Fails with:

[error] /home/travis/build/sbt/sbt/interface/src/test/scala/xsbti/TestCallback.scala:8: class TestCallback needs to be abstract, since method includeSynthToNameHashing in trait AnalysisCallback of type ()Boolean is not defined
[error] class TestCallback(override val nameHashing: Boolean = false) extends AnalysisCallback
[error]       ^
[error] one error found

Assuming this error is fixed, this looks good to me.

@eed3si9n, I'm wondering if we could always include synthetic names. I haven't found a good reason to not to include them. What do you think?

@gkossakowski I can flip the switch and have it on by default. I thought we are concerned that changing apply could cascade into compiling all sources because everyone uses apply.

So maybe does it make sense to add the possibility to specify the list of names which won't be included? It would be only the half-measure, I think, but it anyway may be worth to have it for the test purposes.

@mpociecha For now let's keep it simple on or off, and we can fine tune this more in sbt/zinc for 1.0, which will have synthetic methods included by default.

Note that including synthetic members is not enough, you should also include synthetic classes (which are currently ignored), consider:

case class A(x: Int)
// private object A

object B {
  A(0) // should stop compiling when the private object line is uncommented
}

Forward port in sbt/zinc#110, with a breaking change for 1.0.