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

vendor/symfony/validator/Constraints/Expression.php

@@ -0,0 +1,59 @@
+<?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;
+
+/**
+ * @Annotation
+ * @Target({"CLASS", "PROPERTY", "METHOD", "ANNOTATION"})
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ * @author Bernhard Schussek <bschussek@gmail.com>
+ */
+class Expression extends Constraint
+{
+    public $message = 'This value is not valid.';
+    public $expression;
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getDefaultOption()
+    {
+        return 'expression';
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getRequiredOptions()
+    {
+        return array('expression');
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getTargets()
+    {
+        return array(self::CLASS_CONSTRAINT, self::PROPERTY_CONSTRAINT);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function validatedBy()
+    {
+        return 'validator.expression';
+    }
+}