SI-7402 List extends Serializable

While we are all aware of the issues around Serialization,
I think in this case it is perfectly sound and safe to make
List serializable:

- List is not an interface, it is the base type of an ADT.
  Common behavior of its members should be reflected in the base type.
- List is sealed, there is no chance of an user providing a new
  non-serializable subtype of List.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/library/scala/collection/immutable/List.scala b/src/library/scala/collection/immutable/List.scala
index be233d06cb..f3559f7d26 100644
--- a/src/library/scala/collection/immutable/List.scala
+++ b/src/library/scala/collection/immutable/List.scala
@@ -85,7 +85,8 @@ sealed abstract class List[+A] extends AbstractSeq[A]
                                   with LinearSeq[A]
                                   with Product
                                   with GenericTraversableTemplate[A, List]
-                                  with LinearSeqOptimized[A, List[A]] {
+                                  with LinearSeqOptimized[A, List[A]]
+                                  with Serializable {
   override def companion: GenericCompanion[List] = List
 
   import scala.collection.{Iterable, Traversable, Seq, IndexedSeq}