Deprecate requiring the "symfony/symfony" package

Author: nicolas-grekas

DependencyInjection/FrameworkExtension.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Bundle\FrameworkBundle\DependencyInjection;
 
+use Composer\InstalledVersions;
 use Doctrine\Common\Annotations\AnnotationRegistry;
 use Doctrine\Common\Annotations\Reader;
 use Http\Client\HttpClient;
@@ -246,6 +247,10 @@ public function load(array $configs, ContainerBuilder $container)
     {
         $loader = new PhpFileLoader($container, new FileLocator(\dirname(__DIR__).'/Resources/config'));
 
+        if (class_exists(InstalledVersions::class) && InstalledVersions::isInstalled('symfony/symfony') && 'symfony/symfony' !== (InstalledVersions::getRootPackage()['name'] ?? '')) {
+            trigger_deprecation('symfony/symfony', '6.1', 'Requiring the "symfony/symfony" package is deprecated; replace it with standalone components instead.');
+        }
+
         $loader->load('web.php');
 
         if (!class_exists(BackedEnumValueResolver::class)) {

composer.json

@@ -22,6 +22,7 @@
         "symfony/cache": "^5.4|^6.0",
         "symfony/config": "^5.4|^6.0",
         "symfony/dependency-injection": "^5.4.5|^6.0.5",
+        "symfony/deprecation-contracts": "^2.1|^3",
         "symfony/event-dispatcher": "^5.4|^6.0",
         "symfony/error-handler": "^5.4|^6.0",
         "symfony/http-foundation": "^5.4|^6.0",