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

vendor/symfony/validator/Mapping/Loader/LoaderChain.php

@@ -0,0 +1,62 @@
+<?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\Validator\Mapping\Loader;
+
+use Symfony\Component\Validator\Exception\MappingException;
+use Symfony\Component\Validator\Mapping\ClassMetadata;
+
+/**
+ * Loads validation metadata from multiple {@link LoaderInterface} instances.
+ *
+ * Pass the loaders when constructing the chain. Once
+ * {@link loadClassMetadata()} is called, that method will be called on all
+ * loaders in the chain.
+ *
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+class LoaderChain implements LoaderInterface
+{
+    /**
+     * @var LoaderInterface[]
+     */
+    protected $loaders;
+
+    /**
+     * @param LoaderInterface[] $loaders The metadata loaders to use
+     *
+     * @throws MappingException If any of the loaders has an invalid type
+     */
+    public function __construct(array $loaders)
+    {
+        foreach ($loaders as $loader) {
+            if (!$loader instanceof LoaderInterface) {
+                throw new MappingException(sprintf('Class %s is expected to implement LoaderInterface', get_class($loader)));
+            }
+        }
+
+        $this->loaders = $loaders;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function loadClassMetadata(ClassMetadata $metadata)
+    {
+        $success = false;
+
+        foreach ($this->loaders as $loader) {
+            $success = $loader->loadClassMetadata($metadata) || $success;
+        }
+
+        return $success;
+    }
+}