Update gwt build to run under Java 11

[niloc132]

As of 2.8.2, GWT supports being run under Java7+, but the build itself only works cleanly in Java 7. As of GWT 2.9, this changed to support Java8+ (via https://gwt-review.googlesource.com/c/gwt/+/22320), but Java 9+ still do not work to actually produce the GWT distribution. This issue is a placeholder to track the problems faced.

• Internal build for Java 7 vs "modern" can be removed
• SwingLoggerPanel.java uses improper generics for Java 9+. Previously, the postorderEnumeration() returned a raw Enumeration, but that changed in Java 9 https://docs.oracle.com/javase/9/docs/api/javax/swing/tree/DefaultMutableTreeNode.html#postorderEnumeration--
• CloseableJarHandler.java uses classes in the java.base module that are not exported. An extra compiler arg can either make that accessible, or it is possible that this class is dead and can be removed
• The GWT doctool project uses com.sun.javadoc packages com.sun.tools.doclets package, deprecated in java9, gone in 11. Finding a cross-version way to support this could be difficult (having not tried at all yet), it may be easier to find a different way to support the custom documentation present in GWT.

[niloc132]

niloc132@java9+ is a quick and dirty patch that at least makes it possible to build GWT under java9, 11 (have not yet tested 14). Some aspects can be cherry-picked to address the issues discussed above, but some will need more work.

[MCMicS]

under Windows (version 1.10.7, JDK 11.0.7, 14.0.1 Windows) I got following error if gwt.javac macro is executed:

[gwt.javac] Caused by: java.nio.file.NotDirectoryException: P:\Java\jdk-11.0.7\lib\modules
[gwt.javac]     at java.base/sun.nio.fs.WindowsDirectoryStream.<init>(WindowsDirectoryStream.java:84)
[gwt.javac]     at java.base/sun.nio.fs.WindowsFileSystemProvider.newDirectoryStream(WindowsFileSystemProvider.java:523)
[gwt.javac]     at java.base/java.nio.file.Files.newDirectoryStream(Files.java:471)
[gwt.javac]     at java.base/java.nio.file.Files.list(Files.java:3696)
[gwt.javac]     at com.sun.tools.javac.file.Locations$BootClassPathLocationHandler.systemClasses(Locations.java:665)
[gwt.javac]     at com.sun.tools.javac.file.Locations$BootClassPathLocationHandler.computePath(Locations.java:621)
[gwt.javac]     at com.sun.tools.javac.file.Locations$BootClassPathLocationHandler.lazy(Locations.java:709)
[gwt.javac]     ... 133 more

Tested with ant buildonly and ant -f samples\build.xml hello

[niloc132]

Can you share the full log, and confirm that you have my commit running? Looks like I might have missed some java.tools.path somewhere, but as far as I can tell, in that commit they are all commented out.

[MCMicS]

Sure. Have prepared it and then forget to upload 🤦

9683_Win10_jdk11.txt

[niloc132]

Can you do it again from clean, and confirm that the whole thing is there? I was expecting to see something like this at the end, note the lines after BUILD FAILED:

[gwt.javac] Caused by: java.nio.file.NotDirectoryException: /usr/lib/jvm/java-11-openjdk/lib/modules
[gwt.javac] 	at java.base/sun.nio.fs.UnixFileSystemProvider.newDirectoryStream(UnixFileSystemProvider.java:431)
[gwt.javac] 	at java.base/java.nio.file.Files.newDirectoryStream(Files.java:471)
[gwt.javac] 	at java.base/java.nio.file.Files.list(Files.java:3696)
[gwt.javac] 	at com.sun.tools.javac.file.Locations$BootClassPathLocationHandler.systemClasses(Locations.java:665)
[gwt.javac] 	at com.sun.tools.javac.file.Locations$BootClassPathLocationHandler.computePath(Locations.java:621)
[gwt.javac] 	at com.sun.tools.javac.file.Locations$BootClassPathLocationHandler.lazy(Locations.java:709)
[gwt.javac] 	... 80 more

BUILD FAILED
/home/colin/workspace/gwt/build.xml:40: The following error occurred while executing this line:
/home/colin/workspace/gwt/build.xml:27: The following error occurred while executing this line:
/home/colin/workspace/gwt/build.xml:58: The following error occurred while executing this line:
/home/colin/workspace/gwt/dev/build.xml:200: Compile failed; see the compiler error output for details.

