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

vendor/symfony/validator/Constraints/Luhn.php

@@ -0,0 +1,37 @@
+<?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\Constraints;
+
+use Symfony\Component\Validator\Constraint;
+
+/**
+ * Metadata for the LuhnValidator.
+ *
+ * @Annotation
+ * @Target({"PROPERTY", "METHOD", "ANNOTATION"})
+ *
+ * @author Tim Nagel <t.nagel@infinite.net.au>
+ * @author Greg Knapp http://gregk.me/2011/php-implementation-of-bank-card-luhn-algorithm/
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+class Luhn extends Constraint
+{
+    const INVALID_CHARACTERS_ERROR = 1;
+    const CHECKSUM_FAILED_ERROR = 2;
+
+    protected static $errorNames = array(
+        self::INVALID_CHARACTERS_ERROR => 'INVALID_CHARACTERS_ERROR',
+        self::CHECKSUM_FAILED_ERROR => 'CHECKSUM_FAILED_ERROR',
+    );
+
+    public $message = 'Invalid card number.';
+}