Clarifying cross version behavior in Scala

user_2292791 0
Viewed 98

I wonder what is the difference between the two here:

addCompilerPlugin("org.typelevel" %% "kind-projector" % "0.11.3" cross CrossVersion.full)

// if your project uses multiple Scala versions, use this for cross building
addCompilerPlugin("org.typelevel" % "kind-projector" % "0.11.3" cross CrossVersion.full)

My understanding was that cross CrossVersion.full add the full Scala version to the library e.g.

kind-project_2.13.4:0.11.3

and that %% adds the Scala Binary version e.g.

kind-project_2.13:0.11.3

Hence I do not understand why we need cross CrossVersion.full with both % and %%. What's the difference?

kind-projector sbt scala
1 Answers

I am pretty sure they are the same.

From Overriding the publishing convention:

crossVersion setting can override the publishing convention:

  • CrossVersion.disabled (no suffix)
  • CrossVersion.binary (_)
  • CrossVersion.full (_)

The default is either CrossVersion.binary or CrossVersion.diabled depending on the value of crossPaths.

From More about using cross-built libraries:

These are equivalent:

"a" %% "b" % "1.0"
("a" % "b" % "1.0").cross(CrossVersion.binary)

So eventually all it matters is the value of crossVersion.

In order to test the crossVersion, I created a simple task in my build.sbt:

lazy val getVersion = taskKey[Unit]("A simple task")
getVersion := {
  List(dep1, dep2, dep3, dep4).foreach { d =>
    val att = Seq(d.organization ,d.name ,d.revision ,d.configurations ,d.isChanging ,d.isTransitive ,d.isForce ,d.explicitArtifacts ,d.inclusions ,d.exclusions ,d.extraAttributes ,d.crossVersion ,d.branchName)
    println(att)
  }
}
lazy val dep1 = "org.typelevel" % "kind-projector" % "0.11.3" cross CrossVersion.full
lazy val dep2 = "org.typelevel" %% "kind-projector" % "0.11.3" cross CrossVersion.full
lazy val dep3 = "org.typelevel" % "kind-projector" % "0.11.3"
lazy val dep4 = "org.typelevel" %% "kind-projector" % "0.11.3"

The output of sbt getVersion is:

List(org.typelevel, kind-projector, 0.11.3, None, false, true, false, Vector(), Vector(), Vector(), Map(), Full(, ), None)
List(org.typelevel, kind-projector, 0.11.3, None, false, true, false, Vector(), Vector(), Vector(), Map(), Full(, ), None)
List(org.typelevel, kind-projector, 0.11.3, None, false, true, false, Vector(), Vector(), Vector(), Map(), Disabled(), None)
List(org.typelevel, kind-projector, 0.11.3, None, false, true, false, Vector(), Vector(), Vector(), Map(), Binary(, ), None)

As we can see, all of the modules are equivalent, except for crossVersion, which in both dep1, and dep2 is Full(, ). Unlike the two others which are Disabled() and Binary(, ).

user_23592270
Related