On Fri, 27 Oct 2023 11:35:54 GMT, Jan Lahoda <jlah...@openjdk.org> wrote:
> Consider a simple module, like: > > module test {} > > > And compile it with JDK 22 and JDK 21 using: > javac --release 21 > > The results of the compilations will differ: when compiling with JDK 21, the > mandated java.base dependency will get a version, possibly like > "21-internal". When compiling with JDK 22, the version of the java.base > dependency will be empty. > > This is a) because `module-info.class`es in `ct.sym` do not have any module > version set; b) for JDK N, `--release N` is not using `ct.sym`, but rather > `lib/modules`, which may contain a range of version specifiers. > > This patch does two changes: > a) tweaks the `module-info.class`es in `ct.sym`, so that they contain a > simple version. For `--release N`, the version is `N`. > b) tweaks the whole build so that `ct.sym` is used always for `--release`, a > `lib/modules` is never used. I.e. the appropriate classfiles are copied into > `ct.sym`. This not only allows for a general approach to module versions, but > simplifies the `--release` handling in javac, and should enable future > improvements. This is, however, a relatively big change. > > The use of `lib/modules` for `--release <current>` was made to improve build > performance, but the build has been updated since this has been introduced, > so the slowdown caused by rebuilding `ct.sym` should be much lower now. > > With these changes, compiling with `--release N` should record the same > dependency versions in `module-info` on JDK N and JDK N + 1. The changes are indeed complex. I'm trying to tease out all the implications. I have a few questions/comments. 1) TransitiveDependencies seems to be unused now. I assume this is intended. But maybe the java file can be removed? 2) The definition from spec.gmk says: BUILD_JAVA_FLAGS := @BOOTCYCLE_JVM_ARGS_BIG@ BUILD_JAVA=@FIXPATH@ $(BUILD_JDK)/bin/java $(BUILD_JAVA_FLAGS) Thus it seems that BUILD_JAVA is using the "big" java flags (though I admit I did not follow to check exactly what BOOTCYCLE_JVM_ARGS_BIG means) . But the old code used JAVA_SMALL. Is this an oversight, an assumption that it does not matter, or a measurement-founded decision that it does not matter? Maybe we should add a BUILD_JAVA_SMALL; or maybe it is not worth it. I cannot really say which, though I lend towards the former. 3) The old code did `-add-exports java.base/jdk.internal.javac=java.compiler.interim,jdk.compiler.interim`. I can't say I understand what the meaning of it was, but I don't understand why it is removed now, either. I'd appreciate some explanation about this. ------------- PR Comment: https://git.openjdk.org/jdk/pull/16400#issuecomment-1802223462