symfony
diff --git a/‎src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/UnusedTagsPass.php
Lines changed: 1 addition & 0 deletions b/‎src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Compiler/UnusedTagsPass.php
Lines changed: 1 addition & 0 deletions
diff --git a/‎src/Symfony/Bundle/FrameworkBundle/FrameworkBundle.php
Lines changed: 3 additions & 0 deletions b/‎src/Symfony/Bundle/FrameworkBundle/FrameworkBundle.php
Lines changed: 3 additions & 0 deletions
diff --git a/‎src/Symfony/Bundle/FrameworkBundle/Resources/config/services.xml
Lines changed: 6 additions & 0 deletions b/‎src/Symfony/Bundle/FrameworkBundle/Resources/config/services.xml
Lines changed: 6 additions & 0 deletions
diff --git a/‎src/Symfony/Component/DependencyInjection/CHANGELOG.md
Lines changed: 1 addition & 0 deletions b/‎src/Symfony/Component/DependencyInjection/CHANGELOG.md
Lines changed: 1 addition & 0 deletions
diff --git a/‎src/Symfony/Component/DependencyInjection/Compiler/RegisterReverseContainerPass.php
Lines changed: 66 additions & 0 deletions b/‎src/Symfony/Component/DependencyInjection/Compiler/RegisterReverseContainerPass.php
Lines changed: 66 additions & 0 deletions
diff --git a/‎src/Symfony/Component/DependencyInjection/ReverseContainer.php
Lines changed: 85 additions & 0 deletions b/‎src/Symfony/Component/DependencyInjection/ReverseContainer.php
Lines changed: 85 additions & 0 deletions
diff --git a/‎src/Symfony/Component/DependencyInjection/Tests/Compiler/RegisterReverseContainerPassTest.php
Lines changed: 77 additions & 0 deletions b/‎src/Symfony/Component/DependencyInjection/Tests/Compiler/RegisterReverseContainerPassTest.php
Lines changed: 77 additions & 0 deletions
@@ -26,6 +26,7 @@ class UnusedTagsPass implements CompilerPassInterface
         'cache.pool.clearer',
         'console.command',
         'container.hot_path',
+        'container.reversible',
         'container.service_locator',
         'container.service_subscriber',
         'controller.service_arguments',
 
@@ -31,6 +31,7 @@
 use Symfony\Component\Console\DependencyInjection\AddConsoleCommandPass;
 use Symfony\Component\Debug\ErrorHandler;
 use Symfony\Component\DependencyInjection\Compiler\PassConfig;
+use Symfony\Component\DependencyInjection\Compiler\RegisterReverseContainerPass;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\EventDispatcher\DependencyInjection\RegisterListenersPass;
 use Symfony\Component\Form\DependencyInjection\FormPass;
@@ -123,6 +124,8 @@ public function build(ContainerBuilder $container)
         $container->addCompilerPass(new TestServiceContainerRealRefPass(), PassConfig::TYPE_AFTER_REMOVING);
         $this->addCompilerPassIfExists($container, AddMimeTypeGuesserPass::class);
         $this->addCompilerPassIfExists($container, MessengerPass::class);
+        $container->addCompilerPass(new RegisterReverseContainerPass(true));
+        $container->addCompilerPass(new RegisterReverseContainerPass(false), PassConfig::TYPE_AFTER_REMOVING);
 
         if ($container->getParameter('kernel.debug')) {
             $container->addCompilerPass(new AddDebugLogProcessorPass(), PassConfig::TYPE_BEFORE_OPTIMIZATION, -32);
 
@@ -73,5 +73,11 @@
         </service>
 
         <service id="services_resetter" class="Symfony\Component\HttpKernel\DependencyInjection\ServicesResetter" public="true" />
+
+        <service id="reverse_container" class="Symfony\Component\DependencyInjection\ReverseContainer">
+            <argument type="service" id="service_container" />
+            <argument type="service_locator" />
+        </service>
+        <service id="Symfony\Component\DependencyInjection\ReverseContainer" alias="reverse_container" />
     </services>
 </container>
@@ -8,6 +8,7 @@ CHANGELOG
  * added `%env(default:param_name:...)%` processor to fallback to a parameter or to null when using `%env(default::...)%`
  * added support for deprecating aliases
  * made `ContainerParametersResource` final and not implement `Serializable` anymore
+ * added `ReverseContainer`: a container that turns services back to their ids
  * added ability to define an index for a tagged collection
 
