Widen and timers can be used together, #25318 (#27128)

* because timers are not implemented with interceptor any more,
  https://github.com/akka/akka/pull/26650

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

@@ -123,7 +123,7 @@ class WidenSpec extends ScalaTestWithActorTestKit("""
         }
 
       EventFilter[ActorInitializationException](occurrences = 1).intercept {
-        val ref = spawn(widen(widen(Behaviors.receiveMessage[String] { message =>
+        val ref = spawn(widen(widen(Behaviors.receiveMessage[String] { _ =>
           Behaviors.same
         })))
 
@@ -131,6 +131,50 @@ class WidenSpec extends ScalaTestWithActorTestKit("""
       }
 
     }
+
+    "be possible to combine with inner timers" in {
+      val probe = TestProbe[String]()
+      val behv = Behaviors
+        .withTimers[String] { timers =>
+          timers.startSingleTimer("timer", "a", 10.millis)
+          Behaviors.receiveMessage { msg =>
+            probe.ref ! msg
+            Behaviors.same
+          }
+        }
+        .widen[String] {
+          case msg => msg.toUpperCase()
+        }
+
+      val ref = spawn(behv)
+
+      probe.expectMessage("A")
+
+      ref ! "b"
+      probe.expectMessage("B")
+    }
+
+    "be possible to combine with outer timers" in {
+      val probe = TestProbe[String]()
+      val behv = Behaviors.withTimers[String] { timers =>
+        timers.startSingleTimer("timer", "a", 10.millis)
+        Behaviors
+          .receiveMessage[String] { msg =>
+            probe.ref ! msg
+            Behaviors.same
+          }
+          .widen[String] {
+            case msg => msg.toUpperCase()
+          }
+      }
+
+      val ref = spawn(behv)
+
+      probe.expectMessage("A")
+
+      ref ! "b"
+      probe.expectMessage("B")
+    }
   }
 
 }

akka-actor-typed/src/main/scala/akka/actor/typed/Behavior.scala

@@ -134,8 +134,6 @@ object Behavior {
      * }
      * }}}
      *
-     * Scheduled messages via [[akka.actor.typed.scaladsl.TimerScheduler]] can currently
-     * not be used together with `widen`, see issue #25318.
      */
     def widen[U](matcher: PartialFunction[U, T]): Behavior[U] =
       BehaviorImpl.widened(behavior, matcher)

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

@@ -5,9 +5,10 @@
 package akka.actor.typed.internal
 
 import akka.actor.typed
-import akka.actor.typed.internal.TimerSchedulerImpl.TimerMsg
+
 import akka.actor.typed.scaladsl.Behaviors
-import akka.actor.typed.{ LogOptions, _ }
+import akka.actor.typed.LogOptions
+import akka.actor.typed._
 import akka.annotation.InternalApi
 import akka.util.LineNumbers
 
@@ -179,8 +180,8 @@ private[akka] object WidenedInterceptor {
 @InternalApi
 private[akka] final case class WidenedInterceptor[O, I](matcher: PartialFunction[O, I])
     extends BehaviorInterceptor[O, I] {
-  import WidenedInterceptor._
   import BehaviorInterceptor._
+  import WidenedInterceptor._
 
   override def isSame(other: BehaviorInterceptor[Any, Any]): Boolean = other match {
     // If they use the same pf instance we can allow it, to have one way to workaround defining
@@ -195,13 +196,6 @@ private[akka] final case class WidenedInterceptor[O, I](matcher: PartialFunction
   }
 
   def aroundReceive(ctx: TypedActorContext[O], msg: O, target: ReceiveTarget[I]): Behavior[I] = {
-    // widen would wrap the TimerMessage, which would be wrong, see issue #25318
-    msg match {
-      case t: TimerMsg =>
-        throw new IllegalArgumentException(s"Timers and widen can't be used together, [${t.key}]. See issue #25318")
-      case _ => ()
-    }
-
     matcher.applyOrElse(msg, any2null) match {
       case null        => Behaviors.unhandled
       case transformed => target(ctx, transformed)

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

@@ -267,8 +267,6 @@ object Behaviors {
    *     );
    * }}}
    *
-   * Scheduled messages via [[TimerScheduler]] can currently not be used
-   * together with `widen`, see issue #25318.
    *
    * @param behavior
    *          the behavior that will receive the selected messages