feature #24387 [FORM] Prevent forms from extending itself as a parent (pierredup)

This PR was squashed before being merged into the 3.4 branch (closes #24387).

Discussion
----------

[FORM] Prevent forms from extending itself as a parent

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | yes
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | N/A
| License       | MIT
| Doc PR        | N/A

If a form type defines itself as a parent, it results in an endless recursive loop in the form registry, so throw an exception instead.

Commits
-------

2ee6fd5 [FORM] Prevent forms from extending itself as a parent

src/Symfony/Component/Form/FormRegistry.php

@@ -12,6 +12,7 @@
 namespace Symfony\Component\Form;
 
 use Symfony\Component\Form\Exception\ExceptionInterface;
+use Symfony\Component\Form\Exception\LogicException;
 use Symfony\Component\Form\Exception\UnexpectedTypeException;
 use Symfony\Component\Form\Exception\InvalidArgumentException;
 
@@ -44,6 +45,8 @@ class FormRegistry implements FormRegistryInterface
      */
     private $resolvedTypeFactory;
 
+    private $checkedTypes = array();
+
     /**
      * @param FormExtensionInterface[]         $extensions          An array of FormExtensionInterface
      * @param ResolvedFormTypeFactoryInterface $resolvedTypeFactory The factory for resolved form types
@@ -106,18 +109,29 @@ class FormRegistry implements FormRegistryInterface
         $parentType = $type->getParent();
         $fqcn = get_class($type);
 
-        foreach ($this->extensions as $extension) {
-            $typeExtensions = array_merge(
-                $typeExtensions,
-                $extension->getTypeExtensions($fqcn)
-            );
+        if (isset($this->checkedTypes[$fqcn])) {
+            $types = implode(' > ', array_merge(array_keys($this->checkedTypes), array($fqcn)));
+            throw new LogicException(sprintf('Circular reference detected for form "%s" (%s).', $fqcn, $types));
         }
 
-        return $this->resolvedTypeFactory->createResolvedType(
-            $type,
-            $typeExtensions,
-            $parentType ? $this->getType($parentType) : null
-        );
+        $this->checkedTypes[$fqcn] = true;
+
+        try {
+            foreach ($this->extensions as $extension) {
+                $typeExtensions = array_merge(
+                    $typeExtensions,
+                    $extension->getTypeExtensions($fqcn)
+                );
+            }
+
+            return $this->resolvedTypeFactory->createResolvedType(
+                $type,
+                $typeExtensions,
+                $parentType ? $this->getType($parentType) : null
+            );
+        } finally {
+            unset($this->checkedTypes[$fqcn]);
+        }
     }
 
     /**

src/Symfony/Component/Form/Tests/Fixtures/FormWithSameParentType.php

@@ -0,0 +1,22 @@
+<?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\Form\Tests\Fixtures;
+
+use Symfony\Component\Form\AbstractType;
+
+class FormWithSameParentType extends AbstractType
+{
+    public function getParent()
+    {
+        return self::class;
+    }
+}

src/Symfony/Component/Form/Tests/Fixtures/RecursiveFormTypeBar.php

@@ -0,0 +1,22 @@
+<?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\Form\Tests\Fixtures;
+
+use Symfony\Component\Form\AbstractType;
+
+class RecursiveFormTypeBar extends AbstractType
+{
+    public function getParent()
+    {
+        return RecursiveFormTypeBaz::class;
+    }
+}

src/Symfony/Component/Form/Tests/Fixtures/RecursiveFormTypeBaz.php

@@ -0,0 +1,22 @@
+<?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\Form\Tests\Fixtures;
+
+use Symfony\Component\Form\AbstractType;
+
+class RecursiveFormTypeBaz extends AbstractType
+{
+    public function getParent()
+    {
+        return RecursiveFormTypeFoo::class;
+    }
+}

src/Symfony/Component/Form/Tests/Fixtures/RecursiveFormTypeFoo.php

@@ -0,0 +1,22 @@
+<?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\Form\Tests\Fixtures;
+
+use Symfony\Component\Form\AbstractType;
+
+class RecursiveFormTypeFoo extends AbstractType
+{
+    public function getParent()
+    {
+        return RecursiveFormTypeBar::class;
+    }
+}

src/Symfony/Component/Form/Tests/FormRegistryTest.php

@@ -16,6 +16,10 @@ use Symfony\Component\Form\FormRegistry;
 use Symfony\Component\Form\FormTypeGuesserChain;
 use Symfony\Component\Form\ResolvedFormType;
 use Symfony\Component\Form\ResolvedFormTypeFactoryInterface;
+use Symfony\Component\Form\Tests\Fixtures\FormWithSameParentType;
+use Symfony\Component\Form\Tests\Fixtures\RecursiveFormTypeBar;
+use Symfony\Component\Form\Tests\Fixtures\RecursiveFormTypeBaz;
+use Symfony\Component\Form\Tests\Fixtures\RecursiveFormTypeFoo;
 use Symfony\Component\Form\Tests\Fixtures\FooSubType;
 use Symfony\Component\Form\Tests\Fixtures\FooType;
 use Symfony\Component\Form\Tests\Fixtures\FooTypeBarExtension;
@@ -156,6 +160,36 @@ class FormRegistryTest extends TestCase
         $this->assertSame($resolvedType, $this->registry->getType(get_class($type)));
     }
 
+    /**
+     * @expectedException \Symfony\Component\Form\Exception\LogicException
+     * @expectedExceptionMessage Circular reference detected for form "Symfony\Component\Form\Tests\Fixtures\FormWithSameParentType" (Symfony\Component\Form\Tests\Fixtures\FormWithSameParentType > Symfony\Component\Form\Tests\Fixtures\FormWithSameParentType).
+     */
+    public function testFormCannotHaveItselfAsAParent()
+    {
+        $type = new FormWithSameParentType();
+
+        $this->extension2->addType($type);
+
+        $this->registry->getType(FormWithSameParentType::class);
+    }
+
+    /**
+     * @expectedException \Symfony\Component\Form\Exception\LogicException
+     * @expectedExceptionMessage Circular reference detected for form "Symfony\Component\Form\Tests\Fixtures\RecursiveFormTypeFoo" (Symfony\Component\Form\Tests\Fixtures\RecursiveFormTypeFoo > Symfony\Component\Form\Tests\Fixtures\RecursiveFormTypeBar > Symfony\Component\Form\Tests\Fixtures\RecursiveFormTypeBaz > Symfony\Component\Form\Tests\Fixtures\RecursiveFormTypeFoo).
+     */
+    public function testRecursiveFormDependencies()
+    {
+        $foo = new RecursiveFormTypeFoo();
+        $bar = new RecursiveFormTypeBar();
+        $baz = new RecursiveFormTypeBaz();
+
+        $this->extension2->addType($foo);
+        $this->extension2->addType($bar);
+        $this->extension2->addType($baz);
+
+        $this->registry->getType(RecursiveFormTypeFoo::class);
+    }
+
     /**
      * @expectedException \Symfony\Component\Form\Exception\InvalidArgumentException
      */