Detect usage of `Symfony\Component\Yaml\Yaml::parse` and suggest `Drupal\Core\Serialization\Yaml::decode`

[Kingdutch]

Feature request

When developers work with Yaml the autocomplete from IDEs often suggests Yaml::parse which will give them the Symfony component and they may be unaware of the existence of Drupal's Yaml serialization component which is strictly better.

Developers should prefer calling Drupal\Component\Serialization\Yaml::decode which can delegate to Symfony, but will prefer the PHP Yaml extension if it's available which provides a free performance benefit.

[mglaman]

Actually, it should recommend https://git.drupalcode.org/project/drupal/-/blob/11.x/core/lib/Drupal/Core/Serialization/Yaml.php?ref_type=heads

I know. We have two. But this respects the ability to override it

[mglaman]

@Kingdutch actually, I think we should open a Drupal core issue to kill this class. Drupal\Component\Serialization\Yaml should have a setSerializer method. DrupalKernel as part of bootEnvironment process could call the method to set the serializer.

Drupal\Component\Serialization\Yaml::setSerializer(Settings::get('yaml_parser_class'))

What do you think?

[mglaman]

I went an opened one https://www.drupal.org/project/drupal/issues/3401665

[Kingdutch]

Yeah that sounds like a good Drupal core issue :) I still agree with the title change to get people to switch to the most flexible class first, then they'll eventually automatically get the "deprecation" warning to move to the component when that is more flexible.

We'll need to include some logic in the rule that suggests Drupal\Core\Serialization\Yaml, to check whether that class is not deprecated and suggest Drupal\Component\Serialization\Yaml otherwise (or we risk people getting stuck between a rock and a hard place when the deprecation lands in Drupal).

[mglaman]

🤖

Revisited the linked Drupal.org issues to check current status:

• #3205480 was closed (fixed) in Drupal 10.3/11.x — PECL YAML support was dropped and Drupal\Core\Serialization\Yaml was converted to a plain class_alias() pointing to Drupal\Component\Serialization\Yaml.
• #3401665 (the issue I opened) was closed as a duplicate of the above. The full deprecation of Drupal\Core\Serialization\Yaml was not implemented — it remains a simple alias.

This actually simplifies the rule. The concern from @Kingdutch about needing branching logic ("check if Core\Serialization\Yaml is deprecated, suggest Component otherwise") is no longer needed. The two classes are now functionally identical.

The rule is still worth implementing: detect direct usage of Symfony\Component\Yaml\Yaml::parse and suggest Drupal\Component\Serialization\Yaml::decode instead. Using Symfony's class directly bypasses Drupal's yaml_parser_class setting, so the nudge is still valid.