Fix #4147: Add test case

18ce5d2 fixed it.

Author: smarter

tests/pos/i4147.scala

@@ -0,0 +1,10 @@
+trait Higher[F[_]]
+trait Super[A]
+trait Sub[A] extends Super[A]
+
+object Test {
+  implicit def higherSub: Higher[Sub] = ???
+  implicit def deriv[F[_]](implicit bla: Higher[F]): F[String] = ???
+
+  val x: Super[String] = deriv
+}