Upgrade to Scala 2.13.5 (#30072)

akka-actor-testkit-typed/src/main/mima-filters/2.6.13.backwards.excludes/fish-for-message-pf.excludes

@@ -0,0 +1,2 @@
+# 2 new methods, TestProbe is not for user extension
+ProblemFilters.exclude[ReversedMissingMethodProblem]("akka.actor.testkit.typed.scaladsl.TestProbe.fishForMessagePF")

akka-actor-testkit-typed/src/main/scala/akka/actor/testkit/typed/internal/TestProbeImpl.scala

@@ -105,6 +105,7 @@ private[akka] final class TestProbeImpl[M](name: String, system: ActorSystem[_])
     case x if x eq Duration.Undefined => duration
     case x if !x.isFinite             => throw new IllegalArgumentException("`end` cannot be infinite")
     case f: FiniteDuration            => f - now
+    case _                            => throw new RuntimeException() // compiler exhaustiveness check pleaser
   }
 
   override def getRemainingOr(duration: JDuration): JDuration =
@@ -266,9 +267,16 @@ private[akka] final class TestProbeImpl[M](name: String, system: ActorSystem[_])
   override def fishForMessage(max: FiniteDuration, hint: String)(fisher: M => FishingOutcome): immutable.Seq[M] =
     fishForMessage_internal(max.dilated, hint, fisher)
 
+  override def fishForMessagePF(max: FiniteDuration, hint: String)(
+      fisher: PartialFunction[M, FishingOutcome]): immutable.Seq[M] =
+    fishForMessage(max, hint)(fisher)
+
   override def fishForMessage(max: FiniteDuration)(fisher: M => FishingOutcome): immutable.Seq[M] =
     fishForMessage(max, "")(fisher)
 
+  override def fishForMessagePF(max: FiniteDuration)(fisher: PartialFunction[M, FishingOutcome]): immutable.Seq[M] =
+    fishForMessage(max)(fisher)
+
   override def fishForMessage(max: JDuration, fisher: java.util.function.Function[M, FishingOutcome]): JList[M] =
     fishForMessage(max, "", fisher)
 

akka-actor-testkit-typed/src/main/scala/akka/actor/testkit/typed/scaladsl/TestProbe.scala

@@ -198,11 +198,21 @@ object TestProbe {
    */
   def fishForMessage(max: FiniteDuration, hint: String)(fisher: M => FishingOutcome): immutable.Seq[M]
 
+  /**
+   * Same as `fishForMessage` but accepting a partial function and failing for non-matches
+   */
+  def fishForMessagePF(max: FiniteDuration, hint: String)(fisher: PartialFunction[M, FishingOutcome]): immutable.Seq[M]
+
   /**
    * Same as the other `fishForMessage` but with no hint
    */
   def fishForMessage(max: FiniteDuration)(fisher: M => FishingOutcome): immutable.Seq[M]
 
+  /**
+   * Same as `fishForMessage` but with no hint, accepting a partial function and failing for non-matches
+   */
+  def fishForMessagePF(max: FiniteDuration)(fisher: PartialFunction[M, FishingOutcome]): immutable.Seq[M]
+
   /**
    * Expect the given actor to be stopped or stop within the given timeout or
    * throw an [[AssertionError]].

akka-actor-testkit-typed/src/test/scala/akka/actor/testkit/typed/scaladsl/BehaviorTestKitSpec.scala

@@ -138,6 +138,8 @@ object BehaviorTestKitSpec {
             case IsTimerActive(key, replyTo) =>
               replyTo ! timers.isTimerActive(key)
               Behaviors.same
+            case unexpected =>
+              throw new RuntimeException(s"Unexpected command: $unexpected")
           }
         }
         .receiveSignal {

akka-actor-testkit-typed/src/test/scala/akka/actor/testkit/typed/scaladsl/TestProbeSpec.scala

@@ -105,7 +105,7 @@ class TestProbeSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with
       probe.ref ! "two"
 
       intercept[AssertionError] {
-        probe.fishForMessage(shortDuration) {
+        probe.fishForMessagePF(shortDuration) {
           case "one" => FishingOutcomes.continue
         }
       }
@@ -117,7 +117,7 @@ class TestProbeSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with
       probe.ref ! "one"
 
       intercept[AssertionError] {
-        probe.fishForMessage(shortDuration) {
+        probe.fishForMessagePF(shortDuration) {
           case "one" => FishingOutcomes.continue
         }
       }

akka-actor-tests/src/test/scala/akka/actor/ActorSelectionSpec.scala

@@ -51,6 +51,7 @@ class ActorSelectionSpec extends AkkaSpec with DefaultTimeout {
   def empty(path: String) =
     new EmptyLocalActorRef(sysImpl.provider, path match {
       case RelativeActorPath(elems) => sysImpl.lookupRoot.path / elems
+      case _                        => throw new RuntimeException()
     }, system.eventStream)
 
   val idProbe = TestProbe()
@@ -79,6 +80,7 @@ class ActorSelectionSpec extends AkkaSpec with DefaultTimeout {
     Await.result(node ? query, timeout.duration) match {
       case ref: ActorRef             => Some(ref)
       case selection: ActorSelection => identify(selection)
+      case _                         => throw new RuntimeException()
     }
   }
 
@@ -365,8 +367,13 @@ class ActorSelectionSpec extends AkkaSpec with DefaultTimeout {
 
       val probe = TestProbe()
       system.actorSelection("/user/a/*").tell(Identify(1), probe.ref)
-      probe.receiveN(2).map { case ActorIdentity(1, r) => r }.toSet should ===(
-        Set[Option[ActorRef]](Some(b1), Some(b2)))
+      probe
+        .receiveN(2)
+        .map {
+          case ActorIdentity(1, r) => r
+          case _                   => throw new IllegalArgumentException()
+        }
+        .toSet should ===(Set[Option[ActorRef]](Some(b1), Some(b2)))
       probe.expectNoMessage()
 
       system.actorSelection("/user/a/b1/*").tell(Identify(2), probe.ref)

akka-actor-tests/src/test/scala/akka/actor/ActorSystemSpec.scala

@@ -94,6 +94,7 @@ object ActorSystemSpec {
           TestKit.awaitCond(mbox.actor.actor != null, 1.second)
           mbox.actor.actor match {
             case FastActor(latch, _) => Await.ready(latch, 1.second)
+            case _                   => throw new IllegalStateException()
           }
         }
         ret

akka-actor-tests/src/test/scala/akka/actor/Bench.scala

@@ -14,7 +14,7 @@ object Chameneos {
   final case class MeetingCount(count: Int) extends ChameneosEvent
   case object Exit extends ChameneosEvent
 
-  abstract class Colour
+  abstract sealed class Colour
   case object RED extends Colour
   case object YELLOW extends Colour
   case object BLUE extends Colour

akka-actor-tests/src/test/scala/akka/actor/SupervisorHierarchySpec.scala

@@ -683,6 +683,7 @@ object SupervisorHierarchySpec {
           if (depth > 0) {
             l.underlying.children.foreach(getErrors(_, depth - 1))
           }
+        case _ => throw new IllegalArgumentException()
       }
     }
 
@@ -694,6 +695,7 @@ object SupervisorHierarchySpec {
             case _            => errors :+= target -> ErrorLog("fetched", stateCache.get(target.path).log)
           }
           if (target != hierarchy) getErrorsUp(l.getParent)
+        case _ => throw new IllegalArgumentException()
       }
     }
 

akka-actor-tests/src/test/scala/akka/actor/TypedActorSpec.scala

@@ -212,6 +212,7 @@ object TypedActorSpec {
     override def onReceive(msg: Any, sender: ActorRef): Unit = {
       ensureContextAvailable(msg match {
         case "pigdog" => sender ! "dogpig"
+        case _        =>
       })
     }
   }

akka-actor-tests/src/test/scala/akka/dispatch/MailboxConfigSpec.scala

@@ -122,6 +122,7 @@ abstract class MailboxSpec extends AkkaSpec with BeforeAndAfterAll with BeforeAn
         config match {
           case BoundedMailbox(capacity, _) => aQueue.remainingCapacity should ===(capacity)
           case UnboundedMailbox()          => aQueue.remainingCapacity should ===(Int.MaxValue)
+          case _                           => fail()
         }
       case _ =>
     }
@@ -187,6 +188,7 @@ class DefaultMailboxSpec extends MailboxSpec {
   def factory = {
     case u: UnboundedMailbox => u.create(None, None)
     case b: BoundedMailbox   => b.create(None, None)
+    case _                   => throw new RuntimeException() // compiler exhaustiveness check pleaser
   }
 }
 
@@ -197,6 +199,7 @@ class PriorityMailboxSpec extends MailboxSpec {
     case UnboundedMailbox() => new UnboundedPriorityMailbox(comparator).create(None, None)
     case BoundedMailbox(capacity, pushTimeOut) =>
       new BoundedPriorityMailbox(comparator, capacity, pushTimeOut).create(None, None)
+    case _ => throw new RuntimeException() // compiler exhaustiveness check pleaser
   }
 }
 
@@ -207,6 +210,7 @@ class StablePriorityMailboxSpec extends MailboxSpec {
     case UnboundedMailbox() => new UnboundedStablePriorityMailbox(comparator).create(None, None)
     case BoundedMailbox(capacity, pushTimeOut) =>
       new BoundedStablePriorityMailbox(comparator, capacity, pushTimeOut).create(None, None)
+    case _ => throw new RuntimeException() // compiler exhaustiveness check pleaser
   }
 }
 
@@ -216,6 +220,7 @@ class ControlAwareMailboxSpec extends MailboxSpec {
     case UnboundedMailbox() => new UnboundedControlAwareMailbox().create(None, None)
     case BoundedMailbox(capacity, pushTimeOut) =>
       new BoundedControlAwareMailbox(capacity, pushTimeOut).create(None, None)
+    case _ => throw new RuntimeException() // compiler exhaustiveness check pleaser
   }
 }
 
@@ -258,6 +263,7 @@ class SingleConsumerOnlyMailboxSpec extends MailboxSpec {
   def factory = {
     case _: UnboundedMailbox            => SingleConsumerOnlyUnboundedMailbox().create(None, None)
     case _ @BoundedMailbox(capacity, _) => NonBlockingBoundedMailbox(capacity).create(None, None)
+    case _                              => throw new RuntimeException() // compiler exhaustiveness check pleaser
   }
 }
 

akka-actor-tests/src/test/scala/akka/dispatch/PriorityDispatcherSpec.scala

@@ -30,12 +30,14 @@ object PriorityDispatcherSpec {
       extends UnboundedPriorityMailbox(PriorityGenerator({
         case i: Int => i //Reverse order
         case Result => Int.MaxValue
+        case _      => throw new RuntimeException() // compiler exhaustiveness check pleaser
       }: Any => Int))
 
   class Bounded(@unused settings: ActorSystem.Settings, @unused config: Config)
       extends BoundedPriorityMailbox(PriorityGenerator({
         case i: Int => i //Reverse order
         case Result => Int.MaxValue
+        case _      => throw new RuntimeException() // compiler exhaustiveness check pleaser
       }: Any => Int), 1000, 10 seconds)
 
 }

akka-actor-tests/src/test/scala/akka/dispatch/StablePriorityDispatcherSpec.scala

@@ -30,6 +30,7 @@ object StablePriorityDispatcherSpec {
         case i: Int if i <= 100 => i // Small integers have high priority
         case _: Int             => 101 // Don't care for other integers
         case Result             => Int.MaxValue
+        case _                  => throw new RuntimeException() // compiler exhaustiveness check pleaser
       }: Any => Int))
 
   class Bounded(@unused settings: ActorSystem.Settings, @unused config: Config)
@@ -37,6 +38,7 @@ object StablePriorityDispatcherSpec {
         case i: Int if i <= 100 => i // Small integers have high priority
         case _: Int             => 101 // Don't care for other integers
         case Result             => Int.MaxValue
+        case _                  => throw new RuntimeException() // compiler exhaustiveness check pleaser
       }: Any => Int), 1000, 10 seconds)
 
