diff -r 3d4e9c994f10 -r a86126ab1dd4 wp/wp-includes/widgets/class-wp-nav-menu-widget.php
--- a/wp/wp-includes/widgets/class-wp-nav-menu-widget.php	Tue Oct 22 16:11:46 2019 +0200
+++ b/wp/wp-includes/widgets/class-wp-nav-menu-widget.php	Tue Dec 15 13:49:49 2020 +0100
@@ -39,14 +39,15 @@
 	 * @param array $instance Settings for the current Navigation Menu widget instance.
 	 */
 	public function widget( $args, $instance ) {
-		// Get menu
+		// Get menu.
 		$nav_menu = ! empty( $instance['nav_menu'] ) ? wp_get_nav_menu_object( $instance['nav_menu'] ) : false;
 
 		if ( ! $nav_menu ) {
 			return;
 		}
 
-		$title = ! empty( $instance['title'] ) ? $instance['title'] : '';
+		$default_title = __( 'Menu' );
+		$title         = ! empty( $instance['title'] ) ? $instance['title'] : '';
 
 		/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */
 		$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );
@@ -57,10 +58,36 @@
 			echo $args['before_title'] . $title . $args['after_title'];
 		}
 
-		$nav_menu_args = array(
-			'fallback_cb' => '',
-			'menu'        => $nav_menu,
-		);
+		$format = current_theme_supports( 'html5', 'navigation-widgets' ) ? 'html5' : 'xhtml';
+
+		/**
+		 * Filters the HTML format of widgets with navigation links.
+		 *
+		 * @since 5.5.0
+		 *
+		 * @param string $format The type of markup to use in widgets with navigation links.
+		 *                       Accepts 'html5', 'xhtml'.
+		 */
+		$format = apply_filters( 'navigation_widgets_format', $format );
+
+		if ( 'html5' === $format ) {
+			// The title may be filtered: Strip out HTML and make sure the aria-label is never empty.
+			$title      = trim( strip_tags( $title ) );
+			$aria_label = $title ? $title : $default_title;
+
+			$nav_menu_args = array(
+				'fallback_cb'          => '',
+				'menu'                 => $nav_menu,
+				'container'            => 'nav',
+				'container_aria_label' => $aria_label,
+				'items_wrap'           => '<ul id="%1$s" class="%2$s">%3$s</ul>',
+			);
+		} else {
+			$nav_menu_args = array(
+				'fallback_cb' => '',
+				'menu'        => $nav_menu,
+			);
+		}
 
 		/**
 		 * Filters the arguments for the Navigation Menu widget.
@@ -68,15 +95,15 @@
 		 * @since 4.2.0
 		 * @since 4.4.0 Added the `$instance` parameter.
 		 *
-		 * @param array    $nav_menu_args {
+		 * @param array   $nav_menu_args {
 		 *     An array of arguments passed to wp_nav_menu() to retrieve a navigation menu.
 		 *
 		 *     @type callable|bool $fallback_cb Callback to fire if the menu doesn't exist. Default empty.
 		 *     @type mixed         $menu        Menu ID, slug, or name.
 		 * }
-		 * @param WP_Term  $nav_menu      Nav menu object for the current menu.
-		 * @param array    $args          Display arguments for the current widget.
-		 * @param array    $instance      Array of settings for the current widget.
+		 * @param WP_Term $nav_menu      Nav menu object for the current menu.
+		 * @param array   $args          Display arguments for the current widget.
+		 * @param array   $instance      Array of settings for the current widget.
 		 */
 		wp_nav_menu( apply_filters( 'widget_nav_menu_args', $nav_menu_args, $nav_menu, $args, $instance ) );
 
@@ -117,10 +144,11 @@
 		$title    = isset( $instance['title'] ) ? $instance['title'] : '';
 		$nav_menu = isset( $instance['nav_menu'] ) ? $instance['nav_menu'] : '';
 
-		// Get menus
+		// Get menus.
 		$menus = wp_get_nav_menus();
 
-		$empty_menus_style = $not_empty_menus_style = '';
+		$empty_menus_style     = '';
+		$not_empty_menus_style = '';
 		if ( empty( $menus ) ) {
 			$empty_menus_style = ' style="display:none" ';
 		} else {
@@ -141,8 +169,10 @@
 			} else {
 				$url = admin_url( 'nav-menus.php' );
 			}
+
+			/* translators: %s: URL to create a new menu. */
+			printf( __( 'No menus have been created yet. <a href="%s">Create some</a>.' ), esc_attr( $url ) );
 			?>
-			<?php echo sprintf( __( 'No menus have been created yet. <a href="%s">Create some</a>.' ), esc_attr( $url ) ); ?>
 		</p>
 		<div class="nav-menu-widget-form-controls" <?php echo $empty_menus_style; ?>>
 			<p>