Total time: 0 seconds

[MCMicS]

your "hack and slash commit" produce following:

gwt-master_niloc>set JAVA_HOME=P:\Java\jdk-11.0.7

gwt-master_niloc>ant buildonly
Buildfile: gwt-master_niloc\build.xml

buildonly:

dev:

buildtools:

build:

doctool:

-do:

compiler.standalone:
[gwt.javac] Compiling 7 source files to gwt-master_niloc\build\out\dev\bin
[gwt.javac] error: option --add-exports not allowed with target 1.8

BUILD FAILED
gwt-master_niloc\build.xml:40: The following error occurred while executing this line:
gwt-master_niloc\build.xml:27: The following error occurred while executing this line:
gwt-master_niloc\build.xml:58: The following error occurred while executing this line:
gwt-master_niloc\dev\build.xml:200: Compile failed; see the compiler error output for details.

Total time: 2 seconds

for sample without your hack commit and use the one from gerrit (+ + gwt master):
9683_Win10_jdk11_sample_hello.txt

I try a full rebuild now (first create gwt-user with java8).

[niloc132]

Looks like I might have changed/reverted something else in an attempt to "clean" it up for commit and broken it? Will get back to you.

[niloc132]

Okay, I force pushed a commit to that branch to replace it - this is better in a few ways than what I had intended to push last time:

• compiling on java9+ is still runnable on java8
• no need for extra conditional wiring on the gwt.javac task

Sorry about that, let me know if this new commit works any better for you. Be sure to do a clean between builds, I've seen odd issues in the past even when you don't change JDK. Tested the build on both java8 and java11, have not tried running both on java8 projects, only checked the magic number in bytecode in a few files.

[MCMicS]

getting same error

compiler.standalone:
    [mkdir] Created dir: gwt\build\out\dev\bin
[gwt.javac] Compiling 7 source files to build\out\dev\bin
[gwt.javac] javac: invalid flag: --add-exports
[gwt.javac] Usage: javac <options> <source files>
[gwt.javac] use -help for a list of possible options

BUILD FAILED
gwt\build.xml:40: The following error occurred while executing this line:
gwt\build.xml:27: The following error occurred while executing this line:
gwt\build.xml:58: The following error occurred while executing this line:
dev\build.xml:200: Compile failed; see the compiler error output for details.

used this: https://github.com/niloc132/gwt/tree/java9+
Am I on the wrong branch or where you have pushed ;)

[niloc132]

Sorry, I pushed the branch to the wrong place - I re-pushed, here's the commit to be sure, with no more --add-exports.
niloc132@d51a0e8

[MCMicS]

Now it seems to work
tested with jdk11,jdk14 and jdk15

thanks for that

[niloc132]

https://gwt-review.googlesource.com/c/gwt/+/22360

[niloc132]

https://gwt-review.googlesource.com/c/gwt/+/22640

[jncanches]

Tested with OpenJDK 17 and it worked.
Thanks!

[niloc132]

Javadocs will still not work, and some tests won't either, but at least producing a build (and running it) should all function at this point. Javadoc is still not going to work until we make the decision to drop java 8/9/10 support for producing javadoc, so we'll continue producing official builds using java8 or so for the time being, until someone adopts that migration work.

[niloc132]

With https://gwt-review.googlesource.com/c/gwt/+/23700 / b6cc5cf merged and https://gwt-review.googlesource.com/c/gwt/+/23740 ready to go (will probably merge later today, just doing a bit more testing first after rebasing), most of the build (and some tests) can work on java8, java11, and java17, as long as the docs part of the build is disabled.

If we want to keep Java 8 support for a while longer, we need to decide if docs should continue to be built in Java 8 or assume something newer. Either approach requires that the other build cannot produce javadocs, so any "builds with docs" produced needs to be tested with other Java versions.

The time will come when GWT will be held back by supporting the Java 8 runtime at all - Jetty has announced that Jetty 9.4.x will EOL in April 2022 (and 10, 11 require Java 11+), and recent Eclipse JDT versions (which support Java 17 syntax) require a minimum of Java 11 as well.

[tbroyer]

AFAICT, there are two tools that are problematic because they're using the old doclet API: the javadoc generation itself, and the JRE emulation reference ("ezt" in the codebase).
If I'm not mistaken, javadoc is only about the @example, @gwt.include, and @tip tags. Those could be inlined the classes' javadoc, instead of trying to make the taglets work with the new API (@tip would likely be easy to keep, maybe even just as -tag tip:a:"Tip:").
EztDoclet looks much easier to port to the new API (and might not even need to be ported in the near future as the com.sun.javadoc package is still available in JDK 11).

[niloc132]

Inlining example is only really problematic because the examples are actual Java classes, getting formatting and linking right (and keeping them up to date when minor changes have to be made) could be irritating, but not hard by any means.

My understanding of Ezt is very limited, thanks for the details there. Naively, it seems like it might be straightforward to just find a more compatible way to walk the available super source and generate links. Especially since it seems that this tool keys off of a properties file, which in turn is just printed out disk from the FindPackages main?

As you say, Ezt at least can safely wait until after we've dealt with the end of Java 8.