avoid new exhaustive match warnings in 2.13.4

Author: SethTisue

core/src/main/scala/scala/collection/immutable/TrieIterator.scala

@@ -45,12 +45,12 @@ private[collection] abstract class TrieIterator[+T](elems: Array[Iterable[T]]) e
   private[this] var posD                                      = initPosD
   private[this] var subIter                                   = initSubIter
 
-  private[this] def getElems(x: Iterable[T]): Array[Iterable[T]] = (x match {
+  private[this] def getElems(x: Iterable[T]): Array[Iterable[T]] = ((x: @unchecked) match {
     case x: HashTrieMap[_, _] => x.elems
     case x: HashTrieSet[_]    => x.elems
   }).asInstanceOf[Array[Iterable[T]]]
 
-  private[this] def collisionToArray(x: Iterable[T]): Array[Iterable[T]] = (x match {
+  private[this] def collisionToArray(x: Iterable[T]): Array[Iterable[T]] = ((x: @unchecked) match {
     case x: OldHashMapCollision1[_, _] => x.kvs.map((x: (Any, Any)) => OldHashMap(x)).toArray
     case x: OldHashSetCollision1[_]    => x.ks.map(x => OldHashSet(x)).toArray
   }).asInstanceOf[Array[Iterable[T]]]

core/src/main/scala/scala/collection/parallel/ParIterableLike.scala

@@ -1381,7 +1381,7 @@ extends IterableOnce[T @uncheckedVariance]
 
   protected[this] def scanBlockSize = (thresholdFromSize(size, tasksupport.parallelismLevel) / 2) max 1
 
-  protected[this] trait ScanTree[U >: T] {
+  protected[this] sealed trait ScanTree[U >: T] {
     def beginsAt: Int
     def pushdown(v: U): Unit
     def leftmost: ScanLeaf[U]

core/src/main/scala/scala/collection/parallel/mutable/ParTrieMap.scala

@@ -79,7 +79,7 @@ extends ParMap[K, V]
   override def size = {
     val in = ctrie.readRoot()
     val r = in.gcasRead(ctrie)
-    r match {
+    (r: @unchecked) match {
       case tn: TNode[_, _] => tn.cachedSize(ctrie)
       case ln: LNode[_, _] => ln.cachedSize(ctrie)
       case cn: CNode[_, _] =>
@@ -102,7 +102,7 @@ extends ParMap[K, V]
       var i = offset
       val until = offset + howmany
       while (i < until) {
-        array(i) match {
+        (array(i): @unchecked) match {
           case sn: SNode[_, _] => sz += 1
           case in: INode[K @unchecked, V @unchecked] => sz += in.cachedSize(ctrie)
         }

testmacros/src/main/scala-2/testutil/ShouldNotTypecheck.scala

@@ -29,8 +29,8 @@ object ShouldNotTypecheck {
   def applyImpl(ctx: Context)(code: ctx.Expr[String], expected: ctx.Expr[String]): ctx.Expr[Unit] = {
     import ctx.universe._
 
-    val Expr(Literal(Constant(codeStr: String))) = code
-    val (expPat, expMsg) = expected match {
+    val Expr(Literal(Constant(codeStr: String))) = code: @unchecked
+    val (expPat, expMsg) = (expected: @unchecked) match {
       case null => (null, "Expected some error.")
       case Expr(Literal(Constant(s: String))) =>
         (Pattern.compile(s, Pattern.CASE_INSENSITIVE | Pattern.DOTALL), "Expected error matching: "+s)