From c61fdb4ef5dbe0c26a17e57203e0bf99aa0e2440 Mon Sep 17 00:00:00 2001
From: Kevin Israel <pleasestand@live.com>
Date: Thu, 21 Nov 2013 23:13:03 -0500
Subject: [PATCH] Mechanism for renaming/aliasing classes

Sometimes it is desirable to change a class name that is still referenced
in extensions or config files (e.g. for consistency, as in I507ba00a).
PHP's class_alias() function can help in preserving backward compatibility;
however, creating an alias first requires that the class be loaded.

Hence this is implemented in AutoLoader. Lazy loading continues to work,
the list of class names is still maintained in a central location, and
optionally, deprecation warnings can be generated.

Change-Id: I1d3fb04a448647b5be10bed7fec05238b9fc6fc7
---
 includes/AutoLoader.php                       | 26 +++++++++++++++
 .../TestAutoloadedAliasedClassNew.php         |  4 +++
 tests/phpunit/structure/AutoLoaderTest.php    | 33 ++++++++++++++++++-
 3 files changed, 62 insertions(+), 1 deletion(-)
 create mode 100644 tests/phpunit/data/autoloader/TestAutoloadedAliasedClassNew.php

diff --git a/includes/AutoLoader.php b/includes/AutoLoader.php
index cd062e01cd..e6ce693ca1 100644
--- a/includes/AutoLoader.php
+++ b/includes/AutoLoader.php
@@ -1209,6 +1209,32 @@ class AutoLoader {
 			return;
 		}
 
+		if ( substr( $filename, 0, 6 ) === 'alias:' ) {
+			// Supported alias formats:
+			// - No deprecation warning: alias:MyNewClassName
+			// - Deprecated in MediaWiki 1.1: alias:MyNewClassName?v=1.1
+			// - Deprecated in MyExtension 1.1: alias:MyNewClassName?c=MyExtension&v=1.1
+			$parts = explode( '?', substr( $filename, 6 ), 2 );
+			$newClassName = $parts[0];
+
+			// If necessary, this will make a recursive call to this function to
+			// load the class using its actual, canonical name.
+			class_alias( $newClassName, $className );
+
+			if ( isset( $parts[1] ) && function_exists( 'wfDeprecated' ) ) {
+				$info = wfCgiToArray( $parts[1] );
+				$function = "name $className for class $newClassName";
+				$version = isset( $info['v'] ) ? $info['v'] : false;
+				$component = isset( $info['c'] ) ? $info['c'] : false;
+
+				// https://github.com/facebook/hhvm/issues/1018
+				$callerOffset = wfIsHHVM() ? 2 : 3;
+				wfDeprecated( $function, $version, $component, $callerOffset );
+			}
+
+			return;
+		}
+
 		# Make an absolute path, this improves performance by avoiding some stat calls
 		if ( substr( $filename, 0, 1 ) != '/' && substr( $filename, 1, 1 ) != ':' ) {
 			global $IP;
diff --git a/tests/phpunit/data/autoloader/TestAutoloadedAliasedClassNew.php b/tests/phpunit/data/autoloader/TestAutoloadedAliasedClassNew.php
new file mode 100644
index 0000000000..5ce8483c89
--- /dev/null
+++ b/tests/phpunit/data/autoloader/TestAutoloadedAliasedClassNew.php
@@ -0,0 +1,4 @@
+<?php
+
+class TestAutoloadedAliasedClassNew {
+}
diff --git a/tests/phpunit/structure/AutoLoaderTest.php b/tests/phpunit/structure/AutoLoaderTest.php
index d8b90d5021..1ffe81106d 100644
--- a/tests/phpunit/structure/AutoLoaderTest.php
+++ b/tests/phpunit/structure/AutoLoaderTest.php
@@ -11,6 +11,9 @@ class AutoLoaderTest extends MediaWikiTestCase {
 			'TestAutoloadedLocalClass' => __DIR__ . '/../data/autoloader/TestAutoloadedLocalClass.php',
 			'TestAutoloadedCamlClass' => __DIR__ . '/../data/autoloader/TestAutoloadedCamlClass.php',
 			'TestAutoloadedSerializedClass' => __DIR__ . '/../data/autoloader/TestAutoloadedSerializedClass.php',
+			'TestAutoloadedAliasedClass' => 'alias:TestAutoloadedAliasedClassNew',
+			'TestAutoloadedAliasedClassDeprecated' => 'alias:TestAutoloadedAliasedClassNew?v=1.1',
+			'TestAutoloadedAliasedClassNew' => __DIR__ . '/../data/autoloader/TestAutoloadedAliasedClassNew.php',
 		);
 		$this->setMwGlobals( 'wgAutoloadLocalClasses', $this->testLocalClasses + $wgAutoloadLocalClasses );
 		AutoLoader::resetAutoloadLocalClassesLower();
@@ -44,7 +47,23 @@ class AutoLoaderTest extends MediaWikiTestCase {
 		$expected = $wgAutoloadLocalClasses + $wgAutoloadClasses;
 		$actual = array();
 
-		$files = array_unique( $expected );
+		// Check aliases
+		foreach ( $expected as $class => $file ) {
+			if ( substr( $file, 0, 6 ) !== 'alias:' ) {
+				// Not an alias, so should be an actual file
+				$files[] = $file;
+			} else {
+				$newClass = substr( $file, 6, strcspn( $file, '?', 6 ) );
+				if ( isset( $expected[$newClass] ) ) {
+					if ( substr( $expected[$newClass], 0, 6 ) !== 'alias:' ) {
+						// Alias pointing to an existing MediaWiki class
+						$actual[$class] = $file;
+					}
+				}
+			}
+		}
+
+		$files = array_unique( $files );
 
 		foreach ( $files as $file ) {
 			// Only prefix $IP if it doesn't have it already.
@@ -92,4 +111,16 @@ class AutoLoaderTest extends MediaWikiTestCase {
 		$this->assertFalse( $uncerealized instanceof __PHP_Incomplete_Class,
 			"unserialize() can load classes case-insensitively." );
 	}
+
+	function testAliasedClass() {
+		$this->assertSame( 'TestAutoloadedAliasedClassNew',
+			get_class( new TestAutoloadedAliasedClass ) );
+	}
+
+	function testAliasedClassDeprecated() {
+		wfSuppressWarnings();
+		$this->assertSame( 'TestAutoloadedAliasedClassNew',
+			get_class( new TestAutoloadedAliasedClassDeprecated ) );
+		wfRestoreWarnings();
+	}
 }
-- 
2.20.1