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.

1 files changed, 12 insertions, 0 deletions

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])
+}