CCE with enum value serialization, only with -Dpartest.exec.in.process

[lrytz]

Current 2.13.x, with a test re-enabled (was disabled in https://github.com/scala/scala/pull/6676/files#diff-e24063c0aa9e2f16a3cffeb86a736d90)

➜  scala13 git:(2.13.x) ✗ git diff | cat
diff --git a/test/files/run/enums.scala b/test/files/run/enums.scala
index b4e8e523db..164874634f 100644
--- a/test/files/run/enums.scala
+++ b/test/files/run/enums.scala
@@ -119,7 +119,7 @@ object SerializationTest {

   def run: Unit = {
     /* This is no longer possible with the proxy-based serialization for collections: */
-    //serialize(new B())
+    serialize(new B())
     serialize(new A())
   }
 }

➜  scala13 git:(2.13.x) ✗ sbt
> partest test/files/run/enums.scala --show-log
!! 1 - run/enums.scala                           [output differs]
java.lang.ClassCastException: cannot assign instance of scala.collection.generic.DefaultSerializationProxy to field SerializationTest$B.types of type scala.collection.immutable.Set in instance of SerializationTest$B
	at java.io.ObjectStreamClass$FieldReflector.setObjFieldValues(ObjectStreamClass.java:2233)

> set (javaOptions in test in IntegrationTest) := (javaOptions in test in IntegrationTest).value.filterNot(_.contains("exec.in.process"))

> partest test/files/run/enums.scala
ok 1 - run/enums.scala

Compiling and running the test on the command line also succeeds. We should figure out what's going on here.

[szeiger]

It's probably an instance of #9237. Running with partest.exec.in.process puts the test classes into a different ClassLoader than the standard library so you get circular dependencies between the classloaders on deserialization. When you run it standalone everything is in the same classloader.

[lrytz]

Ah, that makes sense, thanks.

[szeiger]

Closing as duplicate of #9237