Ticket #53332: 53332.patch

src/wp-includes/class-wp-widget-factory.php

@@ -55 +55 @@
          * @param string|WP_Widget $widget Either the name of a `WP_Widget` subclass or an instance of a `WP_Widget` subclass.
          */
         public function register( $widget ) {
+                $widget_id = '';
+
                 if ( $widget instanceof WP_Widget ) {
-                        $this->widgets[ spl_object_hash( $widget ) ] = $widget;
+                        $widget_id                   = spl_object_hash( $widget );
+                        $this->widgets[ $widget_id ] = $widget;
                 } else {
-                        $this->widgets[ $widget ] = new $widget();
+                        $widget_id                   = $widget;
+                        $this->widgets[ $widget_id ] = new $widget();
+                }
+
+                /**
+                 * The WordPress Block Developer documentation site first informed allowing
+                 * a Legacy Widget migration to a Block Widget needed the Legacy Widget to
+                 * add a `$show_instance_in_rest` property to their class and set it to `true`.
+                 *
+                 * As WordPress 5.8.0 will finally use a widget option to allow this migration,
+                 * it seems fair to check for this property to eventually add the corresponding
+                 * option to the widget in case the early developer missed that change.
+                 *
+                 * see https://core.trac.wordpress.org/ticket/53332
+                 */
+                if ( isset( $this->widgets[ $widget_id ]->show_instance_in_rest ) && ! isset( $this->widgets[ $widget_id ]->widget_options['show_instance_in_rest'] ) ) {
+                        $widget_options = array();
+                        if ( is_array( $this->widgets[ $widget_id ]->widget_options ) ) {
+                                $widget_options = $this->widgets[ $widget_id ]->widget_options;
+                        }
+
+                        $this->widgets[ $widget_id ]->widget_options = array_merge(
+                                $widget_options,
+                                array(
+                                        'show_instance_in_rest' => $this->widgets[ $widget_id ]->show_instance_in_rest,
+                                )
+                        );
                 }
         }