 }

akka-actor-tests/src/test/scala/akka/io/UdpIntegrationSpec.scala

@@ -6,7 +6,6 @@ package akka.io
 
 import java.net.DatagramSocket
 import java.net.InetSocketAddress
-
 import akka.actor.ActorRef
 import akka.io.Inet._
 import akka.io.Udp._
@@ -64,7 +63,9 @@ class UdpIntegrationSpec extends AkkaSpec("""
     }
 
     "be able to send several packet back and forth with binding" in {
-      val Seq(serverAddress, clientAddress) = temporaryServerAddresses(2, udp = true)
+      val addresses = temporaryServerAddresses(2, udp = true)
+      val serverAddress = addresses(0)
+      val clientAddress = addresses(1)
       val server = bindUdp(serverAddress, testActor)
       val client = bindUdp(clientAddress, testActor)
       val data = ByteString("Fly little packet!")

akka-actor-tests/src/test/scala/akka/io/dns/internal/AsyncDnsManagerSpec.scala

@@ -37,7 +37,10 @@ class AsyncDnsManagerSpec extends AkkaSpec("""
 
     "support ipv6" in {
       dns ! Resolve("::1") // ::1 will short circuit the resolution
-      val Resolved("::1", Seq(AAAARecord("::1", Ttl.effectivelyForever, _)), Nil) = expectMsgType[Resolved]
+      expectMsgType[Resolved] match {
+        case Resolved("::1", Seq(AAAARecord("::1", Ttl.effectivelyForever, _)), Nil) =>
+        case other                                                                   => fail(other.toString)
+      }
     }
 
     "support ipv6 also using the old protocol" in {

akka-actor-tests/src/test/scala/akka/io/dns/internal/AsyncDnsResolverSpec.scala

@@ -123,8 +123,9 @@ class AsyncDnsResolverSpec extends AkkaSpec("""
       r ! Resolve(name)
       dnsClient1.expectNoMessage(50.millis)
       val answer = senderProbe.expectMsgType[Resolved]
-      val Seq(aaaaRecord) = answer.records.collect {
-        case r: AAAARecord => r
+      val aaaaRecord = answer.records match {
+        case Seq(r: AAAARecord) => r
+        case _                  => throw new RuntimeException() // compiler exhaustiveness check pleaser
       }
       aaaaRecord.name should be("1:2:3:0:0:0:0:0")
       aaaaRecord.ttl should be(Ttl.effectivelyForever)

akka-actor-tests/src/test/scala/akka/routing/ConfiguredLocalRoutingSpec.scala

@@ -113,7 +113,9 @@ class ConfiguredLocalRoutingSpec
       r.underlying match {
         case c: RoutedActorCell => c.routerConfig
         case _: UnstartedCell   => awaitCond(r.isStarted, 1 second, 10 millis); routerConfig(ref)
+        case _                  => throw new IllegalArgumentException(s"Unexpected underlying cell ${r.underlying}")
       }
+    case _ => throw new IllegalArgumentException(s"Unexpected actorref $ref")
   }
 
   def collectRouteePaths(probe: TestProbe, router: ActorRef, n: Int): immutable.Seq[ActorPath] = {

akka-actor-tests/src/test/scala/akka/serialization/AsyncSerializeSpec.scala

@@ -6,11 +6,8 @@ package akka.serialization
 
 import java.util.concurrent.CompletableFuture
 import java.util.concurrent.CompletionStage
-
 import scala.concurrent.Future
-
 import com.typesafe.config.ConfigFactory
-
 import akka.actor.ExtendedActorSystem
 import akka.testkit.{ AkkaSpec, EventFilter }
 
@@ -45,6 +42,7 @@ object AsyncSerializeSpec {
       o match {
         case Message1(msg) => Future.successful(msg.getBytes)
         case Message2(msg) => Future.successful(msg.getBytes)
+        case _             => throw new IllegalArgumentException(s"Unknown type $o")
       }
     }
 
@@ -52,6 +50,7 @@ object AsyncSerializeSpec {
       manifest match {
         case "1" => Future.successful(Message1(new String(bytes)))
         case "2" => Future.successful(Message2(new String(bytes)))
+        case _   => throw new IllegalArgumentException(s"Unknown manifest $manifest")
       }
     }
 
@@ -60,6 +59,7 @@ object AsyncSerializeSpec {
     override def manifest(o: AnyRef): String = o match {
       case _: Message1 => "1"
       case _: Message2 => "2"
+      case _           => throw new IllegalArgumentException(s"Unknown type $o")
     }
   }
 
@@ -69,6 +69,7 @@ object AsyncSerializeSpec {
       o match {
         case Message3(msg) => CompletableFuture.completedFuture(msg.getBytes)
         case Message4(msg) => CompletableFuture.completedFuture(msg.getBytes)
+        case _             => throw new IllegalArgumentException(s"Unknown type $o")
       }
     }
 
@@ -76,6 +77,7 @@ object AsyncSerializeSpec {
       manifest match {
         case "1" => CompletableFuture.completedFuture(Message3(new String(bytes)))
         case "2" => CompletableFuture.completedFuture(Message4(new String(bytes)))
+        case _   => throw new IllegalArgumentException(s"Unknown manifest $manifest")
       }
     }
 
@@ -84,6 +86,7 @@ object AsyncSerializeSpec {
     override def manifest(o: AnyRef): String = o match {
       case _: Message3 => "1"
       case _: Message4 => "2"
+      case _           => throw new IllegalArgumentException(s"Unknown type $o")
     }
   }
 

akka-actor-tests/src/test/scala/akka/util/BoundedBlockingQueueSpec.scala

@@ -621,7 +621,7 @@ trait CustomContainsMatcher {
         (remainingTruth, remainingSequence) match {
           case (_, Nil)                     => matchResult(true)
           case (Nil, _)                     => matchResult(false)
-          case (x :: xs, y :: ys) if x.equals(y) => attemptMatch(xs, ys)
+          case (x :: xs, y :: ys) if x == y => attemptMatch(xs, ys)
           case (_ :: xs, ys)                => attemptMatch(xs, ys)
         }
 

akka-actor-typed-tests/src/test/scala/akka/actor/typed/InterceptSpec.scala

@@ -55,6 +55,7 @@ object InterceptSpec {
         val wrapped = msg match {
           case c: Command          => InternalProtocol.WrappedCommand(c)
           case r: ExternalResponse => InternalProtocol.WrappedExternalResponse(r)
+          case unexpected          => throw new RuntimeException(s"Unexpected: $unexpected")
         }
         target(ctx, wrapped)
       }
@@ -63,7 +64,7 @@ object InterceptSpec {
 
     def apply(probe: ActorRef[String]): Behavior[Command] = {
       Behaviors
-        .intercept(() => new ProtocolTransformer)(Behaviors.receiveMessage[InternalProtocol] {
+        .intercept(() => new ProtocolTransformer)(Behaviors.receiveMessagePartial[InternalProtocol] {
           case InternalProtocol.WrappedCommand(cmd) =>
             probe ! cmd.s
             Behaviors.same
@@ -396,6 +397,7 @@ class InterceptSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with
           signal match {
             case PostStop =>
               probe.ref ! "interceptor-post-stop"
+            case _ =>
           }
           target(ctx, signal)
         }

akka-actor-typed-tests/src/test/scala/akka/actor/typed/MailboxSelectorSpec.scala

@@ -38,7 +38,9 @@ class MailboxSelectorSpec extends ScalaTestWithActorTestKit("""
               adapter.classicContext match {
                 case cell: ActorCell =>
                   cell.mailbox.messageQueue
+                case unexpected => throw new RuntimeException(s"Unexpected: $unexpected")
               }
+            case unexpected => throw new RuntimeException(s"Unexpected: $unexpected")
           }
 
           replyTo ! mailbox

akka-actor-typed-tests/src/test/scala/akka/actor/typed/SupervisionSpec.scala

@@ -1195,6 +1195,7 @@ class SupervisionSpec extends ScalaTestWithActorTestKit("""
                 case "boom" =>
                   probe.ref ! context.self
                   Behaviors.stopped
+                case unexpected => throw new RuntimeException(s"Unexpected: $unexpected")
               }
             })
             context.watch(child)
@@ -1420,7 +1421,7 @@ class SupervisionSpec extends ScalaTestWithActorTestKit("""
                   Behaviors.stopped
                 } else {
                   stopInSetup.set(true)
-                  Behaviors.receiveMessage {
+                  Behaviors.receiveMessagePartial {
                     case "boom" => throw TestException("boom")
                   }
                 }

akka-actor-typed-tests/src/test/scala/akka/actor/typed/TerminatedSpec.scala

@@ -21,10 +21,12 @@ class TerminatedSpec extends AnyWordSpec with Matchers with LogCapturing {
 
       (childFailed match {
         case Terminated(r) => r
+        case unexpected    => throw new RuntimeException(s"Unexpected: $unexpected")
       }) shouldEqual probe.ref
 
       (childFailed match {
         case ChildFailed(ref, e) => (ref, e)
+        case unexpected          => throw new RuntimeException(s"Unexpected: $unexpected")
       }) shouldEqual ((probe.ref, ex))
 
     }

akka-actor-typed-tests/src/test/scala/akka/actor/typed/coexistence/ClassicSupervisingTypedSpec.scala

@@ -19,7 +19,7 @@ import akka.testkit.TestProbe
 object ProbedBehavior {
   def behavior(probe: u.ActorRef): Behavior[String] = {
     Behaviors
-      .receiveMessage[String] {
+      .receiveMessagePartial[String] {
         case "throw" => throw TestException("oh dear")
       }
       .receiveSignal {

akka-actor-typed-tests/src/test/scala/akka/actor/typed/delivery/TestConsumer.scala

@@ -5,14 +5,11 @@
 package akka.actor.typed.delivery
 
 import java.nio.charset.StandardCharsets
-
 import scala.concurrent.duration.Duration
 import scala.concurrent.duration.FiniteDuration
 import scala.concurrent.duration._
-
 import com.typesafe.config.Config
 import com.typesafe.config.ConfigFactory
-
 import akka.actor.typed.ActorRef
 import akka.actor.typed.Behavior
 import akka.actor.typed.delivery.ConsumerController.SequencedMessage
@@ -21,6 +18,8 @@ import akka.actor.typed.scaladsl.ActorContext
 import akka.actor.typed.scaladsl.Behaviors
 import akka.serialization.SerializerWithStringManifest
 
+import java.io.NotSerializableException
+
 object TestConsumer {
 
   final case class Job(payload: String)
@@ -140,6 +139,7 @@ class TestSerializer extends SerializerWithStringManifest {
   override def toBinary(o: AnyRef): Array[Byte] =
     o match {
       case TestConsumer.Job(payload) => payload.getBytes(StandardCharsets.UTF_8)
+      case unexpected                => throw new NotSerializableException(s"Unexpected: $unexpected")
     }
 
   override def fromBinary(bytes: Array[Byte], manifest: String): AnyRef =

akka-actor-typed-tests/src/test/scala/akka/actor/typed/delivery/TestDurableProducerQueue.scala

@@ -55,7 +55,7 @@ class TestDurableProducerQueue[A](
 
   private def active(state: State[A]): Behavior[Command[A]] = {
     stateHolder.set(state)
-    Behaviors.receiveMessage {
+    Behaviors.receiveMessagePartial {
       case cmd: LoadState[A] @unchecked =>
         maybeFail(cmd)
         if (delay == Duration.Zero) cmd.replyTo ! state else context.scheduleOnce(delay, cmd.replyTo, state)

akka-actor-typed-tests/src/test/scala/akka/actor/typed/delivery/TestProducer.scala

