Create ecj.jar file in Eclipse

I made some changes to elipse.jdt.core plugin in order to support a language (MaxJ) similar to Java. Changes that I made can be found here:

https://github.com/maxeler/eclipse.jdt.core/tree/MAXJ_4_4_maintenance

Release of my plugin can be found here:

https://github.com/maxeler/eclipse/releases

Everything works fine when I use eclipse in GUI mode but I want to compile different projects from command line (in headless build or using ant) and for that I need to create new ecj.jar file. I tried building this library:

https://github.com/maxeler/maxpower

According to this article:

http://help.eclipse.org/kepler/index.jsp?topic=%2Forg.eclipse.jdt.doc.user%2Ftasks%2Ftask-ant_javac_adapter.htm

jdtCompilerAdapter.jar can be used instead of ecj.jar but that didn't work because it doesn't contain compiler classes (like CompilerOptions etc.). In build.xml file I changed the following lines:

<taskdef name="maxjcompiler" classname="org.eclipse.jdt.core.ant.taskdef.MaxjTask" classpath="${env.MAXCOMPILERDIR}/lib/MaxIDE/ecj.jar" onerror="ignore"/>
<taskdef name="maxjdoc" classname="org.eclipse.jdt.core.ant.taskdef.MaxjDocTask" classpath="${env.MAXCOMPILERDIR}/lib/MaxIDE/ecj.jar"/>

with this:

<taskdef name="maxjcompiler" classname="org.eclipse.jdt.core.ant.taskdef.MaxjTask" classpath="/pathToMyJar/jdtCompilerAdapter.jar" onerror="ignore"/>
<taskdef name="maxjdoc" classname="org.eclipse.jdt.core.ant.taskdef.MaxjDocTask" classpath="/home/ikulezic/Desktop/jdtCompilerAdapter.jar"/>

And then I run this command to start build process:

ant

It produces the following error:

Buildfile: /home/ikulezic/Desktop/maxpower/build.xml
 [taskdef] Could not load definitions from resource org/jacoco/ant/antlib.xml. It could not be found.

clean:
  [delete] Deleting directory /home/ikulezic/Desktop/maxpower/bin

compile:
    [echo] 
    [echo] Using maxeda classpath '/opt/maxcompiler/lib/MaxCompiler.jar'
    [echo]   (Precedence: 1. $MAXCOMPILERJCP, 2. $MAXCOMPILERDIR)
    [echo] 
    [echo]                 
   [mkdir] Created dir: /home/ikulezic/Desktop/maxpower/bin

BUILD FAILED
/home/ikulezic/Desktop/maxpower/build.xml:66: Could not create type maxjcompiler due to java.lang.NoClassDefFoundError: org/eclipse/jdt/internal/compiler/impl/CompilerOptions
       at org.eclipse.jdt.core.ant.taskdef.MaxjTask.<init>(MaxjTask.java:80)
       at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
       at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
       at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
       at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
       at org.apache.tools.ant.AntTypeDefinition.innerCreateAndSet(AntTypeDefinition.java:328)
       at org.apache.tools.ant.AntTypeDefinition.createAndSet(AntTypeDefinition.java:274)
       at org.apache.tools.ant.AntTypeDefinition.icreate(AntTypeDefinition.java:219)
       at org.apache.tools.ant.AntTypeDefinition.create(AntTypeDefinition.java:206)
       at org.apache.tools.ant.ComponentHelper.createComponent(ComponentHelper.java:285)
       at org.apache.tools.ant.ComponentHelper.createComponent(ComponentHelper.java:263)
       at org.apache.tools.ant.UnknownElement.makeObject(UnknownElement.java:429)
       at org.apache.tools.ant.UnknownElement.maybeConfigure(UnknownElement.java:163)
       at org.apache.tools.ant.Task.perform(Task.java:347)
       at org.apache.tools.ant.Target.execute(Target.java:435)
       at org.apache.tools.ant.Target.performTasks(Target.java:456)
       at org.apache.tools.ant.Project.executeSortedTargets(Project.java:1393)
       at org.apache.
 at org.apache.tools.ant.helper.DefaultExecutor.executeTargets(DefaultExecutor.java:41)
       at org.apache.tools.ant.Project.executeTargets(Project.java:1248)
       at org.apache.tools.ant.Main.runBuild(Main.java:851)
       at org.apache.tools.ant.Main.startAnt(Main.java:235)
       at org.apache.tools.ant.launch.Launcher.run(Launcher.java:280)
       at org.apache.tools.ant.launch.Launcher.main(Launcher.java:109)
Caused by: java.lang.ClassNotFoundException: org.eclipse.jdt.internal.compiler.impl.CompilerOptions
       at org.apache.tools.ant.AntClassLoader.findClassInComponents(AntClassLoader.java:1366)
       at org.apache.tools.ant.AntClassLoader.findClass(AntClassLoader.java:1315)
       at org.apache.tools.ant.AntClassLoader.loadClass(AntClassLoader.java:1068)
       at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
       ... 24 more

Total time: 0 seconds

At the moment it seems like the only option is to build a new ecj.jar file but I couldn't find a way to do it.

Solution

How to build ecj.jar depends on what build technology you use.

If you have the context configured so that you can build org.eclipse.jdt.core with Maven/Tycho, then you should adjust the batch-compiler execution within the project's pom.xml.

Otherwise, a more light-weight approach should be to invoke Ant with scripts/export-ecj.xml. That file may be a bit out-of-date, but you could take a look at how this is adapted for creating another variant of ecj (for OT/J), see: http://git.eclipse.org/c/objectteams/org.eclipse.objectteams.git/tree/org.eclipse.jdt.core/scripts/export-ecj.xml.

For OT/J this script is invoked from the Ant-based PDE-build process, so for standalone invocation a bunch of properites needs to be configured first.

integrating apt and tool requires those sibling projects to sit in expected locations, and properties like build.root.dir set. Otherwise, commenting the section for apt and tool should get you going.
set buildLabel to something useful

With these preparations I can successfully run Ant from within the IDE.