From 7b4dbb1c85d1a924bccb449f93a77d770ec5f308 Mon Sep 17 00:00:00 2001
From: Brown <github@muglug.com>
Date: Thu, 20 Jun 2019 20:13:36 -0400
Subject: [PATCH] =?UTF-8?q?Fix=20#1826=20-=20don=E2=80=99t=20allow=20mixed?=
 =?UTF-8?q?=20unions=20when=20combining=20with=20object-like=20array?=
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---
 src/Psalm/Internal/Type/TypeCombination.php | 17 ++++++++++-------
 tests/ArrayAccessTest.php                   | 11 -----------
 tests/TypeCombinationTest.php               |  7 +++++++
 3 files changed, 17 insertions(+), 18 deletions(-)

diff --git a/src/Psalm/Internal/Type/TypeCombination.php b/src/Psalm/Internal/Type/TypeCombination.php
index b50038a86..4af1c1678 100644
--- a/src/Psalm/Internal/Type/TypeCombination.php
+++ b/src/Psalm/Internal/Type/TypeCombination.php
@@ -371,13 +371,16 @@ class TypeCombination
                     $overwrite_empty_array,
                     $allow_mixed_union
                 );
-                $generic_type_params[1] = Type::combineUnionTypes(
-                    $generic_type_params[1],
-                    $objectlike_generic_type,
-                    $codebase,
-                    $overwrite_empty_array,
-                    $allow_mixed_union
-                );
+
+                if (!$generic_type_params[1]->isMixed()) {
+                    $generic_type_params[1] = Type::combineUnionTypes(
+                        $generic_type_params[1],
+                        $objectlike_generic_type,
+                        $codebase,
+                        $overwrite_empty_array,
+                        $allow_mixed_union
+                    );
+                }
             }
 
             if ($combination->array_always_filled
diff --git a/tests/ArrayAccessTest.php b/tests/ArrayAccessTest.php
index 970e88849..3fa528668 100644
--- a/tests/ArrayAccessTest.php
+++ b/tests/ArrayAccessTest.php
@@ -672,17 +672,6 @@ class ArrayAccessTest extends TestCase
                     }',
                 'error_message' => 'PossiblyInvalidArrayOffset',
             ],
-            'possiblyInvalidMixedUnionArrayOffset' => [
-                '<?php
-                    function foo(?array $index): void {
-                        if (!$index) {
-                            $index = ["foo", []];
-                        }
-                        $index[1][] = "bar";
-                    }',
-                'error_message' => 'PossiblyInvalidArrayOffset',
-                'error_level' => ['MixedArrayAssignment'],
-            ],
             'arrayAccessOnIterable' => [
                 '<?php
                     function foo(iterable $i) {
diff --git a/tests/TypeCombinationTest.php b/tests/TypeCombinationTest.php
index ba8151790..3d16ab5c1 100644
--- a/tests/TypeCombinationTest.php
+++ b/tests/TypeCombinationTest.php
@@ -379,6 +379,13 @@ class TypeCombinationTest extends TestCase
                     'string',
                 ],
             ],
+            'combineMixedArrayWithObjectLike' => [
+                'array<array-key, mixed>',
+                [
+                    'array{a: int}',
+                    'array',
+                ],
+            ],
             'traversableAorB' => [
                 'Traversable<mixed, A|B>',
                 [