scalac 2.11 regression. Scalac is not honouring the SerialVersionUID annotation

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Compiling this code:

package test

@SerialVersionUID(1)
class Ser extends Serializable

using 2.10 and then running the following:

object Main extends App {
  println( classOf[test.Ser].getDeclaredField("serialVersionUID") )
}

Will print public static final long test.Ser.serialVersionUID

However, compiling the same with 2.11 gives a NoSuchFIeldException

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Imported From: https://issues.scala-lang.org/browse/SI-8549?orig=1
Reporter: @oxbowlakes
Affected Versions: 2.11.0

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@oxbowlakes said:
I can see that this has affected scala library classes as well. This is a terrrible regression!

Welcome to Scala version 2.10.2 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_45).
Type in expressions to have them evaluated.
Type :help for more information.

scala> Nil.getClass.getDeclaredField("serialVersionUID").get(null)
res0: Object = -8256821097970055419

But with 2.11

Welcome to Scala version 2.11.0 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_45).
Type in expressions to have them evaluated.
Type :help for more information.

scala> Nil.getClass.getDeclaredField("serialVersionUID").get(null)
java.lang.NoSuchFieldException: serialVersionUID
  at java.lang.Class.getDeclaredField(Class.java:1948)
  ... 32 elided

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@retronym said:
Regressed in scala/scala#1673

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@oxbowlakes said:
It strikes me that you're in a dilemma here. Are the serialization IDs of things like Nil part of the "binary compatibility" of scala to be kept between minor versions? If so, there's a task to retrofit the new-and-incorrect IDs onto the source for 2.11.1

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@retronym said:
You read my mind. I've tabled the options in your thread: https://groups.google.com/forum/#!topic/scala-user/lauGrJItfX4

I am leaning towards retrofitting. I believe I can automate the process so we don't miss any.

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@paulp said:
For what it's worth it has previously been decreed that "binary compatibility does not cover serialization" in #5697.

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@paulp said:
Also it would appear scala/scala#1673 was intended to fix #6988 but that ticket is still open. Actually no, the commit is Nov 2012 but the ticket was opened in Jan 2013.

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@oxbowlakes said:
(Duplicating comment from ML):

Also note that for any non-trivial scala project which uses serialization, then doing trying to make SerialUIDs consistent in the scala library between 2.11.0/1 is pretty useless unless all library dependencies (which include serialized classes) also follow this route. For example, if I'm using akka, an ActorRef is serializable (see SerializedActorRef at https://github.com/akka/akka/blob/master/akka-actor/src/main/scala/akka/actor/ActorRef.scala): they may have to do exactly the same.

It seems unlikely that all my dependencies are going to "fix" their codebase's Serial IDs, so it's really unlikely that my non-trivial scala project is actually going to end up being really binary+serialization-compatible for 2.11.0/1.

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@retronym said:
scala/scala#3711

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@retronym said:
Reopening to track the partial reversion of the serialization stability test case here: scala/scala#3739