Upgrade to Scala 3.0.0-RC1

Author: Jakob Odersky

build.sc

@@ -10,7 +10,7 @@ import de.tobiasroeser.mill.vcs.version.VcsVersion
 
 val dottyVersions = sys.props.get("dottyVersion").toList
 
-val scalaVersions = "2.12.13" :: "2.13.4" :: "3.0.0-M3" :: dottyVersions
+val scalaVersions = "2.12.13" :: "2.13.4" :: "3.0.0-RC1" :: dottyVersions
 val scala2Versions = scalaVersions.filter(_.startsWith("2."))
 
 val scalaJSVersions = for {
@@ -31,6 +31,16 @@ object os extends Module {
     object test extends Tests with OsLibTestModule{
       def platformSegment = "jvm"
     }
+    // FIXME: scaladoc 3 is not supported by mill yet. Remove the override
+    // once it is.
+    override def docJar =
+      if (crossScalaVersion.startsWith("2")) super.docJar
+      else T {
+        val outDir = T.ctx().dest
+        val javadocDir = outDir / 'javadoc
+        _root_.os.makeDir.all(javadocDir)
+        mill.api.Result.Success(mill.modules.Jvm.createJar(Agg(javadocDir))(outDir))
+      }
   }
   object native extends Cross[OsNativeModule](scalaNativeVersions:_*)