From e300550209c787e0aad04027dcee2eef788d0865 Mon Sep 17 00:00:00 2001
From: Matt Brown <github@muglug.com>
Date: Thu, 12 Jan 2017 11:16:00 -0500
Subject: [PATCH] Be less brittle when interface does not exist

---
 src/Psalm/Checker/ClassLikeChecker.php |  4 ++++
 tests/InterfaceTest.php                | 17 +++++++++++++++++
 2 files changed, 21 insertions(+)

diff --git a/src/Psalm/Checker/ClassLikeChecker.php b/src/Psalm/Checker/ClassLikeChecker.php
index c3b637b28..842239a57 100644
--- a/src/Psalm/Checker/ClassLikeChecker.php
+++ b/src/Psalm/Checker/ClassLikeChecker.php
@@ -329,6 +329,10 @@ abstract class ClassLikeChecker extends SourceChecker implements StatementsSourc
             $class_interfaces = ClassChecker::getInterfacesForClass($this->fq_class_name);
 
             foreach ($class_interfaces as $interface_id => $interface_name) {
+                if (!isset(self::$storage[strtolower($interface_name)])) {
+                    continue;
+                }
+
                 $interface_storage = self::$storage[strtolower($interface_name)];
 
                 $storage->public_class_constants += $interface_storage->public_class_constants;
diff --git a/tests/InterfaceTest.php b/tests/InterfaceTest.php
index 922aa3247..874c71553 100644
--- a/tests/InterfaceTest.php
+++ b/tests/InterfaceTest.php
@@ -365,4 +365,21 @@ class InterfaceTest extends PHPUnit_Framework_TestCase
         $context = new Context('somefile.php');
         $file_checker->visitAndAnalyzeMethods($context);
     }
+
+    /**
+     * @expectedException \Psalm\Exception\CodeException
+     * @expectedExceptionMessage UndefinedClass
+     */
+    public function testInvalidImplements()
+    {
+        $this->project_checker->registerFile(
+            getcwd() . '/somefile.php',
+            '<?php
+        class C2 implements A {
+        }
+        ');
+        $file_checker = new FileChecker(getcwd() . '/somefile.php', $this->project_checker);
+        $context = new Context('somefile.php');
+        $file_checker->visitAndAnalyzeMethods($context);
+    }
 }