Drop the container reference in LazyClassReflectionExtensionRegistryProvider after building the registry

Every ClassReflection instance holds this provider as a constructor
dependency. Because the provider kept its Container reference for the whole
process, every ClassReflection — and transitively every ObjectType that ever
resolved its class, every ResolvedPhpDocBlock tag type, every cached
signature — was a handle on the entire DI container.

That reference is only needed once, to build the registry lazily. Null it out
afterwards. Verified with retention-path instrumentation on a large project:
no reference chain from ClassReflection to the container remains, which is a
prerequisite for any future eviction of class reflections to actually free
memory (and prevents a stale reflection from keeping a dead container alive,
e.g. after stub validation).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NrTvR9j1mW2NNNC8RkuTsF

Author: ondrejmirtes

src/DependencyInjection/Reflection/LazyClassReflectionExtensionRegistryProvider.php

@@ -15,6 +15,7 @@
 use PHPStan\Reflection\Php\UniversalObjectCratesClassReflectionExtension;
 use PHPStan\Reflection\RequireExtension\RequireExtendsMethodsClassReflectionExtension;
 use PHPStan\Reflection\RequireExtension\RequireExtendsPropertiesClassReflectionExtension;
+use PHPStan\ShouldNotHappenException;
 use function array_merge;
 
 #[AutowiredService(as: ClassReflectionExtensionRegistryProvider::class)]
@@ -23,29 +24,39 @@ final class LazyClassReflectionExtensionRegistryProvider implements ClassReflect
 
 	private ?ClassReflectionExtensionRegistry $registry = null;
 
-	public function __construct(private Container $container)
+	public function __construct(private ?Container $container)
 	{
 	}
 
 	public function getRegistry(): ClassReflectionExtensionRegistry
 	{
 		if ($this->registry === null) {
-			$annotationsMethodsClassReflectionExtension = $this->container->getByType(AnnotationsMethodsClassReflectionExtension::class);
-			$annotationsPropertiesClassReflectionExtension = $this->container->getByType(AnnotationsPropertiesClassReflectionExtension::class);
+			$container = $this->container;
+			if ($container === null) {
+				throw new ShouldNotHappenException();
+			}
 
-			$mixinMethodsClassReflectionExtension = $this->container->getByType(MixinMethodsClassReflectionExtension::class);
-			$mixinPropertiesClassReflectionExtension = $this->container->getByType(MixinPropertiesClassReflectionExtension::class);
-			$soapClientMethodsClassReflectionExtension = $this->container->getByType(SoapClientMethodsClassReflectionExtension::class);
-			$universalObjectCratesClassReflectionExtension = $this->container->getByType(UniversalObjectCratesClassReflectionExtension::class);
+			$annotationsMethodsClassReflectionExtension = $container->getByType(AnnotationsMethodsClassReflectionExtension::class);
+			$annotationsPropertiesClassReflectionExtension = $container->getByType(AnnotationsPropertiesClassReflectionExtension::class);
+
+			$mixinMethodsClassReflectionExtension = $container->getByType(MixinMethodsClassReflectionExtension::class);
+			$mixinPropertiesClassReflectionExtension = $container->getByType(MixinPropertiesClassReflectionExtension::class);
+			$soapClientMethodsClassReflectionExtension = $container->getByType(SoapClientMethodsClassReflectionExtension::class);
+			$universalObjectCratesClassReflectionExtension = $container->getByType(UniversalObjectCratesClassReflectionExtension::class);
 
 			$this->registry = new ClassReflectionExtensionRegistry(
-				array_merge($this->container->getServicesByTag(BrokerFactory::PROPERTIES_CLASS_REFLECTION_EXTENSION_TAG), [$annotationsPropertiesClassReflectionExtension, $mixinPropertiesClassReflectionExtension, $universalObjectCratesClassReflectionExtension]),
-				array_merge($this->container->getServicesByTag(BrokerFactory::METHODS_CLASS_REFLECTION_EXTENSION_TAG), [$annotationsMethodsClassReflectionExtension, $mixinMethodsClassReflectionExtension, $soapClientMethodsClassReflectionExtension]),
-				$this->container->getServicesByTag(BrokerFactory::ALLOWED_SUB_TYPES_CLASS_REFLECTION_EXTENSION_TAG),
-				$this->container->getByType(RequireExtendsPropertiesClassReflectionExtension::class),
-				$this->container->getByType(RequireExtendsMethodsClassReflectionExtension::class),
-				$this->container->getByType(PhpClassReflectionExtension::class),
+				array_merge($container->getServicesByTag(BrokerFactory::PROPERTIES_CLASS_REFLECTION_EXTENSION_TAG), [$annotationsPropertiesClassReflectionExtension, $mixinPropertiesClassReflectionExtension, $universalObjectCratesClassReflectionExtension]),
+				array_merge($container->getServicesByTag(BrokerFactory::METHODS_CLASS_REFLECTION_EXTENSION_TAG), [$annotationsMethodsClassReflectionExtension, $mixinMethodsClassReflectionExtension, $soapClientMethodsClassReflectionExtension]),
+				$container->getServicesByTag(BrokerFactory::ALLOWED_SUB_TYPES_CLASS_REFLECTION_EXTENSION_TAG),
+				$container->getByType(RequireExtendsPropertiesClassReflectionExtension::class),
+				$container->getByType(RequireExtendsMethodsClassReflectionExtension::class),
+				$container->getByType(PhpClassReflectionExtension::class),
 			);
+
+			// Every ClassReflection instance holds this provider; keeping the container
+			// reference here would make each of them a transitive handle on the entire DI
+			// container. After the registry is built the container is no longer needed.
+			$this->container = null;
 		}
 
 		return $this->registry;