APC and doctrine cache are not to use - framework documentation indicate to use abandonned components with no alternative

[bruno-ds]

This page https://symfony.com/doc/4.4/reference/configuration/framework.html#validation
indicate:

cache

type: string

The service that is used to persist class metadata in a cache. The service has to implement the CacheInterface.

Set this option to validator.mapping.cache.doctrine.apc to use the APC cache provided by the Doctrine project.

this is wrong two times:

• APC is discontinued, APCu-bc provide a compatibility layer but "As of PHP 8.0.0, apcu-bc is no longer supported" (source)
• doctrine cache is deprecated and will no longer receive bug fixes from the Doctrine Project (source)

So the documentation should not stipulate:

Set this option to validator.mapping.cache.doctrine.apc to use the APC cache provided by the Doctrine project.

What the doc should stipulate?

Honestly, I don't know (I'm in the process of migrating to php 8 and so out of apcu-bc and validator.mapping.cache.doctrine.apc :/)

NB: I don't know if the doc is just out of date or if symfony still uses doctrine's APC cache.

[bruno-ds]

I slept on it, and found this upgrade note:

The validator.mapping.cache.doctrine.apc service has been removed.

so the doc. indicate to use a service that do not exists since the 4.0

Maybe it is acceptable to just remove the statement:

Set this option to validator.mapping.cache.doctrine.apc to use the APC cache provided by the Doctrine project.

But, as the expected values are not straightforwards, for a good enough DX, I'd expect at least on possible value.

[bruno-ds]

After further investigations, here what I conclude:

// SF 4.4, line 1341, method \Symfony\Bundle\FrameworkBundle\DependencyInjection\FrameworkExtension::registerValidationConfiguration
        if (!$container->getParameter('kernel.debug')) {
            $validatorBuilder->addMethodCall('setMappingCache', [new Reference('validator.mapping.cache.adapter')]);
        }

        <service id="validator.mapping.cache.adapter" class="Symfony\Component\Cache\Adapter\PhpArrayAdapter">
            <factory class="Symfony\Component\Cache\Adapter\PhpArrayAdapter" method="create" />
            <argument>%validator.mapping.cache.file%</argument>
            <argument type="service" id="cache.validator" />
        </service>

=> the framework.validation.cache entry is no more read, instead, a PhpArrayAdapter store in an "OPCache" cache.
This is done automatically as soon as %kernel.debug% is false.
Which is fun as it cannot be controlled using the profiler :)

=> I created a PR to remove this from the doc: #17286

[javiereguiluz]

Let's close as fixed thanks to #17286.