Part 1 - fix compilation errors and stub macros

- use Scala 3.5.0
- add Scala 3 dialect to scalafmt.conf

Author: bishabosha

.scalafmt.conf

@@ -20,5 +20,4 @@ newlines.source = keep
 
 project.git = true
 
-runner.dialect = scala213
-
+runner.dialect = scala3

bsp/src/mill/bsp/BspServerResult.scala

@@ -1,6 +1,7 @@
 package mill.bsp
 
 import mill.api.internal
+import scala.deriving.Mirror
 
 @internal
 sealed trait BspServerResult
@@ -28,4 +29,15 @@ object BspServerResult {
 
   implicit val jsonify: upickle.default.ReadWriter[BspServerResult] =
     upickle.default.macroRW
+
+  // GENERATED CODE BY ci/scripts/manual_mirror_gen.sc - DO NOT EDIT
+  private type SingletonMirrorProxy[T <: AnyRef & Singleton] = Mirror.SingletonProxy { val value: T }
+  private def genSingletonMirror[T <: AnyRef & Singleton](ref: T): SingletonMirrorProxy[T] =
+    new Mirror.SingletonProxy(ref).asInstanceOf[SingletonMirrorProxy[T]]
+  private given Mirror_ReloadWorkspace: SingletonMirrorProxy[ReloadWorkspace.type] =
+    genSingletonMirror(ReloadWorkspace)
+  private given Mirror_Shutdown: SingletonMirrorProxy[Shutdown.type] =
+    genSingletonMirror(Shutdown)
+  private given Mirror_Failure: SingletonMirrorProxy[Failure.type] =
+    genSingletonMirror(Failure)
 }

build.mill

@@ -52,7 +52,8 @@ object Deps {
   // The Scala version to use
   // When updating, run "Publish Bridges" Github Actions for the new version
   // and then add to it `bridgeScalaVersions`
-  val scalaVersion = "2.13.14"
+  val scalaVersion = "3.5.0"
+  val scala2Version = "2.13.14"
   // Scoverage 1.x will not get releases for newer Scala versions
   val scalaVersionForScoverageWorker1 = "2.13.8"
   // The Scala 2.12.x version to use for some workers
@@ -67,14 +68,14 @@ object Deps {
 
   object Scalajs_1 {
     val scalaJsVersion = "1.16.0"
-    val scalajsEnvJsdomNodejs = ivy"org.scala-js::scalajs-env-jsdom-nodejs:1.1.0"
-    val scalajsEnvExoegoJsdomNodejs = ivy"net.exoego::scalajs-env-jsdom-nodejs:2.1.0"
-    val scalajsEnvNodejs = ivy"org.scala-js::scalajs-env-nodejs:1.4.0"
-    val scalajsEnvPhantomjs = ivy"org.scala-js::scalajs-env-phantomjs:1.0.0"
-    val scalajsEnvSelenium = ivy"org.scala-js::scalajs-env-selenium:1.1.1"
-    val scalajsSbtTestAdapter = ivy"org.scala-js::scalajs-sbt-test-adapter:${scalaJsVersion}"
-    val scalajsLinker = ivy"org.scala-js::scalajs-linker:${scalaJsVersion}"
-    val scalajsImportMap = ivy"com.armanbilge::scalajs-importmap:0.1.1"
+    val scalajsEnvJsdomNodejs = ivy"org.scala-js::scalajs-env-jsdom-nodejs:1.1.0".withDottyCompat(scalaVersion)
+    val scalajsEnvExoegoJsdomNodejs = ivy"net.exoego::scalajs-env-jsdom-nodejs:2.1.0".withDottyCompat(scalaVersion)
+    val scalajsEnvNodejs = ivy"org.scala-js::scalajs-env-nodejs:1.4.0".withDottyCompat(scalaVersion)
+    val scalajsEnvPhantomjs = ivy"org.scala-js::scalajs-env-phantomjs:1.0.0".withDottyCompat(scalaVersion)
+    val scalajsEnvSelenium = ivy"org.scala-js::scalajs-env-selenium:1.1.1".withDottyCompat(scalaVersion)
+    val scalajsSbtTestAdapter = ivy"org.scala-js:scalajs-sbt-test-adapter_2.13:${scalaJsVersion}"
+    val scalajsLinker = ivy"org.scala-js:scalajs-linker_2.13:${scalaJsVersion}"
+    val scalajsImportMap = ivy"com.armanbilge::scalajs-importmap:0.1.1".withDottyCompat(scalaVersion)
   }
 
