Tasty UUID test is an error in Scala 2.13 and a warning in Scala 3

[jjudd]

I noticed that in Scala 2.13 the Tasty UUID check is an error: https://github.com/scala/scala/blob/2.13.x/src/compiler/scala/tools/nsc/symtab/classfile/ClassfileParser.scala#L1268

In Scala 3 it was changed from an error to a warning: https://github.com/lampepfl/dotty/blob/master/compiler/src/dotty/tools/dotc/core/classfile/ClassfileParser.scala#L955

The change In Scala 3 happened in this issue: scala/scala3#8839

To me, this difference seems like a bug. I'm curious if the same change should be made on the Scala 2.13 side? I'm happy to make the change if people are open to it being made.

I ask because I think I'm running into 8839 from the 2.13 side in a codebase which has both 2.13 and 3 code that utilizes Scala 2<->3's backwards and forwards compatibility. I'm running the compilers standalone. Eventually, after building and killing builds one or many times, this error tends to show up.

I'm also happy to be wrong and to not be running into 8839.

[SethTisue]

@bishabosha opinion?

[bishabosha]

I think it would be reasonable to replicate Scala 3 here

[jjudd]

Sounds like a plan. I replicated the change from Scala 3 to the Scala 2.13.x branch in this PR: scala/scala#9755