Uses tagged arguments for the message bus (for now)

Author: sroze

src/Symfony/Bundle/FrameworkBundle/Resources/config/message.xml

@@ -9,7 +9,7 @@
 
         <!-- Bus -->
         <service id="message_bus" class="Symfony\Component\Message\MessageBus" public="true">
-            <argument type="collection" /> <!-- Middlewares -->
+            <argument type="tagged" tag="message_middleware" /> <!-- Middlewares -->
         </service>
 
         <service id="Symfony\Component\Message\MessageBusInterface" alias="message_bus" />

src/Symfony/Component/Message/DependencyInjection/MessagePass.php

@@ -28,14 +28,12 @@ class MessagePass implements CompilerPassInterface
     use PriorityTaggedServiceTrait;
 
     private $messageBusService;
-    private $middlewareTag;
     private $messageHandlerResolverService;
     private $handlerTag;
 
-    public function __construct(string $messageBusService = 'message_bus', string $middlewareTag = 'message_middleware', string $messageHandlerResolverService = 'message.handler_resolver', string $handlerTag = 'message_handler')
+    public function __construct(string $messageBusService = 'message_bus', string $messageHandlerResolverService = 'message.handler_resolver', string $handlerTag = 'message_handler')
     {
         $this->messageBusService = $messageBusService;
-        $this->middlewareTag = $middlewareTag;
         $this->messageHandlerResolverService = $messageHandlerResolverService;
         $this->handlerTag = $handlerTag;
     }
@@ -49,13 +47,6 @@ public function process(ContainerBuilder $container)
             return;
         }
 
-        if (!$middlewares = $this->findAndSortTaggedServices($this->middlewareTag, $container)) {
-            throw new RuntimeException(sprintf('You must tag at least one service as "%s" to use the "%s" service.', $this->middlewareTag, $this->messageBusService));
-        }
-
-        $busDefinition = $container->getDefinition($this->messageBusService);
-        $busDefinition->replaceArgument(0, $middlewares);
-
         $this->registerHandlers($container);
     }
 

src/Symfony/Component/Message/HandlerLocator.php

@@ -35,7 +35,7 @@ public function resolve($message): callable
     {
         $messageKey = get_class($message);
 
-        if (!array_key_exists($messageKey, $this->messageToHandlerMapping)) {
+        if (!isset($this->messageToHandlerMapping[$messageKey])) {
             throw new NoHandlerForMessageException(sprintf('No handler for message "%s"', $messageKey));
         }
 

src/Symfony/Component/Message/MessageBus.php

@@ -23,11 +23,11 @@ class MessageBus implements MessageBusInterface
     private $middlewares;
 
     /**
-     * @param MiddlewareInterface[] $middlewares
+     * @param MiddlewareInterface[]|iterable $middlewares
      */
-    public function __construct(array $middlewares = array())
+    public function __construct(iterable $middlewares = array())
     {
-        $this->middlewares = $middlewares;
+        $this->middlewares = is_array($middlewares) ? array_values($middlewares) : iterator_to_array($middlewares, false);
     }
 
     /**