fix: enable strict-unsealed-patmat lint and fix exhaustiveness warnings

He-Pin · He-Pin · commit 5f5c838140bf · 2026-07-11T22:24:35.000+08:00
Motivation: The strict-unsealed-patmat lint was disabled globally in #264 to unblock the build, leaving many pattern matches on non-sealed traits unchecked. Issue #265 tracks re-enabling this lint. Modification: Remove the -Xlint:-strict-unsealed-patmat silencing flag from PekkoDisciplinePlugin for Scala 2.13. Fix all resulting exhaustiveness warnings across the codebase: - Seal Command traits where all subtypes are in the same file - Add @nowarn annotations where traits are intentionally non-sealed (cross-file protocols in tutorials) - Add catch-all cases for matches on OptionVal and other extractor-only types (Collections, stream operators) Result: The strict-unsealed-patmat lint is now active for Scala 2.13, catching future pattern match exhaustiveness issues at compile time. Tests: sbt "docs / Test / compile" — success, no exhaustiveness errors References: Fixes #265
diff --git a/actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/delivery/TestProducerWithAsk.scala b/actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/delivery/TestProducerWithAsk.scala
@@ -26,7 +26,7 @@ import pekko.util.Timeout
 
 object TestProducerWithAsk {
 
-  trait Command
+  sealed trait Command
   final case class RequestNext(askTo: ActorRef[ProducerController.MessageWithConfirmation[TestConsumer.Job]])
       extends Command
   private case object Tick extends Command
diff --git a/actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/delivery/TestProducerWorkPulling.scala b/actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/delivery/TestProducerWorkPulling.scala
@@ -22,7 +22,7 @@ import pekko.actor.typed.scaladsl.Behaviors
 
 object TestProducerWorkPulling {
 
-  trait Command
+  sealed trait Command
   final case class RequestNext(sendTo: ActorRef[TestConsumer.Job]) extends Command
   private case object Tick extends Command
 
diff --git a/actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/eventstream/EventStreamDocSpec.scala b/actor-typed-tests/src/test/scala/org/apache/pekko/actor/typed/eventstream/EventStreamDocSpec.scala
@@ -82,6 +82,9 @@ object EventStreamDocSpec {
                 case UnhandledMessage(message, sender, recipient) =>
                   context.log.info("UnhandledMessage received from sender ({}) to recipient ({}) with message: {}",
                     sender.path.name, recipient.path.name, message.toString)
+
+                case other =>
+                  context.log.warn("Unexpected AllDeadLetters: {}", other)
               }
               Behaviors.same
           }
diff --git a/actor/src/main/scala/org/apache/pekko/util/Collections.scala b/actor/src/main/scala/org/apache/pekko/util/Collections.scala
@@ -39,6 +39,7 @@ private[pekko] object Collections {
         pf.applyOrElse(t, NotApplied) match {
           case _: NotApplied.type => // do nothing
           case r: R @unchecked    => builder += r
+          case _                  => // unreachable, NotApplied handled above, everything else is R
         }
       })
       builder.result()
diff --git a/bench-jmh/src/main/scala/org/apache/pekko/actor/typed/delivery/ReliableDeliveryBenchmark.scala b/bench-jmh/src/main/scala/org/apache/pekko/actor/typed/delivery/ReliableDeliveryBenchmark.scala
@@ -36,7 +36,7 @@ import pekko.actor.typed.scaladsl.Behaviors
 import com.typesafe.config.ConfigFactory
 
 object Producer {
-  trait Command
+  sealed trait Command
 
   case object Run extends Command
   private case class WrappedRequestNext(r: ProducerController.RequestNext[Consumer.Command]) extends Command
@@ -83,7 +83,7 @@ object Producer {
 }
 
 object Consumer {
-  trait Command
+  sealed trait Command
 
   case object TheMessage extends Command
 
@@ -111,7 +111,7 @@ object Consumer {
 }
 
 object WorkPullingProducer {
-  trait Command
+  sealed trait Command
 
   case object Run extends Command
   private case class WrappedRequestNext(r: WorkPullingProducerController.RequestNext[Consumer.Command]) extends Command
@@ -148,7 +148,7 @@ object WorkPullingProducer {
 
