[libcxx-commits] [libcxx] [libc++] Add a release note about C++03 being frozen after LLVM 21 (PR #95894)

[Louis Dionne via libcxx-commits]

================
@@ -155,8 +155,12 @@ LLVM 20
 
 LLVM 21
 ~~~~~~~
-TODO
 
+- The status of the C++03 implementation will be frozen. This means that non-critical bug fixes will 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 C++03 is a legacy platform, where most projects are no longer actively maintained.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++ freezes
+  the current status of the headers and avoids making any changes to these headers.
+  See https://discourse.llvm.org/t/rfc-freezing-c-03-headers-in-libc for more details.
----------------
ldionne wrote:

```suggestion
- 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 C++03 is a legacy platform, where most projects are no longer actively maintained.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  If you are using C++03 in your project, you should consider moving to a newer version of the Standard to get the most out of libc++.
```

https://github.com/llvm/llvm-project/pull/95894