   object Scalanative_0_5 {
@@ -101,9 +102,11 @@ object Deps {
   }
   object Play_2_7 extends Play {
     val playVersion = "2.7.9"
+    override def scalaVersion: String = Deps.scala2Version
   }
   object Play_2_8 extends Play {
     val playVersion = "2.8.22"
+    override def scalaVersion: String = Deps.scala2Version
   }
   object Play_2_9 extends Play {
     val playVersion = "2.9.5"
@@ -117,9 +120,9 @@ object Deps {
   val acyclic = ivy"com.lihaoyi:::acyclic:0.3.12"
   val ammoniteVersion = "3.0.0-M2-15-9bed9700"
   val asmTree = ivy"org.ow2.asm:asm-tree:9.7"
-  val bloopConfig = ivy"ch.epfl.scala::bloop-config:1.5.5"
+  val bloopConfig = ivy"ch.epfl.scala::bloop-config:1.5.5".withDottyCompat(scalaVersion)
 
-  val coursier = ivy"io.get-coursier::coursier:2.1.13"
+  val coursier = ivy"io.get-coursier::coursier:2.1.13".withDottyCompat(scalaVersion)
   val coursierInterface = ivy"io.get-coursier:interface:1.0.19"
 
   val cask = ivy"com.lihaoyi::cask:0.9.4"
@@ -159,8 +162,11 @@ object Deps {
   // can't use newer versions, as these need higher Java versions
   val testng = ivy"org.testng:testng:7.5.1"
   val sbtTestInterface = ivy"org.scala-sbt:test-interface:1.0"
-  def scalaCompiler(scalaVersion: String) = ivy"org.scala-lang:scala-compiler:${scalaVersion}"
-  val scalafmtDynamic = ivy"org.scalameta::scalafmt-dynamic:3.8.3"
+  def scalaCompiler(scalaVersion: String) = {
+    if (scalaVersion.startsWith("3.")) ivy"org.scala-lang:scala3-compiler_3:${scalaVersion}"
+    else ivy"org.scala-lang:scala-compiler:${scalaVersion}"
+  }
+  val scalafmtDynamic = ivy"org.scalameta::scalafmt-dynamic:3.8.3".withDottyCompat(scalaVersion)
   def scalap(scalaVersion: String) = ivy"org.scala-lang:scalap:${scalaVersion}"
   def scalaReflect(scalaVersion: String) = ivy"org.scala-lang:scala-reflect:${scalaVersion}"
   val scalacScoveragePlugin = ivy"org.scoverage:::scalac-scoverage-plugin:1.4.11"
@@ -179,11 +185,11 @@ object Deps {
   val sourcecode = ivy"com.lihaoyi::sourcecode:0.3.1"
   val upickle = ivy"com.lihaoyi::upickle:3.3.1"
   val windowsAnsi = ivy"io.github.alexarchambault.windows-ansi:windows-ansi:0.0.5"
-  val zinc = ivy"org.scala-sbt::zinc:1.10.2"
+  val zinc = ivy"org.scala-sbt::zinc:1.10.2".withDottyCompat(scalaVersion)
   // keep in sync with doc/antora/antory.yml
   val bsp4j = ivy"ch.epfl.scala:bsp4j:2.2.0-M2"
   val fansi = ivy"com.lihaoyi::fansi:0.5.0"
-  val jarjarabrams = ivy"com.eed3si9n.jarjarabrams::jarjar-abrams-core:1.14.0"
+  val jarjarabrams = ivy"com.eed3si9n.jarjarabrams::jarjar-abrams-core:1.14.0".withDottyCompat(scalaVersion)
   val requests = ivy"com.lihaoyi::requests:0.9.0"
   val logback = ivy"ch.qos.logback:logback-classic:1.5.7"
   val sonatypeCentralClient = ivy"com.lumidion::sonatype-central-client-requests:0.3.0"
@@ -243,7 +249,7 @@ def millBinPlatform: T[String] = T {
 def baseDir = build.millSourcePath
 
 val essentialBridgeScalaVersions =
-  Seq(Deps.scalaVersion, Deps.scalaVersionForScoverageWorker1, Deps.workerScalaVersion212)
+  Seq(Deps.scalaVersion, Deps.scala2Version, Deps.scalaVersionForScoverageWorker1, Deps.workerScalaVersion212)
 // published compiler bridges
 val bridgeScalaVersions = Seq(
   // Our version of Zinc doesn't work with Scala 2.12.0 and 2.12.4 compiler
@@ -380,20 +386,23 @@ trait MillPublishJavaModule extends MillJavaModule with PublishModule {
  */
 trait MillScalaModule extends ScalaModule with MillJavaModule with ScalafixModule { outer =>
   def scalaVersion = Deps.scalaVersion
+  def scalapVersion = T { Deps.scala2Version }
   def scalafixScalaBinaryVersion = ZincWorkerUtil.scalaBinaryVersion(scalaVersion())
   def semanticDbVersion = Deps.semanticDBscala.version
   def scalacOptions =
     super.scalacOptions() ++ Seq(
       "-deprecation",
-      "-P:acyclic:force",
       "-feature",
       "-Xlint:unused",
       "-Xlint:adapted-args"
+    ) ++ (
+      if (scalaVersion().startsWith("3.")) Seq.empty
+      else Seq("-P:acyclic:force")
     )
 
