From 49acdfc7646e50f4ed82fed7c5fefb2480fee962 Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Fri, 3 May 2019 09:09:51 -0400
Subject: [PATCH] Fix issue when reconciling is_subclass_of on
 possibly-undefined variable

---
 src/Psalm/Type/Reconciler.php |  6 +++++-
 tests/ClassStringTest.php     | 12 ++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/Psalm/Type/Reconciler.php b/src/Psalm/Type/Reconciler.php
index 0809a3b9c..f02d3800a 100644
--- a/src/Psalm/Type/Reconciler.php
+++ b/src/Psalm/Type/Reconciler.php
@@ -365,7 +365,11 @@ class Reconciler
                     }
                 }
 
-                return Type::parseString($new_var_type, null, $template_type_map);
+                try {
+                    return Type::parseString($new_var_type, null, $template_type_map);
+                } catch (\Exception $e) {
+                    return Type::getMixed();
+                }
             }
 
             return Type::getMixed();
diff --git a/tests/ClassStringTest.php b/tests/ClassStringTest.php
index e2d3d4c17..c46f2e45d 100644
--- a/tests/ClassStringTest.php
+++ b/tests/ClassStringTest.php
@@ -557,6 +557,18 @@ class ClassStringTest extends TestCase
                         return array_merge($generic_classes, $literal_classes);
                     }',
             ],
+            'noCrashWithIsSubclassOfNonExistentVariable' => [
+                '<?php
+                    class A {}
+
+                    function foo() : void {
+                        /**
+                         * @psalm-suppress UndefinedVariable
+                         * @psalm-suppress MixedArgument
+                         */
+                        if (!is_subclass_of($s, A::class)) {}
+                    }',
+            ],
         ];
     }