Steve Lawrence created DAFFODIL-3073:
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Summary: Use of varargs in serialized classes can lead to reload
incompatablities
Key: DAFFODIL-3073
URL: https://issues.apache.org/jira/browse/DAFFODIL-3073
Project: Daffodil
Issue Type: Bug
Components: Front End
Reporter: Steve Lawrence
Fix For: 4.2.0
Daffodil implements saved parsers by just serializing the DataProcessor.
Although Scala guarantees binary compatibility, it does not guarantee
serialization compatibility. This means that if you serialize a saved processor
using one version of Scala and try to reload it on another version of scala,
it's possible things could break. In practice, this doesn't seem to break
things with Daffodil usage of the scala library and things we happen to
serialize--most classes we use are written to be compatible.
One type where this isn't the case is with scala's ArraySeq. This type does not
implement serialVersionUID so any changes to the class could lead to a new UID
and incompatibilities.
We don't intentionally use ArraySeq directly in any of our serialized classes,
but scala implements vararg using ArraySeq. For example, if you have this class:
{code:scala}
class Foo(args: Type*) \{ ... }
{code}
And try to serialize it, you will end up with serialized ArraySeq.
We do use this in one specific place, in CompiledDPath:
{code}
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