add convertToNewSyntax setting. prepare Scala 3.4

.scalafmt.conf

@@ -22,3 +22,9 @@ danglingParentheses.preset = true
 trailingCommas = preserve
 
 runner.dialect = Scala212Source3
+
+rewrite.scala3.convertToNewSyntax = true
+runner.dialectOverride.allowSignificantIndentation = false
+runner.dialectOverride.allowAsForImportRename = false
+runner.dialectOverride.allowStarWildcardImport = false
+runner.dialectOverride.allowPostfixStarVarargSplices = false

build.sbt

@@ -43,7 +43,7 @@ ThisBuild / publishTo := {
   Some("releases" at nexus + "service/local/staging/deploy/maven2")
 }
 
-def commonSettings: Seq[Setting[_]] = Seq(
+def commonSettings: Seq[Setting[?]] = Seq(
   scalaVersion := scala212,
   compile / javacOptions ++= Seq("-Xlint", "-Xlint:-serial"),
   crossScalaVersions := Seq(scala212, scala213, scala3),

io/src/main/scala/sbt/internal/io/Retry.scala

@@ -20,18 +20,18 @@ private[sbt] object Retry {
     try System.getProperty("sbt.io.retry.limit", defaultLimit.toString).toInt
     catch { case NonFatal(_) => defaultLimit }
   }
-  private[sbt] def apply[@specialized T](f: => T, excludedExceptions: Class[_ <: IOException]*): T =
+  private[sbt] def apply[@specialized T](f: => T, excludedExceptions: Class[? <: IOException]*): T =
     apply(f, limit, excludedExceptions: _*)
   private[sbt] def apply[@specialized T](
       f: => T,
       limit: Int,
-      excludedExceptions: Class[_ <: IOException]*,
+      excludedExceptions: Class[? <: IOException]*,
   ): T = apply(f, limit, 100, excludedExceptions: _*)
   private[sbt] def apply[@specialized T](
       f: => T,
       limit: Int,
       sleepInMillis: Long,
-      excludedExceptions: Class[_ <: IOException]*,
+      excludedExceptions: Class[? <: IOException]*,
   ): T = {
     require(limit >= 1, "limit must be 1 or higher: was: " + limit)
     def filter(e: Exception): Boolean = excludedExceptions match {

io/src/main/scala/sbt/internal/io/SourceModificationWatch.scala

@@ -116,7 +116,7 @@ private[sbt] final class WatchState private (
   }
 
   /** Retrieve events from the `WatchService` */
-  private[sbt] def pollEvents(): Iterable[(Path, WatchEvent[_])] = {
+  private[sbt] def pollEvents(): Iterable[(Path, WatchEvent[?])] = {
     val events = service.pollEvents()
     events.toIterable.flatMap { case (k, evs) =>
       evs.map((k.watchable().asInstanceOf[Path], _))

io/src/main/scala/sbt/internal/nio/LegacyFileTreeRepository.scala

@@ -46,7 +46,7 @@ private[sbt] class LegacyFileTreeRepository(logger: WatchLogger, watchService: W
   private[this] val handle =
     observable.addObserver((event: FileEvent[FileAttributes]) => {
       val attributes = event match {
-        case _: Deletion[_] => NonExistent
+        case _: Deletion[?] => NonExistent
         case _              => event.attributes
       }
       val events: Seq[FileEvent[FileAttributes]] = fileCache.update(event.path, attributes)

io/src/main/scala/sbt/internal/nio/PollingWatchService.scala

@@ -139,8 +139,8 @@ private[sbt] class PollingWatchService(delay: FiniteDuration, timeSource: TimeSo
       ()
     }
     override def isValid: Boolean = true
-    override def pollEvents(): JList[WatchEvent[_]] =
-      pollEventsImpl.asInstanceOf[JList[WatchEvent[_]]]
+    override def pollEvents(): JList[WatchEvent[?]] =
+      pollEventsImpl.asInstanceOf[JList[WatchEvent[?]]]
     override def reset(): Boolean = events.synchronized {
       events.clear()
       true
@@ -181,9 +181,9 @@ private[sbt] class PollingWatchService(delay: FiniteDuration, timeSource: TimeSo
         Some(this)
       }
       event match {
-        case _: Creation[_] if acceptCreate => offer(event)
-        case _: Deletion[_] if acceptDelete => offer(event)
-        case _: Update[_] if acceptModify   => offer(event)
+        case _: Creation[?] if acceptCreate => offer(event)
+        case _: Deletion[?] if acceptDelete => offer(event)
+        case _: Update[?] if acceptModify   => offer(event)
         case _                              => None
       }
     }

