Index: includes/theme.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/theme.inc,v
retrieving revision 1.622
diff -u -p -r1.622 theme.inc
--- includes/theme.inc	30 Oct 2010 03:57:20 -0000	1.622
+++ includes/theme.inc	16 Nov 2010 23:13:16 -0000
@@ -758,6 +758,7 @@ function theme($hook, $variables = array
         break;
       }
     }
+    $suggestions = $hook;
     $hook = $candidate;
   }
 
@@ -767,6 +768,7 @@ function theme($hook, $variables = array
     // Iteratively strip everything after the last '__' delimiter, until an
     // implementation is found.
     while ($pos = strrpos($hook, '__')) {
+      $suggestions[] = $hook;
       $hook = substr($hook, 0, $pos);
       if (isset($hooks[$hook])) {
         break;
@@ -829,13 +831,34 @@ function theme($hook, $variables = array
     $base_hook = $info['base hook'];
     $base_hook_info = $hooks[$base_hook];
     if (isset($base_hook_info['preprocess functions']) || isset($base_hook_info['process functions'])) {
+      // Retain the requested suggestion as the highest priority one, even if
+      // the base hook's preprocess functions add to the
+      // 'theme_hook_suggestions' array.
       $variables['theme_hook_suggestion'] = $hook;
+
+      // Enable the base hook's preprocess functions to know all implicit
+      // suggestions requested by the calling context. For base theme hooks that
+      // use the default pattern of '__' to delimit suggestions, include all
+      // implicit intermediary suggestions. For example, for
+      // 'links__node__comment', ensure that 'link__node' is added as an
+      // implicit suggestion.
+      if ((!isset($base_hook_info['pattern']) || $base_hook_info['pattern'] == ($base_hook . '__')) && (strpos($hook, $base_hook . '__') === 0)) {
+        while ($hook != $base_hook && $pos = strrpos($hook, '__')) {
+          $suggestions[] = $hook;
+          $hook = substr($hook, 0, $pos);
+        }
+      }
+      elseif ($hook != $base_hook) {
+        $suggestions[] = $hook;
+      }
+
       $hook = $base_hook;
       $info = $base_hook_info;
     }
   }
   if (isset($info['preprocess functions']) || isset($info['process functions'])) {
-    $variables['theme_hook_suggestions'] = array();
+    // 'theme_hook_suggestions' is defined to be in FILO order (see below).
+    $variables['theme_hook_suggestions'] = isset($suggestions) ? array_reverse($suggestions) : array();
     foreach (array('preprocess functions', 'process functions') as $phase) {
       if (!empty($info[$phase])) {
         foreach ($info[$phase] as $processor_function) {