fix: Scala 3.8 syntax compat fixes and import cleanup

actor-tests/src/test/scala/org/apache/pekko/io/dns/DockerBindDnsService.scala

@@ -19,6 +19,7 @@ import scala.concurrent.duration._
 import scala.jdk.CollectionConverters._
 import scala.util.Try
 import scala.util.control.NonFatal
+
 import com.github.dockerjava.api.DockerClient
 import com.github.dockerjava.api.async.ResultCallback
 import com.github.dockerjava.api.command.CreateContainerCmd
@@ -29,10 +30,11 @@ import com.github.dockerjava.httpclient5.ApacheDockerHttpClient
 import org.apache.pekko
 import pekko.actor.Props
 import pekko.io.dns.internal.DnsClient
+import pekko.testkit.PekkoSpec
 import pekko.util.Timeout
 
-import pekko.testkit.PekkoSpec
 import org.scalatest.concurrent.Eventually
+
 import com.typesafe.config.Config
 
 abstract class DockerBindDnsService(config: Config) extends PekkoSpec(config) with Eventually {

actor-tests/src/test/scala/org/apache/pekko/util/SWARUtilSpec.scala

@@ -19,8 +19,8 @@ package org.apache.pekko.util
 
 import java.nio.ByteOrder
 
-import org.scalatest.wordspec.AnyWordSpec
 import org.scalatest.matchers.should.Matchers
+import org.scalatest.wordspec.AnyWordSpec
 
 class SWARUtilSpec extends AnyWordSpec with Matchers {
 

actor-typed/src/main/scala-3/org/apache/pekko/actor/typed/internal/receptionist/Platform.scala

@@ -23,11 +23,11 @@ import pekko.annotation.InternalApi
 @InternalApi private[receptionist] object Platform {
   type Aux[P] = AbstractServiceKey { type Protocol = P }
 
-  type Service[K <: Aux[_]] = K match {
+  type Service[K <: Aux[?]] = K match {
     case Aux[t] => ActorRef[t]
   }
 
-  type Subscriber[K <: Aux[_]] = K match {
+  type Subscriber[K <: Aux[?]] = K match {
     case Aux[t] => ActorRef[ReceptionistMessages.Listing[t]]
   }
 }

actor/src/main/scala-3/org/apache/pekko/util/ByteIterator.scala

@@ -256,28 +256,28 @@ object ByteIterator {
     override def getShort(implicit byteOrder: ByteOrder): Short = {
       val cur = current
       if cur.len >= java.lang.Short.BYTES then {
-        val r = cur.getShort(byteOrder)
+        val r = cur.getShort(using byteOrder)
         normalize()
         r
-      } else super.getShort(byteOrder)
+      } else super.getShort(using byteOrder)
     }
 
     override def getInt(implicit byteOrder: ByteOrder): Int = {
       val cur = current
       if cur.len >= java.lang.Integer.BYTES then {
-        val r = cur.getInt(byteOrder)
+        val r = cur.getInt(using byteOrder)
         normalize()
         r
-      } else super.getInt(byteOrder)
+      } else super.getInt(using byteOrder)
     }
 
     override def getLong(implicit byteOrder: ByteOrder): Long = {
       val cur = current
       if cur.len >= java.lang.Long.BYTES then {
-        val r = cur.getLong(byteOrder)
+        val r = cur.getLong(using byteOrder)
         normalize()
         r
-      } else super.getLong(byteOrder)
+      } else super.getLong(using byteOrder)
     }
 
     final override def len: Int = iterators.foldLeft(0) { _ + _.len }
@@ -417,19 +417,19 @@ object ByteIterator {
       getToArray(xs, offset, n, 1) { getByte } { current.getBytes(_, _, _) }
 
     def getShorts(xs: Array[Short], offset: Int, n: Int)(implicit byteOrder: ByteOrder): this.type =
-      getToArray(xs, offset, n, 2) { getShort(byteOrder) } { current.getShorts(_, _, _)(byteOrder) }
+      getToArray(xs, offset, n, 2) { getShort(using byteOrder) } { current.getShorts(_, _, _)(using byteOrder) }
 