 object Guardian {
 
-  trait Command
+  sealed trait Command
   final case class RunPointToPoint(id: String, numberOfMessages: Int, useAsk: Boolean, replyTo: ActorRef[Done])
       extends Command
   final case class RunWorkPulling(id: String, numberOfMessages: Int, workers: Int, replyTo: ActorRef[Done])
diff --git a/cluster-sharding-typed/src/multi-jvm/scala/org/apache/pekko/cluster/sharding/typed/ShardedDaemonProcessSpec.scala b/cluster-sharding-typed/src/multi-jvm/scala/org/apache/pekko/cluster/sharding/typed/ShardedDaemonProcessSpec.scala
@@ -43,7 +43,7 @@ object ShardedDaemonProcessSpec extends MultiNodeConfig {
   case class ProcessActorEvent(id: Int, event: Any) extends CborSerializable
 
   object ProcessActor {
-    trait Command
+    sealed trait Command
     case object Stop extends Command
 
     def apply(id: Int): Behavior[Command] = Behaviors.setup { ctx =>
diff --git a/cluster-sharding-typed/src/test/scala/docs/org/apache/pekko/cluster/sharding/typed/ShardingCompileOnlySpec.scala b/cluster-sharding-typed/src/test/scala/docs/org/apache/pekko/cluster/sharding/typed/ShardingCompileOnlySpec.scala
@@ -161,7 +161,7 @@ object ShardingCompileOnlySpec {
 
     // a sharded counter that sends responses to another sharded actor
     object Counter {
-      trait Command
+      sealed trait Command
       case object Increment extends Command
       final case class GetValue(replyToEntityId: String) extends Command
       val TypeKey: EntityTypeKey[Command] = EntityTypeKey[Command]("example-sharded-counter")
diff --git a/cluster-sharding/src/test/scala/org/apache/pekko/cluster/sharding/ShardRegionDataTypesSpec.scala b/cluster-sharding/src/test/scala/org/apache/pekko/cluster/sharding/ShardRegionDataTypesSpec.scala
@@ -58,6 +58,7 @@ class ShardRegionDataTypesSpec extends AnyWordSpec with Matchers {
       s match {
         case ShardRegionStats(stats) =>
           stats shouldBe Map("s1" -> 1)
+        case _ => fail("Should match ShardRegionStats")
       }
     }
 
@@ -103,6 +104,7 @@ class ShardRegionDataTypesSpec extends AnyWordSpec with Matchers {
       state match {
         case CurrentShardRegionState(shards) =>
           shards shouldBe Set(ShardState("s1", Set("e1")))
+        case _ => fail("Should match CurrentShardRegionState")
       }
     }
 
diff --git a/docs/src/test/scala/docs/actor/typed/CoordinatedActorShutdownSpec.scala b/docs/src/test/scala/docs/actor/typed/CoordinatedActorShutdownSpec.scala
@@ -28,7 +28,7 @@ class CoordinatedActorShutdownSpec {
   // #coordinated-shutdown-addTask
   object MyActor {
 
-    trait Messages
+    sealed trait Messages
     case class Stop(replyTo: ActorRef[Done]) extends Messages
 
     def behavior: Behavior[Messages] =
diff --git a/docs/src/test/scala/docs/actor/typed/SharedMutableStateDocSpec.scala b/docs/src/test/scala/docs/actor/typed/SharedMutableStateDocSpec.scala
@@ -27,7 +27,7 @@ class SharedMutableStateDocSpec {
   def expensiveCalculation(): Future[String] = ???
 
   object MyActor {
-    trait Command
+    sealed trait Command
     case class Message(msg: String, replyTo: ActorRef[Any]) extends Command
     case class UpdateState(newState: String) extends Command
 
diff --git a/docs/src/test/scala/typed/tutorial_4/DeviceGroup.scala b/docs/src/test/scala/typed/tutorial_4/DeviceGroup.scala
@@ -13,6 +13,8 @@
 
 package typed.tutorial_4
 
+import scala.annotation.nowarn
+
 import org.apache.pekko.actor.typed.ActorRef
 import org.apache.pekko.actor.typed.Behavior
 import org.apache.pekko.actor.typed.PostStop
@@ -47,6 +49,7 @@ class DeviceGroup(context: ActorContext[DeviceGroup.Command], groupId: String)
 
   context.log.info("DeviceGroup {} started", groupId)
 
