On Mon, 10 Nov 2025 10:06:31 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 45 commits: > > - 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 > - Change -Xcheck:jni to be warning rather than fatal error > - Merge branch 'master' into JDK-8353835 > - Simplify filter > - Merge branch 'master' into JDK-8353835 > - Update Xcheck:jni description > - ... and 35 more: https://git.openjdk.org/jdk/compare/066810c8...6671ae02 I still wonder about the decision for JNI to call final Field.set with an unconditional export check instead of an unconditional open check - the open check is done for all Java code already. src/java.base/share/classes/java/lang/reflect/doc-files/MutationMethods.html line 56: > 54: <li><a href="../Field.html#setDouble(java.lang.Object,double)"> > 55: java.lang.reflect.Field.setDouble(Object, double)</a></li> > 56: <li><a > href="{@docRoot}/java.base/java/lang/invoke/MethodHandles.Lookup.html#unreflectSetter(java.lang.reflect.Field)"> Nit: Since javadoc process tags here, you could just use `{@link Field#set java.lang.reflect.Field.set(Object, Object)}` instead of full-fledged a tags. src/java.base/share/classes/java/lang/reflect/doc-files/MutationMethods.html line 66: > 64: <p> In the reference implementation, a module can be granted the > capability to mutate > 65: final instance fields of classes in packages that are open to the module > using > 66: the command line option <code>--enable-final-field-mutation=M1,M2, ... > M}</code> where Suggestion: the command line option <code>--enable-final-field-mutation=M1,M2, ... Mn}</code> where src/java.base/share/classes/java/lang/reflect/doc-files/MutationMethods.html line 72: > 70: <em>illegal</em>. > 71: > 72: The command line option <code>--illegal-final-field-mutation</code> > controls how illegal Missing `<p>`? test/jdk/java/lang/reflect/Field/mutateFinals/cli/CommandLineTest.java line 234: > 232: @Test > 233: void testSetPropertyToAllow() throws Exception { > 234: test("setSystemPropertyToAllow+testFieldSetInt") I thought this was setting the property before the VM boot. Can we have another test that does something like: test("testFieldSetInt", "-Djdk.module.illegal.final.field.mutation=allow") Which I think is closer to what @vy asks for. ------------- PR Review: https://git.openjdk.org/jdk/pull/25115#pullrequestreview-3444803078 PR Review Comment: https://git.openjdk.org/jdk/pull/25115#discussion_r2511838513 PR Review Comment: https://git.openjdk.org/jdk/pull/25115#discussion_r2511840059 PR Review Comment: https://git.openjdk.org/jdk/pull/25115#discussion_r2511841318 PR Review Comment: https://git.openjdk.org/jdk/pull/25115#discussion_r2511708135
