[llvm-branch-commits] [libcxx] Add release note for #95264 (PR #96116)

[Louis Dionne via llvm-branch-commits]

https://github.com/ldionne created https://github.com/llvm/llvm-project/pull/96116

None

>From 4044e7c930381e5e070c7131c5b14a3dfd373259 Mon Sep 17 00:00:00 2001
From: Louis Dionne <ldionne.2 at gmail.com>
Date: Wed, 19 Jun 2024 16:50:07 -0400
Subject: [PATCH] [libc++] Add release note for #95264

---
 libcxx/docs/ReleaseNotes/18.rst | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/libcxx/docs/ReleaseNotes/18.rst b/libcxx/docs/ReleaseNotes/18.rst
index 7ea13e6943dd4..3e19e7c33f6af 100644
--- a/libcxx/docs/ReleaseNotes/18.rst
+++ b/libcxx/docs/ReleaseNotes/18.rst
@@ -328,6 +328,15 @@ ABI Affecting Changes
   done to fix `#70494 <https://github.com/llvm/llvm-project/issues/70494>`_ and the vendor communication is handled
   in `#70820 <https://github.com/llvm/llvm-project/issues/70820>`_.
 
+- LLVM 18.1.8 Fixed an issue that caused ``std::string`` to pass an incorrect size to ``allocator_traits::deallocate``
+  when deallocating memory. The impact is different depending on a few factors:
+  - Users who don't use a custom allocator in ``std::string`` and don't enable sized deallocation (which is
+    off by default in Clang 18) will not be affected. This is expected to be the vast majority of users.
+  - Users who don't use a custom allocator in ``std::string`` but are enabling sized deallocation (e.g. with
+    ``-fsized-deallocation``) will notice that ``operator delete(void*, size_t)`` is now being passed the correct
+    size. This likely has no impact if they were not customizing ``operator delete``.
+  - Users who use a custom allocator in ``std::string`` will notice that they now get passed the correct allocation
+    size upon deallocation.
 
 Build System Changes
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