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?

6 files changed, 50 insertions, 28 deletions

diff --git a/test/files/jvm/serialization.scala b/test/files/jvm/serialization.scala
index b16d46adad..2e34079505 100644
--- a/test/files/jvm/serialization.scala
+++ b/test/files/jvm/serialization.scala
@@ -40,7 +40,6 @@ object Test1_scala {
     (a1.length == a2.length) &&
     (Iterator.range(0, a1.length) forall { i => a1(i) == a2(i) })
 
-  @serializable
   object WeekDay extends Enumeration {
     type WeekDay = Value
     val Monday, Tuesday, Wednesday, Thusday, Friday, Saturday, Sunday = Value
@@ -187,7 +186,6 @@ object Test1_scala {
 //############################################################################
 // Test classes in package "scala.collection.immutable"
 
-@serializable
 object Test2_immutable {
   import scala.collection.immutable.{
     BitSet, HashMap, HashSet, ListMap, ListSet, Queue, Range, SortedMap,
@@ -353,10 +351,6 @@ object Test3_mutable {
     val _hs1: HashSet[String] = read(write(hs1))
     check(hs1, _hs1)
 
-    // History
-    @serializable
-    class Feed extends Publisher[String]
-
     val h1 = new History[String, Int]
     val _h1: History[String, Int] = read(write(h1))
     check(h1, _h1)
@@ -373,8 +367,6 @@ object Test3_mutable {
     val _lb1: ListBuffer[String] = read(write(lb1))
     check(lb1, _lb1)
 
-    // Publisher
-
     // Queue
     val q1 = new Queue[Int]
     q1 ++= List(20, 2, 3).iterator
@@ -471,8 +463,7 @@ object Test4_xml {
 //############################################################################
 // Test user-defined classes WITHOUT nesting
 
-@serializable
-class Person(_name: String) {
+class Person(_name: String) extends Serializable {
   private var name = _name
   override def toString() = name
   override def equals(that: Any): Boolean =
@@ -480,12 +471,11 @@ class Person(_name: String) {
     (name == that.asInstanceOf[Person].name)
 }
 
-@serializable
-class Employee(_name: String) {
+class Employee(_name: String) extends Serializable {
   private var name = _name
   override def toString() = name
 }
-@serializable
+
 object bob extends Employee("Bob")
 
 object Test5 {
@@ -508,13 +498,10 @@ object Test5 {
 //############################################################################
 // Test user-defined classes WITH nesting
 
-@serializable
 object Test6 {
-  @serializable
   object bill extends Employee("Bill") {
     val x = paul
   }
-  @serializable
   object paul extends Person("Paul") {
     val x = 4  //  bill; => StackOverflowException !!!
   }
@@ -540,11 +527,8 @@ object Test6 {
 //############################################################################
 // Nested objects cannot get readresolve automatically because after deserialization
 // they would be null (they are treated as lazy vals)
-@serializable
-class Outer {
-
-    @serializable
-    object Inner
+class Outer extends Serializable {
+    object Inner extends Serializable
 }
 
 object Test7 {
@@ -564,11 +548,10 @@ object Test7 {
 
 
 // Verify that transient lazy vals don't get serialized
-@serializable
-class WithTransient {
+class WithTransient extends Serializable {
   @transient lazy val a1 = 1
   @transient private lazy val a2 = 2
-  @transient @serializable object B
+  @transient object B extends Serializable
 
   def test = {
     println(a1)
diff --git a/test/files/pos/t3924.scala b/test/files/pos/t3924.scala
new file mode 100644
index 0000000000..35165baaf0
--- /dev/null
+++ b/test/files/pos/t3924.scala
@@ -0,0 +1,6 @@
+object Test {
+  class Hoe extends Serializable {
+    def add(a: java.io.Serializable): Unit = println(a)
+    def someMethod() { add(this) }
+  }
+}
diff --git a/test/files/run/t3667.check b/test/files/run/t3667.check
index 01e79c32a8..bbe5d1bc48 100644
--- a/test/files/run/t3667.check
+++ b/test/files/run/t3667.check
@@ -1,3 +1,6 @@
 1
 2
 3
+4
+2
+3
diff --git a/test/files/run/t3667.scala b/test/files/run/t3667.scala
index 7bd0b4ec5e..f30d57ce3a 100644
--- a/test/files/run/t3667.scala
+++ b/test/files/run/t3667.scala
@@ -3,6 +3,9 @@ object Test {
     val o1 = new Outer1
     val o2 = new Outer2
     val o3 = new Outer3
+    val o4 = new Outer4
+    val o5 = new Outer5
+    val o6 = new Outer6
 
     println(1)
     ser(new o1.Inner(1))
@@ -19,6 +22,21 @@ object Test {
     o3.Inner
     ser(new o3.Inner(1))
 
+    println(4)
+    ser(new o4.Inner(1))
+    o4.Inner
+    ser(new o4.Inner(1))
+
+    println(2)
+    ser(new o5.Inner(1))
+    o5.Inner
+    ser(new o5.Inner(1))
+
+    println(3)
+    ser(new o6.Inner(1))
+    o6.Inner
+    ser(new o6.Inner(1))
+
     foo
   }
 
@@ -51,3 +69,16 @@ class Outer2 {
 class Outer3 {
   case class Inner(x: Int)
 }
+
+
+class Outer4 extends Serializable {
+  class Inner(x: Int = 1) extends Serializable
+}
+
+class Outer5 extends Serializable {
+  case class Inner(x: Int = 1)
+}
+
+class Outer6 extends Serializable {
+  case class Inner(x: Int)
+}
diff --git a/test/files/scalap/caseClass/result.test b/test/files/scalap/caseClass/result.test
index eb1ad74295..9b65be4b48 100644
--- a/test/files/scalap/caseClass/result.test
+++ b/test/files/scalap/caseClass/result.test
@@ -1,5 +1,4 @@
-@scala.serializable
-case class CaseClass[A <: scala.Seq[scala.Int]](i : A, s : scala.Predef.String) extends java.lang.Object with scala.ScalaObject with scala.Product {
+case class CaseClass[A <: scala.Seq[scala.Int]](i : A, s : scala.Predef.String) extends java.lang.Object with scala.ScalaObject with scala.Product with scala.Serializable {
   val i : A = { /* compiled code */ }
   val s : scala.Predef.String = { /* compiled code */ }
   def foo : scala.Int = { /* compiled code */ }
@@ -11,4 +10,4 @@ case class CaseClass[A <: scala.Seq[scala.Int]](i : A, s : scala.Predef.String)
   override def productArity : scala.Int = { /* compiled code */ }
   override def productElement(x$1 : scala.Int) : scala.Any = { /* compiled code */ }
   override def canEqual(x$1 : scala.Any) : scala.Boolean = { /* compiled code */ }
-}
\ No newline at end of file
+}
diff --git a/test/files/scalap/caseObject/result.test b/test/files/scalap/caseObject/result.test
index d888191919..d4e90a0375 100644
--- a/test/files/scalap/caseObject/result.test
+++ b/test/files/scalap/caseObject/result.test
@@ -1,4 +1,4 @@
-case object CaseObject extends java.lang.Object with scala.ScalaObject with scala.Product {
+case object CaseObject extends java.lang.Object with scala.ScalaObject with scala.Product with scala.Serializable {
   def bar : scala.Int = { /* compiled code */ }
   final override def toString() : java.lang.String = { /* compiled code */ }
   override def productPrefix : java.lang.String = { /* compiled code */ }