@@ -15,7 +15,7 @@ import akka.actor.typed.scaladsl.Behaviors
 
 object TestProducer {
 
-  trait Command
+  sealed trait Command
   final case class RequestNext(sendTo: ActorRef[TestConsumer.Job]) extends Command
   private case object Tick extends Command
 
@@ -62,14 +62,12 @@ object TestProducer {
   }
 
   private def activeNoDelay(n: Int): Behavior[Command] = {
-    Behaviors.receive { (ctx, msg) =>
-      msg match {
-        case RequestNext(sendTo) =>
+    Behaviors.receivePartial {
+      case (ctx, RequestNext(sendTo)) =>
         sendMessage(n, sendTo, ctx)
         activeNoDelay(n + 1)
     }
   }
-  }
 
   private def sendMessage(n: Int, sendTo: ActorRef[TestConsumer.Job], ctx: ActorContext[Command]): Unit = {
     val msg = s"msg-$n"

akka-actor-typed-tests/src/test/scala/akka/actor/typed/delivery/TestProducerWithAsk.scala

@@ -43,27 +43,24 @@ object TestProducerWithAsk {
   }
 
   private def idle(n: Int, replyProbe: ActorRef[Long]): Behavior[Command] = {
-    Behaviors.receive { (ctx, msg) =>
-      msg match {
-        case Tick                => Behaviors.same
-        case RequestNext(sendTo) => active(n + 1, replyProbe, sendTo)
-        case Confirmed(seqNr) =>
+    Behaviors.receivePartial {
+      case (_, Tick)                => Behaviors.same
+      case (_, RequestNext(sendTo)) => active(n + 1, replyProbe, sendTo)
+      case (_, Confirmed(seqNr)) =>
         replyProbe ! seqNr
         Behaviors.same
-        case AskTimeout =>
+      case (ctx, AskTimeout) =>
         ctx.log.warn("Timeout")
         Behaviors.same
     }
   }
-  }
 
   private def active(
       n: Int,
       replyProbe: ActorRef[Long],
       sendTo: ActorRef[ProducerController.MessageWithConfirmation[TestConsumer.Job]]): Behavior[Command] = {
-    Behaviors.receive { (ctx, msg) =>
-      msg match {
-        case Tick =>
+    Behaviors.receivePartial {
+      case (ctx, Tick) =>
         val msg = s"msg-$n"
         ctx.log.info("sent {}", msg)
         ctx.ask(
@@ -75,19 +72,19 @@ object TestProducerWithAsk {
         }
         idle(n, replyProbe)
 
-        case RequestNext(_) =>
+      case (_, RequestNext(_)) =>
         throw new IllegalStateException("Unexpected RequestNext, already got one.")
 
-        case Confirmed(seqNr) =>
+      case (ctx, Confirmed(seqNr)) =>
         ctx.log.info("Reply Confirmed [{}]", seqNr)
         replyProbe ! seqNr
         Behaviors.same
 
-        case AskTimeout =>
+      case (ctx, AskTimeout) =>
         ctx.log.warn("Timeout")
         Behaviors.same
     }
-    }
+
   }
 
 }

akka-actor-typed-tests/src/test/scala/akka/actor/typed/delivery/TestProducerWorkPulling.scala

@@ -33,25 +33,23 @@ object TestProducerWorkPulling {
   }
 
   private def idle(n: Int): Behavior[Command] = {
-    Behaviors.receiveMessage {
+    Behaviors.receiveMessagePartial {
       case Tick                => Behaviors.same
       case RequestNext(sendTo) => active(n + 1, sendTo)
     }
   }
 
   private def active(n: Int, sendTo: ActorRef[TestConsumer.Job]): Behavior[Command] = {
-    Behaviors.receive { (ctx, msg) =>
-      msg match {
-        case Tick =>
+    Behaviors.receivePartial {
+      case (ctx, Tick) =>
         val msg = s"msg-$n"
         ctx.log.info("sent {}", msg)
         sendTo ! TestConsumer.Job(msg)
         idle(n)
 
-        case RequestNext(_) =>
+      case (_, RequestNext(_)) =>
         throw new IllegalStateException("Unexpected RequestNext, already got one.")
     }
   }
-  }
 
 }

akka-actor-typed-tests/src/test/scala/akka/actor/typed/javadsl/AdaptationFailureSpec.scala

@@ -86,6 +86,7 @@ class AdaptationFailureSpec extends ScalaTestWithActorTestKit with AnyWordSpecLi
               case (_, Terminated(`ref`)) =>
                 probe.ref ! "actor-stopped"
                 Behaviors.same
+              case _ => Behaviors.unhandled
             }
           })
 

akka-actor-typed-tests/src/test/scala/akka/actor/typed/receptionist/ReceptionistApiSpec.scala

@@ -68,7 +68,7 @@ object ReceptionistApiSpec {
       // to cover as much of the API as possible
       context.system.receptionist ! Receptionist.Register(key, context.self.narrow, context.self.narrow)
 
-      Behaviors.receiveMessage {
+      Behaviors.receiveMessagePartial {
         case key.Listing(services) =>
           services.foreach(_ ! "woho")
           Behaviors.same

akka-actor-typed-tests/src/test/scala/akka/actor/typed/scaladsl/ActorContextAskSpec.scala

@@ -79,12 +79,11 @@ class ActorContextAskSpec
       case class Ping(respondTo: ActorRef[Pong.type]) extends Protocol
       case object Pong extends Protocol
 
-      val pingPong = spawn(Behaviors.receive[Protocol]((_, message) =>
-        message match {
+      val pingPong = spawn(Behaviors.receiveMessagePartial[Protocol] {
         case Ping(respondTo) =>
           respondTo ! Pong
           Behaviors.same
-        }))
+      })
 
       val snitch = Behaviors.setup[AnyRef] { context =>
         context.ask(pingPong, Ping) {
@@ -93,7 +92,7 @@ class ActorContextAskSpec
         }
 
         Behaviors
-          .receive[AnyRef] {
+          .receivePartial[AnyRef] {
             case (_, message) =>
               probe.ref ! message
               Behaviors.same

akka-actor-typed-tests/src/test/scala/akka/actor/typed/scaladsl/MessageAdapterSpec.scala

@@ -93,7 +93,7 @@ class MessageAdapterSpec
 
       case class Wrapped(qualifier: String, response: Response)
 
-      val pingPong = spawn(Behaviors.receiveMessage[Ping] {
+      val pingPong = spawn(Behaviors.receiveMessagePartial[Ping] {
         case Ping1(sender) =>
           sender ! Pong1("hello-1")
           Behaviors.same
@@ -131,10 +131,10 @@ class MessageAdapterSpec
     }
 
     "not break if wrong/unknown response type" in {
-      trait Ping
+      sealed trait Ping
       case class Ping1(sender: ActorRef[Pong1]) extends Ping
       case class Ping2(sender: ActorRef[Pong2]) extends Ping
-      trait Response
+      sealed trait Response
       case class Pong1(greeting: String) extends Response
       case class Pong2(greeting: String) extends Response
 

akka-actor-typed-tests/src/test/scala/akka/actor/typed/scaladsl/OnSignalSpec.scala

@@ -39,7 +39,7 @@ final class OnSignalSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike
         }, s"$i")
       }
       Behaviors
-        .receiveMessage[String] {
+        .receiveMessagePartial[String] {
           case "stop" =>
             Behaviors.stopped
         }

akka-actor-typed-tests/src/test/scala/akka/actor/typed/scaladsl/RoutersSpec.scala

@@ -119,7 +119,7 @@ class RoutersSpec extends ScalaTestWithActorTestKit("""
       case object BCast extends Cmd
 
       def behavior(replyTo: ActorRef[AnyRef]) = Behaviors.setup[Cmd] { ctx =>
-        Behaviors.receiveMessage[Cmd] {
+        Behaviors.receiveMessagePartial[Cmd] {
           case ReplyWithAck | BCast =>
             val reply = ctx.self.path
             replyTo ! reply

akka-actor-typed-tests/src/test/scala/akka/actor/typed/scaladsl/StashSpec.scala

@@ -299,7 +299,7 @@ class UnstashingSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with
                 Behaviors.same
             }
 
-        Behaviors.receiveMessage[String] {
+        Behaviors.receiveMessagePartial[String] {
           case msg if msg.startsWith("stash") =>
             stash.stash(msg)
             Behaviors.same
@@ -635,14 +635,14 @@ class UnstashingSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with
         stash.stash("handled")
 
         def unstashing(n: Int): Behavior[String] =
-          Behaviors.receiveMessage {
+          Behaviors.receiveMessagePartial {
             case "unhandled" => Behaviors.unhandled
             case "handled" =>
               probe.ref ! s"handled $n"
               unstashing(n + 1)
           }
 
-        Behaviors.receiveMessage {
+        Behaviors.receiveMessagePartial {
           case "unstash" =>
             stash.unstashAll(unstashing(1))
         }
@@ -665,7 +665,7 @@ class UnstashingSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with
       val ref = spawn(Behaviors.withStash[String](10) { stash =>
         stash.stash("one")
 
-        Behaviors.receiveMessage {
+        Behaviors.receiveMessagePartial {
           case "unstash" =>
             stash.unstashAll(Behaviors.stopped)
         }
@@ -683,7 +683,7 @@ class UnstashingSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with
         stash.stash("one")
         stash.stash("two")
 
-        Behaviors.receiveMessage {
+        Behaviors.receiveMessagePartial {
           case "unstash" =>
             stash.unstashAll(Behaviors.receiveMessage { unstashed =>
               probe.ref ! unstashed

akka-actor-typed-tests/src/test/scala/akka/actor/typed/scaladsl/StopSpec.scala

@@ -32,7 +32,7 @@ class StopSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with LogCa
 
     "execute the post stop" in {
       val probe = TestProbe[Done]()
-      val ref = spawn(Behaviors.receiveMessage[String] {
+      val ref = spawn(Behaviors.receiveMessagePartial[String] {
         case "stop" =>
           Behaviors.stopped { () =>
             probe.ref ! Done
@@ -46,7 +46,7 @@ class StopSpec extends ScalaTestWithActorTestKit with AnyWordSpecLike with LogCa
       val probe = TestProbe[String]()
       val ref = spawn(
         Behaviors
-          .receiveMessage[String] {
+          .receiveMessagePartial[String] {
             case "stop" =>
               Behaviors.stopped { () =>
                 probe.ref ! "callback"

akka-actor-typed-tests/src/test/scala/docs/akka/typed/Aggregator.scala

@@ -32,8 +32,8 @@ object Aggregator {
 
       def collecting(replies: immutable.IndexedSeq[Reply]): Behavior[Command] = {
         Behaviors.receiveMessage {
-          case WrappedReply(reply: Reply) =>
-            val newReplies = replies :+ reply
+          case WrappedReply(reply) =>
+            val newReplies = replies :+ reply.asInstanceOf[Reply]
             if (newReplies.size == expectedReplies) {
               val result = aggregateReplies(newReplies)
               replyTo ! result

akka-actor-typed-tests/src/test/scala/docs/akka/typed/AggregatorSpec.scala

@@ -51,6 +51,7 @@ object AggregatorSpec {
                     .map {
                       case Hotel1.Quote(hotel, price) => Quote(hotel, price)
                       case Hotel2.Price(hotel, price) => Quote(hotel, price)
+                      case unknown                    => throw new RuntimeException(s"Unknown reply $unknown")
                     }
                     .sortBy(_.price)
                     .toList),

akka-actor-typed-tests/src/test/scala/docs/akka/typed/IntroSpec.scala

@@ -145,7 +145,7 @@ object IntroSpec {
     final case class SessionDenied(reason: String) extends SessionEvent
     final case class MessagePosted(screenName: String, message: String) extends SessionEvent
 
-    trait SessionCommand
+    sealed trait SessionCommand
     final case class PostMessage(message: String) extends SessionCommand
     private final case class NotifyClient(message: MessagePosted) extends SessionCommand
     //#chatroom-protocol

akka-actor-typed-tests/src/test/scala/docs/akka/typed/OOIntroSpec.scala

@@ -39,7 +39,7 @@ object OOIntroSpec {
     final case class SessionDenied(reason: String) extends SessionEvent
     final case class MessagePosted(screenName: String, message: String) extends SessionEvent
 
