bug #25364 [DependencyInjection] Prevent a loop in aliases within the `findDefinition` method (sroze)

This PR was merged into the 3.3 branch.

Discussion
----------

[DependencyInjection] Prevent a loop in aliases within the `findDefinition` method

| Q             | A
| ------------- | ---
| Branch?       | 3.3
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #25338
| License       | MIT
| Doc PR        | ø

This prevents an infinite loop going when aliases reference themselves. This is based on 3.3 as the "normalized ID" changed to allow non-lowercase names. Fixing this in 2.7 would mean a merge conflict that IMO is not worth it.

Commits
-------

22f35239a4 Prevent a loop in aliases within the `findDefinition` method

src/Symfony/Component/DependencyInjection/ContainerBuilder.php

@@ -993,8 +993,15 @@ class ContainerBuilder extends Container implements TaggedContainerInterface
     {
         $id = $this->normalizeId($id);
 
+        $seen = array();
         while (isset($this->aliasDefinitions[$id])) {
             $id = (string) $this->aliasDefinitions[$id];
+
+            if (isset($seen[$id])) {
+                throw new ServiceCircularReferenceException($id, array_keys($seen));
+            }
+
+            $seen[$id] = true;
         }
 
         return $this->getDefinition($id);

src/Symfony/Component/DependencyInjection/Tests/ContainerBuilderTest.php

@@ -1044,6 +1044,22 @@ class ContainerBuilderTest extends TestCase
         $this->assertNotSame($bar->foo, $barUser->foo);
     }
 
+    /**
+     * @expectedException \Symfony\Component\DependencyInjection\Exception\ServiceCircularReferenceException
+     * @expectedExceptionMessage Circular reference detected for service "app.test_class", path: "app.test_class -> App\TestClass".
+     */
+    public function testThrowsCircularExceptionForCircularAliases()
+    {
+        $builder = new ContainerBuilder();
+
+        $builder->setAliases(array(
+            'app.test_class' => new Alias('App\\TestClass'),
+            'App\\TestClass' => new Alias('app.test_class'),
+        ));
+
+        $builder->findDefinition('App\\TestClass');
+    }
+
     public function testInitializePropertiesBeforeMethodCalls()
     {
         $container = new ContainerBuilder();