annot-nonconst.scala:1: warning: implementation restriction: subclassing Classfile does not
make your annotation visible at runtime.  If that is what
you want, you must write the annotation class in Java.
class Length(value: Int) extends ClassfileAnnotation
      ^
annot-nonconst.scala:5: error: annotation argument needs to be a constant; found: n
  @Length(n) def foo = "foo"
          ^
one warning found
one error found