diff -r 3d4e9c994f10 -r a86126ab1dd4 wp/wp-includes/customize/class-wp-customize-new-menu-control.php
--- a/wp/wp-includes/customize/class-wp-customize-new-menu-control.php	Tue Oct 22 16:11:46 2019 +0200
+++ b/wp/wp-includes/customize/class-wp-customize-new-menu-control.php	Tue Dec 15 13:49:49 2020 +0100
@@ -8,6 +8,8 @@
  * @deprecated 4.9.0 This file is no longer used as of the menu creation UX introduced in #40104.
  */
 
+_deprecated_file( basename( __FILE__ ), '4.9.0' );
+
 /**
  * Customize control class for new menus.
  *
@@ -30,13 +32,18 @@
 	 * Constructor.
 	 *
 	 * @since 4.9.0
+	 * @deprecated 4.9.0
 	 *
-	 * @param WP_Customize_Manager $manager Manager.
-	 * @param string               $id      ID.
-	 * @param array                $args    Args.
+	 * @see WP_Customize_Control::__construct()
+	 *
+	 * @param WP_Customize_Manager $manager Customizer bootstrap instance.
+	 * @param string               $id      The control ID.
+	 * @param array                $args    Optional. Arguments to override class property defaults.
+	 *                                      See WP_Customize_Control::__construct() for information
+	 *                                      on accepted arguments. Default empty array.
 	 */
 	public function __construct( WP_Customize_Manager $manager, $id, array $args = array() ) {
-		_deprecated_file( basename( __FILE__ ), '4.9.0' ); // @todo Move this outside of class, and remove its require_once() from class-wp-customize-control.php. See #42364.
+		_deprecated_function( __METHOD__, '4.9.0' );
 		parent::__construct( $manager, $id, $args );
 	}
 
@@ -44,8 +51,10 @@
 	 * Render the control's content.
 	 *
 	 * @since 4.3.0
+	 * @deprecated 4.9.0
 	 */
 	public function render_content() {
+		_deprecated_function( __METHOD__, '4.9.0' );
 		?>
 		<button type="button" class="button button-primary" id="create-new-menu-submit"><?php _e( 'Create Menu' ); ?></button>
 		<span class="spinner"></span>