From 772fd496b7f164269674daf0706e886621d23d2f Mon Sep 17 00:00:00 2001
From: Matt Brown <github@muglug.com>
Date: Thu, 24 May 2018 12:23:50 -0400
Subject: [PATCH] Fix issue with array_key_exists not having an effect

---
 src/Psalm/Type/Reconciler.php    | 4 +++-
 tests/RedundantConditionTest.php | 9 +++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/Psalm/Type/Reconciler.php b/src/Psalm/Type/Reconciler.php
index 6a74dac73..7ee5d9591 100644
--- a/src/Psalm/Type/Reconciler.php
+++ b/src/Psalm/Type/Reconciler.php
@@ -112,7 +112,9 @@ class Reconciler
                             $has_equality = true;
                     }
 
-                    $has_isset = $has_isset || $new_type_part_part === 'isset';
+                    $has_isset = $has_isset
+                        || $new_type_part_part === 'isset'
+                        || $new_type_part_part === 'array-key-exists';
 
                     $result_type_candidate = self::reconcileTypes(
                         $new_type_part_part,
diff --git a/tests/RedundantConditionTest.php b/tests/RedundantConditionTest.php
index b1be5a5bb..21795e2bc 100644
--- a/tests/RedundantConditionTest.php
+++ b/tests/RedundantConditionTest.php
@@ -423,6 +423,15 @@ class RedundantConditionTest extends TestCase
                         var_export($x);
                     }',
             ],
+            'arrayKeyExistsAccess' => [
+                '<?php
+                    /** @param array<int, string> $arr */
+                    function foo(array $arr) : void {
+                        if (array_key_exists(1, $arr)) {
+                            $a = ($arr[1] === "b") ? true : false;
+                        }
+                    }',
+            ],
         ];
     }