Rename RenderElement and FormElement plugin abstract classes to RenderElementBase and FormElementBase

Created CR: https://www.drupal.org/node/3436275 →
MR with updated test for deprecation: https://git.drupalcode.org/project/drupal/-/merge_requests/7195

This actually seems like a large change, probably safer to deprecated for removal in D12

Updated CR and MR to 12 for removal version.

Thanks appears to need manual rebasing though.

Rebased and resolved conflict.

THanks conflict appears to be resolved.

Thanks for reviewing.

Separately, I wish that there were a similar way to deal with validation Constraint plugins, since my guess is that there are a lot more contrib and custom validation plugins being written than render element plugins, but since Constraint is a Symfony class, not sure there's a solution.

As things are called statically on the class we need to issue deprecations from there too because this will avoid the constructor.

So for example we need to add things like \Drupal\Core\Render\Element\FormElement::processPattern() with the code:

  /**
   * {@inheritdoc}
   */
  public static function processPattern(&$element, FormStateInterface $form_state, &$complete_form) {
    @trigger_error('\Drupal\Core\Render\Element\FormElement::processPattern() is deprecated in drupal:10.3.0 and is removed from drupal:12.0.0. Use \Drupal\Core\Render\Element\FormElementBase::processPattern() instead. See https://www.drupal.org/node/3436275', E_USER_DEPRECATED);
    return parent::processPattern($element, $form_state, $complete_form);
  }

Not pretty but the best we can do.

Added deprecation warnings to all the static methods with corresponding tests.

Will remember that about static methods going forward

Deprecations look good though.

@godotislate thanks for getting this done. It's great to have this complete before people start to covert to attributes as it was pretty icky.

Committed and pushed 8d1ff20647 to 11.x and b89ad7f9c8 to 10.3.x. Thanks!

godotislate → closed merge request !7195

Automatically closed - issue fixed for 2 weeks with no activity.

I guess it's not possible to backport empty RenderElementBase and FormElementBase classes to 10.2 that extend the old ones to allow contrib to fix depreciations now vs having to wait until end of 10.2 security coverage on December 9th? Happy to do the legwork there if it is an option but I guess it's not as no further non-security releases to 10.2 right?