From 79274e1f4404721a1d4236c2068310be5e378ee1 Mon Sep 17 00:00:00 2001
From: Brad Jorsch <bjorsch@wikimedia.org>
Date: Tue, 1 Nov 2016 14:58:13 -0400
Subject: [PATCH] Better handling of Message objects as Message parameters

If a Message object is a parameter of another Message object, it should
use the same language, use-database flag, and so on as the outer Message
when it's being stringified.

Change-Id: I92762a1a63c90a16e8581edc96bd1da699880157
---
 includes/Message.php                   | 20 +++++++++++++++++-
 tests/phpunit/includes/MessageTest.php | 28 ++++++++++++++++++++++++++
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/includes/Message.php b/includes/Message.php
index 7d86d07517..85c78d640c 100644
--- a/includes/Message.php
+++ b/includes/Message.php
@@ -766,6 +766,7 @@ class Message implements MessageSpecifier, Serializable {
 	 */
 	public function useDatabase( $useDatabase ) {
 		$this->useDatabase = (bool)$useDatabase;
+		$this->message = null;
 		return $this;
 	}
 
@@ -1132,10 +1133,27 @@ class Message implements MessageSpecifier, Serializable {
 				return [ 'before', '[INVALID]' ];
 			}
 		} elseif ( $param instanceof Message ) {
+			// Match language, flags, etc. to the current message.
+			$msg = clone $param;
+			if ( $msg->language !== $this->language || $msg->useDatabase !== $this->useDatabase ) {
+				// Cache depends on these parameters
+				$msg->message = null;
+			}
+			$msg->interface = $this->interface;
+			$msg->language = $this->language;
+			$msg->useDatabase = $this->useDatabase;
+			$msg->title = $this->title;
+
+			// DWIM
+			if ( $format === 'block-parse' ) {
+				$format = 'parse';
+			}
+			$msg->format = $format;
+
 			// Message objects should not be before parameters because
 			// then they'll get double escaped. If the message needs to be
 			// escaped, it'll happen right here when we call toString().
-			return [ 'after', $param->toString( $format ) ];
+			return [ 'after', $msg->toString( $format ) ];
 		} else {
 			return [ 'before', $param ];
 		}
diff --git a/tests/phpunit/includes/MessageTest.php b/tests/phpunit/includes/MessageTest.php
index 8390e1fd39..e8afb4ccee 100644
--- a/tests/phpunit/includes/MessageTest.php
+++ b/tests/phpunit/includes/MessageTest.php
@@ -512,6 +512,34 @@ class MessageTest extends MediaWikiLangTestCase {
 		);
 	}
 
+	/**
+	 * @covers Message::extractParam
+	 */
+	public function testMessageAsParam() {
+		$this->setMwGlobals( [
+			'wgScript' => '/wiki/index.php',
+			'wgArticlePath' => '/wiki/$1',
+		] );
+
+		$msg = new Message( 'returnto', [
+			new Message( 'apihelp-link', [
+				'foo', new Message( 'mainpage', [], Language::factory( 'en' ) )
+			], Language::factory( 'de' ) )
+		], Language::factory( 'es' ) );
+
+		$this->assertEquals(
+			'Volver a [[Special:ApiHelp/foo|Página principal]].',
+			$msg->text(),
+			'Process with ->text()'
+		);
+		$this->assertEquals(
+			'<p>Volver a <a href="/wiki/Special:ApiHelp/foo" title="Special:ApiHelp/foo">Página '
+				. "principal</a>.\n</p>",
+			$msg->parseAsBlock(),
+			'Process with ->parseAsBlock()'
+		);
+	}
+
 	public static function provideParser() {
 		return [
 			[
-- 
2.20.1