Merge pull request github#3584 from github/idrissrio/cpp/overlay

Feature flag: C/C++ overlay

Author: IdrissRio

CHANGELOG.md

@@ -5,6 +5,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 ## [UNRELEASED]
 
 - Added an experimental change which disables TRAP caching when [improved incremental analysis](https://github.com/github/roadmap/issues/1158) is enabled, since improved incremental analysis supersedes TRAP caching. This will improve performance and reduce Actions cache usage. We expect to roll this change out to everyone in March. [#3569](https://github.com/github/codeql-action/pull/3569)
+- We are rolling out improved incremental analysis to C/C++ analyses that use build mode `none`. We expect this rollout to be complete by the end of April 2026. [#3584](https://github.com/github/codeql-action/pull/3584)
 - Update default CodeQL bundle version to [2.25.0](https://github.com/github/codeql-action/releases/tag/codeql-bundle-v2.25.0). [#3585](https://github.com/github/codeql-action/pull/3585)
 
 ## 4.33.0 - 16 Mar 2026