More robust check of argument

diff --git a/lib/weblib.php b/lib/weblib.php
index 2ad2651fbb1229ab9bd756692f0ee3719eb031bc..ac2130b9f8446c109f0ecdc2c36efb69174dbcb1 100644 (file)
--- a/lib/weblib.php
+++ b/lib/weblib.php
@@ -726,7 +726,7 @@ function print_footer ($course=NULL) {
 function user_login_string($course, $user=NULL) {
     global $USER, $CFG;
 
-    if (!$user) {
+    if (empty($user)) {
         $user = $USER;
     }