Symfony version(s) affected

8.1.0, and surely >6.4.36, >7.4.8, >8.0.8

Description

Spotted while investigating failed production deployments on https://ux.symfony.com after a dependency upgrade.

Previously, injecting a service by name via #[Autowire(service: '...')] on a nullable parameter silently resolved to null when the service did not exist in the current environment. Now, container compilation fails with an exception instead.

I believe this is a BC break. The nullable type on the parameter signals that the absence of the service is acceptable. The previous behavior respected that contract. The current behavior does not.

The error:

The service "App\Controller\Toolkit\ComponentsController::previewComponent()" has a dependency on a non-existent service "profiler".

Thrown by CheckExceptionOnInvalidReferenceBehaviorPass.php line 116.

Previously:

• dev: $profiler is the real Profiler instance, ->disable() is nicely called
• prod: profiler service does not exist, $profiler is null, no error.

Now:

• prod: container compilation fails. The service is missing, and the nullable type is no longer enough to suppress the error. Production deploys of ux.symfony.com broke on this.

PR #63724 changed how invalid reference behavior is handled in CheckExceptionOnInvalidReferenceBehaviorPass

How to reproduce

class ComponentsController
{
    #[Route('/toolkit/component_preview', name: 'app_toolkit_component_preview')]
    public function previewComponent(
        /* ... */
        #[Autowire(service: 'profiler')]
        ?Profiler $profiler,
    ) {
        $profiler?->disable();
        // ...
    }
}

That you can find here.

Possible Solution

PR #63724 changed how invalid reference behavior is handled in CheckExceptionOnInvalidReferenceBehaviorPass

Additional Context

A nullable parameter decorated with #[Autowire(service: '...')] should resolve to null when the service is absent from the container, matching the previous behavior.