Global Styles: Skip registration of variation styles when unsupported

[aaronrobertshaw]

What?

Prevents going through all the work of searching for theme.json partials, parsing them and the core theme.json etc when the theme doesn't have its own theme.json.

Why?

Performance and simplicity.

How?

Make a check to wp_theme_has_theme_json() and return early if applicable.

Testing Instructions

1. Add a block style variation to a theme via any source e.g. through its theme.json and the snippet below:

                       "variations": {
                               "FromTheme": {
                                       "blockTypes": [
                                               "core/group",
                                               "core/columns"
                                       ],
                                       "color": {
                                               "background": "blue"
                                       }
                               }
                       },

2. Confirm this variation still shows and works appropriately
3. Switch theme to a classic theme and confirm no variations are shown
4. Update a hybrid theme to have a block style variation within its theme.json via snippet below.

{
	"$schema": "https://schemas.wp.org/trunk/theme.json",
	"version": 2,
	"styles": {
		"blocks": {
			"variations": {
				"FromTheme": {
					"blockTypes": [ "core/group", "core/columns" ],
					"color": {
						"background": "blue"
					}
				}
			}
		}
	}
}

5. Confirm the variation shows

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: aaronrobertshaw <aaronrobertshaw@git.wordpress.org>
Co-authored-by: oandregal <oandregal@git.wordpress.org>
Co-authored-by: andrewserong <andrewserong@git.wordpress.org>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[github-actions]

This pull request has changed or added PHP files. Please confirm whether these changes need to be synced to WordPress Core, and therefore featured in the next release of WordPress.

If so, it is recommended to create a new Trac ticket and submit a pull request to the WordPress Core GitHub repository soon after this pull request is merged.

If you're unsure, you can always ask for help in the #core-editor channel in WordPress Slack.

Thank you! ❤️

View changed files

❔ lib/block-supports/block-style-variations.php

[aaronrobertshaw]

I'm holding off on merging this one for the moment.

The solution would work nicely for block themes but also impacts hybrid themes. I'll take another run at this tomorrow.

[github-actions]

Flaky tests detected in 34f4768.
Some tests passed with failed attempts. The failures may not be related to this commit but are still reported for visibility. See the documentation for more information.

🔍 Workflow run URL: https://github.com/WordPress/gutenberg/actions/runs/9542559209
📝 Reported issues:

• [Flaky Test] Navigates from items list to preview via TAB, and vice versa #62434 in /test/e2e/specs/site-editor/dataviews-list-layout-keyboard.spec.js
• [Flaky Test] submenu click on the arrow interactions #61884 in /test/e2e/specs/editor/blocks/navigation-frontend-interactivity.spec.js

[ellatrix]

I just cherry-picked this PR to the wp/6.6-beta-3 branch to get it included in the next release: f0327a0