+  @nowarn("msg=match may not be exhaustive")
   override def onMessage(msg: Command): Behavior[Command] =
     msg match {
       case trackMsg @ RequestTrackDevice(`groupId`, deviceId, replyTo) =>
diff --git a/docs/src/test/scala/typed/tutorial_5/DeviceGroup.scala b/docs/src/test/scala/typed/tutorial_5/DeviceGroup.scala
@@ -13,6 +13,7 @@
 
 package typed.tutorial_5
 
+import scala.annotation.nowarn
 import scala.concurrent.duration._
 import org.apache.pekko
 import pekko.actor.typed.ActorRef
@@ -51,6 +52,7 @@ class DeviceGroup(context: ActorContext[DeviceGroup.Command], groupId: String)
 
   context.log.info("DeviceGroup {} started", groupId)
 
+  @nowarn("msg=match may not be exhaustive")
   override def onMessage(msg: Command): Behavior[Command] =
     msg match {
       // #query-added
diff --git a/docs/src/test/scala/typed/tutorial_5/DeviceGroupQuery.scala b/docs/src/test/scala/typed/tutorial_5/DeviceGroupQuery.scala
@@ -13,6 +13,7 @@
 
 package typed.tutorial_5
 
+import scala.annotation.nowarn
 import scala.concurrent.duration._
 
 import org.apache.pekko
@@ -85,6 +86,7 @@ class DeviceGroupQuery(
 
   // #query-outline
   // #query-state
+  @nowarn("msg=match may not be exhaustive")
   override def onMessage(msg: Command): Behavior[Command] =
     msg match {
       case WrappedRespondTemperature(response) => onRespondTemperature(response)
diff --git a/persistence-typed-tests/src/test/scala/org/apache/pekko/persistence/typed/ReplicatedEventPublishingSpec.scala b/persistence-typed-tests/src/test/scala/org/apache/pekko/persistence/typed/ReplicatedEventPublishingSpec.scala
@@ -34,7 +34,7 @@ object ReplicatedEventPublishingSpec {
   val EntityType = "EventPublishingSpec"
 
   object MyReplicatedBehavior {
-    trait Command
+    sealed trait Command
     case class Add(text: String, replyTo: ActorRef[Done]) extends Command
     case class Get(replyTo: ActorRef[Set[String]]) extends Command
     case object Stop extends Command
diff --git a/persistence-typed/src/test/scala/org/apache/pekko/persistence/typed/internal/RecoveryPermitterSpec.scala b/persistence-typed/src/test/scala/org/apache/pekko/persistence/typed/internal/RecoveryPermitterSpec.scala
@@ -45,7 +45,7 @@ object RecoveryPermitterSpec {
 
   object EventState extends State
 
-  trait Command
+  sealed trait Command
 
   case object StopActor extends Command
 
diff --git a/project/PekkoDisciplinePlugin.scala b/project/PekkoDisciplinePlugin.scala
@@ -140,8 +140,7 @@ object PekkoDisciplinePlugin extends AutoPlugin {
                 "-Ywarn-nullary-override",
                 "-Ywarn-nullary-unit",
                 "-Ypartial-unification",
-                "-Yno-adapted-args") ++ Set(
-                "-Xlint:-strict-unsealed-patmat")
+                "-Yno-adapted-args")
             case Some((2, 12)) =>
               disciplineScalacOptions
             case _ =>
diff --git a/stream/src/main/scala/org/apache/pekko/stream/impl/UnfoldResourceSourceAsync.scala b/stream/src/main/scala/org/apache/pekko/stream/impl/UnfoldResourceSourceAsync.scala
@@ -117,6 +117,7 @@ import pekko.util.OptionVal
         // we got a pull but there is no open resource, we are either
         // currently creating/restarting then the read will be triggered when creating the
         // resource completes, or shutting down and then the pull does not matter anyway
+        case _ => // unreachable, OptionVal.Some and OptionVal.None cover all cases
       }
 
