From 750d18d20ab859295b012fa670397f692c21feec Mon Sep 17 00:00:00 2001
From: Matt Brown <github@muglug.com>
Date: Tue, 7 Nov 2017 17:38:54 -0500
Subject: [PATCH] Fix #266 - do better analysis of array_rand

And also have better fallback when accessing string key on object-like array
---
 .../Checker/Statements/Expression/FetchChecker.php   |  2 ++
 src/Psalm/Stubs/CoreGenericFunctions.php             |  8 ++++++++
 tests/FunctionCallTest.php                           | 12 ++++++++++++
 3 files changed, 22 insertions(+)

diff --git a/src/Psalm/Checker/Statements/Expression/FetchChecker.php b/src/Psalm/Checker/Statements/Expression/FetchChecker.php
index 6f63a6bbb..fdf2afefb 100644
--- a/src/Psalm/Checker/Statements/Expression/FetchChecker.php
+++ b/src/Psalm/Checker/Statements/Expression/FetchChecker.php
@@ -1130,6 +1130,8 @@ class FetchChecker
                             )) {
                                 return false;
                             }
+                        } elseif ($key_type->hasString()) {
+                            $stmt->inferredType = $type->getGenericTypeParam();
                         }
                     }
                     continue;
diff --git a/src/Psalm/Stubs/CoreGenericFunctions.php b/src/Psalm/Stubs/CoreGenericFunctions.php
index e76a07182..44b5dcdc6 100644
--- a/src/Psalm/Stubs/CoreGenericFunctions.php
+++ b/src/Psalm/Stubs/CoreGenericFunctions.php
@@ -107,3 +107,11 @@ function array_pop(array $arr) {}
  * @return array<TKey, TValue>
  */
 function array_reverse(array $arr) {}
+
+/**
+ * @template TKey
+ *
+ * @param array<TKey, mixed> $arr
+ * @return TKey
+ */
+function array_rand(array $arr) {}
diff --git a/tests/FunctionCallTest.php b/tests/FunctionCallTest.php
index 7affbc8d8..d8e78b300 100644
--- a/tests/FunctionCallTest.php
+++ b/tests/FunctionCallTest.php
@@ -281,6 +281,18 @@ class FunctionCallTest extends TestCase
                     fooFoo($a->foo);
                     fooFoo($b);',
             ],
+            'arrayRand' => [
+                '<?php
+                    $vars = ["x" => "a", "y" => "b"];
+                    $c = array_rand($vars);
+                    $d = $vars[$c];',
+
+                'assertions' => [
+                    '$vars' => 'array{x:string, y:string}',
+                    '$c' => 'string',
+                    '$d' => 'string',
+                ],
+            ],
         ];
     }