[HttpKernel] Deprecate StreamedResponseListener, it serves no purpose anymore

Author: nicolas-grekas

CHANGELOG.md

@@ -5,6 +5,7 @@ CHANGELOG
 ---
 
  * Add `BackedEnumValueResolver` to resolve backed enum cases from request attributes in controller arguments
+ * Deprecate StreamedResponseListener, it's not needed anymore
 
 6.0
 ---

EventListener/AbstractSessionListener.php

@@ -246,7 +246,7 @@ public static function getSubscribedEvents(): array
     {
         return [
             KernelEvents::REQUEST => ['onKernelRequest', 128],
-            // low priority to come after regular response listeners, but higher than StreamedResponseListener
+            // low priority to come after regular response listeners
             KernelEvents::RESPONSE => ['onKernelResponse', -1000],
         ];
     }

EventListener/StreamedResponseListener.php

@@ -16,13 +16,17 @@
 use Symfony\Component\HttpKernel\Event\ResponseEvent;
 use Symfony\Component\HttpKernel\KernelEvents;
 
+trigger_deprecation('symfony/http-kernel', '6.1', 'The "%s" class is deprecated.', StreamedResponseListener::class);
+
 /**
  * StreamedResponseListener is responsible for sending the Response
  * to the client.
  *
  * @author Fabien Potencier <fabien@symfony.com>
  *
  * @final
+ *
+ * @deprecated since Symfony 6.1
  */
 class StreamedResponseListener implements EventSubscriberInterface
 {