Lombok in Java 9 makes Netbeans 9.0 go crazy

[victorwss]

I already reported this here sometime ago. [Edit: It was in #1435. It also relates to #985]

Trying to use lombok in Java 9 within a Netbeans 9.0 project makes the IDE go crazy spamming a lot of IllegalArgumentException: URI is not absolute exceptions making it unusable.

The cause of the issue is that Netbeans 9.0 uses javax.tools.JavaFileObject instances and calls toUri().toURL() on them. But this happens in code specific to handle modules, so it will only trigger in Java 9. To be precise, this happens in the org.netbeans.modules.java.source.parsing.PatchModuleFileManager.java class.

The toURL() method throws that exception when it is called in a URI that is not constructed as an absolute URI. This was never a problem until now, but now it is.

The JavaFileObject javadocs do not say anything about requiring or not that the URIs should be absolute. Jan Lahoda from the Netbeans project replied:

I believe the code in NetBeans expects that it will get JFOs which NetBeans
has constructed. Which apparently is not the case here. This is not a
completely wrong assumption: I am not aware about any API that would allow
to inject external JFOs into javac. I guess a solution here might be to
ignore unknown JFOs, which is what the standard file manager in javac is
doing, for better or worse.

After hacking around lombok, I determined that the offending JavaFileObject is an instance of lombok.javac.apt.EmptyLombokFileObject. The name which produces the bad URI is lombok.dummy.ForceNewRound0 and it is produced in the forceNewRound(String, JavacFiler) method of the lombok.javac.apt.LombokProcessor class.

A simple fix would be to rewrite the toUri() method of EmptyLombokFileObject. Instead of this:

	@Override public URI toUri() {
		return URI.create(name);
	}

Let's use this:

	@Override public URI toUri() {
		return URI.create("file://" + name);
	}

After that, I:

1. Recompiled lombok with my changes.
2. Closed Netbeans and obliterated its cache in the disk.
3. Replaced the lombok.jar in my project with the one that I compiled.
4. Restarted Netbeans and reopened my project.
5. Profit!

And, it worked like a charm. A simple one-line fix!

Ok, to be fair, I had to twist some other things in order to make it able to compile in my Java 9 environment, but this is for some other issue. I don't think that this is really important here, but I should say it anyway in the case of somebody else failing to reproduce my fix.

Should I submit a PR on that?

Side note: Some people on Netbeans side are very angry about lombok due to unhappy past iteractions here. Surely, there are many things that we all could improve...

[victorwss]

Relevant PR: #1626

[rspilker]

Merged related pull request.

[victorwss]

@rspilker @rzwitserloot Can we have an edge release with this?

[rspilker]

The edge release is available.