tlVersionIntroduced as a function of scalaVersion

[rossabaker]

Modules get introduced in different versions for different crossbuilds. sbt-spiewak takes a function of Scala versions to version introduced:

    versionIntroduced := Map(
      "3.0.0-RC1" -> "1.0.0",
      "3.0.0-RC2" -> "1.0.1",
      "3.0.0-RC3" -> "1.1.3"
    ),

I'm not sure how we express that in tlVersionIntroduced.

[armanbilge]

I was thinking like:

.settings(
  tlVersionIntroduced := {
    if (tlIsScala3.value) Some("1.1.4") else None
  }
)

But, maybe not for everyone.

BTW, the mdoc build has a crossSetting helper to make defining version-specific settings even easier:

  scalacOptions ++= crossSetting(
    scalaVersion.value,
    if2 = List("-target:jvm-1.8", "-Yrangepos", "-deprecation"),
    if212 = List("-Xexperimental"),
    if211 = List("-Xexperimental"),
    if3 = List("-language:implicitConversions", "-Ximport-suggestion-timeout", "0")
  )

[armanbilge]

Yeah, the Map thing seems good actually. Should have done that, let me fix it.

[rossabaker]

I don't know without looking whether sbt-spiewak is a function or a map. Maybe a function is more power than is needed. I've always provided a map.

[armanbilge]

Yeah, I'm working on this now and I remembered why I don't like it: Scala version parsing from String and all its caveats, e.g. what if a user puts in "3.0" and "3.1" or just "3". I'd really rather just have something like this:

case class TLVersionIntroduced(
  scala212: Option[String] = None,
  scala213: Option[String] = None,
  scala3: Option[String] = None,
)

Or a solution like the crossSetting thing I posted above. Is there any reason we need to support Scala 3 RCs and stuff?

Edit: spiewak just expects binary version, so it would be 2.13 or just 3. I guess that works.

[rossabaker]

case-insensitive needed the RCs because it was checking old versions, but we could have just turned it off for Scala 3. I removed it entirely in typelevel/case-insensitive#208.

I don't like the case class, because that bundles binary compatibility of this plugin with the set of Scala versions supported today. crossSetting looks dubious to me for a similar reason, though I don't know what it did under the hood. I could be happy with pattern matching on scalaBinaryVersion.value as long as it recalculates itself when we switch Scala versions.

[armanbilge]

Oh, here's one more layer of complexity: now that we are checking MiMa for Scala.js and native as well, we also need to consider that axis, since these crosses were introduced later for some projects/modules. I guess that can be handled by defining a separate tlVersionIntroduced in .jvmSettings and .jsSettings etc., but there might be some duplication between those...

[rossabaker]

After questioning life choices that brought me to that point, I'd do separate tlVersionIntroduced settings.