Menus: Remove redundant `title` attributes.

Omit `title` attributes if they are defined but are the same text as the menu item title, either before or after filtering. If a navigation menu filter makes significant changes to the menu title without changing the title attribute, this will still remove them. The cases where this occurs and the title attribute is still a useful value will be very uncommon, however.

Props hareesh-pillai, audrasjb, sabernhardt, afercia, sergeybiryukov, tirth03, joedolson.
Fixes #51299.
Built from https://develop.svn.wordpress.org/trunk@59179


git-svn-id: http://core.svn.wordpress.org/trunk@58574 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-walker-nav-menu.php

@@ -126,6 +126,7 @@ class Walker_Nav_Menu extends Walker {
 	 * @since 4.4.0 The {@see 'nav_menu_item_args'} filter was added.
 	 * @since 5.9.0 Renamed `$item` to `$data_object` and `$id` to `$current_object_id`
 	 *              to match parent class for PHP 8 named parameter support.
+	 * @since 6.7.0 Removed redundant title attributes.
 	 *
 	 * @see Walker::start_el()
 	 *
@@ -212,8 +213,25 @@ class Walker_Nav_Menu extends Walker {
 
 		$output .= $indent . '<li' . $li_attributes . '>';
 
+		/** This filter is documented in wp-includes/post-template.php */
+		$title = apply_filters( 'the_title', $menu_item->title, $menu_item->ID );
+
+		// Save filtered value before filtering again.
+		$the_title_filtered = $title;
+
+		/**
+		 * Filters a menu item's title.
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param string   $title     The menu item's title.
+		 * @param WP_Post  $menu_item The current menu item object.
+		 * @param stdClass $args      An object of wp_nav_menu() arguments.
+		 * @param int      $depth     Depth of menu item. Used for padding.
+		 */
+		$title = apply_filters( 'nav_menu_item_title', $title, $menu_item, $args, $depth );
+
 		$atts           = array();
-		$atts['title']  = ! empty( $menu_item->attr_title ) ? $menu_item->attr_title : '';
 		$atts['target'] = ! empty( $menu_item->target ) ? $menu_item->target : '';
 		$atts['rel']    = ! empty( $menu_item->xfn ) ? $menu_item->xfn : '';
 
@@ -229,6 +247,17 @@ class Walker_Nav_Menu extends Walker {
 
 		$atts['aria-current'] = $menu_item->current ? 'page' : '';
 
+		// Add title attribute only if it does not match the link text (before or after filtering).
+		if ( ! empty( $menu_item->attr_title )
+			&& trim( strtolower( $menu_item->attr_title ) ) !== trim( strtolower( $menu_item->title ) )
+			&& trim( strtolower( $menu_item->attr_title ) ) !== trim( strtolower( $the_title_filtered ) )
+			&& trim( strtolower( $menu_item->attr_title ) ) !== trim( strtolower( $title ) )
+		) {
+			$atts['title'] = $menu_item->attr_title;
+		} else {
+			$atts['title'] = '';
+		}
+
 		/**
 		 * Filters the HTML attributes applied to a menu item's anchor element.
 		 *
@@ -251,21 +280,6 @@ class Walker_Nav_Menu extends Walker {
 		$atts       = apply_filters( 'nav_menu_link_attributes', $atts, $menu_item, $args, $depth );
 		$attributes = $this->build_atts( $atts );
 
-		/** This filter is documented in wp-includes/post-template.php */
-		$title = apply_filters( 'the_title', $menu_item->title, $menu_item->ID );
-
-		/**
-		 * Filters a menu item's title.
-		 *
-		 * @since 4.4.0
-		 *
-		 * @param string   $title     The menu item's title.
-		 * @param WP_Post  $menu_item The current menu item object.
-		 * @param stdClass $args      An object of wp_nav_menu() arguments.
-		 * @param int      $depth     Depth of menu item. Used for padding.
-		 */
-		$title = apply_filters( 'nav_menu_item_title', $title, $menu_item, $args, $depth );
-
 		$item_output  = $args->before;
 		$item_output .= '<a' . $attributes . '>';
 		$item_output .= $args->link_before . $title . $args->link_after;

wp-includes/version.php

@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.7-beta1-59178';
+$wp_version = '6.7-beta1-59179';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.