Enable Mima for native build

[ashawley]

There are native artifacts to compare, now.

[SethTisue]

Is it actually meaningful to do this?

[ashawley]

I suppose not. We don't have any Scala native specific code at the moment. If it seems unnecessary we can keep it disabled. That's fine with me.

[SethTisue]

@dwijnand is there any case for doing this? like even if we had Scala Native specific code, MiMa only checks .class files for them, so perhaps checking those is some kind of proxy for some kind of bincompat? iirc Scala.js always generates .class files anyway (for some reason I've heard Seb give and then forgot)

[dwijnand]

I don't think so. I don't see why it wouldn't be some kind of proxy for some false positives. I don't know enough about what Scala Native emits and how the dependencies link together to talk intelligently, but I don't see anything helpful being achieved with this change.

[ashawley]

I always assumed Mima was unable to grok actual compatibility for non-Java targets (Scala.js and native). Having Mima at least check that something didn't unexpectedly go missing because of an innocuous build change still seems worthwhile. It's not uncommon for libraries to have to compile and ship different source directories for certain versions of Scala or code target. As I said, scala-xml doesn't have any of those bits at the moment for native, but it seems like a good safety to have.

[SethTisue]

I'm okay with enabling it but I would suggest including a comment referencing this discussion.

[ashawley]

Ok, will do.