     def getInts(xs: Array[Int], offset: Int, n: Int)(implicit byteOrder: ByteOrder): this.type =
-      getToArray(xs, offset, n, 4) { getInt(byteOrder) } { current.getInts(_, _, _)(byteOrder) }
+      getToArray(xs, offset, n, 4) { getInt(using byteOrder) } { current.getInts(_, _, _)(using byteOrder) }
 
     def getLongs(xs: Array[Long], offset: Int, n: Int)(implicit byteOrder: ByteOrder): this.type =
-      getToArray(xs, offset, n, 8) { getLong(byteOrder) } { current.getLongs(_, _, _)(byteOrder) }
+      getToArray(xs, offset, n, 8) { getLong(using byteOrder) } { current.getLongs(_, _, _)(using byteOrder) }
 
     def getFloats(xs: Array[Float], offset: Int, n: Int)(implicit byteOrder: ByteOrder): this.type =
-      getToArray(xs, offset, n, 8) { getFloat(byteOrder) } { current.getFloats(_, _, _)(byteOrder) }
+      getToArray(xs, offset, n, 8) { getFloat(using byteOrder) } { current.getFloats(_, _, _)(using byteOrder) }
 
     def getDoubles(xs: Array[Double], offset: Int, n: Int)(implicit byteOrder: ByteOrder): this.type =
-      getToArray(xs, offset, n, 8) { getDouble(byteOrder) } { current.getDoubles(_, _, _)(byteOrder) }
+      getToArray(xs, offset, n, 8) { getDouble(using byteOrder) } { current.getDoubles(_, _, _)(using byteOrder) }
 
     /** For performance sensitive code, call copyToBuffer() directly on ByteString (it's optimised there) */
     override def copyToBuffer(buffer: ByteBuffer): Int = {
@@ -649,10 +649,10 @@ abstract class ByteIterator extends BufferedIterator[Byte] {
   }
 
   def getFloat(implicit byteOrder: ByteOrder): Float =
-    java.lang.Float.intBitsToFloat(getInt(byteOrder))
+    java.lang.Float.intBitsToFloat(getInt(using byteOrder))
 
   def getDouble(implicit byteOrder: ByteOrder): Double =
-    java.lang.Double.longBitsToDouble(getLong(byteOrder))
+    java.lang.Double.longBitsToDouble(getLong(using byteOrder))
 
   /**
    * Get a specific number of Bytes from this iterator. In contrast to
@@ -690,7 +690,7 @@ abstract class ByteIterator extends BufferedIterator[Byte] {
    * Get a number of Shorts from this iterator.
    */
   def getShorts(xs: Array[Short])(implicit byteOrder: ByteOrder): this.type =
-    getShorts(xs, 0, xs.length)(byteOrder)
+    getShorts(xs, 0, xs.length)(using byteOrder)
 
   /**
    * Get a number of Shorts from this iterator.
@@ -701,7 +701,7 @@ abstract class ByteIterator extends BufferedIterator[Byte] {
    * Get a number of Ints from this iterator.
    */
   def getInts(xs: Array[Int])(implicit byteOrder: ByteOrder): this.type =
-    getInts(xs, 0, xs.length)(byteOrder)
+    getInts(xs, 0, xs.length)(using byteOrder)
 
   /**
    * Get a number of Ints from this iterator.
@@ -712,7 +712,7 @@ abstract class ByteIterator extends BufferedIterator[Byte] {
    * Get a number of Longs from this iterator.
    */
   def getLongs(xs: Array[Long])(implicit byteOrder: ByteOrder): this.type =
-    getLongs(xs, 0, xs.length)(byteOrder)
+    getLongs(xs, 0, xs.length)(using byteOrder)
 
   /**
    * Get a number of Longs from this iterator.
@@ -723,7 +723,7 @@ abstract class ByteIterator extends BufferedIterator[Byte] {
    * Get a number of Floats from this iterator.
    */
   def getFloats(xs: Array[Float])(implicit byteOrder: ByteOrder): this.type =
-    getFloats(xs, 0, xs.length)(byteOrder)
+    getFloats(xs, 0, xs.length)(using byteOrder)
 
