diff --git a/src/Symfony/Bridge/Doctrine/DependencyInjection/AbstractDoctrineExtension.php b/src/Symfony/Bridge/Doctrine/DependencyInjection/AbstractDoctrineExtension.php
index ad4ba455919fe..a3083d2b1e07d 100644
--- a/src/Symfony/Bridge/Doctrine/DependencyInjection/AbstractDoctrineExtension.php
+++ b/src/Symfony/Bridge/Doctrine/DependencyInjection/AbstractDoctrineExtension.php
@@ -279,8 +279,8 @@ protected function detectMetadataDriver(string $dir, ContainerBuilder $container
             }
             $container->fileExists($resource, false);
 
-            if ($container->fileExists($dir.'/'.$this->getMappingObjectDefaultName(), false)) {
-                return $this->detectMappingType($dir, $container);
+            if ($container->fileExists($discoveryPath = $dir.'/'.$this->getMappingObjectDefaultName(), false)) {
+                return $this->detectMappingType($discoveryPath, $container);
             }
 
             return null;
diff --git a/src/Symfony/Bridge/Doctrine/Tests/Fixtures/Bundles/AttributesBundle/AnnotatedEntity/Person.php b/src/Symfony/Bridge/Doctrine/Tests/Fixtures/Bundles/AttributesBundle/AnnotatedEntity/Person.php
new file mode 100644
index 0000000000000..0ec41bb096861
--- /dev/null
+++ b/src/Symfony/Bridge/Doctrine/Tests/Fixtures/Bundles/AttributesBundle/AnnotatedEntity/Person.php
@@ -0,0 +1,39 @@
+<?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 Fixtures\Bundles\AttributesBundle\AnnotatedEntity;
+
+use Doctrine\ORM\Mapping\Column;
+use Doctrine\ORM\Mapping\Entity;
+use Doctrine\ORM\Mapping\Id;
+
+/**
+ * @Entity
+ */
+class Person
+{
+    /** @Id @Column(type="integer") */
+    protected $id;
+
+    /** @Column(type="string") */
+    public $name;
+
+    public function __construct($id, $name)
+    {
+        $this->id = $id;
+        $this->name = $name;
+    }
+
+    public function __toString(): string
+    {
+        return (string) $this->name;
+    }
+}