$ copy-file changes/A0.scala A.scala

# compile and run for the first time to verify that everything works
> run

# introduce private var and refer to it in a trait that we inherit from
# there'll be pair of getters and setters generated for private var that
# has to be implemented by a class (where you can declare corresponding field)
$ copy-file changes/A1.scala A.scala

# If the introduction of a private var did not trigger the recompilation of B,
# then this will fail with AbstractMethodError because the getters and setters
# for the private var have not been generated.
> run

# Try again with a private val
> clean

$ copy-file changes/A0.scala A.scala

# compile and run a clean project to verify that everything works
> run

# introduce a private val in the trait
$ copy-file changes/A2.scala A.scala

# Verify that B has been recompiled and that everything runs fine.
> run