Description Julian Honnen 2021-05-28 07:50:38 EDT

I'm trying to get a tycho build with an annotation processor to work, but ECJ can't find the annotation processor class.

I've found that the order of the arguments matters. Specifying the classpath before processorpath works correctly:

java -cp "C:\Users\visjho\.p2\pool\plugins\org.eclipse.jdt.compiler.apt_1.3.1300.v20210419-1022.jar;C:\Users\visjho\.p2\pool\plugins\org.eclipse.jdt.core_3.26.0.v20210524-0947.jar" org.eclipse.jdt.internal.compiler.batch.Main -11 -classpath <classpath> -processor some.annotation.Processor -processorpath path/to/processor.jar Source.java

But when I specify the -processorpath first (like tycho does), the processor can't be found:

java -cp "C:\Users\visjho\.p2\pool\plugins\org.eclipse.jdt.compiler.apt_1.3.1300.v20210419-1022.jar;C:\Users\visjho\.p2\pool\plugins\org.eclipse.jdt.core_3.26.0.v20210524-0947.jar" org.eclipse.jdt.internal.compiler.batch.Main -11 -processorpath path/to/processor.jar -classpath <classpath> -processor some.annotation.Processor Source.java

1. ERROR in Source.java (at line 0)
        /*******************************************************************************
        ^
Internal compiler error: java.lang.ClassNotFoundException: some.annotation.Processor at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:435)



Looking at the source code, the processorpath is ignored in the second invocation:

1) EclipseFileManager.handleOption for -processorpath
   - sets ANNOTATION_PROCESSOR_PATH location and HAS_PROCESSORPATH flag
2) EclipseFileManager.handleOption for -cp
   - sees that HAS_PROCESSORPATH is set and initializes the ANNOTATION_PROCESSOR_MODULE_PATH location with the classpath

	if ((this.flags & EclipseFileManager.HAS_PROCESSORPATH) == 0) {
		setLocation(StandardLocation.ANNOTATION_PROCESSOR_PATH, classpaths);
	} else if ((this.flags & EclipseFileManager.HAS_PROC_MODULEPATH) == 0) {
		if (this.isOnJvm9)
			setLocation(StandardLocation.ANNOTATION_PROCESSOR_MODULE_PATH, classpaths);
	}

3) BatchAnnotationProcessorManager.configure finds a non-null ANNOTATION_PROCESSOR_MODULE_PATH location and prefers that over ANNOTATION_PROCESSOR_PATH



In the first, working, invocation the -cp option initializes the ANNOTATION_PROCESSOR_PATH location instead which is afterwards overwritten by the -processorpath option.


This effectively breaks the -processorpath option in tycho when running on java9+ as you can't control the order of the -classpath argument.
Using the --processor-module-path option instead (with a regular jar) seems to work though.