Sitemaps: Remove XSL stylesheets.

Browser support for client-side XSLT is being deprecated and removed. For sites including an XSL stylesheet, the display of the XML sitemaps may fail.

This removes the stylesheets in favour of allowing browsers to render them as they will.

This change deprecates:

* `WP_Sitemaps_Renderer::$stylesheet`
* `WP_Sitemaps_Renderer::$stylesheet_index`
* `WP_Sitemaps_Renderer::get_sitemap_stylesheet_url()`
* `WP_Sitemaps_Renderer::get_sitemap_index_stylesheet_url()`
* `WP_Sitemaps_Stylesheet` in its entirety
* the `sitemap-stylesheet` rewrite tag
* the `sitemap-stylesheet` query variable
* the `*.xls` rewrite rules
* the `wp_sitemaps_stylesheet_url` filter
* the `wp_sitemaps_stylesheet_index_url` filter
* the `wp_sitemaps_stylesheet_index_content` filter
* the `wp_sitemaps_stylesheet_content` filter
* the `wp_sitemaps_stylesheet_css` filter

The outcome of the deprecated filters is ignored, the filters are now only fired in order to provide deprecation notices to developers.

Developed in #12448

Props masteradhoc, pbiron, westonruter, peterwilsoncc.
Fixes #65593.


git-svn-id: https://develop.svn.wordpress.org/trunk@64073 602fd350-edb4-49c9-b593-d223f7449a82

Author: peterwilsoncc

src/wp-includes/canonical.php

@@ -707,9 +707,7 @@ function redirect_canonical( $requested_url = null, $do_redirect = true ) {
 	}
 
 	// Remove trailing slash for robots.txt or sitemap requests.
-	if ( is_robots()
-		|| ! empty( get_query_var( 'sitemap' ) ) || ! empty( get_query_var( 'sitemap-stylesheet' ) )
-	) {
+	if ( is_robots() || ! empty( get_query_var( 'sitemap' ) ) ) {
 		$redirect['path'] = untrailingslashit( $redirect['path'] );
 	}
 

src/wp-includes/class-wp.php

@@ -748,7 +748,7 @@ public function handle_404() {
 
 		// Never 404 here for the admin, robots, favicon, or sitemaps.
 		// Sitemap routes send their own status in WP_Sitemaps::render_sitemaps().
-		if ( is_admin() || is_robots() || is_favicon() || is_sitemap() || get_query_var( 'sitemap-stylesheet' ) ) {
+		if ( is_admin() || is_robots() || is_favicon() || is_sitemap() ) {
 			$set_404 = false;
 
 			// If posts were found, check for paged content.

src/wp-includes/sitemaps/class-wp-sitemaps-renderer.php

@@ -20,6 +20,7 @@ class WP_Sitemaps_Renderer {
 	 * XSL stylesheet for styling a sitemap for web browsers.
 	 *
 	 * @since 5.5.0
+	 * @deprecated 7.2.0 Stylesheets are no longer supported.
 	 *
 	 * @var string
 	 */
@@ -29,6 +30,7 @@ class WP_Sitemaps_Renderer {
 	 * XSL stylesheet for styling a sitemap for web browsers.
 	 *
 	 * @since 5.5.0
+	 * @deprecated 7.2.0 Stylesheets are no longer supported.
 	 *
 	 * @var string
 	 */
@@ -38,81 +40,64 @@ class WP_Sitemaps_Renderer {
 	 * WP_Sitemaps_Renderer constructor.
 	 *
 	 * @since 5.5.0
+	 * @since 7.2.0 No longer sets up the stylesheets, which are no longer supported.
 	 */
-	public function __construct() {
-		$stylesheet_url = $this->get_sitemap_stylesheet_url();
-
-		if ( $stylesheet_url ) {
-			$this->stylesheet = '<?xml-stylesheet type="text/xsl" href="' . esc_url( $stylesheet_url ) . '" ?>';
-		}
-
-		$stylesheet_index_url = $this->get_sitemap_index_stylesheet_url();
-
-		if ( $stylesheet_index_url ) {
-			$this->stylesheet_index = '<?xml-stylesheet type="text/xsl" href="' . esc_url( $stylesheet_index_url ) . '" ?>';
-		}
-	}
+	public function __construct() {}
 
 	/**
 	 * Gets the URL for the sitemap stylesheet.
 	 *
 	 * @since 5.5.0
+	 * @deprecated 7.2.0 Stylesheets are no longer supported.
 	 *
-	 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
-	 *
-	 * @return string The sitemap stylesheet URL.
+	 * @return string Empty string.
 	 */
 	public function get_sitemap_stylesheet_url() {
-		global $wp_rewrite;
-
-		$sitemap_url = home_url( '/wp-sitemap.xsl' );
-
-		if ( ! $wp_rewrite->using_permalinks() ) {
-			$sitemap_url = home_url( '/?sitemap-stylesheet=sitemap' );
-		}
+		_deprecated_function( __METHOD__, '7.2.0' );
 
 		/**
 		 * Filters the URL for the sitemap stylesheet.
 		 *
 		 * If a falsey value is returned, no stylesheet will be used and
-		 * the "raw" XML of the sitemap will be displayed.
+		 * Following the deprecation of XSLT by browser manufacturers the
+		 * outcome of this filter is ignored.
 		 *
 		 * @since 5.5.0
+		 * @deprecated 7.2.0 Stylesheets are no longer supported.
 		 *
 		 * @param string $sitemap_url Full URL for the sitemaps XSL file.
 		 */
-		return apply_filters( 'wp_sitemaps_stylesheet_url', $sitemap_url );
+		apply_filters_deprecated( 'wp_sitemaps_stylesheet_url', array( '' ), '7.2.0' );
+
+		return '';
 	}
 
