Do not use init to register block style variations defined via theme.json

src/wp-includes/block-supports/block-style-variations.php

@@ -461,58 +461,3 @@ function wp_register_block_style_variations_from_theme_json_data( $variations )
 		}
 	}
 }
-
-/**
- * Register shared block style variations defined by the theme.
- *
- * These can come in three forms:
- * - the theme's theme.json
- * - the theme's partials (standalone files in `/styles` that only define block style variations)
- * - the user's theme.json (for example, theme style variations the user selected)
- *
- * @since 6.6.0
- * @access private
- */
-function wp_register_block_style_variations_from_theme() {
-	/*
-	 * Skip any registration of styles if no theme.json or variation partials are present.
-	 *
-	 * Given the possibility of hybrid themes, this check can't rely on if the theme
-	 * is a block theme or not. Instead:
-	 *   - If there is a primary theme.json, continue.
-	 *   - If there is a partials directory, continue.
-	 *   - The only variations to be registered from the global styles user origin,
-	 *     are those that have been copied in from the selected theme style variation.
-	 *     For a theme style variation to be selected it would have to have a partial
-	 *     theme.json file covered by the previous check.
-	 */
-	$has_partials_directory = is_dir( get_stylesheet_directory() . '/styles' ) || is_dir( get_template_directory() . '/styles' );
-	if ( ! wp_theme_has_theme_json() && ! $has_partials_directory ) {
-		return;
-	}
-
-	// Partials from `/styles`.
-	$variations_partials = WP_Theme_JSON_Resolver::get_style_variations( 'block' );
-	wp_register_block_style_variations_from_theme_json_data( $variations_partials );
-
-	/*
-	 * Pull the data from the specific origin instead of the merged data.
-	 * This is because, for 6.6, we only support registering block style variations
-	 * for the 'theme' and 'custom' origins but not for 'default' (core theme.json)
-	 * or 'custom' (theme.json in a block).
-	 *
-	 * When/If we add support for every origin, we should switch to using the public API
-	 * instead, e.g.: wp_get_global_styles( array( 'blocks', 'variations' ) ).
-	 */
-
-	// theme.json of the theme.
-	$theme_json_theme = WP_Theme_JSON_Resolver::get_theme_data();
-	$variations_theme = $theme_json_theme->get_data()['styles']['blocks']['variations'] ?? array();
-	wp_register_block_style_variations_from_theme_json_data( $variations_theme );
-
-	// User data linked for this theme.
-	$theme_json_user = WP_Theme_JSON_Resolver::get_user_data();
-	$variations_user = $theme_json_user->get_data()['styles']['blocks']['variations'] ?? array();
-	wp_register_block_style_variations_from_theme_json_data( $variations_user );
-}
-add_action( 'init', 'wp_register_block_style_variations_from_theme' );

src/wp-includes/class-wp-theme-json-resolver.php

@@ -221,6 +221,7 @@ protected static function has_same_registered_blocks( $origin ) {
 	 * @since 5.9.0 Theme supports have been inlined and the `$theme_support_data` argument removed.
 	 * @since 6.0.0 Added an `$options` parameter to allow the theme data to be returned without theme supports.
 	 * @since 6.6.0 Add support for 'default-font-sizes' and 'default-spacing-sizes' theme supports.
+	 *              Register the block style variations coming from the partials and the theme.json.
 	 *
 	 * @param array $deprecated Deprecated. Not used.
 	 * @param array $options {
@@ -247,6 +248,14 @@ public static function get_theme_data( $deprecated = array(), $options = array()
 				$theme_json_data = array( 'version' => WP_Theme_JSON::LATEST_SCHEMA );
 			}
 