   def scalacPluginIvyDeps =
     super.scalacPluginIvyDeps() ++
-      Agg(Deps.acyclic) ++
+      Agg.when(!scalaVersion().startsWith("3."))(Deps.acyclic) ++
       Agg.when(scalaVersion().startsWith("2.13."))(Deps.millModuledefsPlugin)
 
   def mandatoryIvyDeps =
@@ -413,7 +422,8 @@ trait MillScalaModule extends ScalaModule with MillJavaModule with ScalafixModul
 trait MillBaseTestsModule extends TestModule {
   def forkArgs = T {
     Seq(
-      s"-DMILL_SCALA_2_13_VERSION=${Deps.scalaVersion}",
+      s"-DMILL_SCALA_3_NEXT_VERSION=${Deps.scalaVersion}",
+      s"-DMILL_SCALA_2_13_VERSION=${Deps.scala2Version}",
       s"-DMILL_SCALA_2_12_VERSION=${Deps.workerScalaVersion212}",
       s"-DTEST_SCALA_2_13_VERSION=${Deps.testScala213Version}",
       s"-DTEST_SCALA_2_13_VERSION_FOR_SCALANATIVE_4_2=${Deps.testScala213VersionForScalaNative42}",
@@ -556,7 +566,9 @@ trait BridgeModule extends MillPublishJavaModule with CrossScalaModule {
   def ivyDeps = Agg(
     ivy"org.scala-sbt:compiler-interface:${Deps.zinc.version}",
     ivy"org.scala-sbt:util-interface:${Deps.zinc.version}",
-    ivy"org.scala-lang:scala-compiler:${crossScalaVersion}"
+  ) ++ Agg(
+    if (crossScalaVersion.startsWith("3.")) ivy"org.scala-lang::scala3-compiler:${crossScalaVersion}"
+    else ivy"org.scala-lang:scala-compiler:${crossScalaVersion}"
   )
 
   def resources = T.sources {
@@ -565,7 +577,8 @@ trait BridgeModule extends MillPublishJavaModule with CrossScalaModule {
   }
 
   def compilerBridgeIvyDeps: T[Agg[Dep]] = Agg(
-    ivy"org.scala-sbt::compiler-bridge:${Deps.zinc.version}".exclude("*" -> "*")
+    (if (crossScalaVersion.startsWith("3.")) ivy"org.scala-lang:scala3-sbt-bridge:${crossScalaVersion}"
+    else ivy"org.scala-sbt::compiler-bridge:${Deps.zinc.version}").exclude("*" -> "*")
   )
 
   def compilerBridgeSourceJars: T[Agg[PathRef]] = T {
@@ -726,19 +739,19 @@ object dist0 extends MillPublishJavaModule {
 
   def testTransitiveDeps = build.runner.testTransitiveDeps() ++ Seq(
     build.main.graphviz.testDep(),
-    build.runner.linenumbers.testDep(),
+    // build.runner.linenumbers.testDep(),
     build.scalalib.backgroundwrapper.testDep(),
     build.contrib.bloop.testDep(),
     build.contrib.buildinfo.testDep(),
-    build.contrib.scoverage.testDep(),
-    build.contrib.scoverage.worker2.testDep(),
-    build.contrib.jmh.testDep(),
-    build.contrib.playlib.testDep(),
-    build.contrib.playlib.worker("2.8").testDep(),
-    build.contrib.errorprone.testDep(),
-    build.contrib.checkstyle.testDep(),
-    build.bsp.worker.testDep(),
-    build.testkit.testDep()
+    // build.contrib.scoverage.testDep(),
+    // build.contrib.scoverage.worker2.testDep(),
+    // build.contrib.jmh.testDep(),
+    // build.contrib.playlib.testDep(),
+    // build.contrib.playlib.worker("2.8").testDep(),
+    // build.contrib.errorprone.testDep(),
+    // build.contrib.checkstyle.testDep(),
+    // build.bsp.worker.testDep(),
+    // build.testkit.testDep()
   )
 }
 
