From 85454ac4565aa2182895080c8159580f535b33f1 Mon Sep 17 00:00:00 2001
From: Christoph Wurst <christoph@winzerhof-wurst.at>
Date: Tue, 29 Dec 2020 20:43:01 +0100
Subject: [PATCH] Use the Symfony dispatcher correctly

* Event object as first arg (otherwise there is a notice in the logs)
* `dispatch` MUST return the event object

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>
---
 .../EventDispatcher/SymfonyAdapter.php        | 36 +++++++++++--------
 1 file changed, 22 insertions(+), 14 deletions(-)

diff --git a/lib/private/EventDispatcher/SymfonyAdapter.php b/lib/private/EventDispatcher/SymfonyAdapter.php
index 9389e72540559..b1e5aa86049af 100644
--- a/lib/private/EventDispatcher/SymfonyAdapter.php
+++ b/lib/private/EventDispatcher/SymfonyAdapter.php
@@ -63,27 +63,35 @@ public function __construct(EventDispatcher $eventDispatcher, ILogger $logger) {
 	 * @param Event|null $event The event to pass to the event handlers/listeners
 	 *                              If not supplied, an empty Event instance is created
 	 *
-	 * @return void
+	 * @return object the emitted event
 	 * @deprecated 20.0.0
 	 */
-	public function dispatch($eventName, $event = null) {
+	public function dispatch($eventName, $event = null): object {
 		// type hinting is not possible, due to usage of GenericEvent
 		if ($event instanceof Event) {
 			$this->eventDispatcher->dispatch($eventName, $event);
+			return $event;
+		}
+
+		if ($event instanceof GenericEvent && get_class($event) === GenericEvent::class) {
+			$newEvent = new GenericEventWrapper($this->logger, $eventName, $event);
 		} else {
-			if ($event instanceof GenericEvent && get_class($event) === GenericEvent::class) {
-				$newEvent = new GenericEventWrapper($this->logger, $eventName, $event);
-			} else {
-				$newEvent = $event;
-
-				// Legacy event
-				$this->logger->info(
-					'Deprecated event type for {name}: {class}',
-					['name' => $eventName, 'class' => is_object($event) ? get_class($event) : 'null']
-				);
-			}
-			$this->eventDispatcher->getSymfonyDispatcher()->dispatch($eventName, $newEvent);
+			$newEvent = $event;
+
+			// Legacy event
+			$this->logger->info(
+				'Deprecated event type for {name}: {class}',
+				['name' => $eventName, 'class' => is_object($event) ? get_class($event) : 'null']
+			);
 		}
+
+		// Event with no payload (object) need special handling
+		if ($newEvent === null) {
+			return $this->eventDispatcher->getSymfonyDispatcher()->dispatch($eventName);
+		}
+
+		// Flip the argument order for Symfony to prevent a trigger_error
+		return $this->eventDispatcher->getSymfonyDispatcher()->dispatch($newEvent, $eventName);
 	}
 
 	/**