A.scala:

class A(a: Int) // change Int to String, B.scala should not be recompiled
object A { val x = 3 }

B.scala:

class B { val y = A.x }

B does not use the constructor of A, but every constructor has the same name <init>, so if we change a constructor in a class, then all dependencies of that class are inevitably recompiled. This should be easy to fix: just special case constructors and prepend the class name to the method name, like A<init>, B<init>.

(Note that this change will break value-class-underlying if #95 gets merged (see the PR description), this can be fixed by including the underlying val of a value class in its name hash)