7 +19,7 @@
 
 #include <__cxxabi_config.h>
 
-#define _LIBCPPABI_VERSION 15000
+#define _LIBCPPABI_VERSION 230000
 #define _LIBCXXABI_NORETURN  __attribute__((noreturn))
 #define _LIBCXXABI_ALWAYS_COLD __attribute__((cold))
 

libunwind/include/__libunwind_config.h

@@ -9,7 +9,7 @@
 #ifndef ____LIBUNWIND_CONFIG_H__
 #define ____LIBUNWIND_CONFIG_H__
 
-#define _LIBUNWIND_VERSION 15000
+#define _LIBUNWIND_VERSION 230000
 
 #if defined(__arm__) && !defined(__USING_SJLJ_EXCEPTIONS__) && \
     !defined(__ARM_DWARF_EH__) && !defined(__SEH__)