+			// Register variations defined by the theme.
+			$variations = $theme_json_data['styles']['blocks']['variations'] ?? array();
+			wp_register_block_style_variations_from_theme_json_data( $variations );
+
+			// Register variations defined by theme partials (theme.json files in the styles directory).
+			$variations = static::get_style_variations( 'block' );
+			wp_register_block_style_variations_from_theme_json_data( $variations );
+
 			/**
 			 * Filters the data provided by the theme for global styles and settings.
 			 *
@@ -488,6 +497,7 @@ public static function get_user_data_from_wp_global_styles( $theme, $create_post
 	 *
 	 * @since 5.9.0
 	 * @since 6.6.0 The 'isGlobalStylesUserThemeJSON' flag is left on the user data.
+	 *              Register the block style variations coming from the user data.
 	 *
 	 * @return WP_Theme_JSON Entity that holds styles for user data.
 	 */
@@ -528,6 +538,10 @@ public static function get_user_data() {
 				unset( $decoded_data['isGlobalStylesUserThemeJSON'] );
 				$config = $decoded_data;
 			}
+
+			// Register variations defined by the user.
+			$variations = $config['styles']['blocks']['variations'] ?? array();
+			wp_register_block_style_variations_from_theme_json_data( $variations );
 		}
 
 		/** This filter is documented in wp-includes/class-wp-theme-json-resolver.php */

src/wp-includes/rest-api/endpoints/class-wp-rest-global-styles-controller.php

@@ -231,7 +231,7 @@ public function update_item_permissions_check( $request ) {
 	 *
 	 * @since 5.9.0
 	 * @since 6.2.0 Added validation of styles.css property.
-	 * @since 6.6.0 Added registration of newly created style variations provided by the user.
+	 * @since 6.6.0 Added registration of block style variations from theme.json sources (theme.json, user theme.json, partials).
 	 *
 	 * @param WP_REST_Request $request Request object.
 	 * @return stdClass|WP_Error Prepared item on success. WP_Error on when the custom CSS is not valid.
@@ -265,22 +265,12 @@ protected function prepare_item_for_database( $request ) {
 				$config['styles'] = $existing_config['styles'];
 			}
 
-			/*
-			 * If the incoming request is going to create a new variation
-			 * that is not yet registered, we register it here.
-			 * This is because the variations are registered on init,
-			 * but we want this endpoint to return the new variation immediately:
-			 * if we don't register it, it'll be stripped out of the response
-			 * just in this request (subsequent ones will be ok).
-			 * Take the variations defined in styles.blocks.variations from the incoming request
-			 * that are not part of the $exsting_config.
-			 */
-			if ( isset( $request['styles']['blocks']['variations'] ) ) {
-				$existing_variations = isset( $existing_config['styles']['blocks']['variations'] ) ? $existing_config['styles']['blocks']['variations'] : array();
-				$new_variations      = array_diff_key( $request['styles']['blocks']['variations'], $existing_variations );
-				if ( ! empty( $new_variations ) ) {
-					wp_register_block_style_variations_from_theme_json_data( $new_variations );
-				}
+			// Register theme-defined variations.
+			WP_Theme_JSON_Resolver::get_theme_data();
+
+			// Register user-defined variations.
+			if ( ! empty( $config['styles']['blocks']['variations'] ) ) {
+				wp_register_block_style_variations_from_theme_json_data( $config['styles']['blocks']['variations'] );
 			}
 
 			if ( isset( $request['settings'] ) ) {

tests/phpunit/tests/block-supports/block-style-variations.php

@@ -66,12 +66,10 @@ public function filter_set_theme_root() {
 	public function test_add_registered_block_styles_to_theme_data() {
 		switch_theme( 'block-theme' );
 
-		/*
-		 * Trigger block style registration that occurs on `init` action.
-		 * do_action( 'init' ) could be used here however this direct call
-		 * means only the updates being tested are performed.
-		 */
-		wp_register_block_style_variations_from_theme();
+		// Register theme-defined variations.
+		WP_Theme_JSON_Resolver::get_theme_data();
+		// Register user-defined variations.
+		WP_Theme_JSON_Resolver::get_user_data();
 
 		$variation_styles_data = array(
 			'color'    => array(