io/src/main/scala/sbt/io/IO.scala

@@ -63,7 +63,7 @@ object IO {
    * If the location cannot be determined, an error is generated.
    * Note that for JDK 11 onwards, a module will return a jrt path.
    */
-  def classLocationPath(cl: Class[_]): NioPath = {
+  def classLocationPath(cl: Class[?]): NioPath = {
     val u = classLocation(cl)
     val p = u.getProtocol match {
       case FileScheme => Option(toFile(u).toPath)
@@ -87,7 +87,7 @@ object IO {
    * If the location cannot be determined or it is not a file, an error is generated.
    * Note that for JDK 11 onwards, the returned module path cannot be expressed as `File`, so it will return `None`.
    */
-  def classLocationFileOption(cl: Class[_]): Option[File] = {
+  def classLocationFileOption(cl: Class[?]): Option[File] = {
     val u = classLocation(cl)
     urlAsFile(u)
   }
@@ -109,7 +109,7 @@ object IO {
     "classLocationFile may not work on JDK 11. Use classfileLocation, classLocationFileOption, or classLocationPath instead.",
     "1.3.0"
   )
-  def classLocationFile(cl: Class[_]): File =
+  def classLocationFile(cl: Class[?]): File =
     classLocationFileOption(cl).getOrElse(sys.error(s"Unable to create File from $cl"))
 
   /**
@@ -128,7 +128,7 @@ object IO {
    * If the location cannot be determined or it is not a file, an error is generated.
    * Note that for JDK 11 onwards, a module will return a jrt URL such as `jrt:/java.base`.
    */
-  def classLocation(cl: Class[_]): URL = {
+  def classLocation(cl: Class[?]): URL = {
     def localcl: Option[URL] =
       Option(cl.getProtectionDomain.getCodeSource) flatMap { codeSource =>
         Option(codeSource.getLocation)
@@ -187,7 +187,7 @@ object IO {
    * Returns a URL for the classfile containing the given class
    * If the location cannot be determined, an error is generated.
    */
-  def classfileLocation(cl: Class[_]): URL = {
+  def classfileLocation(cl: Class[?]): URL = {
     val clsfile = s"${cl.getName.replace('.', '/')}.class"
     def localcl: Option[URL] =
       Option(cl.getClassLoader) flatMap { classLoader =>
@@ -1232,7 +1232,7 @@ object IO {
    */
   def objectInputStream(wrapped: InputStream, loader: ClassLoader): ObjectInputStream =
     new ObjectInputStream(wrapped) {
-      override def resolveClass(osc: ObjectStreamClass): Class[_] = {
+      override def resolveClass(osc: ObjectStreamClass): Class[?] = {
         val c = Class.forName(osc.getName, false, loader)
         if (c eq null) super.resolveClass(osc) else c
       }
@@ -1491,7 +1491,7 @@ object IO {
     setModifiedTimeOrFalse(targetFile, math.max(last, 0L))
   }
 
-  private val excludeFileNotFound: immutable.Seq[Class[_ <: IOException]] = List(
+  private val excludeFileNotFound: immutable.Seq[Class[? <: IOException]] = List(
     classOf[FileNotFoundException]
   )
 }

io/src/test/scala/sbt/internal/io/RetrySpec.scala

@@ -17,7 +17,7 @@ import java.util.concurrent.atomic.AtomicInteger
 import org.scalatest.flatspec.AnyFlatSpec
 
 final class RetrySpec extends AnyFlatSpec {
-  private val noExcluded: List[Class[_ <: IOException]] = List[Class[_ <: IOException]]()
+  private val noExcluded: List[Class[? <: IOException]] = List[Class[? <: IOException]]()
   "retry" should "throw first exception after number of failures" in {
     val i = new AtomicInteger()
     def throww(): Any = throw new IOException(i.incrementAndGet().toString)

io/src/test/scala/sbt/internal/io/SourceModificationWatchSpec.scala

@@ -458,16 +458,16 @@ private[sbt] trait EventMonitorSpec { self: AnyFlatSpec with Matchers =>
     }
 
   def watchTest(
-      monitor: FileEventMonitor[FileEvent[_]],
-      filter: FileEvent[_] => Boolean,
-      check: Seq[FileEvent[_]] => Boolean
+      monitor: FileEventMonitor[FileEvent[?]],
+      filter: FileEvent[?] => Boolean,
+      check: Seq[FileEvent[?]] => Boolean
   )(modifier: => Unit): Boolean = {
     modifier
     val events = monitor.poll(maxWait * 2, filter)
     check(events)
   }
 