       override def postStop(): Unit = maybeResource match {
diff --git a/stream/src/main/scala/org/apache/pekko/stream/impl/fusing/DropRepeated.scala b/stream/src/main/scala/org/apache/pekko/stream/impl/fusing/DropRepeated.scala
@@ -65,6 +65,7 @@ private[pekko] final class DropRepeated[T](predicate: (T, T) => Boolean) extends
           case OptionVal.None =>
             last = OptionVal.Some(elem)
             push(out, last.get)
+          case _ => // unreachable, OptionVal.Some and OptionVal.None cover all cases
         }
       }
 
diff --git a/stream/src/main/scala/org/apache/pekko/stream/impl/fusing/GroupedAdjacentByWeighted.scala b/stream/src/main/scala/org/apache/pekko/stream/impl/fusing/GroupedAdjacentByWeighted.scala
@@ -149,6 +149,7 @@ private[pekko] final case class GroupedAdjacentByWeighted[T, R](
           } else {
             pendingGroup = OptionVal.Some(group)
           }
+        case _ => // unreachable, OptionVal.Some and OptionVal.None cover all cases
       }
 
       private def tryPullIfNeeded(): Unit = pendingGroup match {
@@ -182,6 +183,7 @@ private[pekko] final case class GroupedAdjacentByWeighted[T, R](
             } else {
               completeStage()
             }
+          case _ => // unreachable
         }
       }
 
diff --git a/stream/src/main/scala/org/apache/pekko/stream/impl/fusing/Switch.scala b/stream/src/main/scala/org/apache/pekko/stream/impl/fusing/Switch.scala
@@ -79,6 +79,7 @@ import pekko.util.OptionVal
               else removeCurrentSource(completeIfClosed = true)
             }
           case OptionVal.None =>
+          case _              => // unreachable
         }
       }
 
@@ -123,6 +124,7 @@ import pekko.util.OptionVal
           case OptionVal.Some(src) =>
             src.cancel()
           case OptionVal.None =>
+          case _              => // unreachable
         }
       }
 

Original file line number	Diff line number	Diff line change
`@@ -82,6 +82,9 @@ object EventStreamDocSpec {`
`82`	`82`	`case UnhandledMessage(message, sender, recipient) =>`
`83`	`83`	`context.log.info("UnhandledMessage received from sender ({}) to recipient ({}) with message: {}",`
`84`	`84`	`sender.path.name, recipient.path.name, message.toString)`
	`85`	`+`
	`86`	`+ case other =>`
	`87`	`+ context.log.warn("Unexpected AllDeadLetters: {}", other)`
`85`	`88`	`}`
`86`	`89`	`Behaviors.same`
`87`	`90`	`}`
Original file line number	Diff line number	Diff line change
`@@ -39,6 +39,7 @@ private[pekko] object Collections {`
`39`	`39`	`pf.applyOrElse(t, NotApplied) match {`
`40`	`40`	`case _: NotApplied.type => // do nothing`
`41`	`41`	`case r: R @unchecked => builder += r`
	`42`	`+ case _ => // unreachable, NotApplied handled above, everything else is R`
`42`	`43`	`}`
`43`	`44`	`})`
`44`	`45`	`builder.result()`
Original file line number	Diff line number	Diff line change
`@@ -58,6 +58,7 @@ class ShardRegionDataTypesSpec extends AnyWordSpec with Matchers {`
`58`	`58`	`s match {`
`59`	`59`	`case ShardRegionStats(stats) =>`
`60`	`60`	`stats shouldBe Map("s1" -> 1)`
	`61`	`+ case _ => fail("Should match ShardRegionStats")`
`61`	`62`	`}`
`62`	`63`	`}`
`63`	`64`
`@@ -103,6 +104,7 @@ class ShardRegionDataTypesSpec extends AnyWordSpec with Matchers {`
`103`	`104`	`state match {`
`104`	`105`	`case CurrentShardRegionState(shards) =>`
`105`	`106`	`shards shouldBe Set(ShardState("s1", Set("e1")))`
	`107`	`+ case _ => fail("Should match CurrentShardRegionState")`
`106`	`108`	`}`
`107`	`109`	`}`
`108`	`110`