From 8acb5869d587dea0ce60af5f216a9f5119c0c00b Mon Sep 17 00:00:00 2001
From: Timo Tijhof <krinklemail@gmail.com>
Date: Thu, 10 Aug 2017 16:26:08 -0400
Subject: [PATCH] SpecialDoubleRedirects: Fix undefined '$result->namespace'
 notice

Follows-up 7be1a8c0bc4d29d.

$result is used for both the original and the on-demand deep
query (in case of cache). However this re-query can fail if the
page no longer exists.

This used to be accounted for by creating the Title object before
(possibly) trying to re-query, and also checked for with "if !$result",
which is only intended to happen if the re-query failed (the initial
value of $result comes from the main (cacheable) query, and always
exists.

Could be moved by moving the $titleA assignment back up, but that
doesn't address the confusion problem that led to this.

Fix it by using a separate variable names.

Bug: T173045
Change-Id: I0e9ae89a3772b33b916b506033bd334ade5f03fa
---
 includes/specials/SpecialDoubleRedirects.php | 47 +++++++++++---------
 1 file changed, 26 insertions(+), 21 deletions(-)

diff --git a/includes/specials/SpecialDoubleRedirects.php b/includes/specials/SpecialDoubleRedirects.php
index ba14c664ce..d73ac19875 100644
--- a/includes/specials/SpecialDoubleRedirects.php
+++ b/includes/specials/SpecialDoubleRedirects.php
@@ -122,28 +122,33 @@ class DoubleRedirectsPage extends QueryPage {
 		// That does save the bulk of the query cost, but now we need to
 		// get a little more detail about each individual entry quickly
 		// using the filter of reallyGetQueryInfo.
-		if ( $result && !isset( $result->b_namespace ) ) {
-			$dbr = wfGetDB( DB_REPLICA );
-			$qi = $this->reallyGetQueryInfo(
-				$result->namespace,
-				$result->title
-			);
-			$res = $dbr->select(
-				$qi['tables'],
-				$qi['fields'],
-				$qi['conds'],
-				__METHOD__
-			);
-
-			if ( $res ) {
-				$result = $dbr->fetchObject( $res );
+		$deep = false;
+		if ( $result ) {
+			if ( isset( $result->b_namespace ) ) {
+				$deep = $result;
+			} else {
+				$dbr = wfGetDB( DB_REPLICA );
+				$qi = $this->reallyGetQueryInfo(
+					$result->namespace,
+					$result->title
+				);
+				$res = $dbr->select(
+					$qi['tables'],
+					$qi['fields'],
+					$qi['conds'],
+					__METHOD__
+				);
+
+				if ( $res ) {
+					$deep = $dbr->fetchObject( $res ) ?: false;
+				}
 			}
 		}
 
 		$titleA = Title::makeTitle( $result->namespace, $result->title );
 
 		$linkRenderer = $this->getLinkRenderer();
-		if ( !$result ) {
+		if ( !$deep ) {
 			return '<del>' . $linkRenderer->makeLink( $titleA, null, [], [ 'redirect' => 'no' ] ) . '</del>';
 		}
 
@@ -171,7 +176,7 @@ class DoubleRedirectsPage extends QueryPage {
 			[ 'redirect' => 'no' ]
 		);
 
-		$titleB = Title::makeTitle( $result->b_namespace, $result->b_title );
+		$titleB = Title::makeTitle( $deep->b_namespace, $deep->b_title );
 		$linkB = $linkRenderer->makeKnownLink(
 			$titleB,
 			null,
@@ -180,10 +185,10 @@ class DoubleRedirectsPage extends QueryPage {
 		);
 
 		$titleC = Title::makeTitle(
-			$result->c_namespace,
-			$result->c_title,
-			$result->c_fragment,
-			$result->c_interwiki
+			$deep->c_namespace,
+			$deep->c_title,
+			$deep->c_fragment,
+			$deep->c_interwiki
 		);
 		$linkC = $linkRenderer->makeKnownLink( $titleC, $titleC->getFullText() );
 
-- 
2.20.1