Compiler error when mocking classes with generics

[barkhorn]

worked in 3.4.2, broken in 3.5.0

real example:

      class MockableBroadcast[T: ClassTag] extends org.apache.spark.broadcast.Broadcast[T](42L) {
        override protected def getValue(): Nothing = ???
        override protected def doUnpersist(blocking: Boolean): Unit = ???
        override protected def doDestroy(blocking: Boolean): Unit = ???
      }
      val lookup= mock[MockableBroadcast[Map[String, Long]]]

minified example:

      class Foo[T: ClassTag]
      val mf = mock[Foo[Nothing]]

compiler error:

Error:(55, 20) type mismatch;
 found   : scala.reflect.ClassTag[T]
 required: scala.reflect.ClassTag[Nothing]
Note: T >: Nothing, but trait ClassTag is invariant in type T.
You may wish to investigate a wildcard type such as `_ >: Nothing`. (SLS 3.2.10)
      val mf = mock[Foo[Nothing]]

[barkhorn]

cause: changes to MockMaker.initDef in e07cca3

[barkhorn]

ScalaMock/core/shared/src/main/scala/org/scalamock/clazz/MockMaker.scala

Line 222 in 88504cc

symbols => symbols.map(_.typeSignatureIn(constructorTypeContext))

typeSignatureIn returns the parameter T, not the materialised type (e.g. Int)

[barkhorn]

Bit stuck on this one, so I asked at https://stackoverflow.com/questions/42044540/obtaining-the-realised-type-for-a-scala-class-using-macros and gitter

[barkhorn]

very stuck, the solution with .dealias is more difficult to implement than I thought. Also MockAdapter for 2.10 redirects this to .normalize

[kell18]

Hello, is there maybe any workaround for this one? It's quite painful... Thanks!

[kell18]

Okay, I found workaround, you need to specify all the types (including _ in F[_]) explicitly by creating another class which extends from the generic one