How do I get the log output of a Scala Compiler Plugin?

From the scala compiler help, I would have thought that "-Xprint:MyPhase" would do just that, but despite the fact that the plugin does it's job, and that I know it makes log output, I still don't see any output from coming from scalac when it runs. All I see are "[[syntax trees at end of MyPhase]] ..." Since logging seems to simply involve calling log("..."), I can't imagine what I would be doing wrong in the code that produces the log output. As an ugly work-around I can still do System.out.println开发者_开发知识库(), but if there is a log() method, than I have to assume that it's actually meant to do something ...

-Ylog:<phase>

Use scalac -Y to see all the "private" options.