From d56dd6bed67398c46cc844b7e682970f2033a692 Mon Sep 17 00:00:00 2001
From: Matt Brown <github@muglug.com>
Date: Thu, 14 Jun 2018 13:49:16 -0400
Subject: [PATCH] Fix #818 - prevent class of 0

---
 src/Psalm/Type.php | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/Psalm/Type.php b/src/Psalm/Type.php
index ba4ffb416..35eb47530 100644
--- a/src/Psalm/Type.php
+++ b/src/Psalm/Type.php
@@ -649,10 +649,14 @@ abstract class Type
      */
     public static function getFQCLNFromString($class, Aliases $aliases)
     {
-        if (empty($class)) {
+        if ($class === '') {
             throw new \InvalidArgumentException('$class cannot be empty');
         }
 
+        if ($class === '0') {
+            throw new TypeParseTreeException('Unrecognised class 0');
+        }
+
         if ($class[0] === '\\') {
             return substr($class, 1);
         }