From 363084d4fa91c36938d79532dbe7372154b01530 Mon Sep 17 00:00:00 2001
From: epriestley <git@epriestley.com>
Date: Fri, 6 Jan 2017 13:29:30 -0800
Subject: [PATCH] Fix an issue where setting a recurrence end date on a
 Calendar event without one could fatal

Summary: Ref T11816. The underlying format of recurrence end dates swapped around a bit and we now try to compare `null` to a valid date if you're setting it for the first time.

Test Plan:
  - On a new event, set a recurrence end date.
  - Then, removed a recurrence end date.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11816

Differential Revision: https://secure.phabricator.com/D17150
---
 .../xaction/PhabricatorCalendarEventDateTransaction.php   | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/applications/calendar/xaction/PhabricatorCalendarEventDateTransaction.php b/src/applications/calendar/xaction/PhabricatorCalendarEventDateTransaction.php
index 38e044b3d6..b79a560422 100644
--- a/src/applications/calendar/xaction/PhabricatorCalendarEventDateTransaction.php
+++ b/src/applications/calendar/xaction/PhabricatorCalendarEventDateTransaction.php
@@ -23,6 +23,14 @@ abstract class PhabricatorCalendarEventDateTransaction
   }
 
   public function getTransactionHasEffect($object, $old, $new) {
+    // If either value is `null` (for example, when setting a recurring event
+    // end date for the first time) and the other value is not `null`, this
+    // transaction has an effect.
+    $has_null = (($old === null) || ($new === null));
+    if ($has_null) {
+      return ($old !== $new);
+    }
+
     $editor = $this->getEditor();
 
     $actor = $this->getActor();