static S invokeEcj(S options) ctex {
  StringWriter writer = new StringWriter();
  PrintWriter printWriter = new PrintWriter(writer);
  
  File optionsFile = File.createTempFile("javax", "");
  saveTextFile(optionsFile, options);

  String[] args = { "@" + optionsFile.getPath() };
      
  Class ecjClass = Class.forName("org.eclipse.jdt.internal.compiler.batch.Main");
  Object main = newInstance(ecjClass, printWriter, printWriter, false);
  call(main, "compile", new Object[]{args});
  int errors = (Integer) get(main, "globalErrorsCount");

  S output = str(writer);
  if (errors != 0) {
    print(output);
    throw new RuntimeException("Java compiler returned errors.");
  }
  ret output;
}