From dcec735d11d5d0084939a3bb5e0b2012ac56205c Mon Sep 17 00:00:00 2001
From: Matthew Brown <github@muglug.com>
Date: Thu, 15 Dec 2016 01:28:36 -0500
Subject: [PATCH] Fix generation of MixedArrayAccess issue

---
 .../Statements/Expression/FetchChecker.php    | 19 +++++++++--
 tests/ArrayAccessTest.php                     | 34 +++++++++++++++++++
 2 files changed, 50 insertions(+), 3 deletions(-)

diff --git a/src/Psalm/Checker/Statements/Expression/FetchChecker.php b/src/Psalm/Checker/Statements/Expression/FetchChecker.php
index f31c4b8e5..ccfdbab2a 100644
--- a/src/Psalm/Checker/Statements/Expression/FetchChecker.php
+++ b/src/Psalm/Checker/Statements/Expression/FetchChecker.php
@@ -784,6 +784,8 @@ class FetchChecker
             return false;
         }
 
+        $inferred_key_type = null;
+
         if (isset($stmt->var->inferredType)) {
             /** @var Type\Union */
             $var_type = $stmt->var->inferredType;
@@ -808,6 +810,12 @@ class FetchChecker
                                 } else {
                                     $key_type = $type->type_params[0];
                                 }
+
+                                if ($inferred_key_type) {
+                                    Type::combineUnionTypes($key_type, $type->type_params[0]);
+                                } else {
+                                    $inferred_key_type = $type->type_params[0];
+                                }
                             }
                         }
                     }
@@ -950,6 +958,12 @@ class FetchChecker
                         $key_type = Type::getInt();
                     }
 
+                    if (!$inferred_key_type) {
+                        $inferred_key_type = Type::getInt();
+                    } else {
+                        $inferred_key_type = Type::combineUnionTypes($inferred_key_type, Type::getInt());
+                    }
+
                     $stmt->inferredType = Type::getString();
                 } elseif ($type->isNull()) {
                     if (IssueBuffer::accepts(
@@ -961,8 +975,7 @@ class FetchChecker
                     )) {
                         if (isset($stmt->inferredType)) {
                             $stmt->inferredType = Type::combineUnionTypes($stmt->inferredType, Type::getNull());
-                        }
-                        else {
+                        } else {
                             $stmt->inferredType = Type::getNull();
                         }
                         continue;
@@ -1013,7 +1026,7 @@ class FetchChecker
         if ($stmt->dim) {
             if (isset($stmt->dim->inferredType) && $key_type && !$key_type->isEmpty()) {
                 foreach ($stmt->dim->inferredType->types as $at) {
-                    if (($at->isMixed() || $at->isEmpty()) && !$key_type->isMixed()) {
+                    if (($at->isMixed() || $at->isEmpty()) && !$inferred_key_type->isMixed()) {
                         if (IssueBuffer::accepts(
                             new MixedArrayOffset(
                                 'Cannot access value on variable ' . $var_id . ' using mixed offset - expecting ' .
diff --git a/tests/ArrayAccessTest.php b/tests/ArrayAccessTest.php
index a22d30d34..7cd235606 100644
--- a/tests/ArrayAccessTest.php
+++ b/tests/ArrayAccessTest.php
@@ -116,4 +116,38 @@ class ArrayAccessTest extends PHPUnit_Framework_TestCase
         $file_checker = new \Psalm\Checker\FileChecker('somefile.php', $stmts);
         $file_checker->check(true, true, $context);
     }
+
+    /**
+     * @expectedException \Psalm\Exception\CodeException
+     * @expectedExceptionMessage MixedArrayAccess
+     */
+    public function testMixedArrayAccess()
+    {
+        $context = new Context('somefile.php');
+        $stmts = self::$parser->parse('<?php
+        /** @var mixed */
+        $a = [];
+        echo $a[0];
+        ');
+
+        $file_checker = new \Psalm\Checker\FileChecker('somefile.php', $stmts);
+        $file_checker->check(true, true, $context);
+    }
+
+    /**
+     * @expectedException \Psalm\Exception\CodeException
+     * @expectedExceptionMessage MixedArrayOffset
+     */
+    public function testMixedArrayOffset()
+    {
+        $context = new Context('somefile.php');
+        $stmts = self::$parser->parse('<?php
+        /** @var mixed */
+        $a = 5;
+        echo [1, 2, 3, 4][$a];
+        ');
+
+        $file_checker = new \Psalm\Checker\FileChecker('somefile.php', $stmts);
+        $file_checker->check(true, true, $context);
+    }
 }