[libcxx-commits] [libcxx] [libc++][doc] Update the release notes for LLVM 20. (PR #124403)

[Mark de Wever via libcxx-commits]

https://github.com/mordante created https://github.com/llvm/llvm-project/pull/124403

This is a preparation for the upcoming LLVM 20 release.

>From b03e001b0715b984ff32cefdac71d96e0e6c2fe9 Mon Sep 17 00:00:00 2001
From: Mark de Wever <koraq at xs4all.nl>
Date: Sat, 25 Jan 2025 13:21:30 +0100
Subject: [PATCH] [libc++][doc] Update the release notes for LLVM 20.

This is a preparation for the upcoming LLVM 20 release.
---
 libcxx/docs/ReleaseNotes/20.rst | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/libcxx/docs/ReleaseNotes/20.rst b/libcxx/docs/ReleaseNotes/20.rst
index 2736061544c531..dd5d7f40c1bacd 100644
--- a/libcxx/docs/ReleaseNotes/20.rst
+++ b/libcxx/docs/ReleaseNotes/20.rst
@@ -35,6 +35,8 @@ 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
 ------------------
 
@@ -111,6 +113,13 @@ Improvements and New Features
   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``.
+
 Deprecations and Removals
 -------------------------
 
@@ -196,8 +205,3 @@ ABI Affecting Changes
 
 - 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.
-
-Build System Changes
---------------------
-
-- TODO