From 213220c159a07c287a084ab698a698d37d315bf6 Mon Sep 17 00:00:00 2001
From: Ruslan Kabalin <r.kabalin@lancaster.ac.uk>
Date: Thu, 14 Aug 2014 15:50:34 +0100
Subject: [PATCH] MDL-46833 mod_assign: Fix assignment view when available for
 group members only.

When assignment is "Available for group members only" and no users with
mod/assign:submit role permision is enrolled (students),
groups_filter_users_by_course_module_visible is causing error (as $users
array is empty). The patch resolves the issue.
---
 lib/grouplib.php | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/grouplib.php b/lib/grouplib.php
index 8fc93e48bfe..5cc566b81ec 100644
--- a/lib/grouplib.php
+++ b/lib/grouplib.php
@@ -860,6 +860,9 @@ function groups_get_activity_allowed_groups($cm,$userid=0) {
 function groups_filter_users_by_course_module_visible($cm, $users) {
     global $CFG, $DB;
 
+    if (empty($users)) {
+        return $users;
+    }
     if (empty($CFG->enablegroupmembersonly)) {
         return $users;
     }