Script loader: remove 6.1 wp actions

[ramonjd]

What?

Now that 6.1-beta is running in development, we should remove the backported hook callbacks for wp_enqueue_stored_styles.

Why?

This prevents the callback running twice.

How?

remove_action YO!

Testing Instructions

In trunk, you can test the before state by creating a post with some layout blocks.

Here, kind reviewer, is some test HTML

Example

<!-- wp:group {"style":{"spacing":{"blockGap":"var:preset|spacing|50"}},"layout":{"type":"constrained","justifyContent":"left","contentSize":"577px"}} -->
<div class="wp-block-group"><!-- wp:site-title {"style":{"color":{"background":"#b92c2c"},"typography":{"lineHeight":5.7,"letterSpacing":"41px"}},"fontSize":"large"} /-->

<!-- wp:site-title {"style":{"color":{"background":"#88c7b4"},"typography":{"lineHeight":5.7,"letterSpacing":"41px"}},"fontSize":"large"} /--></div>
<!-- /wp:group -->

In the published post's frontend HTML source, you'll see that the block supports inline CSS has two comments Core styles: block-supports:

<style id='core-block-supports-inline-css'>
/**
 * Core styles: block-supports
 */

/**
 * Core styles: block-supports
 */

This means that the callback has been called twice.

Apply this PR and see that the duplicate comment is GONE BABY

[tellthemachines]

Don't we still need these somewhere in order for the plugin to be compatible with previous versions of WP?

[ramonjd]

Don't we still need these somewhere in order for the plugin to be compatible with previous versions of WP?

Thanks for taking a look @tellthemachines!

Sorry, I'm not sure I follow 🤔

Do you mean the wp hooks removed by remove_action?

wp_enqueue_stored_styles will be introduced with 6.1 so no previous WP version will have it.

Also, I was going on the assumption that the plugin will always want to use gutenberg_enqueue_stored_styles to allow continuous development (if any). That's also the case with wp_enqueue_global_styles etc

Am I understanding things right?

[tellthemachines]

Do you mean the wp hooks removed by remove_action?

wp_enqueue_stored_styles will be introduced with 6.1 so no previous WP version will have it.

Yes, sorry, I think my yesterday evening brain was processing it the other way around 😂

So the assumption is every WP version > 6.0 will have wp_enqueue_stored_styles, and we'll still want to use gutenberg_enqueue_stored_styles in the plugin for the foreseeable future, right?

If that's the case, we should move this to somewhere outside the compat/wordpress-6.1/ folder because that will be removed once the plugin no longer supports 6.1 (we only support the latest 2 versions of WP), lib/load.php might be a good place?

[ramonjd]

If that's the case, we should move this to somewhere outside the compat/wordpress-6.1/ folder because that will be removed once the plugin no longer supports 6.1 (we only support the latest 2 versions of WP

OMG, the folder name totally went over my head. Thanks for pointing that out. I'm still living in the past 🤣

I'll update

[ramonjd]

The following is just a brain dump in case we need to come back to it later, and it's not necessarily coherent :)

TL;DR We don't need this PR as it is right now, but there might be case to remove the WP hooks later.

---

So the assumption is every WP version > 6.0 will have wp_enqueue_stored_styles, and we'll still want to use gutenberg_enqueue_stored_styles in the plugin for the foreseeable future, right?

Yes. In fact, because, like gutenberg_enqueue_global_styles, gutenberg_enqueue_stored_styles calls internal gutenberg_ function.

Furthermore, it's envisaged that Gutenberg will only use the style engine's gutenberg_* functions and _Gutenberg classes to aid continuous development of the Style Engine for the foreseeable future.

For now however, I don't think there's much of an immediate problem because we really only care about block support styles in Gutenberg.

Gutenberg, when activated, re-reregisters blocks supports (overwriting Core's).

Styles for Gutenberg's blocks supports are currently being generated using the style engine's gutenberg_* functions and _Gutenberg classes.

Core block supports, therefore, are not registering any styles at all with the plugin activated.

The worst thing that is happening is that the Core styles: block-supports comment is being printed twice, and ONLY in development mode.

Catch 22

In fact I think we can't call remove_action on gutenberg_enqueue_stored_styles hooks at all because in it we've included functionality to enqueue any styles registered by third parties. If we removed the WP hooks, we would short-circuit any styles registered via the Core WP Style Engine, by, for example, a theme. 😄

The Catch 22 will be when we start enqueuing global styles, and there's the possibility of styles being printed twice or Core and Gutenberg styles clashing. To be safe, I think we have to remove the action hooks. 🙃

So in that respect we've painted ourselves into nice little corner.

Going forward

My proposal in this PR therefore is to move gutenberg_enqueue_stored_styles into client-assets.php, which is not a versioned compat file, to indicate that it's a permanent fixture of Gutenberg for now.

Then, continue to remove the wp hooks in that file:

remove_action( 'wp_enqueue_scripts', 'wp_enqueue_stored_styles' );
remove_action( 'wp_footer', 'wp_enqueue_stored_styles', 1 );

And, to ensure that we support printed out 3rd party styles registered with the Style Engine, we check for Core stores

	// If there are any other stores registered by themes etc., print them out.
	$additional_stores = WP_Style_Engine_CSS_Rules_Store_Gutenberg::get_stores();

	/*
	 * Since the corresponding action hook in Core is removed below,
	 * this function should still honour any styles stored using the Core Style Engine store.
	 */
	if ( class_exists( 'WP_Style_Engine_CSS_Rules_Store' ) ) {
		$additional_stores = array_merge( $additional_stores, WP_Style_Engine_CSS_Rules_Store_Gutenberg::get_stores() );
	}

Sorry if this sounds like rubbish. I've been thinking about it for too long.

cc @andrewserong for the obligatory sanity check 😄

I'm wondering if gutenberg_enqueue_global_styles will face a similar compat fork in the road too, or whether it'll continue to be copied into compat/wordpress-6.2/script-loader.php, then compat/wordpress-6.3/script-loader.php etc

[andrewserong]

My proposal in this PR therefore is to move gutenberg_enqueue_stored_styles into client-assets.php, which is not a versioned compat file, to indicate that it's a permanent fixture of Gutenberg for now.

Thanks for laying all that out @ramonjd — the logic of doing that and then removing the core hooks sounds good to me!

[andrewserong]

Thanks for following up @ramonjd! This is testing well for me:

✅ Still outputs styles correctly in 6.0 + Gutenberg plugin
✅ Confirmed that prior to this PR, 6.1 beta + Gutenberg plugin resulted in double "Core styles" string
✅ With this PR applied, there is only a single output 👍

Before	After

LGTM! ✨

[aristath]

LGTM! 👍