Cross compile the runner module against Scala 3 Next versions

Author: Gedochao

build.mill.scala

@@ -104,7 +104,7 @@ object directives extends Cross[Directives](Scala.scala3MainVersions)
 object core           extends Cross[Core](Scala.scala3MainVersions) with CrossScalaDefaultToInternal
 object `build-module` extends Cross[Build](Scala.scala3MainVersions)
     with CrossScalaDefaultToInternal
-object runner        extends Runner
+object runner        extends Cross[Runner](Scala.runnerScalaVersions) with CrossScalaDefaultToRunner
 object `test-runner` extends TestRunner
 object `tasty-lib`   extends Cross[TastyLib](Scala.scala3MainVersions)
     with CrossScalaDefaultToInternal
@@ -439,7 +439,7 @@ trait Core extends ScalaCliCrossSbtModule
     val testRunnerMainClass = `test-runner`
       .mainClass()
       .getOrElse(sys.error("No main class defined for test-runner"))
-    val runnerMainClass = build.runner
+    val runnerMainClass = build.runner(crossScalaVersion)
       .mainClass()
       .getOrElse(sys.error("No main class defined for runner"))
     val detailedVersionValue =
@@ -469,9 +469,9 @@ trait Core extends ScalaCliCrossSbtModule
          |  def testRunnerVersion = "${`test-runner`.publishVersion()}"
          |  def testRunnerMainClass = "$testRunnerMainClass"
          |
-         |  def runnerOrganization = "${build.runner.pomSettings().organization}"
-         |  def runnerModuleName = "${build.runner.artifactName()}"
-         |  def runnerVersion = "${build.runner.publishVersion()}"
+         |  def runnerOrganization = "${build.runner(crossScalaVersion).pomSettings().organization}"
+         |  def runnerModuleName = "${build.runner(crossScalaVersion).artifactName()}"
+         |  def runnerVersion = "${build.runner(crossScalaVersion).publishVersion()}"
          |  def runnerScala30LegacyVersion = "${Cli.runnerScala30LegacyVersion}"
          |  def runnerScala2LegacyVersion = "${Cli.runnerScala2LegacyVersion}"
          |  def runnerMainClass = "$runnerMainClass"
@@ -1258,17 +1258,17 @@ trait CliIntegrationDocker extends SbtModule with ScalaCliPublishModule with Has
   )
 }
 
-trait Runner extends SbtModule
+trait Runner extends CrossSbtModule
     with ScalaCliPublishModule
     with ScalaCliScalafixModule {
-  override def scalaVersion: T[String]       = Scala.runnerScala3
   override def scalacOptions: T[Seq[String]] = Task {
     super.scalacOptions() ++ Seq("-release", "8", "-deprecation")
   }
   override def mainClass: T[Option[String]] = Some("scala.cli.runner.Runner")
   override def sources: T[Seq[PathRef]]     = Task.Sources {
-    val scala3DirName = if (scalaVersion().contains("-RC")) "scala-3-unstable" else "scala-3-stable"
-    val extraDirs     = Seq(PathRef(moduleDir / "src" / "main" / scala3DirName))
+    val scala3DirName =
+      if (crossScalaVersion.contains("-RC")) "scala-3-unstable" else "scala-3-stable"
+    val extraDirs = Seq(PathRef(moduleDir / "src" / "main" / scala3DirName))
     super.sources() ++ extraDirs
   }
 }
@@ -1320,9 +1320,10 @@ object `local-repo` extends LocalRepo {
    */
   def developingOnStubModules = false
 
-  override def stubsModules: Seq[PublishLocalNoFluff] = Seq(runner, `test-runner`)
+  override def stubsModules: Seq[PublishLocalNoFluff] =
+    Seq(runner(Scala.runnerScala3), `test-runner`)
 
-  override def version: T[String] = runner.publishVersion()
+  override def version: T[String] = runner(Scala.runnerScala3).publishVersion()
 }
 
 // Helper CI commands

project/deps/package.mill.scala

@@ -32,7 +32,7 @@ object Scala {
   val allScala3           = Seq(scala3Lts, scala3Next, scala3NextAnnounced, scala3NextRc).distinct
   val all                 = (allScala2 ++ allScala3 ++ defaults).distinct
   val scala3MainVersions  = (defaults ++ allScala3).distinct
-  val runnerScalaVersions = Seq(runnerScala3, scala3MainVersions).distinct
+  val runnerScalaVersions = (Seq(runnerScala3) ++ scala3MainVersions).distinct
 
   def scalaJs    = "1.20.1"
   def scalaJsCli = scalaJs // this must be compatible with the Scala.js version