On Tue, 11 Nov 2025 17:48:43 GMT, Alan Bateman <[email protected]> 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/classes/java/lang/reflect/Field.java line 1543: > 1541: * the given possibly-null caller. > 1542: */ > 1543: private String finalFieldMutationWarning(Class<?> caller, boolean > unreflect) { It may make sense to have this method return a StringBuilder instance (and use it internally before returning it) as that would cut down on extra String-instance creation. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/25115#discussion_r2518192839
