Index: includes/theme.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/theme.inc,v
retrieving revision 1.415.2.12
diff -u -p -r1.415.2.12 theme.inc
--- includes/theme.inc	17 Sep 2008 08:57:23 -0000	1.415.2.12
+++ includes/theme.inc	23 Oct 2008 18:51:41 -0000
@@ -262,6 +262,7 @@ function drupal_rebuild_theme_registry()
  */
 function _theme_process_registry(&$cache, $name, $type, $theme, $path) {
   $function = $name .'_theme';
+  $result = array();
   if (function_exists($function)) {
     $result = $function($cache, $type, $theme, $path);
 
@@ -358,6 +359,24 @@ function _theme_process_registry(&$cache
     // Merge the newly created theme hooks into the existing cache.
     $cache = array_merge($cache, $result);
   }
+
+  // Let themes have preprocess functions even if they didn't register a template.
+  if ($type == 'theme' || $type == 'base_theme') {
+    foreach ($cache as $hook => $info) {
+      // Check only if it's a template and not registered by the theme or engine
+      if (!empty($info['template']) && empty($result[$hook])) {
+        if (!isset($info['preprocess functions'])) {
+          $cache[$hook]['preprocess functions'] = array();
+        }
+        if (function_exists($name . '_preprocess')) {
+          $cache[$hook]['preprocess functions'][] = $name . '_preprocess';
+        }
+        if (function_exists($name . '_preprocess_' . $hook)) {
+          $cache[$hook]['preprocess functions'][] = $name . '_preprocess_' . $hook;
+        }
+      }
+    }
+  }
 }
 
 /**