Remove the XSLT xml-stylesheet processing instruction from all sitemaps and sitemap indices...

src/wp-includes/sitemaps.php

@@ -94,21 +94,27 @@ function wp_sitemaps_get_max_urls( $object_type ) {
  * Retrieves the full URL for a sitemap.
  *
  * @since 5.5.1
+ * @since 7.1.0 Added $format parameter.
  *
  * @param string $name         The sitemap name.
  * @param string $subtype_name The sitemap subtype name. Default empty string.
  * @param int    $page         The page of the sitemap. Default 1.
+ * @param string $format       The format for the sitemap index.  Accepts 'xml', 'html'.  Default 'xml'.
  * @return string|false The sitemap URL or false if the sitemap doesn't exist.
  */
-function get_sitemap_url( $name, $subtype_name = '', $page = 1 ) {
+function get_sitemap_url( $name, $subtype_name = '', $page = 1, $format = 'xml' ) {
 	$sitemaps = wp_sitemaps_get_server();
 
 	if ( ! $sitemaps ) {
 		return false;
 	}
 
+	if ( ! in_array( $format, array( 'xml', 'html' ), true ) ) {
+		$format = 'xml';
+	}
+
 	if ( 'index' === $name ) {
-		return $sitemaps->index->get_index_url();
+		return $sitemaps->index->get_index_url( $format );
 	}
 
 	$provider = $sitemaps->registry->get_provider( $name );
@@ -125,5 +131,5 @@ function get_sitemap_url( $name, $subtype_name = '', $page = 1 ) {
 		$page = 1;
 	}
 
-	return $provider->get_sitemap_url( $subtype_name, $page );
+	return $provider->get_sitemap_url( $subtype_name, $page, $format );
 }

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

@@ -49,16 +49,22 @@ public function __construct( WP_Sitemaps_Registry $registry ) {
 	 * Gets a sitemap list for the index.
 	 *
 	 * @since 5.5.0
+	 * @since 7.1.0 Added $format parameter.
 	 *
+	 * @param string $format The format for the sitemap index.  Accepts 'xml', 'html'.
 	 * @return array[] Array of all sitemaps.
 	 */
-	public function get_sitemap_list() {
+	public function get_sitemap_list( $format ) {
 		$sitemaps = array();
 
+		if ( ! in_array( $format, array( 'xml', 'html' ), true ) ) {
+			$format = 'xml';
+		}
+
 		$providers = $this->registry->get_providers();
 		/* @var WP_Sitemaps_Provider $provider */
 		foreach ( $providers as $name => $provider ) {
-			$sitemap_entries = $provider->get_sitemap_entries();
+			$sitemap_entries = $provider->get_sitemap_entries( $format );
 
 			// Prevent issues with array_push and empty arrays on PHP < 7.3.
 			if ( ! $sitemap_entries ) {
@@ -79,18 +85,24 @@ public function get_sitemap_list() {
 	 * Builds the URL for the sitemap index.
 	 *
 	 * @since 5.5.0
+	 * @since 7.1.0 Added $format parameter.
 	 *
 	 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
 	 *
+	 * @param string $format   The format for the sitemap index.  Accepts 'xml', 'html'.
 	 * @return string The sitemap index URL.
 	 */
-	public function get_index_url() {
+	public function get_index_url( $format ) {
 		global $wp_rewrite;
 
+		if ( ! in_array( $format, array( 'xml', 'html' ), true ) ) {
+			$format = 'xml';
+		}
+
 		if ( ! $wp_rewrite->using_permalinks() ) {
-			return home_url( '/?sitemap=index' );
+			return home_url( '/?sitemap=index&sitemap-format=' . $format );
 		}
 
-		return home_url( '/wp-sitemap.xml' );
+		return home_url( "/wp-sitemap.{$format}" );
 	}
 }

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

@@ -100,32 +100,40 @@ public function get_sitemap_type_data() {
 	 * The returned data is used to populate the sitemap entries of the index.
 	 *
 	 * @since 5.5.0
+	 * @since 7.1.0 Added $format parameter.
 	 *
+	 * @param string $format The format for the sitemap index.  Accepts 'xml', 'html'.
 	 * @return array[] Array of sitemap entries.
 	 */
-	public function get_sitemap_entries() {
+	public function get_sitemap_entries( $format ) {
 		$sitemaps = array();
 
+		if ( ! in_array( $format, array( 'xml', 'html' ), true ) ) {
+			$format = 'xml';
+		}
+
 		$sitemap_types = $this->get_sitemap_type_data();
 
 		foreach ( $sitemap_types as $type ) {
 			for ( $page = 1; $page <= $type['pages']; $page++ ) {
 				$sitemap_entry = array(
-					'loc' => $this->get_sitemap_url( $type['name'], $page ),
+					'loc' => $this->get_sitemap_url( $type['name'], $page, $format ),
 				);
 
 				/**
 				 * Filters the sitemap entry for the sitemap index.
 				 *
 				 * @since 5.5.0
+				 * @since 7.1.0 Added $format parameter.
 				 *
 				 * @param array  $sitemap_entry  Sitemap entry for the post.
 				 * @param string $object_type    Object empty name.
 				 * @param string $object_subtype Object subtype name.
 				 *                               Empty string if the object type does not support subtypes.
 				 * @param int    $page           Page number of results.
+				 * @param string $format         The format for the sitemap index.  Accepts 'xml', 'html'.
 				 */
-				$sitemap_entry = apply_filters( 'wp_sitemaps_index_entry', $sitemap_entry, $this->object_type, $type['name'], $page );
+				$sitemap_entry = apply_filters( 'wp_sitemaps_index_entry', $sitemap_entry, $this->object_type, $type['name'], $page, $format );
 
 				$sitemaps[] = $sitemap_entry;
 			}
@@ -138,14 +146,16 @@ public function get_sitemap_entries() {
 	 * Gets the URL of a sitemap entry.
 	 *
 	 * @since 5.5.0
+	 * @since 7.1.0 Added $format parameter.
 	 *
 	 * @global WP_Rewrite $wp_rewrite WordPress rewrite component.
 	 *
-	 * @param string $name The name of the sitemap.
-	 * @param int    $page The page of the sitemap.
+	 * @param string $name   The name of the sitemap.
+	 * @param int    $page   The page of the sitemap.
+	 * @param string $format The format for the sitemap index.  Accepts 'xml', 'html'.
 	 * @return string The composed URL for a sitemap entry.
 	 */
-	public function get_sitemap_url( $name, $page ) {
+	public function get_sitemap_url( $name, $page, $format ) {
 		global $wp_rewrite;
 
 		// Accounts for cases where name is not included, ex: sitemaps-users-1.xml.
@@ -157,12 +167,19 @@ public function get_sitemap_url( $name, $page ) {
 			)
 		);
 
+		if ( ! in_array( $format, array( 'xml', 'html' ), true ) ) {
+			$format = 'xml';
+		}
+
 		$basename = sprintf(
-			'/wp-sitemap-%1$s.xml',
-			implode( '-', $params )
+			'/wp-sitemap-%1$s.%2$s',
+			implode( '-', $params ),
+			$format
 		);
 
 		if ( ! $wp_rewrite->using_permalinks() ) {
+			$params['sitemap-format'] = $format;
+
 			$basename = '/?' . http_build_query( $params, '', '&' );
 		}