Index: includes/form.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/form.inc,v
retrieving revision 1.265.2.1
diff -u -p -r1.265.2.1 form.inc
--- includes/form.inc	4 Feb 2008 16:24:29 -0000	1.265.2.1
+++ includes/form.inc	5 Feb 2008 02:02:09 -0000
@@ -1,5 +1,5 @@
 <?php
-// $Id: form.inc,v 1.265.2.1 2008/02/04 16:24:29 goba Exp $
+// $Id: form.inc,v 1.265 2008/02/04 10:23:32 goba Exp $
 
 /**
  * @defgroup forms Form builder functions
@@ -664,10 +664,10 @@ function _form_validate($elements, &$for
   // Validate the current input.
   if (!isset($elements['#validated']) || !$elements['#validated']) {
     if (isset($elements['#needs_validation'])) {
-      // An empty textfield returns '' so we use empty(). An empty checkbox
-      // and a textfield could return '0' and empty('0') returns TRUE so we
-      // need a special check for the '0' string.
-      if ($elements['#required'] && empty($elements['#value']) && $elements['#value'] !== '0') {
+      // Use count() to check that arrays are not empty, and then check the
+      // trimmed string length since '0' is a valid possible value with some
+      // field types, so empty() is not usable here.
+      if ($elements['#required'] && (!count($elements['#value']) || (is_string($elements['#value']) && strlen(trim($elements['#value'])) == 0))) {
         form_error($elements, $t('!name field is required.', array('!name' => $elements['#title'])));
       }