The /e modifier for preg_replace() is deprecated in PHP 5.5; replace with preg_replace_callback()

Author: Tatsh

DependencyInjection/Compiler/RegisterKernelListenersPass.php

@@ -33,10 +33,11 @@ public function process(ContainerBuilder $container)
                 }
 
                 if (!isset($event['method'])) {
-                    $event['method'] = 'on'.preg_replace(array(
-                        '/(?<=\b)[a-z]/ie',
-                        '/[^a-z0-9]/i'
-                    ), array('strtoupper("\\0")', ''), $event['event']);
+                    $event['method'] = 'on'.preg_replace_callback(array(
+                        '/(?<=\b)[a-z]/i',
+                        '/[^a-z0-9]/i',
+                    ), function ($matches) { return strtoupper($matches[0]); }, $event['event']);
+                    $event['method'] = preg_replace('/[^a-z0-9]/i', '', $event['method']);
                 }
 
                 $definition->addMethodCall('addListenerService', array($event['event'], array($id, $event['method']), $priority));