   /**
    * Get a number of Floats from this iterator.
@@ -734,7 +734,7 @@ abstract class ByteIterator extends BufferedIterator[Byte] {
    * Get a number of Doubles from this iterator.
    */
   def getDoubles(xs: Array[Double])(implicit byteOrder: ByteOrder): this.type =
-    getDoubles(xs, 0, xs.length)(byteOrder)
+    getDoubles(xs, 0, xs.length)(using byteOrder)
 
   /**
    * Get a number of Doubles from this iterator.

actor/src/main/scala/org/apache/pekko/dispatch/ForkJoinExecutorConfigurator.scala

@@ -15,11 +15,11 @@ package org.apache.pekko.dispatch
 
 import java.util.concurrent.{ ExecutorService, ForkJoinPool, ForkJoinTask, ThreadFactory, TimeUnit }
 
-import com.typesafe.config.Config
-
 import org.apache.pekko.annotation.InternalApi
 import org.apache.pekko.util.JavaVersion
 
+import com.typesafe.config.Config
+
 object ForkJoinExecutorConfigurator {
 
   /**

actor/src/main/scala/org/apache/pekko/io/SimpleDnsCache.scala

@@ -34,9 +34,11 @@ private[io] trait PeriodicCacheCleanup {
 
 class SimpleDnsCache extends Dns with PeriodicCacheCleanup with NoSerializationVerificationNeeded {
   import SimpleDnsCache._
+  private implicit val expiryOrdering: Ordering[ExpiryEntry[(String, RequestType)]] =
+    expiryEntryOrdering[(String, RequestType)]()
   private val cacheRef = new AtomicReference(
     new Cache[(String, RequestType), Resolved](
-      immutable.SortedSet()(expiryEntryOrdering()),
+      immutable.SortedSet.empty[ExpiryEntry[(String, RequestType)]],
       immutable.Map(),
       () => clock()))
 

actor/src/main/scala/org/apache/pekko/pattern/Patterns.scala

@@ -129,7 +129,7 @@ object Patterns {
    */
   def askWithReplyTo(actor: ActorRef, messageFactory: japi.function.Function[ActorRef, Any], timeout: Timeout)
       : Future[AnyRef] =
-    extended.ask(actor, messageFactory.apply _)(timeout).asInstanceOf[Future[AnyRef]]
+    extended.ask(actor, ref => messageFactory.apply(ref))(timeout).asInstanceOf[Future[AnyRef]]
 
   /**
    * A variation of ask which allows to implement "replyTo" pattern by including
@@ -150,7 +150,8 @@ object Patterns {
       actor: ActorRef,
       messageFactory: japi.function.Function[ActorRef, Any],
       timeout: java.time.Duration): CompletionStage[AnyRef] =
-    extended.ask(actor, messageFactory.apply _)(Timeout.create(timeout)).asJava.asInstanceOf[CompletionStage[AnyRef]]
+    extended.ask(actor, ref => messageFactory.apply(ref))(Timeout.create(timeout)).asJava.asInstanceOf[CompletionStage[
+      AnyRef]]
 
   /**
    * <i>Java API for `org.apache.pekko.pattern.ask`:</i>
@@ -201,7 +202,7 @@ object Patterns {
       actor: ActorRef,
       messageFactory: japi.function.Function[ActorRef, Any],
       timeoutMillis: Long): Future[AnyRef] =
-    extended.ask(actor, messageFactory.apply _)(Timeout(timeoutMillis.millis)).asInstanceOf[Future[AnyRef]]
+    extended.ask(actor, ref => messageFactory.apply(ref))(Timeout(timeoutMillis.millis)).asInstanceOf[Future[AnyRef]]
 
   /**
    * <i>Java API for `org.apache.pekko.pattern.ask`:</i>
@@ -316,7 +317,8 @@ object Patterns {
       selection: ActorSelection,
       messageFactory: japi.function.Function[ActorRef, Any],
       timeoutMillis: Long): Future[AnyRef] =
-    extended.ask(selection, messageFactory.apply _)(Timeout(timeoutMillis.millis)).asInstanceOf[Future[AnyRef]]
+    extended.ask(selection, ref => messageFactory.apply(ref))(Timeout(timeoutMillis.millis)).asInstanceOf[Future[
+      AnyRef]]
 
