GROOVY-8775, GROOVY-9197: Ant: separate JVM and compilation classpaths

[eric-milles]

GROOVY-8775, GROOVY-9197: Java 10+ compatibility of groovyc ant task

The design of this change is to pass separately the paths necessary for groovyc to run and the classpath of the compiled artifacts. The -classpath argument was previously populated with groovy-all, etc. Now this stuff is passed via the --classpath argument to FileSystemCompilerFacade. Thus, no special URLClassLoader interaction is required (which fails under Java 11).

  [compile] Compilation arguments:
  [compile] C:\Program Files\Java\jdk\11.0.5\bin\java
  [compile] -classpath
  [compile] <enough to execute FileSystemCompilerFacade>
  [compile] -Dfile.encoding=UTF-8
  [compile] org.codehaus.groovy.ant.FileSystemCompilerFacade
  [compile] --classpath
  [compile] <compilation classpath>
  [compile] -j
  [compile] -Fg
  [compile] -Jsource=1.8
  [compile] -Jtarget=1.8
  [compile] -d
  [compile] <output directory>
  [compile] --configscript
  [compile] config.groovy
  [compile] <source files to compile>

The trick to doing all of this is determining what the bootstrap classpath for FileSystemCompilerFacade should be. At the moment, I am getting the Ant runtime from AntClassLoader. But this should be reduced to just groovy and groovy-ant.

    private void doForkCommandLineList(List<String> commandLineList, Path classpath, String separator) {
        //commandLineList.add("java");

        // TODO: Need some help to complete this!  Is it safe to get codesource of FileSystemCompilerFacade.class?
        ClassLoader parent = getClass().getClassLoader();
        if (parent instanceof AntClassLoader) {
            commandLineList.add("-classpath");
            commandLineList.add(((AntClassLoader) parent).getClasspath());
        } else {
            // TODO: add enough classpath entries to support execution of FileSystemCompilerFacade
            throw new AssertionError("not yet implemented");
        }

[eric-milles]

Here is the ProtectionDomain/CodeSource idea:

    private void doForkCommandLineList(List<String> commandLineList, Path classpath, String separator) {
        //commandLineList.add("java");

        commandLineList.add("-classpath");
        commandLineList.add(
FileSystemCompiler.class.getProtectionDomain().getCodeSource().getLocation().getPath() +
File.pathSeparator +
FileSystemCompilerFacade.class.getProtectionDomain().getCodeSource().getLocation().getPath()
);

I have tested this and it does compile successfully. I'm not sure how portable or safe this is. Does anyone know the constraints/limits of using ProtectionDomain/CodeSource?

[paulk-asert]

@eric-milles Probably worth asking your ProtectionDomain question on the dev mailing list with a pointer back here since not everyone reads each notification message.

[eric-milles]

This is ready to review and merge. I have tested with one of our Ant builds against Java 11.

[daniellansun]

Merged. Thanks!