 	/**
 	 * Gets the URL for the sitemap index stylesheet.
 	 *
 	 * @since 5.5.0
+	 * @deprecated 7.2.0 Stylesheets are no longer supported.
 	 *
-	 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
-	 *
-	 * @return string The sitemap index stylesheet URL.
+	 * @return string Empty string.
 	 */
 	public function get_sitemap_index_stylesheet_url() {
-		global $wp_rewrite;
-
-		$sitemap_url = home_url( '/wp-sitemap-index.xsl' );
-
-		if ( ! $wp_rewrite->using_permalinks() ) {
-			$sitemap_url = home_url( '/?sitemap-stylesheet=index' );
-		}
+		_deprecated_function( __METHOD__, '7.2.0' );
 
 		/**
 		 * Filters the URL for the sitemap index stylesheet.
 		 *
 		 * If a falsey value is returned, no stylesheet will be used and
-		 * the "raw" XML of the sitemap index will be displayed.
+		 * Following the deprecation of XSLT by browser manufacturers the
+		 * outcome of this filter is ignored.
 		 *
 		 * @since 5.5.0
+		 * @deprecated 7.2.0 Stylesheets are no longer supported.
 		 *
 		 * @param string $sitemap_url Full URL for the sitemaps index XSL file.
 		 */
-		return apply_filters( 'wp_sitemaps_stylesheet_index_url', $sitemap_url );
+		apply_filters_deprecated( 'wp_sitemaps_stylesheet_index_url', array( '' ), '7.2.0' );
+
+		return '';
 	}
 
 	/**
@@ -144,11 +129,12 @@ public function render_index( $sitemaps ) {
 	 * @return string|false A well-formed XML string for a sitemap index. False on error.
 	 */
 	public function get_sitemap_index_xml( $sitemaps ) {
+		$this->apply_deprecated_stylesheet_filters( 'index' );
+
 		$sitemap_index = new SimpleXMLElement(
 			sprintf(
-				'%1$s%2$s%3$s',
+				'%1$s%2$s',
 				'<?xml version="1.0" encoding="UTF-8" ?>',
-				$this->stylesheet_index,
 				'<sitemapindex xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" />'
 			)
 		);
@@ -208,11 +194,12 @@ public function render_sitemap( $url_list ) {
 	 * @return string|false A well-formed XML string for a sitemap index. False on error.
 	 */
 	public function get_sitemap_xml( $url_list ) {
+		$this->apply_deprecated_stylesheet_filters( 'sitemap' );
+
 		$urlset = new SimpleXMLElement(
 			sprintf(
-				'%1$s%2$s%3$s',
+				'%1$s%2$s',
 				'<?xml version="1.0" encoding="UTF-8" ?>',
-				$this->stylesheet,
 				'<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9" />'
 			)
 		);
@@ -243,6 +230,56 @@ public function get_sitemap_xml( $url_list ) {
 		return $urlset->asXML();
 	}
 
+	/**
+	 * Applies the removed stylesheet filters so that their callbacks trigger deprecation notices.
+	 *
+	 * The stylesheet filters no longer have any effect. Applying them where a sitemap is
+	 * generated ensures a callback still added to one is reported rather than silently ignored.
+	 * No notice is triggered for a filter that has no callbacks.
+	 *
+	 * @since 7.2.0
+	 *
+	 * @param 'sitemap'|'index' $type Sitemap type.
+	 */
+	private function apply_deprecated_stylesheet_filters( string $type ): void {
+		if ( 'index' === $type ) {
+			/** This filter is documented in wp-includes/sitemaps/class-wp-sitemaps-renderer.php */
+			apply_filters_deprecated( 'wp_sitemaps_stylesheet_index_url', array( '' ), '7.2.0' );
+
+			/**
+			 * Filters the content of the sitemap index stylesheet.
+			 *
+			 * Following the deprecation of XSLT by browser manufacturers the
+			 * outcome of this filter is ignored.
+			 *
+			 * @since 5.5.0
+			 * @deprecated 7.2.0 Stylesheets are no longer supported.
+			 *
+			 * @param string $xsl_content Full content for the XML stylesheet.
+			 */
+			apply_filters_deprecated( 'wp_sitemaps_stylesheet_index_content', array( '' ), '7.2.0' );
+		} else {
+			/** This filter is documented in wp-includes/sitemaps/class-wp-sitemaps-renderer.php */
+			apply_filters_deprecated( 'wp_sitemaps_stylesheet_url', array( '' ), '7.2.0' );
+
+			/**
+			 * Filters the content of the sitemap stylesheet.
+			 *
+			 * Following the deprecation of XSLT by browser manufacturers the
+			 * outcome of this filter is ignored.
+			 *
+			 * @since 5.5.0
+			 * @deprecated 7.2.0 Stylesheets are no longer supported.
+			 *
+			 * @param string $xsl_content Full content for the XML stylesheet.
+			 */
+			apply_filters_deprecated( 'wp_sitemaps_stylesheet_content', array( '' ), '7.2.0' );
+		}
+
+		/** This filter is documented in wp-includes/sitemaps/class-wp-sitemaps-stylesheet.php */
+		apply_filters_deprecated( 'wp_sitemaps_stylesheet_css', array( '' ), '7.2.0' );
+	}
+
 	/**
 	 * Checks for the availability of the SimpleXML extension and errors if missing.
 	 *