   /**
    * A variation of ask which allows to implement "replyTo" pattern by including
@@ -333,7 +335,8 @@ object Patterns {
       selection: ActorSelection,
       messageFactory: japi.function.Function[ActorRef, Any],
       timeout: java.time.Duration): CompletionStage[AnyRef] =
-    extended.ask(selection, messageFactory.apply _)(timeout.toScala).asJava.asInstanceOf[CompletionStage[AnyRef]]
+    extended.ask(selection, ref => messageFactory.apply(ref))(timeout.toScala).asJava.asInstanceOf[CompletionStage[
+      AnyRef]]
 
   /**
    * Register an onComplete callback on this [[scala.concurrent.Future]] to send

actor/src/main/scala/org/apache/pekko/util/LineNumbers.scala

@@ -358,7 +358,7 @@ object LineNumbers {
   private def readAttributes(d: DataInputStream)(implicit c: Constants): Option[String] = {
     val count = d.readUnsignedShort()
     if (debug) println(s"LNB: reading $count attributes")
-    if (c contains "SourceFile") {
+    if (c.contains("SourceFile")) {
       val s = c("SourceFile")
       val attributes =
         for (_ <- 1 to count) yield {

bench-jmh/src/main/scala/org/apache/pekko/stream/GraphStageConstructionBenchmark.scala

@@ -22,6 +22,14 @@ import java.util.concurrent.TimeUnit
 import scala.collection.immutable
 import scala.concurrent.Promise
 
+import org.openjdk.jmh.annotations.Benchmark
+import org.openjdk.jmh.annotations.BenchmarkMode
+import org.openjdk.jmh.annotations.Mode
+import org.openjdk.jmh.annotations.OutputTimeUnit
+import org.openjdk.jmh.annotations.Scope
+import org.openjdk.jmh.annotations.State
+import org.openjdk.jmh.infra.Blackhole
+
 import org.apache.pekko.NotUsed
 import org.apache.pekko.stream.impl.LinearTraversalBuilder
 import org.apache.pekko.stream.impl.Stages.DefaultAttributes
@@ -32,13 +40,6 @@ import org.apache.pekko.stream.scaladsl.Keep
 import org.apache.pekko.stream.scaladsl.Sink
 import org.apache.pekko.stream.scaladsl.Source
 import org.apache.pekko.stream.stage.GraphStageWithMaterializedValue
-import org.openjdk.jmh.annotations.Benchmark
-import org.openjdk.jmh.annotations.BenchmarkMode
-import org.openjdk.jmh.annotations.Mode
-import org.openjdk.jmh.annotations.OutputTimeUnit
-import org.openjdk.jmh.annotations.Scope
-import org.openjdk.jmh.annotations.State
-import org.openjdk.jmh.infra.Blackhole
 
 @State(Scope.Benchmark)
 @BenchmarkMode(Array(Mode.Throughput))

bench-jmh/src/main/scala/org/apache/pekko/stream/io/TlsBenchmark.scala

@@ -25,7 +25,6 @@ import scala.concurrent.Await
 import scala.concurrent.duration._
 import scala.util.{ Success, Try }
 
-import com.typesafe.config.{ Config, ConfigFactory }
 import org.openjdk.jmh.annotations._
 
 import org.apache.pekko
@@ -37,6 +36,8 @@ import pekko.stream.impl.io.{ TlsGraphStage, TlsModule }
 import pekko.stream.scaladsl._
 import pekko.util.ByteString
 
+import com.typesafe.config.{ Config, ConfigFactory }
+
 /**
  * JMH benchmark comparing the legacy actor-based TLS path (`TlsModule`) to the
  * GraphStage path (`TlsGraphStage`).

bench-jmh/src/main/scala/org/apache/pekko/util/ByteStringParser_readNum_Benchmark.scala