@@ -1011,14 +1024,14 @@ def validate(): Command[Unit] = {
 }
 
 val dummyDeps: Seq[Dep] = Seq(
-  Deps.DocDeps.millScip,
+  // Deps.DocDeps.millScip,
   Deps.semanticDbJava,
-  Deps.semanticDBscala,
+  // Deps.semanticDBscala,
   Deps.TestDeps.scalaTest,
   Deps.TestDeps.zioTest,
-  Deps.acyclic,
-  Deps.scalacScoverage2Plugin,
-  ivy"com.lihaoyi:::ammonite:${Deps.ammoniteVersion}"
+  // Deps.acyclic,
+  // Deps.scalacScoverage2Plugin,
+  // ivy"com.lihaoyi:::ammonite:${Deps.ammoniteVersion}"
 ) ++ Deps.transitiveDeps ++ Deps.RuntimeDeps.all
 
 implicit object DepSegment extends Cross.ToSegments[Dep]({ dep =>

ci/scripts/manual_mirror_gen.sc

@@ -0,0 +1,84 @@
+//> using scala 3.5.0-RC6
+//> using options -language:experimental.namedTuples
+
+val cls = (
+  name = "JarManifest",
+  values = List(),
+  sum = false,
+  hasApply = true,
+  modifier = "private",
+  ctor = List(
+    "main" -> "Map[String, String]",
+    "groups" -> "Map[String, Map[String, String]]",
+    // "headless" -> "Boolean"
+    // "dest" -> "mill.PathRef",
+  )
+)
+
+val padding = 2
+
+// derived values
+
+val (ctorNames, ctorTypes) = (cls.ctor: List[(String, String)]).unzip
+
+def asTuple[T](elems: List[T]): String =
+  if elems.isEmpty then "EmptyTuple"
+  else if elems.sizeIs == 1 then s"${elems.head} *: EmptyTuple"
+  else elems.mkString("(", ", ", ")")
+
+def factory(args: List[String]) =
+  val list = args.mkString(",")
+  if cls.hasApply then
+    s"""${cls.name}.apply($list)"""
+  else
+    s"""new ${cls.name}($list)"""
+
+val mod = if cls.modifier.isEmpty() then "" else s"${cls.modifier} "
+
+val typedValues = cls.values: List[String]
+
+val str = (
+  if typedValues.nonEmpty then
+    // singleton
+    s"""// GENERATED CODE BY ${scriptPath} - DO NOT EDIT
+private type SingletonMirrorProxy[T <: AnyRef & Singleton] = Mirror.SingletonProxy { val value: T }
+private def genSingletonMirror[T <: AnyRef & Singleton](ref: T): SingletonMirrorProxy[T] =
+  new Mirror.SingletonProxy(ref).asInstanceOf[SingletonMirrorProxy[T]]
+${typedValues.map{ v =>
+s"""${mod}given Mirror_${v.replace(".", "_")}: SingletonMirrorProxy[${v}.type] =
+  genSingletonMirror(${v})"""}.mkString("\n")}"""
+  else if cls.sum then
+    // enum
+    s"""// GENERATED CODE BY ${scriptPath} - DO NOT EDIT
+${mod}given Mirror_${cls.name.replace(".", "_")}: Mirror.Sum with {
+  final type MirroredMonoType = ${cls.name}
+  final type MirroredType = ${cls.name}
+  final type MirroredElemTypes = ${asTuple(ctorTypes)}
+  final type MirroredElemLabels = ${asTuple(ctorNames.map(s => s"$"$s$""))}
+
+  final def ordinal(p: ${cls.name}): Int = {
+    p match {
+      ${ctorTypes.zipWithIndex.map{ (tpe, i) =>
+        s"case _: $tpe => $i"
+      }.mkString("", "\n      ","")}
+    }
+  }
+}"""
+  else
+    s"""// GENERATED CODE BY ${scriptPath} - DO NOT EDIT
+${mod}given Mirror_${cls.name.replace(".", "_")}: Mirror.Product with {
+  final type MirroredMonoType = ${cls.name}
+  final type MirroredType = ${cls.name}
+  final type MirroredElemTypes = ${asTuple(ctorTypes)}
+  final type MirroredElemLabels = ${asTuple(ctorNames.map(s => s"$"$s$""))}
+
+  final def fromProduct(p: scala.Product): ${cls.name} = {
+    ${ctorTypes.zipWithIndex.map{ (tpe, i) =>
+      s"val _${i + 1}: $tpe = p.productElement($i).asInstanceOf[$tpe]"
+    }.mkString("", "\n    ","\n")}
+    ${factory(ctorTypes.zipWithIndex.map{ (_, i) => s"_${i + 1}"})}
+  }
+}"""
+)
+
+println(str.linesIterator.map(s => s"${" " * padding}$s").mkString("\n"))

contrib/buildinfo/src/mill/contrib/buildinfo/BuildInfo.scala

@@ -35,7 +35,8 @@ trait BuildInfo extends JavaModule {
    */
   def buildInfoMembers: T[Seq[BuildInfo.Value]] = Seq.empty[BuildInfo.Value]
 
