From 6aaa87f14387c861199d2e2336e2ef200edbc7c7 Mon Sep 17 00:00:00 2001
From: Nikita Popov <nikita.ppv@googlemail.com>
Date: Fri, 3 Apr 2015 22:22:39 +0200
Subject: [PATCH] Fix PHP 7 alias registration

This fixes the case where the old name is used before the new one
is ever used, e.g. when manually constructing nodes, as opposed to
parsing them.

The previous approach would try to register the alias from OLD to
NEW. This would trigger autoloading on NEW and afterwards it would
register the alias from OLD to NEW. Afterwards the alias registration
which originally triggered the autoload would run, thus redeclaring
the class.

TL;DR aliases suck, closes #192.
---
 lib/PhpParser/Autoloader.php | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/lib/PhpParser/Autoloader.php b/lib/PhpParser/Autoloader.php
index ecad0e8..1f4c656 100644
--- a/lib/PhpParser/Autoloader.php
+++ b/lib/PhpParser/Autoloader.php
@@ -36,10 +36,19 @@ class Autoloader
     static public function autoload($class) {
         if (0 === strpos($class, 'PhpParser\\')) {
             if (isset(self::$php7AliasesOldToNew[$class])) {
-                // Old class name was used, register alias to new one (which will
-                // be autoloaded, if it wasn't yet).
-                self::registerPhp7Alias(self::$php7AliasesOldToNew[$class], $class);
-                return;
+                if (self::$runningOnPhp7) {
+                    return;
+                }
+
+                $newClass = self::$php7AliasesOldToNew[$class];
+                if (class_exists($newClass, false)) {
+                    // If the new class is already loaded, alias it right away
+                    class_alias($class, $newClass);
+                    return;
+                }
+
+                // Otherwise load the new class and create the alias afterwards
+                $class = $newClass;
             }
 
             $fileName = dirname(__DIR__) . '/' . strtr($class, '\\', '/') . '.php';
@@ -50,7 +59,9 @@ class Autoloader
             if (isset(self::$php7AliasesNewToOld[$class])) {
                 // New class name was used, register alias for old one, otherwise
                 // it won't be usable in "instanceof" and other non-autoloading places.
-                self::registerPhp7Alias($class, self::$php7AliasesNewToOld[$class]);
+                if (!self::$runningOnPhp7) {
+                    class_alias($class, self::$php7AliasesNewToOld[$class]);
+                }
             }
         } else if (0 === strpos($class, 'PHPParser_')) {
             if (isset(self::$nonNamespacedAliases[$class])) {
@@ -60,14 +71,6 @@ class Autoloader
         }
     }
 
-    private static function registerPhp7Alias($old, $new) {
-        // Registering these aliases would throw a fatal error on PHP 7,
-        // we want to avoid that.
-        if (!self::$runningOnPhp7) {
-            class_alias($old, $new);
-        }
-    }
-
     private static function registerNonNamespacedAliases() {
         foreach (self::$nonNamespacedAliases as $old => $new) {
             class_alias($new, $old);