Issue #1158956: Added requirements check for the xmlwriter PHP extension.

xmlsitemap.install

@@ -14,6 +14,23 @@ function xmlsitemap_requirements($phase) {
   $requirements = array();
   $t = get_t();
 
+  // Check that required PHP extensions are enabled.
+  // Note: Drupal 7 already requires the 'xml' extension.
+  $required_extensions = array('xmlwriter');
+  $missing_extensions = array_diff($required_extensions, array_filter($required_extensions, 'extension_loaded'));
+
+  if (!empty($missing_extensions)) {
+    $requirements['xmlsitemap_php_extensions'] = array(
+      'title' => $t('XML sitemap PHP extensions'),
+      'value' => $t('Disabled'),
+      'severity' => REQUIREMENT_ERROR,
+      'description' => $t("The XML sitemap module requires you to enable the PHP extensions in the following list (see the <a href=\"@xmlsitemap_requirements\">module's system requirements page</a> for more information):", array(
+        '@xmlsitemap_requirements' => 'http://drupal.org/documentation/modules/xmlsitemap/requirements',
+      )) . theme('item_list', array('items' => $missing_extensions)),
+    );
+  }
+
+  if ($phase == 'runtime') {
     // If clean URLs are disabled there must not be an actual sitemap.xml in
     // the root directory.
     if (variable_get('clean_url', 0) && file_exists(DRUPAL_ROOT . '/sitemap.xml')) {
@@ -25,7 +42,6 @@ function xmlsitemap_requirements($phase) {
       );
     }
 
-  if ($phase == 'runtime') {
     // Check that the base directory and all its subdirectories are writable.
     $requirements['xmlsitemap_directory'] = array(
       'title' => $t('XML sitemap cache directory'),