RFR: 8353835: Implement JEP 500: Prepare to Make Final Mean Final [v11]

[Viktor Klang]

On Tue, 11 Nov 2025 17:48:43 GMT, Alan Bateman <alanb at openjdk.org> wrote:

>> Implementation changes for [JEP 500: Prepare to Make Final Mean Final](https://openjdk.org/jeps/500).
>> 
>> Field.set (and Lookup.unreflectSetter) are changed to allow/warn/debug/deny when mutating a final instance field. JFR event recorded if final field mutated. Spec updates to Field.set, Field.setAccessible and Module.addOpens to align with the proposal in the JEP.
>> 
>> HotSpot is updated to add support for the new command line options. To aid diagnosability, -Xcheck:jni reports a warning and -Xlog:jni=debug logs a message to help identity JNI code that mutates finals. For now, JNI code is allowed to set the "write-protected" fields System.in/out/err without a warning, we can re-visit once we change the System.setIn/setOut/setErr methods to not use JNI (I prefer to keep this separate to this PR because there is a small startup regression to address when changing System.setXXX).
>> 
>> There are many new tests. A small number of existing tests are changed to run /othervm as reflectively opening a package isn't sufficient. Changing the tests to /othervm means that jtreg will launch the agent with the command line options to open the package.
>> 
>> Testing: tier1-6
>
> Alan Bateman has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 50 commits:
> 
>  - Remove dup end body tag
>  - Change FinalFieldMutationEvent so that caller is top frame in stack trace
>  - Merge branch 'master' into JDK-8353835
>  - Review feedback: Add tests for setting internal properties, improve links in Mutation methods page
>  - Merge branch 'master' into JDK-8353835
>  - Merge branch 'master' into JDK-8353835
>  - Fix typo in test comment
>  - Merge branch 'master' into JDK-8353835
>  - Merge branch 'master' into JDK-8353835
>  - Suppress warnings from some tests
>  - ... and 40 more: https://git.openjdk.org/jdk/compare/2902436f...b22947c7

src/java.base/share/man/java.md line 482:

> 480: 
> 481:     -   `allow`: This mode allows illegal final field mutation in all modules,
> 482:         without any warings.

Suggestion:

        without any warnings.

-------------

PR Review Comment: https://git.openjdk.org/jdk/pull/25115#discussion_r2518551065