-    trait SessionCommand
+    sealed trait SessionCommand
     final case class PostMessage(message: String) extends SessionCommand
     private final case class NotifyClient(message: MessagePosted) extends SessionCommand
     //#chatroom-protocol
@@ -84,7 +84,7 @@ object OOIntroSpec {
         client: ActorRef[SessionEvent])
         extends AbstractBehavior[SessionCommand](context) {
 
-      override def onMessage(msg: SessionCommand): Behavior[SessionCommand] = {
+      override def onMessage(msg: SessionCommand): Behavior[SessionCommand] =
         msg match {
           case PostMessage(message) =>
             // from client, publish to others via the room
@@ -96,7 +96,6 @@ object OOIntroSpec {
             Behaviors.same
         }
     }
-    }
     //#chatroom-protocol
   }
   //#chatroom-protocol

akka-actor-typed-tests/src/test/scala/docs/akka/typed/StyleGuideDocExamples.scala

@@ -471,7 +471,8 @@ object StyleGuideDocExamples {
       private def counterWithGuard(remaining: Int): Behavior[Command] = {
         //#pattern-match-guard
         // no exhaustiveness check because of guard condition
-        Behaviors.receiveMessage {
+        // FIXME not true anymore since Scala 2.13.5
+        Behaviors.receiveMessagePartial {
           case Down if remaining == 1 =>
             notifyWhenZero.tell(Done)
             zero

akka-actor-typed-tests/src/test/scala/docs/akka/typed/TailChopping.scala

@@ -31,8 +31,8 @@ object TailChopping {
 
         def waiting(requestCount: Int): Behavior[Command] = {
           Behaviors.receiveMessage {
-            case WrappedReply(reply: Reply) =>
-              replyTo ! reply
+            case WrappedReply(reply) =>
+              replyTo ! reply.asInstanceOf[Reply]
               Behaviors.stopped
 
             case RequestTimeout =>

akka-actor-typed/src/main/mima-filters/2.6.13.backwards.excludes/scala-2.13.5-upgrade.excludes

@@ -0,0 +1,2 @@
+# Java API with classtag so have likely not been used from Java
+ProblemFilters.exclude[DirectMissingMethodProblem]("akka.actor.typed.delivery.WorkPullingProducerController.apply")

akka-actor-typed/src/main/scala/akka/actor/typed/delivery/WorkPullingProducerController.scala

@@ -237,7 +237,7 @@ object WorkPullingProducerController {
   /**
    * Java API
    */
-  def apply[A: ClassTag](
+  def apply[A](
       messageClass: Class[A],
       producerId: String,
       workerServiceKey: ServiceKey[ConsumerController.Command[A]],

akka-actor-typed/src/main/scala/akka/actor/typed/delivery/internal/ProducerControllerImpl.scala

@@ -193,7 +193,7 @@ object ProducerControllerImpl {
       .narrow
   }
 
-  private def askLoadState[A: ClassTag](
+  private def askLoadState[A](
       context: ActorContext[InternalCommand],
       durableQueueBehavior: Option[Behavior[DurableProducerQueue.Command[A]]],
       settings: ProducerController.Settings): Option[ActorRef[DurableProducerQueue.Command[A]]] = {
@@ -206,7 +206,7 @@ object ProducerControllerImpl {
     }
   }
 
-  private def askLoadState[A: ClassTag](
+  private def askLoadState[A](
       context: ActorContext[InternalCommand],
       durableQueue: Option[ActorRef[DurableProducerQueue.Command[A]]],
       settings: ProducerController.Settings,
@@ -222,11 +222,11 @@ object ProducerControllerImpl {
     }
   }
 
-  private def createInitialState[A: ClassTag](hasDurableQueue: Boolean) = {
+  private def createInitialState[A](hasDurableQueue: Boolean) = {
     if (hasDurableQueue) None else Some(DurableProducerQueue.State.empty[A])
   }
 
-  private def createState[A: ClassTag](
+  private def createState[A](
       self: ActorRef[InternalCommand],
       producerId: String,
       send: SequencedMessage[A] => Unit,
@@ -825,6 +825,9 @@ private class ProducerControllerImpl[A: ClassTag](
 
       case DurableQueueTerminated =>
         throw new IllegalStateException("DurableQueue was unexpectedly terminated.")
+
+      case unexpected =>
+        throw new RuntimeException(s"Unexpected message: $unexpected")
     }
   }
 

akka-actor-typed/src/main/scala/akka/actor/typed/delivery/internal/WorkPullingProducerControllerImpl.scala

@@ -140,7 +140,7 @@ import akka.util.Timeout
       .narrow
   }
 
-  private def createInitialState[A: ClassTag](hasDurableQueue: Boolean) = {
+  private def createInitialState[A](hasDurableQueue: Boolean) = {
     if (hasDurableQueue) None else Some(DurableProducerQueue.State.empty[A])
   }
 
@@ -158,6 +158,7 @@ import akka.util.Timeout
       s.unconfirmed.foreach {
         case DurableProducerQueue.MessageSent(oldSeqNr, msg, _, oldConfirmationQualifier, _) =>
           context.self ! ResendDurableMsg(msg, oldConfirmationQualifier, oldSeqNr)
+        case _ => // please compiler exhaustiveness check
       }
 
       val msgAdapter: ActorRef[A] = context.messageAdapter(msg => Msg(msg, wasStashed = false, replyTo = None))
@@ -220,12 +221,12 @@ import akka.util.Timeout
     }
   }
 
-  private def checkStashFull[A: ClassTag](stashBuffer: StashBuffer[InternalCommand]): Unit = {
+  private def checkStashFull[A](stashBuffer: StashBuffer[InternalCommand]): Unit = {
     if (stashBuffer.isFull)
       throw new IllegalArgumentException(s"Buffer is full, size [${stashBuffer.size}].")
   }
 
-  private def askLoadState[A: ClassTag](
+  private def askLoadState[A](
       context: ActorContext[InternalCommand],
       durableQueueBehavior: Option[Behavior[DurableProducerQueue.Command[A]]],
       settings: WorkPullingProducerController.Settings): Option[ActorRef[DurableProducerQueue.Command[A]]] = {
@@ -238,7 +239,7 @@ import akka.util.Timeout
     }
   }
 
-  private def askLoadState[A: ClassTag](
+  private def askLoadState[A](
       context: ActorContext[InternalCommand],
       durableQueue: Option[ActorRef[DurableProducerQueue.Command[A]]],
       settings: WorkPullingProducerController.Settings,
@@ -658,6 +659,8 @@ private class WorkPullingProducerControllerImpl[A: ClassTag](
       case DurableQueueTerminated =>
         throw new IllegalStateException("DurableQueue was unexpectedly terminated.")
 
+      case unexpected =>
+        throw new RuntimeException(s"Unexpected message: $unexpected")
     }
   }
 

akka-actor-typed/src/main/scala/akka/actor/typed/internal/ActorContextImpl.scala

@@ -105,7 +105,7 @@ import scala.util.Success
   // context-shared timer needed to allow for nested timer usage
   def timer: TimerSchedulerCrossDslSupport[T] = _timer match {
     case OptionVal.Some(timer) => timer
-    case OptionVal.None =>
+    case _ =>
       checkCurrentActorThread()
       val timer = mkTimer()
       _timer = OptionVal.Some(timer)
@@ -152,7 +152,7 @@ import scala.util.Success
     // lazy init of logging setup
     _logging match {
       case OptionVal.Some(l) => l
-      case OptionVal.None =>
+      case _ =>
         val logClass = LoggerClass.detectLoggerClassFromStack(classOf[Behavior[_]])
         val logger = LoggerFactory.getLogger(logClass.getName)
         val l = LoggingContext(logger, classicActorContext.props.deploy.tags, this)
@@ -216,6 +216,7 @@ import scala.util.Success
       case Success(StatusReply.Success(t: Res)) => mapResponse(Success(t))
       case Success(StatusReply.Error(why))      => mapResponse(Failure(why))
       case fail: Failure[_]                     => mapResponse(fail.asInstanceOf[Failure[Res]])
+      case _                                    => throw new RuntimeException() // won't happen, compiler exhaustiveness check pleaser
     }
 
   // Java API impl
@@ -247,6 +248,7 @@ import scala.util.Success
           case StatusReply.Success(value: Res) => applyToResponse(value, null)
           case StatusReply.Error(why)          => applyToResponse(null.asInstanceOf[Res], why)
           case null                            => applyToResponse(null.asInstanceOf[Res], failure)
+          case _                               => throw new RuntimeException() // won't happen, compiler exhaustiveness check pleaser
         })
   }
 
@@ -295,7 +297,7 @@ import scala.util.Success
       _messageAdapters.filterNot { case (cls, _) => cls == boxedMessageClass }
     val ref = messageAdapterRef match {
       case OptionVal.Some(ref) => ref.asInstanceOf[ActorRef[U]]
-      case OptionVal.None      =>
+      case _                   =>
         // AdaptMessage is not really a T, but that is erased
         val ref =
           internalSpawnMessageAdapter[Any](msg => AdaptWithRegisteredMessageAdapter(msg).asInstanceOf[T], "adapter")
@@ -315,12 +317,12 @@ import scala.util.Success
    */
   @InternalApi private[akka] def setCurrentActorThread(): Unit = {
     _currentActorThread match {
-      case OptionVal.None =>
-        _currentActorThread = OptionVal.Some(Thread.currentThread())
       case OptionVal.Some(t) =>
         throw new IllegalStateException(
           s"Invalid access by thread from the outside of $self. " +
           s"Current message is processed by $t, but also accessed from ${Thread.currentThread()}.")
+      case _ =>
+        _currentActorThread = OptionVal.Some(Thread.currentThread())
     }
   }
 
@@ -343,7 +345,7 @@ import scala.util.Success
             s"Unsupported access to ActorContext operation from the outside of $self. " +
             s"Current message is processed by $t, but ActorContext was called from $callerThread.")
         }
-      case OptionVal.None =>
+      case _ =>
         throw new UnsupportedOperationException(
           s"Unsupported access to ActorContext from the outside of $self. " +
           s"No message is currently processed by the actor, but ActorContext was called from $callerThread.")

akka-actor-typed/src/main/scala/akka/actor/typed/internal/BehaviorImpl.scala

@@ -97,7 +97,7 @@ private[akka] object BehaviorTags {
     def onPostStop(ctx: TypedActorContext[T]): Unit = {
       postStop match {
         case OptionVal.Some(callback) => callback(ctx)
-        case OptionVal.None           =>
+        case _                        =>
       }
     }
 

akka-actor-typed/src/main/scala/akka/actor/typed/internal/ExtensionsImpl.scala

@@ -92,7 +92,8 @@ private[akka] trait ExtensionsImpl extends Extensions { self: ActorSystem[_] wit
             .getOrElse(ext.createExtension(self))
           instance match {
             case null => throw new IllegalStateException(s"Extension instance created as 'null' for extension [$ext]")
-            case instance: T @unchecked =>
+            case nonNull =>
+              val instance = nonNull.asInstanceOf[T]
               // Replace our in process signal with the initialized extension
               extensions.replace(ext, inProcessOfRegistration, instance)
               instance

akka-actor-typed/src/main/scala/akka/actor/typed/internal/StashBufferImpl.scala

@@ -219,8 +219,8 @@ import java.util.function.Predicate
         throw new IllegalArgumentException("Cannot unstash with unhandled as starting behavior")
       else if (started == BehaviorImpl.same) {
         currentBehaviorWhenUnstashInProgress match {
-          case OptionVal.None    => ctx.asScala.currentBehavior
           case OptionVal.Some(c) => c
+          case _                 => ctx.asScala.currentBehavior
         }
       } else started
 

akka-actor-typed/src/main/scala/akka/actor/typed/internal/Supervision.scala

@@ -193,14 +193,12 @@ private class RestartSupervisor[T, Thr <: Throwable: ClassTag](initial: Behavior
   private var deadline: OptionVal[Deadline] = OptionVal.None
 
   private def deadlineHasTimeLeft: Boolean = deadline match {
-    case OptionVal.None    => true
     case OptionVal.Some(d) => d.hasTimeLeft()
+    case _                 => true
   }
 
   override def aroundSignal(ctx: TypedActorContext[Any], signal: Signal, target: SignalTarget[T]): Behavior[T] = {
     restartingInProgress match {
-      case OptionVal.None =>
-        super.aroundSignal(ctx, signal, target)
       case OptionVal.Some((stashBuffer, children)) =>
         signal match {
           case Terminated(ref) if strategy.stopChildren && children(ref) =>
@@ -219,6 +217,8 @@ private class RestartSupervisor[T, Thr <: Throwable: ClassTag](initial: Behavior
               stashBuffer.stash(signal)
             Behaviors.same
         }
+      case _ =>
+        super.aroundSignal(ctx, signal, target)
     }
   }
 
