Symfony version(s) affected

7.1.0

Description

Cache attribute's vary property is silently ignored with following config:

framework:
  set_locale_from_accept_language: true

And following controller

use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpKernel\Attribute\Cache;

class SomeController
{
    #[Cache(smaxage: 3600, vary: ['X-Some-Header'])]
    public function index(): Response
    {
         return new JsonResponse("OK");
    }
}

The LocaleListener adds an attribute to the request that is used by the ResponseListener to add a Vary: Accept-Language header.
However, this occurs before the CacheAttributeListener, which doesn't take the attribute's vary property into account if there is already a Vary header on the response.

Is this expected?

How to reproduce

See above.

Possible Solution

No response

Additional Context

No response