From de3fc8f765d9a8e891492615a76cc3223499db89 Mon Sep 17 00:00:00 2001
From: Gilles Dubuc <gilles@wikimedia.org>
Date: Mon, 19 Nov 2018 11:49:23 +0100
Subject: [PATCH] Log error when array_flip fails in MessageCache load

Bug: T208897
Change-Id: If6e7a6a3019abbdc11b6604ec706cc88bfddf128
---
 includes/cache/MessageCache.php | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/includes/cache/MessageCache.php b/includes/cache/MessageCache.php
index 5ada42fb77..b669fcd492 100644
--- a/includes/cache/MessageCache.php
+++ b/includes/cache/MessageCache.php
@@ -270,6 +270,17 @@ class MessageCache {
 
 		$this->overridable = array_flip( Language::getMessageKeysFor( $code ) );
 
+		// T208897 array_flip can fail and return null
+		if ( is_null( $this->overridable ) ) {
+			LoggerFactory::getInstance( 'MessageCache' )->error(
+				__METHOD__ . ': $this->overridable is null',
+				[
+					'message_keys' => Language::getMessageKeysFor( $code ),
+					'code' => $code
+				]
+			);
+		}
+
 		# 8 lines of code just to say (once) that message cache is disabled
 		if ( $this->mDisable ) {
 			static $shownDisabled = false;
-- 
2.20.1