Integration with Drupal core's new Layout Builder

Rerolling this patch based on #81 for 2.0.x compatibility.

#86 Patch does not apply, So moving this to needs work.

Patch seems to have missed the an empty line at the end. This one should work. Unfortunately testing is not enabled for the 2.0.x branch. Could you please test?

On most of our newer sites, we've switched over to using Layout Builder Component Attributes → instead of applying this patch, and that works fine without requiring a core patch -- and does more than this, allowing you to specify id, data- attributes, inline styles on not just the block but also the wrapper and the title (if your theme injects the attributes correctly).

So we're now planning to convert our older sites that used this patch to use that module instead. I've opened an issue #3395068: Migration from block_class → there to provide an upgrade path using a custom Drush command, if anyone else is interested.

Simply reporting that patch https://www.drupal.org/files/issues/2023-10-01/2998114-88.patch → applied successfully on 2.0.11

  - Installing drupal/block_class (2.0.11): Extracting archive
  - Applying patches for drupal/block_class
    https://www.drupal.org/files/issues/2023-10-01/2998114-88.patch (https://www.drupal.org/project/block_class/issues/2998114 Integration with Drupal core's new Layout Builder)

@mmatsoo the previous patch may apply, but I don't think it actually works.

We have entirely moved over to Layout Builder Component Attributes for block classes within layouts (we still use Block Class with core block system placements).

On #3395068: Migration from block_class → , I've posted code we successfully used to update block_class usage inside all node and taxonomy term layout overrides. This doesn't update block_class usage on "manage display" pages (the templates) -- for those we just searched our config for usage of block_class, moved the classes from the block_class field to the manage attributes field, and then we could export the config. The update function is for content with layout overrides.

Hope that helps anyone else stuck on this!

Thanks for sharing @freelock. Layout Builder Component Attributes seems really good.

For the ones still relying on block class for this matter, here's a patch for block_class 2.0.12