Ticket #39692: 39692.diff

src/wp-includes/default-filters.php

@@ -258 +258 @@
 add_action( 'template_redirect',   'wp_shortlink_header',             11, 0 );
 add_action( 'wp_print_footer_scripts', '_wp_footer_scripts'                 );
 add_action( 'init',                'check_theme_switched',            99    );
+add_action( 'after_switch_theme',  '_wp_menus_changed'                      );
 add_action( 'after_switch_theme',  '_wp_sidebars_changed'                   );
 add_action( 'wp_print_styles',     'print_emoji_styles'                     );
 

src/wp-includes/nav-menu.php

@@ -978 +978 @@
                 wp_update_nav_menu_item( $menu_id, 0, $args );
         }
 }
+
+/**
+ * Handle menu config after theme change
+ *
+ * @access private
+ * @since 4.8.0
+ */
+function _wp_menus_changed() {
+        $old_nav_menu_locations = get_option( 'theme_switch_menu_locations' );
+        $new_nav_menu_locations = get_nav_menu_locations();
+        $registered_nav_menus   = get_registered_nav_menus();
+
+        // If old and new theme have just one location, map it.
+        if ( 1 === count( $old_nav_menu_locations ) && 1 === count( $registered_nav_menus ) ) {
+                $new_nav_menu_locations[ key( $registered_nav_menus ) ] = array_pop( $old_nav_menu_locations );
+        } else {
+                $old_locations = array_keys( $old_nav_menu_locations );
+
+                // Map locations with the same slug.
+                foreach ( $registered_nav_menus as $location => $name ) {
+                        if ( in_array( $location, $old_locations ) ) {
+                                $new_nav_menu_locations[ $location ] = $old_nav_menu_locations[ $location ];
+                                unset( $old_nav_menu_locations[ $location ] );
+                        }
+                }
+
+                if ( ! empty( $old_nav_menu_locations ) ) {
+                        /*
+                         * If old and new theme both have locations that contain phrases
+                         * from within the same group, make an educated guess and map it.
+                         */
+                        $common_slug_groups = array(
+                                array( 'main', 'primary', 'navigation', 'top' ),
+                                array( 'secondary', 'footer', 'subsidiary', 'bottom' ),
+                                array( 'social' ),
+                        );
+
+                        foreach( $common_slug_groups as $slug_group ) {
+                                foreach( $old_nav_menu_locations as $location => $menu_id ) {
+                                        foreach ( $slug_group as $slug ) {
+                                                if ( strpos( $location, $slug ) || strpos( $slug, $location ) ) {
+                                                        foreach( $registered_nav_menus as $new_location => $name ) {
+                                                                if ( strpos( $new_location, $slug ) || strpos( $slug, $new_location ) ) {
+                                                                        $new_nav_menu_locations[ $new_location ] = $old_nav_menu_locations[ $location ];
+                                                                }
+                                                        }
+                                                }
+                                        }
+                                }
+                        }
+                }
+        }
+
+        set_theme_mod( 'nav_menu_locations', $new_nav_menu_locations );
+        delete_option( 'theme_switch_menu_locations' );
+}

src/wp-includes/theme.php

@@ -690 +690 @@
         }
 
         $nav_menu_locations = get_theme_mod( 'nav_menu_locations' );
+        add_option( 'theme_switch_menu_locations', $nav_menu_locations );
 
         if ( func_num_args() > 1 ) {
                 $stylesheet = func_get_arg( 1 );
@@ -730 +731 @@
                 if ( 'wp_ajax_customize_save' === current_action() ) {
                         remove_theme_mod( 'sidebars_widgets' );
                 }
-
-                if ( ! empty( $nav_menu_locations ) ) {
-                        $nav_mods = get_theme_mod( 'nav_menu_locations' );
-                        if ( empty( $nav_mods ) ) {
-                                set_theme_mod( 'nav_menu_locations', $nav_menu_locations );
-                        }
-                }
         }
 
         update_option( 'theme_switched', $old_theme->get_stylesheet() );