@@ -235,7 +235,7 @@ private class RestartSupervisor[T, Thr <: Throwable: ClassTag](initial: Behavior
               } else
                 restartCompleted(ctx)
 
-            case OptionVal.None =>
+            case _ =>
               throw new IllegalStateException("Unexpected ScheduledRestart when restart not in progress")
           }
         } else {
@@ -254,18 +254,19 @@ private class RestartSupervisor[T, Thr <: Throwable: ClassTag](initial: Behavior
           target(ctx, msg.asInstanceOf[T])
         }
 
-      case m: T @unchecked =>
+      case msg =>
+        val m = msg.asInstanceOf[T]
         restartingInProgress match {
-          case OptionVal.None =>
-            try {
-              target(ctx, m)
-            } catch handleReceiveException(ctx, target)
           case OptionVal.Some((stashBuffer, _)) =>
             if (stashBuffer.isFull)
               dropped(ctx, m)
             else
               stashBuffer.stash(m)
             Behaviors.same
+          case _ =>
+            try {
+              target(ctx, m)
+            } catch handleReceiveException(ctx, target)
         }
     }
   }
@@ -371,10 +372,10 @@ private class RestartSupervisor[T, Thr <: Throwable: ClassTag](initial: Behavior
     try {
       val newBehavior = Behavior.validateAsInitial(Behavior.start(initial, ctx.asInstanceOf[TypedActorContext[T]]))
       val nextBehavior = restartingInProgress match {
-        case OptionVal.None => newBehavior
         case OptionVal.Some((stashBuffer, _)) =>
           restartingInProgress = OptionVal.None
           stashBuffer.unstashAll(newBehavior.unsafeCast)
+        case _ => newBehavior
       }
       nextBehavior.narrow
     } catch handleException(ctx, signalRestart = {

akka-actor-typed/src/main/scala/akka/actor/typed/internal/adapter/ActorAdapter.scala

@@ -102,8 +102,9 @@ import akka.util.OptionVal
           adaptAndHandle(msg)
         case signal: Signal =>
           handleSignal(signal)
-        case msg: T @unchecked =>
-          handleMessage(msg)
+        case msg =>
+          val t = msg.asInstanceOf[T]
+          handleMessage(t)
       }
     } finally {
       ctx.clearCurrentActorThread()
@@ -119,9 +120,9 @@ import akka.util.OptionVal
           case timerMsg: TimerMsg =>
             //we can only get this kind of message if the timer is of this concrete class
             c.timer.asInstanceOf[TimerSchedulerImpl[T]].interceptTimerMsg(ctx.log, timerMsg) match {
-              case OptionVal.None => // means TimerMsg not applicable, discard
               case OptionVal.Some(m) =>
                 next(Behavior.interpretMessage(behavior, c, m), m)
+              case _ => // means TimerMsg not applicable, discard
             }
           case _ =>
             next(Behavior.interpretMessage(behavior, c, msg), msg)

akka-actor-typed/src/main/scala/akka/actor/typed/internal/adapter/ActorSystemAdapter.scala

@@ -88,6 +88,7 @@ import akka.annotation.InternalApi
         case DispatcherDefault(_)         => system.dispatcher
         case DispatcherFromConfig(str, _) => system.dispatchers.lookup(str)
         case DispatcherSameAsParent(_)    => system.dispatcher
+        case unknown                      => throw new RuntimeException(s"Unsupported dispatcher selector: $unknown")
       }
     override def shutdown(): Unit = () // there was no shutdown in classic Akka
   }

akka-actor-typed/src/main/scala/akka/actor/typed/internal/adapter/PropsAdapter.scala

@@ -25,6 +25,7 @@ import akka.dispatch.Mailboxes
       case _: DispatcherDefault          => classicProps
       case DispatcherFromConfig(name, _) => classicProps.withDispatcher(name)
       case _: DispatcherSameAsParent     => classicProps.withDispatcher(Deploy.DispatcherSameAsParent)
+      case unknown                       => throw new RuntimeException(s"Unsupported dispatcher selector: $unknown")
     }).withDeploy(Deploy.local) // disallow remote deployment for typed actors
 
     val mailboxProps = props.firstOrElse[MailboxSelector](MailboxSelector.default()) match {
@@ -34,6 +35,7 @@ import akka.dispatch.Mailboxes
         dispatcherProps.withMailbox(s"${Mailboxes.BoundedCapacityPrefix}$capacity")
       case MailboxFromConfigSelector(path, _) =>
         dispatcherProps.withMailbox(path)
+      case unknown => throw new RuntimeException(s"Unsupported mailbox selector: $unknown")
     }
 
     val localDeploy = mailboxProps.withDeploy(Deploy.local) // disallow remote deployment for typed actors

akka-actor-typed/src/main/scala/akka/actor/typed/internal/pubsub/TopicImpl.scala

@@ -69,6 +69,7 @@ private[akka] final class TopicImpl[T](topicName: String, context: ActorContext[
   private val receptionist = context.system.receptionist
   private val receptionistAdapter = context.messageAdapter[Receptionist.Listing] {
     case topicServiceKey.Listing(topics) => TopicInstancesUpdated(topics)
+    case _                               => throw new IllegalArgumentException() // FIXME exhaustiveness check fails on receptionist listing match
   }
   receptionist ! Receptionist.Subscribe(topicServiceKey, receptionistAdapter)
 
@@ -139,5 +140,9 @@ private[akka] final class TopicImpl[T](topicName: String, context: ActorContext[
     case GetTopicStats(replyTo) =>
       replyTo ! TopicStats(localSubscribers.size, topicInstances.size)
       this
+
+    case other =>
+      // can't do exhaustiveness check correctly because of protocol internal/public design
+      throw new IllegalArgumentException(s"Unexpected command type ${other.getClass}")
   }
 }

akka-actor-typed/src/main/scala/akka/actor/typed/internal/receptionist/LocalReceptionist.scala

@@ -218,6 +218,10 @@ private[akka] object LocalReceptionist extends ReceptionistBehaviorProvider {
         replyWithListing(key, subscriber)
 
         behavior(state.subscriberAdded(key)(subscriber))
+
+      case other =>
+        // compiler does not know about our division into public and internal commands
+        throw new IllegalArgumentException(s"Unexpected command type ${other.getClass}")
     }
 
     def onInternal(ctx: ActorContext[Any], cmd: InternalCommand): Behavior[Any] = cmd match {

akka-actor-typed/src/main/scala/akka/actor/typed/javadsl/AbstractBehavior.scala

@@ -41,11 +41,11 @@ abstract class AbstractBehavior[T](context: ActorContext[T]) extends ExtensibleB
 
   private var _receive: OptionVal[Receive[T]] = OptionVal.None
   private def receive: Receive[T] = _receive match {
-    case OptionVal.None =>
+    case OptionVal.Some(r) => r
+    case _ =>
       val receive = createReceive
       _receive = OptionVal.Some(receive)
       receive
-    case OptionVal.Some(r) => r
   }
 
   protected def getContext: ActorContext[T] = context

akka-actor-typed/src/main/scala/akka/actor/typed/javadsl/BehaviorBuilder.scala

@@ -82,7 +82,7 @@ final class BehaviorBuilder[T] private (messageHandlers: List[Case[T, T]], signa
   def onMessageEquals(msg: T, handler: Creator[Behavior[T]]): BehaviorBuilder[T] =
     withMessage[T](
       OptionVal.Some(msg.getClass.asInstanceOf[Class[T]]),
-      OptionVal.Some(_.equals(msg)),
+      OptionVal.Some(_ == msg),
       (_: T) => handler.create())
 
   /**

akka-actor/src/main/scala-2.13/akka/util/ByteIterator.scala

@@ -5,15 +5,15 @@
 package akka.util
 
 import java.nio.{ ByteBuffer, ByteOrder }
-
 import scala.annotation.tailrec
 import scala.collection.BufferedIterator
 import scala.collection.LinearSeq
 import scala.collection.mutable.ListBuffer
 import scala.reflect.ClassTag
-
 import akka.util.Collections.EmptyImmutableSeq
 
+import scala.annotation.nowarn
+
 object ByteIterator {
   object ByteArrayIterator {
 
@@ -48,24 +48,25 @@ object ByteIterator {
     final override def size: Int = { val l = len; clear(); l }
 
     final override def ++(that: IterableOnce[Byte]): ByteIterator = that match {
-      case that: ByteIterator =>
-        if (that.isEmpty) this
-        else if (this.isEmpty) that
+      case byteIterator: ByteIterator =>
+        if (byteIterator.isEmpty) this
+        else if (this.isEmpty) byteIterator
         else
-          that match {
-            case that: ByteArrayIterator =>
-              if ((this.array eq that.array) && (this.until == that.from)) {
-                this.until = that.until
-                that.clear()
+          byteIterator match {
+            case bai: ByteArrayIterator =>
+              if ((this.array eq bai.array) && (this.until == bai.from)) {
+                this.until = bai.until
+                bai.clear()
                 this
               } else {
-                val result = MultiByteArrayIterator(List(this, that))
+                val result = MultiByteArrayIterator(List(this, bai))
                 this.clear()
                 result
               }
-            case that: MultiByteArrayIterator => this ++: that
+            case mbai: MultiByteArrayIterator => this ++: mbai
+            case bi                           => super.++(bi)
           }
-      case _ => super.++(that)
+      case io => super.++(io)
     }
 
     final override def clone: ByteArrayIterator = new ByteArrayIterator(array, from, until)
@@ -99,9 +100,11 @@ object ByteIterator {
       this
     }
 
+    @nowarn("msg=deprecated")
     override def copyToArray[B >: Byte](xs: Array[B], start: Int): Int =
       this.copyToArray(xs, start, xs.length)
 
+    @nowarn("msg=deprecated")
     override def copyToArray[B >: Byte](xs: Array[B]): Int =
       this.copyToArray(xs, 0, xs.length)
 
