RFR: 8353835: Implement JEP 500: Prepare to Make Final Mean Final

[Chen Liang]

On Thu, 8 May 2025 11:22:30 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 fatal error when a mutating a final field with JNI, and -Xlog:jni=debug can help identity when JNI code mutates finals. For now, JNI code is allowed to set the "write-protected" fields System.in/out/err, 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

For such a draft pull request, is the rename from "ignore" to the actual issue title an indicator for starting a review for the overall design without concerns about typos or bikeshedding?

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

PR Comment: https://git.openjdk.org/jdk/pull/25115#issuecomment-2869958248