On Mon, 15 Sep 2025 18:18:02 GMT, Chen Liang <[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 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 > > src/java.base/share/classes/java/lang/reflect/Field.java line 1439: > >> 1437: } else { >> 1438: // no java caller, only allowed if field is public in >> exported package >> 1439: if (!Reflection.verifyPublicMemberAccess(clazz, >> modifiers)) { > > Is this sufficient? I know core libraries has APIs as public non-static final > fields, like java.lang.constant.DirectMethodHandleDesc$Kind.refKind. Don't > think they should be allowed to be modified by native code, for example. If a JNI attached thread does an upcall to Field.set with no Java frames on the stack, then it is can mutate a public final field in a public class in an exported package when "illegal final field mutation" is allowed. If denied then IAE will be thrown. > test/langtools/jdk/jshell/CompletionSuggestionTest.java line 35: > >> 33: * @build toolbox.ToolBox toolbox.JarTask toolbox.JavacTask >> 34: * @build KullaTesting TestingInputStream Compiler >> 35: * @run junit/othervm/timeout=480 CompletionSuggestionTest > > Why does this need an update? I mentioned this in the PR description because it is necessary to change a small number of tests ro run in /othervm mode. This is because jtreg reflectively opening a package isn't sufficient, it has to run the test with `--add-opens`. ------------- PR Review Comment: https://git.openjdk.org/jdk/pull/25115#discussion_r2369566678 PR Review Comment: https://git.openjdk.org/jdk/pull/25115#discussion_r2369572798