@@ -234,22 +237,23 @@ object ByteIterator {
     }
 
     final override def ++(that: IterableOnce[Byte]): ByteIterator = that match {
-      case that: ByteIterator =>
-        if (that.isEmpty) this
-        else if (this.isEmpty) that
+      case bi: ByteIterator =>
+        if (bi.isEmpty) this
+        else if (this.isEmpty) bi
         else {
-          that match {
-            case that: ByteArrayIterator =>
-              iterators = this.iterators :+ that
-              that.clear()
+          bi match {
+            case bai: ByteArrayIterator =>
+              iterators = this.iterators :+ bai
+              bai.clear()
               this
-            case that: MultiByteArrayIterator =>
-              iterators = this.iterators ++ that.iterators
-              that.clear()
+            case mbai: MultiByteArrayIterator =>
+              iterators = this.iterators ++ mbai.iterators
+              mbai.clear()
               this
+            case bi => super.++(bi)
           }
         }
-      case _ => super.++(that)
+      case io => super.++(io)
     }
 
     final override def clone: MultiByteArrayIterator = {

akka-actor/src/main/scala-2.13/akka/util/ByteString.scala

@@ -833,6 +833,7 @@ sealed abstract class ByteString
     array
   }
 
+  @nowarn("msg=deprecated")
   final override def copyToArray[B >: Byte](xs: Array[B], start: Int): Int = {
     // super uses byteiterator
     copyToArray(xs, start, size.min(xs.size))

akka-actor/src/main/scala/akka/actor/AbstractProps.scala

@@ -65,6 +65,8 @@ private[akka] trait AbstractProps {
       case c: Class[_] if c == coc =>
         throw new IllegalArgumentException(
           "erased Creator types (e.g. lambdas) are unsupported, use Props.create(actorClass, creator) instead")
+      case unexpected =>
+        throw new IllegalArgumentException(s"unexpected type: $unexpected")
     }
     create(classOf[CreatorConsumer], actorClass, creator)
   }

akka-actor/src/main/scala/akka/actor/ActorCell.scala

@@ -565,6 +565,8 @@ private[akka] class ActorCell(
       case PoisonPill                 => self.stop()
       case sel: ActorSelectionMessage => receiveSelection(sel)
       case Identify(messageId)        => sender() ! ActorIdentity(messageId, Some(self))
+      case unexpected =>
+        throw new RuntimeException(s"Unexpected message for autoreceive: $unexpected") // for exhaustiveness check, will not happen
     }
   }
 

akka-actor/src/main/scala/akka/actor/ActorRef.scala

@@ -241,6 +241,8 @@ private[akka] trait RepointableRef extends ActorRefScope {
       case i: InternalActorRef =>
         (i.isLocal && i.isInstanceOf[PromiseActorRef]) ||
         (!i.isLocal && i.path.elements.head == "temp")
+      case unexpected =>
+        throw new IllegalArgumentException(s"ActorRef is not internal: $unexpected") // will not happen, for exhaustiveness check
     }
 
 }
@@ -924,8 +926,9 @@ private[akka] class VirtualPathContainer(
 
           (oldWatching, wBy)
 
-        case OptionVal.None =>
+        case _ =>
           (ActorCell.emptyActorRefSet, ActorCell.emptyActorRefSet)
+
       }
     }
 
@@ -949,14 +952,14 @@ private[akka] class VirtualPathContainer(
     val toNotify = this.synchronized {
       // cleanup watchedBy since we know they are dead
       _watchedBy match {
-        case OptionVal.None =>
-          // terminated
-          ActorCell.emptyActorRefSet
         case OptionVal.Some(watchedBy) =>
           maintainAddressTerminatedSubscription(OptionVal.None) {
             _watchedBy = OptionVal.Some(watchedBy.filterNot(_.path.address == address))
           }
           watching
+        case _ =>
+          // terminated
+          ActorCell.emptyActorRefSet
       }
     }
 
@@ -978,8 +981,6 @@ private[akka] class VirtualPathContainer(
   private def addWatcher(watchee: ActorRef, watcher: ActorRef): Unit = {
     val selfTerminated = this.synchronized {
       _watchedBy match {
-        case OptionVal.None =>
-          true
         case OptionVal.Some(watchedBy) =>
           val watcheeSelf = watchee == this
           val watcherSelf = watcher == this
@@ -1001,6 +1002,8 @@ private[akka] class VirtualPathContainer(
               Logging.Error(path.toString, classOf[FunctionRef], s"BUG: illegal Watch($watchee,$watcher) for $this"))
           }
           false
+        case _ =>
+          true
       }
     }
     // outside of synchronized block
@@ -1012,7 +1015,6 @@ private[akka] class VirtualPathContainer(
 
   private def remWatcher(watchee: ActorRef, watcher: ActorRef): Unit = this.synchronized {
     _watchedBy match {
-      case OptionVal.None => // do nothing...
       case OptionVal.Some(watchedBy) =>
         val watcheeSelf = watchee == this
         val watcherSelf = watcher == this
@@ -1033,6 +1035,8 @@ private[akka] class VirtualPathContainer(
           publish(
             Logging.Error(path.toString, classOf[FunctionRef], s"BUG: illegal Unwatch($watchee,$watcher) for $this"))
         }
+
+      case _ => // do nothing...
     }
   }
 
@@ -1097,7 +1101,7 @@ private[akka] class VirtualPathContainer(
     def watchedByOrEmpty: Set[ActorRef] =
       _watchedBy match {
         case OptionVal.Some(watchedBy) => watchedBy
-        case OptionVal.None            => ActorCell.emptyActorRefSet
+        case _                         => ActorCell.emptyActorRefSet
       }
 
     change match {

akka-actor/src/main/scala/akka/actor/ActorRefProvider.scala

@@ -756,7 +756,7 @@ private[akka] class LocalActorRefProvider private[akka] (
     Serialization.Information(getDefaultAddress, system)
     serializationInformationCache match {
       case OptionVal.Some(info) => info
-      case OptionVal.None =>
+      case _ =>
         if (system eq null)
           throw new IllegalStateException("Too early access of serializationInformation")
         else {
@@ -773,7 +773,7 @@ private[akka] class LocalActorRefProvider private[akka] (
   override private[akka] def addressString: String = {
     _addressString match {
       case OptionVal.Some(addr) => addr
-      case OptionVal.None =>
+      case _ =>
         val addr = getDefaultAddress.toString
         _addressString = OptionVal.Some(addr)
         addr

akka-actor/src/main/scala/akka/actor/ReflectiveDynamicAccess.scala

@@ -69,6 +69,8 @@ class ReflectiveDynamicAccess(val classLoader: ClassLoader) extends DynamicAcces
           case null                  => throw new NullPointerException
           case x if !t.isInstance(x) => throw new ClassCastException(fqcn + " is not a subtype of " + t)
           case x: T                  => x
+          case unexpected =>
+            throw new IllegalArgumentException(s"Unexpected module field: $unexpected") // will not happen, for exhaustiveness check
         }
       }.recover { case i: InvocationTargetException if i.getTargetException ne null => throw i.getTargetException }
     }

akka-actor/src/main/scala/akka/actor/Timers.scala

@@ -50,7 +50,7 @@ trait Timers extends Actor {
               actorCell.currentMessage = actorCell.currentMessage.copy(message = m)
             }
             super.aroundReceive(receive, m)
-          case OptionVal.None => // discard
+          case _ => // discard
         }
       case _ =>
         super.aroundReceive(receive, msg)

akka-actor/src/main/scala/akka/actor/dungeon/DeathWatch.scala

@@ -33,6 +33,8 @@ private[akka] trait DeathWatch { this: ActorCell =>
           checkWatchingSame(a, None)
       }
       a
+    case unexpected =>
+      throw new IllegalArgumentException(s"ActorRef is not internal: $unexpected") // will not happen, for exhaustiveness check
   }
 
   override final def watchWith(subject: ActorRef, msg: Any): ActorRef = subject match {
@@ -46,6 +48,8 @@ private[akka] trait DeathWatch { this: ActorCell =>
           checkWatchingSame(a, Some(msg))
       }
       a
+    case unexpected =>
+      throw new IllegalArgumentException(s"ActorRef is not internal: $unexpected") // will not happen, for exhaustiveness check
   }
 
   override final def unwatch(subject: ActorRef): ActorRef = subject match {
@@ -58,6 +62,8 @@ private[akka] trait DeathWatch { this: ActorCell =>
       }
       terminatedQueued -= a
       a
+    case unexpected =>
+      throw new IllegalArgumentException(s"ActorRef is not internal: $unexpected") // will not happen, for exhaustiveness check
   }
 
   protected def receivedTerminated(t: Terminated): Unit =

akka-actor/src/main/scala/akka/dispatch/AbstractDispatcher.scala

@@ -186,6 +186,8 @@ abstract class MessageDispatcher(val configurator: MessageDispatcherConfigurator
         if (updateShutdownSchedule(SCHEDULED, RESCHEDULED)) ()
         else ifSensibleToDoSoThenScheduleShutdown()
       case RESCHEDULED =>
+      case unexpected =>
+        throw new IllegalArgumentException(s"Unexpected actor class marker: $unexpected") // will not happen, for exhaustiveness check
     }
   }
 
@@ -245,6 +247,8 @@ abstract class MessageDispatcher(val configurator: MessageDispatcherConfigurator
           if (updateShutdownSchedule(RESCHEDULED, SCHEDULED)) scheduleShutdownAction()
           else run()
         case UNSCHEDULED =>
+        case unexpected =>
+          throw new IllegalArgumentException(s"Unexpected actor class marker: $unexpected") // will not happen, for exhaustiveness check
       }
     }
   }

akka-actor/src/main/scala/akka/dispatch/Mailboxes.scala

@@ -108,6 +108,8 @@ private[akka] class Mailboxes(
           case x =>
             throw new IllegalArgumentException(s"no wildcard type allowed in RequireMessageQueue argument (was [$x])")
         }
+      case unexpected =>
+        throw new IllegalArgumentException(s"Unexpected actor class marker: $unexpected") // will not happen, for exhaustiveness check
     }
 
   // don’t care if this happens twice
@@ -131,6 +133,8 @@ private[akka] class Mailboxes(
               throw new IllegalArgumentException(
                 s"no wildcard type allowed in ProducesMessageQueue argument (was [$x])")
           }
+        case unexpected =>
+          throw new IllegalArgumentException(s"Unexpected message queue type marker: $unexpected") // will not happen, for exhaustiveness check
       }
   }
 

akka-actor/src/main/scala/akka/io/UdpListener.scala

@@ -100,6 +100,8 @@ private[io] class UdpListener(val udp: UdpExt, channelRegistry: ChannelRegistry,
           handler ! Received(ByteString(buffer), sender)
           if (readsLeft > 0) innerReceive(readsLeft - 1, buffer)
         case null => // null means no data was available
+        case unexpected =>
+          throw new RuntimeException(s"Unexpected address in buffer: $unexpected") // will not happen, for exhaustiveness check
       }
     }
 

akka-actor/src/main/scala/akka/io/dns/DnsSettings.scala

@@ -136,9 +136,12 @@ object DnsSettings {
   /**
    * INTERNAL API
    */
-  @InternalApi private[akka] def parseNameserverAddress(str: String): InetSocketAddress = {
-    val inetSocketAddress(host, port) = str
+  @InternalApi private[akka] def parseNameserverAddress(str: String): InetSocketAddress =
+    str match {
+      case inetSocketAddress(host, port) =>
         new InetSocketAddress(host, Option(port).fold(DnsFallbackPort)(_.toInt))
+      case unexpected =>
+        throw new IllegalArgumentException(s"Unparseable address string: $unexpected") // will not happen, for exhaustiveness check
     }
 