-  def watchTest(base: File, filter: FileEvent[_] => Boolean, check: Seq[FileEvent[_]] => Boolean)(
+  def watchTest(base: File, filter: FileEvent[?] => Boolean, check: Seq[FileEvent[?]] => Boolean)(
       modifier: => Unit
   ): Boolean = {
     val globs = base.toPath.toRealPath().toFile.scalaSourceGlobs
@@ -496,7 +496,7 @@ private[sbt] trait EventMonitorSpec { self: AnyFlatSpec with Matchers =>
 object EventMonitorSpec {
   type Event = FileEvent[FileAttributes]
   val AllPass: Any => Boolean = ((_: Any) => true).label("AllPass")
-  val NonEmpty: Seq[FileEvent[_]] => Boolean = ((_: Seq[FileEvent[_]]).nonEmpty).label("NonEmpty")
+  val NonEmpty: Seq[FileEvent[?]] => Boolean = ((_: Seq[FileEvent[?]]).nonEmpty).label("NonEmpty")
   private implicit class LabeledFunction[T, R](val f: T => R) extends AnyVal {
     def label(string: String): T => R = new (T => R) {
       override def apply(t: T): R = f(t)
@@ -514,33 +514,33 @@ object EventMonitorSpec {
       realPath(path.getParent, fileName.map(newFileName.resolve) orElse Some(newFileName))
     }
   }
-  def pathFilter(path: Path): FileEvent[_] => Boolean = {
+  def pathFilter(path: Path): FileEvent[?] => Boolean = {
     val real = realPath(path)
-    ((_: FileEvent[_]).path == real).label(s"PathFilter($real)")
+    ((_: FileEvent[?]).path == real).label(s"PathFilter($real)")
   }
-  def contains(path: Path): Seq[FileEvent[_]] => Boolean = {
+  def contains(path: Path): Seq[FileEvent[?]] => Boolean = {
     val real = realPath(path)
-    ((_: Seq[FileEvent[_]]).exists(_.path == real)).label(s"Contains($real)")
+    ((_: Seq[FileEvent[?]]).exists(_.path == real)).label(s"Contains($real)")
   }
-  def excludes(path: Path): Seq[FileEvent[_]] => Boolean = {
+  def excludes(path: Path): Seq[FileEvent[?]] => Boolean = {
     val real = realPath(path)
-    ((s: Seq[FileEvent[_]]) => s.nonEmpty && s.forall(_.path != real)).label(s"Excludes($real)")
+    ((s: Seq[FileEvent[?]]) => s.nonEmpty && s.forall(_.path != real)).label(s"Excludes($real)")
   }
-  def includesOnly(path: Path): Seq[FileEvent[_]] => Boolean = {
+  def includesOnly(path: Path): Seq[FileEvent[?]] => Boolean = {
     val real = realPath(path)
-    ((s: Seq[FileEvent[_]]) => s.nonEmpty && s.forall(_.path == real)).label(s"IncludesOnly($real)")
+    ((s: Seq[FileEvent[?]]) => s.nonEmpty && s.forall(_.path == real)).label(s"IncludesOnly($real)")
   }
-  def isDeletion(path: Path): FileEvent[_] => Boolean = {
+  def isDeletion(path: Path): FileEvent[?] => Boolean = {
     val real = realPath(path)
-    (_: FileEvent[_]) match {
+    (_: FileEvent[?]) match {
       case Deletion(p, _) if p == real => true
       case _                           => false
     }
   }
-  def hasDeletion(path: Path): Seq[FileEvent[_]] => Boolean = {
+  def hasDeletion(path: Path): Seq[FileEvent[?]] => Boolean = {
     val real = realPath(path)
     val deletion = isDeletion(real)
-    ((_: Seq[FileEvent[_]]).exists(deletion)).label(s"HasDeletion($real)")
+    ((_: Seq[FileEvent[?]]).exists(deletion)).label(s"HasDeletion($real)")
   }
 
   trait Logger extends WatchLogger

io/src/test/scala/sbt/io/IOSpecification.scala

@@ -17,7 +17,7 @@ import java.nio.file.Files
 
 object IOSpecification extends Properties("IO") {
   property("IO.classLocationPath able to determine containing directories") = forAll(classes) {
-    (c: Class[_]) =>
+    (c: Class[?]) =>
       Try(IO.classLocationPath(c)).toOption.exists {
         case jar if jar.getFileName.toString.endsWith(".jar") =>
           Files.isRegularFile(jar)
@@ -28,7 +28,7 @@ object IOSpecification extends Properties("IO") {
       }
   }
 
-  implicit def classes: Gen[Class[_]] =
+  implicit def classes: Gen[Class[?]] =
     Gen.oneOf(
       this.getClass,
       classOf[java.lang.Integer],

project/HouseRulesPluglin.scala

@@ -7,9 +7,9 @@ object HouseRulesPlugin extends AutoPlugin {
   override def requires = plugins.JvmPlugin
   override def trigger = allRequirements
 
-  override def projectSettings: Seq[Def.Setting[_]] = baseSettings
+  override def projectSettings: Seq[Def.Setting[?]] = baseSettings
 
-  lazy val baseSettings: Seq[Def.Setting[_]] = Seq(
+  lazy val baseSettings: Seq[Def.Setting[?]] = Seq(
     scalacOptions ++= Seq("-encoding", "utf8"),
     scalacOptions ++= Seq("-deprecation", "-feature", "-unchecked"),
     scalacOptions += "-language:higherKinds",