From c7d25c7b4463d838f6dbc53b8b5d30b01fbf0adf Mon Sep 17 00:00:00 2001
From: Dylan McGannon <d0x2f@users.noreply.github.com>
Date: Sun, 11 Nov 2018 14:26:39 +1100
Subject: [PATCH] fix(definitionresolver): infinite loop when indexing self
 referencing classes (#670)

---
 fixtures/self_referencing_class.php | 20 ++++++++++++++++++++
 src/DefinitionResolver.php          |  8 +++++++-
 2 files changed, 27 insertions(+), 1 deletion(-)
 create mode 100644 fixtures/self_referencing_class.php

diff --git a/fixtures/self_referencing_class.php b/fixtures/self_referencing_class.php
new file mode 100644
index 0000000..06dc8f0
--- /dev/null
+++ b/fixtures/self_referencing_class.php
@@ -0,0 +1,20 @@
+<?php
+namespace RecursiveTest;
+
+class A extends A {}
+
+class B extends C {}
+class C extends B {}
+
+class D extends E {}
+class E extends F {}
+class F extends D {}
+
+$a = new A;
+$a->undef_prop = 1;
+
+$b = new B;
+$b->undef_prop = 1;
+
+$d = new D;
+$d->undef_prop = 1;
diff --git a/src/DefinitionResolver.php b/src/DefinitionResolver.php
index f3d6fa1..adddf77 100644
--- a/src/DefinitionResolver.php
+++ b/src/DefinitionResolver.php
@@ -438,6 +438,7 @@ class DefinitionResolver
 
         // Find the right class that implements the member
         $implementorFqns = [$classFqn];
+        $visitedFqns = [];
 
         while ($implementorFqn = array_shift($implementorFqns)) {
             // If the member FQN exists, return it
@@ -450,10 +451,15 @@ class DefinitionResolver
             if ($implementorDef === null) {
                 break;
             }
+            // Note the FQN as visited
+            $visitedFqns[] = $implementorFqn;
             // Repeat for parent class
             if ($implementorDef->extends) {
                 foreach ($implementorDef->extends as $extends) {
-                    $implementorFqns[] = $extends;
+                    // Don't add the parent FQN if it's already been visited
+                    if (!\in_array($extends, $visitedFqns)) {
+                        $implementorFqns[] = $extends;
+                    }
                 }
             }
         }