-  def resources: T[Seq[PathRef]] =
+  // TODO: remove override when mill-moduledefs is ported to Scala 3
+  override def resources: T[Seq[PathRef]] =
     if (buildInfoStaticCompiled) super.resources
     else Task.Sources { super.resources() ++ Seq(buildInfoResources()) }
 

contrib/package.mill

@@ -149,11 +149,10 @@ object `package` extends RootModule {
       def compileIvyDeps = T {
         Agg(
           // compile-time only, need to provide the correct scoverage version at runtime
-          build.Deps.scalacScoverage2Plugin,
           build.Deps.scalacScoverage2Reporter,
           build.Deps.scalacScoverage2Domain,
           build.Deps.scalacScoverage2Serializer
-        )
+        ) ++ Agg.when(!scalaVersion().startsWith("3."))(build.Deps.scalacScoverage2Plugin)
       }
     }
   }

contrib/versionfile/src/mill/contrib/versionfile/Version.scala

@@ -34,8 +34,8 @@ sealed trait Version {
     }
 
     this match {
-      case release: Release => Release.tupled(segments)
-      case snapshot: Snapshot => Snapshot.tupled(segments)
+      case release: Release => Release.apply.tupled(segments)
+      case snapshot: Snapshot => Snapshot.apply.tupled(segments)
     }
   }
 }

main/api/src/mill/api/AggWrapper.scala

@@ -33,11 +33,11 @@ private[mill] sealed class AggWrapper(strictUniqueness: Boolean) {
     def map[T](f: V => T): Agg[T]
     def filter(f: V => Boolean): Agg[V]
 
-    def collect[T](f: PartialFunction[V, T]): Agg[T]
-    def zipWithIndex: Agg[(V, Int)]
+    override def collect[T](f: PartialFunction[V, T]): Agg[T] = super.collect(f)
+    override def zipWithIndex: Agg[(V, Int)] = super.zipWithIndex
     def reverse: Agg[V]
     def zip[T](other: Agg[T]): Agg[(V, T)]
-    def ++[T >: V](other: IterableOnce[T]): Agg[T]
+    // def ++[T >: V](other: IterableOnce[T]): Agg[T] // error overriding final method ++ in trait IterableOps
     def length: Int
     def isEmpty: Boolean
     def foreach[U](f: V => U): Unit

main/api/src/mill/api/Ctx.scala

@@ -7,7 +7,7 @@ import scala.language.implicitConversions
  * Provides access to various resources in the context of a currently execution Target.
  */
 object Ctx {
-  @compileTimeOnly("Target.ctx() / T.ctx() / T.* APIs can only be used with a T{...} block")
+  // @compileTimeOnly("Target.ctx() / T.ctx() / T.* APIs can only be used with a T{...} block")
   @ImplicitStub
   implicit def taskCtx: Ctx = ???
 

main/api/src/mill/api/JarManifest.scala

@@ -61,6 +61,22 @@ object JarManifest {
       groups: Map[String, Map[String, String]] = Map.empty
   ): JarManifest = new JarManifest(main, groups)
 
+  import scala.deriving.Mirror
+  // GENERATED CODE BY ci/scripts/manual_mirror_gen.sc - DO NOT EDIT
+  private given Mirror_JarManifest: Mirror.Product with {
+    final type MirroredMonoType = JarManifest
+    final type MirroredType = JarManifest
+    final type MirroredElemTypes = (Map[String, String], Map[String, Map[String, String]])
+    final type MirroredElemLabels = ("main", "groups")
+
+    final def fromProduct(p: scala.Product): JarManifest = {
+      val _1: Map[String, String] = p.productElement(0).asInstanceOf[Map[String, String]]
+      val _2: Map[String, Map[String, String]] = p.productElement(1).asInstanceOf[Map[String, Map[String, String]]]
+
+      JarManifest.apply(_1,_2)
+    }
+  }
+
   implicit val jarManifestRW: ReadWriter[JarManifest] = upickle.default.macroRW
 
 }