Deprecated the @serializable annotation, introd...

Deprecated the @serializable annotation, introduce a new trait
"scala.Serializable" which has to be extended instead (cross-platform).

Known issues:
 - Companion objects of serializable classes (including case classes) are automatically made serializable. However, they don't extend "Serializable" statically because of the known difficulty (should be done before typing, but hard).
 - Writing "case class C() extends Serializable" gives "error: trait Serializable is inherited twice"
 - Functions are serializable, but don't extend Serializable dynamically (could be fixed by making FunctionN Serializable - shouldn't we?)

Note that @SerialVersionUID continues to be an annotation; it generates
a static field, which is not possible otherwise in scala.

Review by dragos, extempore.

Question to dragos: in JavaPlatform.isMaybeBoxed, why is there a test
for "JavaSerializableClass"? Is that correct?

1 files changed, 7 insertions, 1 deletions

diff --git a/src/compiler/scala/tools/nsc/typechecker/Typers.scala b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
index 33db7424bc..03c5d2958c 100644
--- a/src/compiler/scala/tools/nsc/typechecker/Typers.scala
+++ b/src/compiler/scala/tools/nsc/typechecker/Typers.scala
@@ -1337,10 +1337,16 @@ trait Typers { self: Analyzer =>
         for (c <- linkedClass.info.decl(nme.CONSTRUCTOR).alternatives)
           c.initialize
       val clazz = mdef.symbol.moduleClass
+      val maybeAddSerializable = (l: List[Tree]) =>
+        if(linkedClass == NoSymbol || !linkedClass.isSerializable || clazz.isSerializable) l
+        else {
+          clazz.makeSerializable()
+          l ::: List(TypeTree(SerializableClass.tpe))
+        }
       val typedMods = removeAnnotations(mdef.mods)
       assert(clazz != NoSymbol)
       val impl1 = newTyper(context.make(mdef.impl, clazz, new Scope))
-        .typedTemplate(mdef.impl, parentTypes(mdef.impl))
+        .typedTemplate(mdef.impl, maybeAddSerializable(parentTypes(mdef.impl)))
       val impl2 = typerAddSyntheticMethods(impl1, clazz, context)
 
       if (mdef.name == nme.PACKAGEkw)