 4.2.0
 
@@ -0,0 +1,66 @@
+<?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\DependencyInjection\Compiler;
+
+use Symfony\Component\DependencyInjection\Argument\ServiceClosureArgument;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\DependencyInjection\Definition;
+use Symfony\Component\DependencyInjection\Reference;
+
+/**
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+class RegisterReverseContainerPass implements CompilerPassInterface
+{
+    private $beforeRemoving;
+    private $serviceId;
+    private $tagName;
+
+    public function __construct(bool $beforeRemoving, string $serviceId = 'reverse_container', string $tagName = 'container.reversible')
+    {
+        $this->beforeRemoving = $beforeRemoving;
+        $this->serviceId = $serviceId;
+        $this->tagName = $tagName;
+    }
+
+    public function process(ContainerBuilder $container)
+    {
+        if (!$container->hasDefinition($this->serviceId)) {
+            return;
+        }
+
+        $refType = $this->beforeRemoving ? ContainerInterface::IGNORE_ON_UNINITIALIZED_REFERENCE : ContainerInterface::EXCEPTION_ON_INVALID_REFERENCE;
+        $services = [];
+        foreach ($container->findTaggedServiceIds($this->tagName) as $id => $tags) {
+            $services[$id] = new Reference($id, $refType);
+        }
+
+        if ($this->beforeRemoving) {
+            // prevent inlining of the reverse container
+            $services[$this->serviceId] = new Reference($this->serviceId, $refType);
+        }
+        $locator = $container->getDefinition($this->serviceId)->getArgument(1);
+
+        if ($locator instanceof Reference) {
+            $locator = $container->getDefinition((string) $locator);
+        }
+        if ($locator instanceof Definition) {
+            foreach ($services as $id => $ref) {
+                $services[$id] = new ServiceClosureArgument($ref);
+            }
+            $locator->replaceArgument(0, $services);
+        } else {
+            $locator->setValues($services);
+        }
+    }
+}
@@ -0,0 +1,85 @@
+<?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\DependencyInjection;
+
+use Psr\Container\ContainerInterface;
+use Symfony\Component\DependencyInjection\Exception\ServiceNotFoundException;
+
+/**
+ * Turns public and "container.reversible" services back to their ids.
+ *
+ * @author Nicolas Grekas <p@tchwork.com>
+ */
+final class ReverseContainer
+{
+    private $serviceContainer;
+    private $reversibleLocator;
+    private $tagName;
+    private $getServiceId;
+
+    public function __construct(Container $serviceContainer, ContainerInterface $reversibleLocator, string $tagName = 'container.reversible')
+    {
+        $this->serviceContainer = $serviceContainer;
+        $this->reversibleLocator = $reversibleLocator;
+        $this->tagName = $tagName;
+        $this->getServiceId = \Closure::bind(function ($service): ?string {
+            return array_search($service, $this->services, true) ?: array_search($service, $this->privates, true) ?: null;
+        }, $serviceContainer, Container::class);
+    }
+
+    /**
+     * Returns the id of the passed object when it exists as a service.
+     *
+     * To be reversible, services need to be either public or be tagged with "container.reversible".
+     *
+     * @param object $service
+     */
+    public function getId($service): ?string
+    {
+        if ($this->serviceContainer === $service) {
+            return 'service_container';
+        }
+
+        if (null === $id = ($this->getServiceId)($service)) {
+            return null;
+        }
+
+        if ($this->serviceContainer->has($id) || $this->reversibleLocator->has($id)) {
+            return $id;
+        }
+
+        return null;
+    }
+
+    /**
+     * @return object
+     *
+     * @throws ServiceNotFoundException When the service is not reversible
+     */
+    public function getService(string $id)
+    {
+        if ($this->serviceContainer->has($id)) {
+            return $this->serviceContainer->get($id);
+        }
+
+        if ($this->reversibleLocator->has($id)) {
+            return $this->reversibleLocator->get($id);
+        }
+
+        if (isset($this->serviceContainer->getRemovedIds()[$id])) {
+            throw new ServiceNotFoundException($id, null, null, [], sprintf('The "%s" service is private and cannot be accessed by reference. You should either make it public, or tag it as "%s".', $id, $this->tagName));
+        }
+
+        // will throw a ServiceNotFoundException
         $this->serviceContainer->get($id);
+    }
+}
@@ -0,0 +1,77 @@
+<?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\DependencyInjection\Tests\Compiler;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\DependencyInjection\Argument\ServiceLocatorArgument;
+use Symfony\Component\DependencyInjection\Compiler\PassConfig;
+use Symfony\Component\DependencyInjection\Compiler\RegisterReverseContainerPass;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Reference;
+use Symfony\Component\DependencyInjection\ReverseContainer;
+
+class RegisterReverseContainerPassTest extends TestCase
+{
+    public function testCompileRemovesUnusedServices()
+    {
+        $container = new ContainerBuilder();
+        $container->register('foo', 'stdClass');
+        $container->register('reverse_container', ReverseContainer::class)
+            ->addArgument(new Reference('service_container'))
+            ->addArgument(new ServiceLocatorArgument([]))
+            ->setPublic(true);
+
+        $container->addCompilerPass(new RegisterReverseContainerPass(true));
+        $container->compile();
+
+        $this->assertFalse($container->has('foo'));
+    }
+
+    public function testPublicServices()
+    {
+        $container = new ContainerBuilder();
+        $container->register('foo', 'stdClass')->setPublic(true);
+        $container->register('reverse_container', ReverseContainer::class)
+            ->addArgument(new Reference('service_container'))
+            ->addArgument(new ServiceLocatorArgument([]))
+            ->setPublic(true);
+
+        $container->addCompilerPass(new RegisterReverseContainerPass(true));
+        $container->addCompilerPass(new RegisterReverseContainerPass(false), PassConfig::TYPE_AFTER_REMOVING);
+        $container->compile();
+
+        $foo = $container->get('foo');
+
+        $this->assertSame('foo', $container->get('reverse_container')->getId($foo));
+        $this->assertSame($foo, $container->get('reverse_container')->getService('foo'));
+    }
+
+    public function testReversibleServices()
+    {
+        $container = new ContainerBuilder();
+        $container->register('bar', 'stdClass')->setProperty('foo', new Reference('foo'))->setPublic(true);
+        $container->register('foo', 'stdClass')->addTag('container.reversible');
+        $container->register('reverse_container', ReverseContainer::class)
+            ->addArgument(new Reference('service_container'))
+            ->addArgument(new ServiceLocatorArgument([]))
+            ->setPublic(true);
+
+        $container->addCompilerPass(new RegisterReverseContainerPass(true));
+        $container->addCompilerPass(new RegisterReverseContainerPass(false), PassConfig::TYPE_AFTER_REMOVING);
+        $container->compile();
+
+        $foo = $container->get('bar')->foo;
+
+        $this->assertSame('foo', $container->get('reverse_container')->getId($foo));
+        $this->assertSame($foo, $container->get('reverse_container')->getService('foo'));
+    }
+}