From e37e7f1329af4c205439d49dc1297c46f6648ccb Mon Sep 17 00:00:00 2001
From: Jordi Boggiano <j.boggiano@seld.be>
Date: Fri, 13 Apr 2018 10:43:39 +0200
Subject: [PATCH] Fix handling of non-callable event listeners, fixes #7229

---
 src/Composer/EventDispatcher/EventDispatcher.php | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/Composer/EventDispatcher/EventDispatcher.php b/src/Composer/EventDispatcher/EventDispatcher.php
index 2a180614c..7f7a2cd86 100644
--- a/src/Composer/EventDispatcher/EventDispatcher.php
+++ b/src/Composer/EventDispatcher/EventDispatcher.php
@@ -166,7 +166,12 @@ class EventDispatcher
 
         $return = 0;
         foreach ($listeners as $callable) {
-            if (!is_string($callable) && is_callable($callable)) {
+            if (!is_string($callable)) {
+                if (!is_callable($callable)) {
+                    $className = is_object($callable[0]) ? get_class($callable[0]) : $callable[0];
+
+                    throw new \RuntimeException('Subscriber '.$className.'::'.$callable[1].' for event '.$event->getName().' is not callable, make sure the function is defined and public');
+                }
                 $event = $this->checkListenerExpectedEvent($callable, $event);
                 $return = false === call_user_func($callable, $event) ? 1 : 0;
             } elseif ($this->isComposerScript($callable)) {