Hi 👋 . Looks like compiling a native lib with 1.7 requires consuming it with 1.7 (or we get a

Incompatible abi version

) 1. is that true? 2. could we allow consumption with 1.6 by adding

languageVersion = "1.6"

when compiling? Looks like this works for JVM but not for native?

I believe this is what

kotlin.mpp.enableCompatibilityMetadataVariant=true

takes care of. See docs here.

I thought that's for hmpp which changed defaults with 1.6.20

Yea, I was expecting

enableCompatibilityMetadataVariant

to be more about the metadata than the abi but I'll investigate

https://kotlinlang.org/docs/components-stability.html still has native klibs as "alpha stability" so I don't think there's a promise of cross-version compatibility

That sounds reasonable.

There's not a guarantee of backward compatibility for Kotlin/Native but it has been provided experimentally since 1.4. Not sure how that plays into

languageVersion

though. https://youtrack.jetbrains.com/issue/KT-42293

Exactly, the question is whether a newer compiler can generate a binary that uses the older format. JVM can do it with

languageVersion

but looks like native can't

It might be worth asking in that ticket to clarify if that's expected to work or not (and whether it's on the roadmap otherwise)

It's not too much of an issue right now as K/N users usually upgrade quite fast but as the ecosystem matures it could be handy

yeah it's not one I think about as much as I probably should, but it'd be nice to get to the point where we have well-defined best practices around that sort of compatibility.

I guess the question would be whether backwards compatibility exists in language versions or would need to be supported first. That might be the main hurdle while things are changing quickly in Kotlin/Native, probably more difficult to support than not.