Fix tests

Author: liufengyun

compiler/src/dotty/tools/dotc/typer/Typer.scala

@@ -1396,7 +1396,7 @@ class Typer extends Namer
 
                 // skip exhaustivity check in later phase
                 // TODO: move the check above to patternMatcher phase
-                val uncheckedTpe = AnnotatedType(sel.tpe, Annotation(defn.UncheckedAnnot))
+                val uncheckedTpe = AnnotatedType(sel.tpe.widen, Annotation(defn.UncheckedAnnot))
                 tpd.cpy.Match(result)(
                   selector = tpd.Typed(sel, tpd.TypeTree(uncheckedTpe)),
                   cases = result.cases

tests/run/unchecked-patterns.scala

@@ -1,6 +1,6 @@
 object Test extends App {
   val x: Int = 2: @unchecked
-  val (y1: Some[Int]) = Some(1): Option[Int]: @unchecked
+  val (y1: Some[Int]) = Some(1): Option[Int] @unchecked
 
   val a :: as = List(1, 2, 3): @unchecked
   val lst @ b :: bs = List(1, 2, 3): @unchecked