Add minimized test

Author: liufengyun

tests/pos-special/isInstanceOf/i9782.scala

@@ -0,0 +1,15 @@
+trait Txn[T <: Txn[T]]
+
+trait Elem[T <: Txn[T]]
+
+trait Obj[T <: Txn[T]] extends Elem[T]
+
+class Test {
+
+  def apply[Repr[~ <: Txn[~]] <: Elem[~], In <: Txn[In]](in: Repr[In]): Unit = {
+    in match {
+      case inObj: Obj[In] =>     // problem here
+      case _ =>
+    }
+  }
+}