DivergenceTest.scala

package foo.bar.baz

class DivergenceTest {

  trait ColumnBase[T]

  trait ShapeLevel
  trait Flat extends ShapeLevel

  class Shape2[Level <: ShapeLevel, -M, U]

  implicit final def columnBaseShape[Level >: Flat <: ShapeLevel, T, C <: ColumnBase[_]](implicit ev: C <:< ColumnBase[T]): Shape2[Level, C, T] = ???
  implicit final def intShape[Level <: ShapeLevel, T]: Shape2[Level, Int, Int] = ???
  implicit final def tuple2Shape[Level <: ShapeLevel, M1,M2, U1,U2](implicit u1: Shape2[_ <: Level, M1, U1], u2: Shape2[_ <: Level, M2, U2]): Shape2[Level, (M1,M2), (U1,U2)] = ???

  def foo {
    class Coffees extends ColumnBase[Int]

    def map1[F, T](f: F)(implicit shape: Shape2[_ <: Flat, F, T]) = ???

    map1(((1, null: Coffees), 1))
    map1(((null: Coffees, 1), 1)) // fails
  }
}