add test case for unapply return false

Author: liufengyun

tests/pos/i4226b.scala

@@ -0,0 +1,15 @@
+sealed abstract class Maybe[A]
+final case class Just[A](a: A) extends Maybe[A]
+class Empty[A] extends Maybe[A]
+object Empty {
+  def apply[A](): Maybe[A] = new Empty[A]
+  def unapply[A](e: Empty[A]): false = false
+}
+
+object Test {
+  val a: Maybe[Int] = Just(2)
+  def main(args: Array[String]): Unit = a match {
+    case Just(2) => true
+    case Empty() =>
+  }
+}