   /**

akka-actor/src/main/scala/akka/io/dns/internal/AsyncDnsResolver.scala

@@ -94,6 +94,7 @@ private[io] final class AsyncDnsResolver(
           val record = address match {
             case _: Inet4Address           => ARecord(name, Ttl.effectivelyForever, address)
             case ipv6address: Inet6Address => AAAARecord(name, Ttl.effectivelyForever, ipv6address)
+            case unexpected                => throw new IllegalArgumentException(s"Unexpected address: $unexpected")
           }
           DnsProtocol.Resolved(name, record :: Nil)
         }

akka-actor/src/main/scala/akka/io/dns/internal/RecordTypeSerializer.scala

@@ -20,8 +20,8 @@ private[akka] object RecordTypeSerializer {
   def parse(it: ByteIterator): RecordType = {
     val id = it.getShort
     RecordType(id) match {
-      case OptionVal.None    => throw new IllegalArgumentException(s"Illegal id [$id] for DnsRecordType")
       case OptionVal.Some(t) => t
+      case _                 => throw new IllegalArgumentException(s"Illegal id [$id] for DnsRecordType")
     }
   }
 

akka-actor/src/main/scala/akka/pattern/AskSupport.scala

@@ -604,6 +604,7 @@ private[akka] final class PromiseActorRef private (
       updateState(Stopped, StoppedWithPath(provider.tempPath()))
       path
     case Registering => path // spin until registration is completed
+    case unexpected  => throw new IllegalStateException(s"Unexpected state: $unexpected")
   }
 
   override def !(message: Any)(implicit sender: ActorRef = Actor.noSender): Unit = state match {
@@ -668,6 +669,7 @@ private[akka] final class PromiseActorRef private (
         } else stop()
       case Stopped | _: StoppedWithPath => // already stopped
       case Registering                  => stop() // spin until registration is completed before stopping
+      case unexpected                   => throw new IllegalStateException(s"Unexpected state: $unexpected")
     }
   }
 

akka-actor/src/main/scala/akka/pattern/StatusReply.scala

@@ -164,6 +164,8 @@ object StatusReply {
         s match {
           case StatusReply.Success(v) => ScalaSuccess(v.asInstanceOf[T])
           case StatusReply.Error(ex)  => ScalaFailure[T](ex)
+          case unexpected =>
+            ScalaFailure(new IllegalArgumentException(s"Unexpected status reply success value: ${unexpected}"))
         }
       case fail @ ScalaFailure(_) => fail.asInstanceOf[Try[T]]
     }(ExecutionContexts.parasitic)

akka-actor/src/main/scala/akka/routing/ConsistentHashing.scala

@@ -219,6 +219,8 @@ final case class ConsistentHashingRoutingLogic(
               case bytes: Array[Byte] => currentConsistenHash.nodeFor(bytes).routee
               case str: String        => currentConsistenHash.nodeFor(str).routee
               case x: AnyRef          => currentConsistenHash.nodeFor(SerializationExtension(system).serialize(x).get).routee
+              case unexpected =>
+                throw new IllegalArgumentException(s"Unexpected hashdata: $unexpected") // will not happen, for exhaustiveness check
             }
         } catch {
           case NonFatal(e) =>

akka-actor/src/main/scala/akka/serialization/PrimitiveSerializers.scala

@@ -168,6 +168,7 @@ import akka.util.ByteString
     val flag = o match {
       case TRUE  => TrueB
       case FALSE => FalseB
+      case b     => throw new IllegalArgumentException(s"Non boolean flag: $b")
     }
     buf.put(flag)
   }
@@ -176,6 +177,7 @@ import akka.util.ByteString
     buf.get() match {
       case TrueB  => TRUE
       case FalseB => FALSE
+      case b      => throw new IllegalArgumentException(s"Non boolean flag byte: $b")
     }
   }
 
@@ -183,6 +185,7 @@ import akka.util.ByteString
     val flag = o match {
       case TRUE  => TrueB
       case FALSE => FalseB
+      case b     => throw new IllegalArgumentException(s"Non boolean flag: $b")
     }
     val result = new Array[Byte](1)
     result(0) = flag
@@ -193,6 +196,7 @@ import akka.util.ByteString
     bytes(0) match {
       case TrueB  => TRUE
       case FalseB => FALSE
+      case b      => throw new IllegalArgumentException(s"Non boolean flag byte: $b")
     }
   }
 }

akka-actor/src/main/scala/akka/util/HashCode.scala

@@ -40,6 +40,8 @@ object HashCode {
       else if (!isArray(value)) result = hash(result, value.hashCode())
       else for (id <- 0 until JArray.getLength(value)) result = hash(result, JArray.get(value, id)) // is an array
       result
+    case unexpected =>
+      throw new IllegalArgumentException(s"Unexpected hash parameter: $unexpected") // will not happen, for exhaustiveness check
   }
   def hash(seed: Int, value: Boolean): Int = firstTerm(seed) + (if (value) 1 else 0)
   def hash(seed: Int, value: Char): Int = firstTerm(seed) + value.asInstanceOf[Int]

akka-bench-jmh/src/main/scala/akka/actor/typed/TypedBenchmarkActors.scala

@@ -95,7 +95,7 @@ object TypedBenchmarkActors {
         val startNanoTime = System.nanoTime()
         pairs.foreach(_ ! Message)
         var interactionsLeft = numPairs
-        Behaviors.receiveMessage {
+        Behaviors.receiveMessagePartial {
           case Done =>
             interactionsLeft -= 1
             if (interactionsLeft == 0) {

akka-bench-jmh/src/main/scala/akka/actor/typed/delivery/ReliableDeliveryBenchmark.scala

@@ -41,7 +41,7 @@ object Producer {
       val requestNextAdapter =
         context.messageAdapter[ProducerController.RequestNext[Consumer.Command]](WrappedRequestNext(_))
 
-      Behaviors.receiveMessage {
+      Behaviors.receiveMessagePartial {
         case WrappedRequestNext(next) =>
           if (next.confirmedSeqNr >= numberOfMessages) {
             context.log.info("Completed {} messages", numberOfMessages)
@@ -114,7 +114,7 @@ object WorkPullingProducer {
       var remaining = numberOfMessages + context.system.settings.config
           .getInt("akka.reliable-delivery.consumer-controller.flow-control-window")
 
-      Behaviors.receiveMessage {
+      Behaviors.receiveMessagePartial {
         case WrappedRequestNext(next) =>
           remaining -= 1
           if (remaining == 0) {
@@ -183,6 +183,9 @@ object Guardian {
           consumers.foreach(context.stop)
           replyTo ! Done
           Behaviors.same
+
+        case msg =>
+          throw new RuntimeException(s"Unexpected message $msg")
       }
     }
   }

akka-cluster-metrics/src/main/scala/akka/cluster/metrics/ClusterMetricsRouting.scala

@@ -489,6 +489,7 @@ private[metrics] class WeightedRoutees(
       val a = routee match {
         case ActorRefRoutee(ref)       => ref.path.address
         case ActorSelectionRoutee(sel) => sel.anchor.path.address
+        case _                         => throw new RuntimeException()
       }
       a match {
         case Address(_, _, None, None) => selfAddress

akka-cluster-metrics/src/multi-jvm/scala/akka/cluster/metrics/ClusterMetricsRoutingSpec.scala

@@ -156,7 +156,7 @@ abstract class AdaptiveLoadBalancingRouterSpec
     // it may take some time until router receives cluster member events
     awaitAssert { currentRoutees(router).size should ===(roles.size) }
     val routees = currentRoutees(router)
-    routees.map { case ActorRefRoutee(ref) => fullAddress(ref) }.toSet should ===(roles.map(address).toSet)
+    routees.collect { case ActorRefRoutee(ref) => fullAddress(ref) }.toSet should ===(roles.map(address).toSet)
     router
   }
 
@@ -235,7 +235,7 @@ abstract class AdaptiveLoadBalancingRouterSpec
         // it may take some time until router receives cluster member events
         awaitAssert { currentRoutees(router3).size should ===(9) }
         val routees = currentRoutees(router3)
-        routees.map { case ActorRefRoutee(ref) => fullAddress(ref) }.toSet should ===(Set(address(node1)))
+        routees.collect { case ActorRefRoutee(ref) => fullAddress(ref) }.toSet should ===(Set(address(node1)))
       }
       enterBarrier("after-4")
     }
@@ -246,7 +246,7 @@ abstract class AdaptiveLoadBalancingRouterSpec
         // it may take some time until router receives cluster member events
         awaitAssert { currentRoutees(router4).size should ===(6) }
         val routees = currentRoutees(router4)
-        routees.map { case ActorRefRoutee(ref) => fullAddress(ref) }.toSet should ===(
+        routees.collect { case ActorRefRoutee(ref) => fullAddress(ref) }.toSet should ===(
           Set(address(node1), address(node2), address(node3)))
       }
       enterBarrier("after-5")

akka-cluster-metrics/src/test/scala/akka/cluster/metrics/ClusterMetricsExtensionSpec.scala

@@ -82,6 +82,7 @@ class ClusterMetricsExtensionSpec
               loadAverageMock.get should ===(loadAverageEwma +- epsilon)
               cpuCombinedMock.get should ===(cpuCombinedEwma +- epsilon)
               cpuStolenMock.get should ===(cpuStolenEwma +- epsilon)
+            case _ => fail()
           }
       }
     }

akka-cluster-sharding-typed/src/main/scala/akka/cluster/sharding/typed/delivery/internal/ShardingProducerControllerImpl.scala

@@ -125,7 +125,7 @@ import akka.util.Timeout
       .narrow
   }
 
-  private def createInitialState[A: ClassTag](hasDurableQueue: Boolean) = {
+  private def createInitialState[A](hasDurableQueue: Boolean) = {
     if (hasDurableQueue) None else Some(DurableProducerQueue.State.empty[A])
   }
 
@@ -226,12 +226,12 @@ import akka.util.Timeout
     }
   }
 
-  private def checkStashFull[A: ClassTag](stashBuffer: StashBuffer[InternalCommand]): Unit = {
+  private def checkStashFull[A](stashBuffer: StashBuffer[InternalCommand]): Unit = {
     if (stashBuffer.isFull)
       throw new IllegalArgumentException(s"Buffer is full, size [${stashBuffer.size}].")
   }
 
-  private def askLoadState[A: ClassTag](
+  private def askLoadState[A](
       context: ActorContext[InternalCommand],
       durableQueueBehavior: Option[Behavior[DurableProducerQueue.Command[A]]],
       settings: ShardingProducerController.Settings): Option[ActorRef[DurableProducerQueue.Command[A]]] = {
@@ -244,7 +244,7 @@ import akka.util.Timeout
     }
   }
 
-  private def askLoadState[A: ClassTag](
+  private def askLoadState[A](
       context: ActorContext[InternalCommand],
       durableQueue: Option[ActorRef[DurableProducerQueue.Command[A]]],
       settings: ShardingProducerController.Settings,
@@ -565,6 +565,8 @@ private class ShardingProducerControllerImpl[A: ClassTag](
       case DurableQueueTerminated =>
         throw new IllegalStateException("DurableQueue was unexpectedly terminated.")
 