@@ -19,11 +19,11 @@ package org.apache.pekko.util
 
 import java.util.concurrent.TimeUnit
 
+import org.openjdk.jmh.annotations._
+
 import org.apache.pekko
 import pekko.stream.impl.io.ByteStringParser
 
-import org.openjdk.jmh.annotations._
-
 @State(Scope.Benchmark)
 @Measurement(timeUnit = TimeUnit.MILLISECONDS)
 class ByteStringParser_readNum_Benchmark {

cluster-sharding-typed/src/main/scala/org/apache/pekko/cluster/sharding/typed/javadsl/ShardedDaemonProcess.scala

@@ -14,8 +14,8 @@
 package org.apache.pekko.cluster.sharding.typed.javadsl
 
 import java.util.Optional
-import java.util.function.IntFunction
 import java.util.function.{ Function => JFunction }
+import java.util.function.IntFunction
 
 import org.apache.pekko
 import pekko.actor.typed.ActorRef

cluster-sharding-typed/src/test/scala/org/apache/pekko/cluster/sharding/typed/internal/ShardedDaemonProcessIdSpec.scala

@@ -14,6 +14,7 @@
 package org.apache.pekko.cluster.sharding.typed.internal
 
 import org.apache.pekko.cluster.sharding.typed.internal.ShardedDaemonProcessId.DecodedId
+
 import org.scalatest.matchers.should.Matchers
 import org.scalatest.wordspec.AnyWordSpecLike
 

cluster-sharding/src/main/scala/org/apache/pekko/cluster/sharding/ShardRegion.scala

@@ -638,7 +638,10 @@ private[pekko] class ShardRegion(
   // sort by age, oldest first
   val ageOrdering = Member.ageOrdering
   // membersByAge is only used for tracking where coordinator is running
-  var membersByAge: immutable.SortedSet[Member] = immutable.SortedSet.empty(ageOrdering)
+  var membersByAge: immutable.SortedSet[Member] = {
+    implicit val ord: Ordering[Member] = ageOrdering
+    immutable.SortedSet.empty[Member]
+  }
   // membersByAge contains members with these status
   private val memberStatusOfInterest: Set[MemberStatus] =
     Set(MemberStatus.Up, MemberStatus.Leaving, MemberStatus.Exiting)
@@ -772,9 +775,10 @@ private[pekko] class ShardRegion(
   }
 
   def receiveClusterState(state: CurrentClusterState): Unit = {
+    implicit val ord: Ordering[Member] = ageOrdering
     changeMembers(
       immutable.SortedSet
-        .empty(ageOrdering)
+        .empty[Member]
         .union(state.members.filter(m => memberStatusOfInterest(m.status) && matchingCoordinatorRole(m))))
   }
 

cluster-sharding/src/multi-jvm/scala/org/apache/pekko/cluster/sharding/ClusterShardingCoordinatorRoleSpec.scala

@@ -15,16 +15,16 @@ package org.apache.pekko.cluster.sharding
 
 import scala.concurrent.duration._
 
-import com.typesafe.config.Config
-import com.typesafe.config.ConfigFactory
-
 import org.apache.pekko
 import pekko.actor.ActorRef
 import pekko.actor.PoisonPill
 import pekko.actor.Props
 import pekko.cluster.sharding.MultiNodeClusterShardingSpec.EntityActor
 import pekko.testkit._
 
+import com.typesafe.config.Config
+import com.typesafe.config.ConfigFactory
+
 class ClusterShardingCoordinatorRoleSpecConfig(
     mode: String,
     rememberEntities: Boolean,

cluster-sharding/src/test/scala/org/apache/pekko/cluster/sharding/RememberEntitiesAndStartEntitySpec.scala

@@ -13,6 +13,8 @@
 
 package org.apache.pekko.cluster.sharding
 
+import scala.concurrent.duration._
+
 import org.apache.pekko
 import pekko.actor.Actor
 import pekko.actor.ActorRef
@@ -30,7 +32,6 @@ import pekko.testkit.WithLogCapturing
 
 import org.scalatest.wordspec.AnyWordSpecLike
 
-import scala.concurrent.duration._
 import com.typesafe.config.ConfigFactory
 
 object RememberEntitiesAndStartEntitySpec {