Call variation through callback so it's only loaded when needed - in support of trac 59969

lib/compat/wordpress-6.4/block-hooks.php

@@ -79,6 +79,11 @@ function gutenberg_add_hooked_blocks( $settings, $metadata ) {
 
 	$exposed_settings = array_intersect_key( $settings, $fields_to_pick );
 
+	// If the block has a variations callback, call it and add the variations to the block.
+	if ( isset( $exposed_settings['variations'] ) && is_callable( $exposed_settings['variations'] ) ) {
+		$exposed_settings['variations'] = call_user_func( $exposed_settings['variations'] );
+	}
+
 	// TODO: Make work for blocks registered via direct call to gutenberg_add_hooked_block().
 	wp_add_inline_script(
 		'wp-blocks',

packages/block-library/src/navigation-link/index.php

@@ -342,12 +342,11 @@ function register_block_core_navigation_link_variation( $variation ) {
 }
 
 /**
- * Register the navigation link block.
+ * Returns an array of variations for the navigation link block.
  *
- * @uses render_block_core_navigation()
- * @throws WP_Error An WP_Error exception parsing the block definition.
+ * @return array
  */
-function register_block_core_navigation_link() {
+function build_navigation_link_block_variations() {
 	// This will only handle post types and taxonomies registered until this point (init on priority 9).
 	// See action hooks below for other post types and taxonomies.
 	// See https://github.com/WordPress/gutenberg/issues/53826 for details.
@@ -382,11 +381,21 @@ function register_block_core_navigation_link() {
 		}
 	}
 
+	return array_merge( $built_ins, $variations );
+}
+
+/**
+ * Register the navigation link block.
+ *
+ * @uses render_block_core_navigation()
+ * @throws WP_Error An WP_Error exception parsing the block definition.
+ */
+function register_block_core_navigation_link() {
 	register_block_type_from_metadata(
 		__DIR__ . '/navigation-link',
 		array(
 			'render_callback' => 'render_block_core_navigation_link',
-			'variations'      => array_merge( $built_ins, $variations ),
+			'variations'      => 'build_navigation_link_block_variations',
 		)
 	);
 }

packages/block-library/src/post-terms/index.php

@@ -59,9 +59,11 @@ function render_block_core_post_terms( $attributes, $content, $block ) {
 }
 
 /**
- * Registers the `core/post-terms` block on the server.
+ * Returns the available variations for the `core/post-terms` block.
+ *
+ * @return array The available variations for the block.
  */
-function register_block_core_post_terms() {
+function build_post_term_block_variations() {
 	$taxonomies = get_taxonomies(
 		array(
 			'publicly_queryable' => true,
@@ -103,11 +105,18 @@ function register_block_core_post_terms() {
 		}
 	}
 
+	return array_merge( $built_ins, $custom_variations );
+}
+
+/**
+ * Registers the `core/post-terms` block on the server.
+ */
+function register_block_core_post_terms() {
 	register_block_type_from_metadata(
 		__DIR__ . '/post-terms',
 		array(
 			'render_callback' => 'render_block_core_post_terms',
-			'variations'      => array_merge( $built_ins, $custom_variations ),
+			'variations'      => 'build_post_term_block_variations',
 		)
 	);
 }

packages/block-library/src/template-part/index.php

@@ -276,7 +276,7 @@ function register_block_core_template_part() {
 		__DIR__ . '/template-part',
 		array(
 			'render_callback' => 'render_block_core_template_part',
-			'variations'      => build_template_part_block_variations(),
+			'variations'      => 'build_template_part_block_variations',
 		)
 	);
 }