diff -u b/core/lib/Drupal/Component/DependencyInjection/Container.php b/core/lib/Drupal/Component/DependencyInjection/Container.php
--- b/core/lib/Drupal/Component/DependencyInjection/Container.php
+++ b/core/lib/Drupal/Component/DependencyInjection/Container.php
@@ -587,5 +587,6 @@
    * Ensure that cloning doesn't work.
    */
-  private function __clone() {}
+  private function __clone() {
+  }
 
 }