Lombok fails to participate in Java source compilation

Digging deeper it appears that Lombok does not function as an annotation processor for ECJ compilers. Instead it expect to be a javaagent. However running maven with the Lombok java agent yeilds additional errors.

1. ERROR in /Users/sskrla/Documents/workspaces/groovy-eclipse-lombok/groovy-eclipse-lombok-test/src/main/java/com/test/LombokDataClass.java (at line 0)
package com.test;
^
Internal compiler error: java.lang.NoClassDefFoundError: org/eclipse/jdt/internal/compiler/lookup/ReferenceBinding at org.eclipse.jdt.internal.compiler.lookup.ClassScope.buildFieldsAndMethods(ClassScope.java)

Have you gotten this to work in a pure groovy project (ie- without using maven)? I am just wondering if Lombok and groovy are compatible at all.

I sincerely hope not, I was hoping to introduce groovy into our software stack but an incompatibility like that would kill it pretty fast =(

I have patched this issue in a custom implementation of the groovy-eclipse-compiler. Its actually quite simple:

In the method compileOutOfProcess() I added a new command line argument to "cli" specifying a javaagent. I added the following method to discover the lombok jar location in helping figure this location out:

	private String getLombokLocation() throws CompilerException {
		Class<?> cls;
		try {
			cls = Class.forName("lombok.Lombok");
		} catch (ClassNotFoundException e1) {
			return null;
		}

		ProtectionDomain pDomain = cls.getProtectionDomain();
		CodeSource cSource = pDomain.getCodeSource();
		if (cSource != null) {
			URL loc = cSource.getLocation();
			File file;
			try {
				file = new File(URLDecoder.decode(loc.getPath(), "UTF-8"));
			} catch (UnsupportedEncodingException e) {
				getLogger().warn("Unsupported Encoding for URL: " + loc, e);
				file = new File(loc.getPath());
			}
			return file.getPath();
		} else {
			throw new CompilerException(
					"Cannot find the location of the lombok jar");
		}
	}

I also included lombok as a dependency to the maven-compiler-plugin. Can I suggest a way to make this more generic and have it implemented by you guys?

Add a new configuration argument for the groovy-eclipse-compiler. Call it something like "javaAgentClass" or something. Auto-discover the jar using the method like I posted above and include it as a -javaagent argument to java.

Thanks!

Thanks, Jason. This seems like a reasonable fix.

So presumably, if lombok.jar is on the classpath of the maven-compiler-plugin, then the class will be loadable inside of getLombokLocation(). But, what does this extra command line argument look like?

And any desire to package this up as a proper patch, so I can add it to the source tree? Making this more general than just lombok would be the way to go.

I think the command is just something like

-javaagent:${path/to/}lombok.jar

, because it's the way that lombok IDE installer configures Eclipse or Netbeans.

I'm trying to produce a patch to fix this issue, following the suggestion of Jason Clawson to add an extra param to the plugin, but I am hitting the fact that it does not seem easy to extend maven AbstractCompiler and use an extra param (javaAgentClass in our case).
Although the explanation given at http://blog.aggregat4.net/extending-existing-maven-2-plugins-is-harder is Maven 2 related, I think it is still a effective for maven 3.

Would you have any hint on how you would achieve that?

I could make the plugin work with a hardcoded javaAgentClass param, when a forked compilation is requested by patching compileOutOfProcess.

Next step is to pass the javaagent stuff to the org.eclipse.jdt.internal.compiler.batch.Main for non-forked compilation. Any tip on this step will be helpfull too

According to http://groups.google.com/group/project-lombok/browse_thread/thread/3f78910a6a10e3c3 and http://code.google.com/p/projectlombok/issues/detail?id=212 I'm not sure it can be done with fork=false

Please find attached a patch that propose a new compilerArguments name javaAgentClass that is taken into account when fork=true.

The patch contains a lot of diff because of formating changes (sorry, I am a compulsive source code formatter in Eclipse).

I you provide me the rules of formatting used on the project I can give you a smaller patch.

Here is the patch

I forgot to mention that you need to customise your pom like this:

<configuration>
    <compilerId>groovy-eclipse-compiler</compilerId>
	<verbose>true</verbose>
	<fork>true</fork>					
	<compilerArguments>
        	<javaAgentClass>lombok.core.Agent</javaAgentClass>
	</compilerArguments>
</configuration>

Thanks for the patch, but it is not a valid patch file and does not apply. Can you recreate the patch from within Eclipse?

I added formatting preferences to the project. Please check the project out and use the included formatting preferences to format the project. Make the patch as small as possible and use as few white space changes as possible.

Please find a patch that should work better.

Got the patch and tried it on the test project attached to this issue. In addition to the configuration that you have above, you also need to add lombok both as a build and a compile dependency.

This patch looks good and I'll accept it. I'll also take the attached project as an integration test.

All tests pass. I am publishing a new 2.6.1-01-SNAPSHOT. This should be working for you. Let me know if you have any trouble.

Thanks for applying the patch; and yes, I forgot to mention the "add lombok as a build dependency" (mea culpa, again)

The needed pom configuration is then something like that (adjust your versions if needed)

<plugin>
    <artifactId>maven-compiler-plugin</artifactId>
    <version>2.3.1</version>
    <configuration>
    <compilerId>groovy-eclipse-compiler</compilerId>
    <verbose>true</verbose> 
    <fork>true</fork>   
    <compilerArguments>
        <javaAgentClass>lombok.core.Agent</javaAgentClass>
    </compilerArguments>
    </configuration>
    <dependencies>
        <dependency>
            <groupId>org.codehaus.groovy</groupId>
            <artifactId>groovy-eclipse-compiler</artifactId>
            <version>2.6.1-01-SNAPSHOT</version>
        </dependency>
        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
            <version>0.11.0</version>
        </dependency>
    </dependencies>
</plugin>

Works for me with latest snapshot.