+      case unexpected =>
+        throw new RuntimeException(s"Unexpected message: $unexpected")
     }
   }
 

akka-cluster-sharding-typed/src/main/scala/akka/cluster/sharding/typed/internal/ClusterShardingImpl.scala

@@ -55,7 +55,7 @@ import akka.util.JavaDurationConverters._
     message match {
       case ShardingEnvelope(entityId, _) => entityId //also covers ClassicStartEntity in ShardingEnvelope
       case ClassicStartEntity(entityId)  => entityId
-      case msg: E @unchecked             => delegate.entityId(msg)
+      case msg                           => delegate.entityId(msg.asInstanceOf[E])
     }
   }
 
@@ -69,8 +69,8 @@ import akka.util.JavaDurationConverters._
       case msg: ClassicStartEntity =>
         // not really of type M, but erased and StartEntity is only handled internally, not delivered to the entity
         msg.asInstanceOf[M]
-      case msg: E @unchecked =>
-        delegate.unwrapMessage(msg)
+      case msg =>
+        delegate.unwrapMessage(msg.asInstanceOf[E])
     }
   }
 

akka-cluster-sharding-typed/src/multi-jvm/scala/akka/cluster/sharding/typed/ShardedDaemonProcessSpec.scala

@@ -39,7 +39,7 @@ object ShardedDaemonProcessSpec extends MultiNodeConfig {
       val snitchRouter = ctx.spawn(Routers.group(SnitchServiceKey), "router")
       snitchRouter ! ProcessActorEvent(id, "Started")
 
-      Behaviors.receiveMessage {
+      Behaviors.receiveMessagePartial {
         case Stop =>
           snitchRouter ! ProcessActorEvent(id, "Stopped")
           Behaviors.stopped

akka-cluster-sharding-typed/src/multi-jvm/scala/akka/cluster/sharding/typed/delivery/DeliveryThroughputSpec.scala

@@ -77,7 +77,7 @@ object DeliveryThroughputSpec extends MultiNodeConfig {
   }
 
   object Consumer {
-    trait Command
+    sealed trait Command
 
     case object TheMessage extends Command with CborSerializable
     case object Stop extends Command
@@ -122,7 +122,7 @@ object DeliveryThroughputSpec extends MultiNodeConfig {
   }
 
   object Producer {
-    trait Command
+    sealed trait Command
 
     case object Run extends Command
     private case class WrappedRequestNext(r: ProducerController.RequestNext[Consumer.Command]) extends Command
@@ -180,7 +180,7 @@ object DeliveryThroughputSpec extends MultiNodeConfig {
   def serviceKey(testName: String) = ServiceKey[ConsumerController.Command[Consumer.Command]](testName)
 
   object WorkPullingProducer {
-    trait Command
+    sealed trait Command
 
     case object Run extends Command
     private case class WrappedRequestNext(r: WorkPullingProducerController.RequestNext[Consumer.Command])
@@ -225,7 +225,7 @@ object DeliveryThroughputSpec extends MultiNodeConfig {
   def typeKey(testName: String) = EntityTypeKey[ConsumerController.SequencedMessage[Consumer.Command]](testName)
 
   object ShardingProducer {
-    trait Command
+    sealed trait Command
 
     case object Run extends Command
     private case class WrappedRequestNext(r: ShardingProducerController.RequestNext[Consumer.Command]) extends Command

akka-cluster-sharding-typed/src/test/scala/akka/cluster/sharding/typed/ReplicatedShardingSpec.scala

@@ -70,7 +70,7 @@ object ReplicatedShardingSpec {
   val AllReplicas = Set(ReplicaId("DC-A"), ReplicaId("DC-B"))
 
   object MyReplicatedStringSet {
-    trait Command extends CborSerializable
+    sealed trait Command extends CborSerializable
     case class Add(text: String) extends Command
     case class GetTexts(replyTo: ActorRef[Texts]) extends Command
 
@@ -122,7 +122,7 @@ object ReplicatedShardingSpec {
   }
 
   object MyReplicatedIntSet {
-    trait Command extends CborSerializable
+    sealed trait Command extends CborSerializable
     case class Add(text: Int) extends Command
     case class GetInts(replyTo: ActorRef[Ints]) extends Command
     case class Ints(ints: Set[Int]) extends CborSerializable

akka-cluster-sharding-typed/src/test/scala/akka/cluster/sharding/typed/delivery/ReliableDeliveryShardingSpec.scala

@@ -40,7 +40,7 @@ object ReliableDeliveryShardingSpec {
 
   object TestShardingProducer {
 
-    trait Command
+    sealed trait Command
     final case class RequestNext(sendToRef: ActorRef[ShardingEnvelope[TestConsumer.Job]]) extends Command
 
     private case object Tick extends Command

akka-cluster-sharding-typed/src/test/scala/akka/cluster/sharding/typed/scaladsl/ShardedDaemonProcessSpec.scala

@@ -38,7 +38,7 @@ object ShardedDaemonProcessSpec {
       """)
 
   object MyActor {
-    trait Command
+    sealed trait Command
     case object Stop extends Command
 
     case class Started(id: Int, selfRef: ActorRef[Command])

akka-cluster-sharding-typed/src/test/scala/docs/akka/cluster/sharding/typed/HelloWorldPersistentEntityExample.scala

@@ -50,7 +50,7 @@ object HelloWorldPersistentEntityExample {
   object HelloWorld {
 
     // Command
-    trait Command extends CborSerializable
+    sealed trait Command extends CborSerializable
     final case class Greet(whom: String)(val replyTo: ActorRef[Greeting]) extends Command
     // Response
     final case class Greeting(whom: String, numberOfPeople: Int) extends CborSerializable

akka-cluster-sharding-typed/src/test/scala/docs/delivery/WorkPullingDocExample.scala

@@ -67,7 +67,7 @@ object WorkPullingDocExample {
   import akka.actor.typed.scaladsl.StashBuffer
 
   object ImageWorkManager {
-    trait Command
+    sealed trait Command
     final case class Convert(fromFormat: String, toFormat: String, image: Array[Byte]) extends Command
     private case class WrappedRequestNext(r: WorkPullingProducerController.RequestNext[ImageConverter.ConversionJob])
         extends Command
@@ -137,7 +137,7 @@ object WorkPullingDocExample {
     import ImageWorkManager._
 
     private def waitForNext(): Behavior[Command] = {
-      Behaviors.receiveMessage {
+      Behaviors.receiveMessagePartial {
         case WrappedRequestNext(next) =>
           stashBuffer.unstashAll(active(next))
         case c: Convert =>
@@ -156,7 +156,7 @@ object WorkPullingDocExample {
 
     private def active(
         next: WorkPullingProducerController.RequestNext[ImageConverter.ConversionJob]): Behavior[Command] = {
-      Behaviors.receiveMessage {
+      Behaviors.receiveMessagePartial {
         case Convert(from, to, image) =>
           val resultId = UUID.randomUUID()
           next.sendNextTo ! ImageConverter.ConversionJob(resultId, from, to, image)
@@ -178,7 +178,7 @@ object WorkPullingDocExample {
       implicit val askTimeout: Timeout = 5.seconds
 
       private def waitForNext(): Behavior[Command] = {
-        Behaviors.receiveMessage {
+        Behaviors.receiveMessagePartial {
           case WrappedRequestNext(next) =>
             stashBuffer.unstashAll(active(next))
           case c: ConvertRequest =>
@@ -201,7 +201,7 @@ object WorkPullingDocExample {
 
       private def active(
           next: WorkPullingProducerController.RequestNext[ImageConverter.ConversionJob]): Behavior[Command] = {
-        Behaviors.receiveMessage {
+        Behaviors.receiveMessagePartial {
           case ConvertRequest(from, to, image, originalReplyTo) =>
             val resultId = UUID.randomUUID()
             context.ask[MessageWithConfirmation[ImageConverter.ConversionJob], Done](

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/ClusterSharding.scala

@@ -301,7 +301,7 @@ class ClusterSharding(system: ExtendedActorSystem) extends Extension {
             extractShardId,
             allocationStrategy,
             handOffStopMessage)
-          val Started(shardRegion) = Await.result(guardian ? startMsg, timeout.duration)
+          val shardRegion = Await.result((guardian ? startMsg).mapTo[Started], timeout.duration).shardRegion
           regions.put(typeName, shardRegion)
           shardRegion
         case ref => ref // already started, use cached ActorRef
@@ -545,7 +545,7 @@ class ClusterSharding(system: ExtendedActorSystem) extends Extension {
         implicit val timeout = system.settings.CreationTimeout
         val settings = ClusterShardingSettings(system).withRole(role)
         val startMsg = StartProxy(typeName, dataCenter, settings, extractEntityId, extractShardId)
-        val Started(shardRegion) = Await.result(guardian ? startMsg, timeout.duration)
+        val shardRegion = Await.result((guardian ? startMsg).mapTo[Started], timeout.duration).shardRegion
         // it must be possible to start several proxies, one per data center
         proxies.put(proxyName(typeName, dataCenter), shardRegion)
         shardRegion
@@ -777,6 +777,8 @@ private[akka] class ClusterShardingGuardian extends Actor {
                 new EventSourcedRememberEntitiesProvider(typeName, settings)
               case ClusterShardingSettings.RememberEntitiesStoreCustom =>
                 new CustomStateStoreModeProvider(typeName, context.system, settings)
+              case unknown =>
+                throw new IllegalArgumentException(s"Unknown store type: $unknown") // compiler exhaustiveness check pleaser
             })
           }
 

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/Shard.scala

@@ -960,7 +960,7 @@ private[akka] class Shard(
               entityId,
               unexpected)
         }
-      case OptionVal.None =>
+      case _ =>
         log.warning("{}: Unexpected entity terminated: {}", typeName, ref)
     }
   }
@@ -982,7 +982,7 @@ private[akka] class Shard(
           entity ! stopMessage
           flightRecorder.entityPassivate(id)
         }
-      case OptionVal.None =>
+      case _ =>
         log.debug("{}: Unknown entity passivating [{}]. Not sending stopMessage back to entity", typeName, entity)
     }
   }
@@ -1108,7 +1108,7 @@ private[akka] class Shard(
   def getOrCreateEntity(id: EntityId): ActorRef = {
     entities.entity(id) match {
       case OptionVal.Some(child) => child
-      case OptionVal.None =>
+      case _ =>
         val name = URLEncoder.encode(id, "utf-8")
         val a = context.actorOf(entityProps(id), name)
         context.watchWith(a, EntityTerminated(a))

akka-cluster-sharding/src/main/scala/akka/cluster/sharding/external/internal/ExternalShardAllocationClientImpl.scala

@@ -70,6 +70,7 @@ final private[external] class ExternalShardAllocationClientImpl(system: ActorSys
       case UpdateSuccess(_, _) => Future.successful(Done)
       case UpdateTimeout =>
         Future.failed(new ClientTimeoutException(s"Unable to update shard location after ${timeout.duration.pretty}"))
+      case _ => throw new IllegalArgumentException() // compiler exhaustiveness check pleaser
     }
   }
 
@@ -86,6 +87,7 @@ final private[external] class ExternalShardAllocationClientImpl(system: ActorSys
           Future.successful(Map.empty[ShardId, ShardLocation])
         case GetFailure(_, _) =>
           Future.failed((new ClientTimeoutException(s"Unable to get shard locations after ${timeout.duration.pretty}")))
+        case _ => throw new IllegalArgumentException() // compiler exhaustiveness check pleaser
       }
       .map { locations =>
         new ShardLocations(locations)
@@ -104,6 +106,7 @@ final private[external] class ExternalShardAllocationClientImpl(system: ActorSys
       case UpdateSuccess(_, _) => Future.successful(Done)
       case UpdateTimeout =>
         Future.failed(new ClientTimeoutException(s"Unable to update shard location after ${timeout.duration.pretty}"))
+      case _ => throw new IllegalArgumentException() // compiler exhaustiveness check pleaser
     }
   }
 

akka-cluster-sharding/src/multi-jvm/scala/akka/cluster/sbr/GlobalRegistry.scala

@@ -31,9 +31,9 @@ object GlobalRegistry {
       case id: Int => (id.toString, id)
     }
 
-    val extractShardId: ShardRegion.ExtractShardId = msg =>
-      msg match {
+    val extractShardId: ShardRegion.ExtractShardId = {
       case id: Int => (id % 10).toString
+      case _       => throw new IllegalArgumentException()
     }
   }
 

akka-cluster-sharding/src/multi-jvm/scala/akka/cluster/sharding/ClusterShardCoordinatorDowning2Spec.scala

@@ -42,6 +42,7 @@ object ClusterShardCoordinatorDowning2Spec {
 
   val extractShardId: ShardRegion.ExtractShardId = {
     case Ping(id: String) => id.charAt(0).toString
+    case _                => throw new IllegalArgumentException()
   }
 }
 

akka-cluster-sharding/src/multi-jvm/scala/akka/cluster/sharding/ClusterShardCoordinatorDowningSpec.scala

@@ -42,6 +42,7 @@ object ClusterShardCoordinatorDowningSpec {
 
   val extractShardId: ShardRegion.ExtractShardId = {
     case Ping(id: String) => id.charAt(0).toString
+    case _                => throw new IllegalArgumentException()
   }
 }
 

akka-cluster-sharding/src/multi-jvm/scala/akka/cluster/sharding/ClusterShardingFailureSpec.scala

@@ -46,6 +46,7 @@ object ClusterShardingFailureSpec {
     case Get(id)         => id.charAt(0).toString
     case Add(id, _)      => id.charAt(0).toString
     case StartEntity(id) => id
+    case _               => throw new IllegalArgumentException()
   }
 }