From 224986af634e1dfc40916e5baee76897db4c907f Mon Sep 17 00:00:00 2001
From: Josh Cox <joshcox@uberatc.com>
Date: Tue, 7 Feb 2017 16:03:48 -0500
Subject: [PATCH] Provide a better error message when an invalid ID is given to
 arc patch

Summary:
Fixes T8937. Previously when running `arc patch D9999999999` or `arc export --revision 99999999` with a non-existent diff or revision ID you would get a rather unhelpful error message. Now you'll get a slightly more helpful error message:
```
$ arc patch D99999999
Exception
Couldn't find a revision or diff that matches the given ID
(Run with `--trace` for a full exception trace.)
```

Test Plan: Ran arc patch with a valid revision and saw it patch successfully. Ran again with an invalid revision, saw the error message.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley, yelirekim

Maniphest Tasks: T8937

Differential Revision: https://secure.phabricator.com/D17325
---
 src/workflow/ArcanistWorkflow.php | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/workflow/ArcanistWorkflow.php b/src/workflow/ArcanistWorkflow.php
index b4b105d6..2365083a 100644
--- a/src/workflow/ArcanistWorkflow.php
+++ b/src/workflow/ArcanistWorkflow.php
@@ -1196,6 +1196,14 @@ abstract class ArcanistWorkflow extends Phobject {
     $future = $conduit->callMethod('differential.querydiffs', $params);
     $diff = head($future->resolve());
 
+    if ($diff == null) {
+      throw new Exception(
+        phutil_console_wrap(
+          pht("The diff or revision you specified is either invalid or you ".
+          "don't have permission to view it."))
+      );
+    }
+
     $changes = array();
     foreach ($diff['changes'] as $changedict) {
       $changes[] = ArcanistDiffChange::newFromDictionary($changedict);