What to do about the Scala 3-specific artifact?

[sjrd]

We merged support for Scala 3 in #450. The question is now: what do we do about the Scala 3-specific artifacts of scalajs-dom?

If we release a version 1.2.0 with a new artifacts for _sjs1_3, we can create problems in the binary ecosystem:

• There can be a library A compiled against the _2.13 artifact of scalajs-dom 1.1.0
• And a library a B compiled against the _3 artifact of scalajs-dom 1.2.0

Mixing A and B in the same project will cause both scalajs-dom_2.13 v1.1.0 and scalajs-dom_3 v1.2.0 to be on the classpath. This can cause serious issues.

There are two solutions, IMO:

• Not release the _3 artifact. After all, it does not bring any actual value compared to the _2.13 artifact at the moment. Users will still have to declare their dependency on scalajs-dom using .cross(CrossVersion.for3Use2_13), as they currently do.
• Bump to scalajs-dom 2.0.0, clearly advertising that there is binary conflict with the previous versions of scalajs-dom.

@gzm0 Any opinion?

Anyone else?

[Daenyth]

I'd say that anything normal developers run into that advises them to use for3Use2_13 is undesirable. Bumping the version seems fine.

[gzm0]

Maybe I'm missing something here, but is anything of this specific to scala-js-dom? Feels like the argument above applies to any Scala library that is Scala 2 and 3 compatible.

[sjrd]

Yes, it applies to any Scala library that

• Had a period where its 2.13 artifact was used by Scala 3
• Now wants to publish a real artifact for Scala 3

It seems most library maintainers just pretend that there is no issue. They release a _3 artifact in a minor (or even patch) release.

[armanbilge]

See also: https://gist.github.com/djspiewak/b8f2b4547951442102488964bc351cf9#5-dont-rely-on-withdottycompat

[sjrd]

Daniel Spiewak's advice is harsh precisely because library maintainers have been doing willy-nilly releases of _3 artifacts in random versions. His advice does not hold if we correctly acknowledge and deal with the issue.

[armanbilge]

I do see your point, but as far as I can tell (in my limited experience) this is just deferring an inevitably necessary change which risks increasing downstream pain.

[SethTisue]

Might as well rip the bandaid off IMO

I guess I see for3Use2_13 as temporary, transitional, experimental stuff where as soon as it enters the picture, buyer beware.

So the best thing is to make it unnecessary, one library at a time, and do it as soon as possible.

(I'm agreeing with Arman.)

[sjrd]

So, apparently I am getting flagged down to death here with my controversial opinions, so I guess we'll just bump it to 2.0.0.

[larsrh]

because library maintainers have been doing willy-nilly releases of _3 artifacts in random versions

Speaking for Typelevel, nothing could be further from the truth.

[gzm0]

Huh? That is not how I interpret #451 (comment). From the link:

In other words, treat this like a "normal" breaking Scala update. Try to forget that withDottyCompat exists, because for most intents and purposes, it doesn't exist.

The way I understand this: 2.13 -> 3 is no different than 2.12 -> 2.13. So simply publish _3 for the first version you support it and be done.

FWIW: It seems that bumping to 2.0.0 only improves the situation you describe marginally: The dependency resolver will flag it, but it will still not work.

Another way of looking at this, isn't really the library that introduces a _2.13 / _3 dependency (without appropriate flagging, I do not know how the whole dotty compatibility system works) the culprit?

[sjrd]

The way I understand this: 2.13 -> 3 is no different than 2.12 -> 2.13. So simply publish _3 for the first version you support it and be done.

It's different because using 2.12 from 2.13 simply never worked, never works and will never work. However, it is perfectly possible to use 2.13 from 3 and conversely.

FWIW: It seems that bumping to 2.0.0 only improves the situation you describe marginally: The dependency resolver will flag it, but it will still not work.

Yes, clearly. It's a major version bump to make it clear that it will not work. It doesn't solve anything.

Another way of looking at this, isn't really the library that introduces a _2.13 / _3 dependency (without appropriate flagging, I do not know how the whole dotty compatibility system works) the culprit?

Only if we say that publishing anything that uses for3Use2_13 or for2_13Use3 is a reason for a library to be blamed. If we allow libraries to be published like that, then it was in its right to do so.

It's possible that the consensus among maintainers was that publishing such a library is bad. If that is the case, then we can start publishing for _3 in a minor version, clearly.

[SethTisue]

So, apparently I am getting flagged down to death here with my controversial opinions

Well, we still love you anyway :-)

Perhaps we can re-conceive/re-market “willy-nilly” as, rather, “freedom” 🇺🇸 and/or “diversity” 🏳️‍🌈