Update to drupal 8.0.0-rc1. For more information, see https://www.drupal.org/node/2582663

vendor/symfony/routing/Loader/ClosureLoader.php

@@ -0,0 +1,52 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Routing\Loader;
+
+use Symfony\Component\Config\Loader\Loader;
+use Symfony\Component\Routing\RouteCollection;
+
+/**
+ * ClosureLoader loads routes from a PHP closure.
+ *
+ * The Closure must return a RouteCollection instance.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ *
+ * @api
+ */
+class ClosureLoader extends Loader
+{
+    /**
+     * Loads a Closure.
+     *
+     * @param \Closure    $closure A Closure
+     * @param string|null $type    The resource type
+     *
+     * @return RouteCollection A RouteCollection instance
+     *
+     * @api
+     */
+    public function load($closure, $type = null)
+    {
+        return $closure();
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @api
+     */
+    public function supports($resource, $type = null)
+    {
+        return $resource instanceof \Closure && (!$type || 'closure' === $type);
+    }
+}