Avoid dealiasing on type application

When applying a type alias of a type lambda, keep the original
application instead of reducing. But reduce anyway if

 - the reduced type is an application where the type
   constructor has the same kind as the original type constructor, or
 - some of the arguments are wildcards.

4 files changed, 14 insertions, 13 deletions

diff --git a/tests/neg/boundspropagation.scala b/tests/neg/boundspropagation.scala
index b545b09da..dd4ebf513 100644
--- a/tests/neg/boundspropagation.scala
+++ b/tests/neg/boundspropagation.scala
@@ -40,5 +40,5 @@ object test4 {
 }
 
 class Test5 {
-"": ({ type U = this.type })#U                        // error // error
+"": ({ type U = this.type })#U                        // error
 }
diff --git a/tests/neg/i94-nada.scala b/tests/neg/i94-nada.scala
deleted file mode 100644
index 8ca104e06..000000000
--- a/tests/neg/i94-nada.scala
+++ /dev/null
@@ -1,11 +0,0 @@
-trait Test1 {
-  trait Monad[MX] {
-    def x: MX
-  }
-  sealed abstract class Either[A,B]
-  case class Left[A,B](x: A) extends Either[A,B] with Monad[A]
-  case class Right[A,B](x: B) extends Either[A,B] with Monad[B]
-  def flatMap[FX,FY,M[FMX]<:Monad[FMX]](m: M[FX], f: FX => M[FY]): M[FY] = f(m.x)
-  println(flatMap(Left(1), {x: Int => Left(x)})) // error: Left does not conform to [X] -> Monad[X]
-
-}
diff --git a/tests/pos/i94-nada.scala b/tests/pos/i94-nada.scala
index 1c7d88a10..2c3cf895c 100644
--- a/tests/pos/i94-nada.scala
+++ b/tests/pos/i94-nada.scala
@@ -35,7 +35,7 @@ trait Test2 {
   case class Left[A,B](x: A) extends Either[A,B] with Monad[A]
   case class Right[A,B](x: B) extends Either[A,B] with Monad[B]
   def flatMap[X,Y,M[X]](m: M[X], f: X => M[Y]): M[Y]
-  println(flatMap(Right(1), {x: Int => Right(x)}))
+  println(flatMap(Left(1), {x: Int => Left(x)}))
 }
 trait Test3 {
   def flatMap[X,Y,M[X]](m: M[X], f: X => M[Y]): M[Y]
diff --git a/tests/pos/t2712-6.scala b/tests/pos/t2712-6.scala
new file mode 100644
index 000000000..dbba60472
--- /dev/null
+++ b/tests/pos/t2712-6.scala
@@ -0,0 +1,12 @@
+package test
+
+object Tags {
+  type Tagged[A, T] = {type Tag = T; type Self = A}
+
+  type @@[T, Tag] = Tagged[T, Tag]
+
+  trait Disjunction
+
+  def meh[M[_], A](ma: M[A]): M[A] = ma
+  meh(null: Int @@ Disjunction)//.asInstanceOf[Int @@ Disjunction])
+}