From 68f6ba873e7f6fdae9786af69db0c9f9b7649a43 Mon Sep 17 00:00:00 2001
From: Steven Dickinson <sd@tonic.works>
Date: Tue, 11 Oct 2022 14:11:58 +0100
Subject: [PATCH] Fix MinMaxReturnTypeProvider when handling TDependentListKeys

---
 .../MinMaxReturnTypeProvider.php              | 10 ++--
 .../MinMaxReturnTypeProviderTest.php          | 53 +++++++++++++++++++
 2 files changed, 58 insertions(+), 5 deletions(-)
 create mode 100644 tests/ReturnTypeProvider/MinMaxReturnTypeProviderTest.php

diff --git a/src/Psalm/Internal/Provider/ReturnTypeProvider/MinMaxReturnTypeProvider.php b/src/Psalm/Internal/Provider/ReturnTypeProvider/MinMaxReturnTypeProvider.php
index 1a24e22b30b..e23ff30b125 100644
--- a/src/Psalm/Internal/Provider/ReturnTypeProvider/MinMaxReturnTypeProvider.php
+++ b/src/Psalm/Internal/Provider/ReturnTypeProvider/MinMaxReturnTypeProvider.php
@@ -8,17 +8,16 @@
 use Psalm\Plugin\EventHandler\Event\FunctionReturnTypeProviderEvent;
 use Psalm\Plugin\EventHandler\FunctionReturnTypeProviderInterface;
 use Psalm\Type;
+use Psalm\Type\Atomic\TDependentListKey;
 use Psalm\Type\Atomic\TInt;
 use Psalm\Type\Atomic\TIntRange;
 use Psalm\Type\Atomic\TLiteralInt;
 use Psalm\Type\Atomic\TPositiveInt;
 use Psalm\Type\Union;
-use UnexpectedValueException;
 
 use function array_filter;
 use function assert;
 use function count;
-use function get_class;
 use function in_array;
 use function max;
 use function min;
@@ -72,11 +71,12 @@ public static function getFunctionReturnType(FunctionReturnTypeProviderEvent $ev
                     } elseif ($atomic_type instanceof TPositiveInt) {
                         $min_bounds[] = 1;
                         $max_bounds[] = null;
-                    } elseif (get_class($atomic_type) === TInt::class) {
+                    } elseif ($atomic_type instanceof TDependentListKey) {
+                        $min_bounds[] = 0;
+                        $max_bounds[] = null;
+                    } else {//already guarded by the `instanceof TInt` check above
                         $min_bounds[] = null;
                         $max_bounds[] = null;
-                    } else {
-                        throw new UnexpectedValueException('Unexpected type');
                     }
                 }
             } else {
diff --git a/tests/ReturnTypeProvider/MinMaxReturnTypeProviderTest.php b/tests/ReturnTypeProvider/MinMaxReturnTypeProviderTest.php
new file mode 100644
index 00000000000..1bbdff97d82
--- /dev/null
+++ b/tests/ReturnTypeProvider/MinMaxReturnTypeProviderTest.php
@@ -0,0 +1,53 @@
+<?php
+
+namespace Psalm\Tests\ReturnTypeProvider;
+
+use Psalm\Tests\TestCase;
+use Psalm\Tests\Traits\ValidCodeAnalysisTestTrait;
+
+class MinMaxReturnTypeProviderTest extends TestCase
+{
+    use ValidCodeAnalysisTestTrait;
+
+    public function providerValidCodeParse(): iterable
+    {
+        yield 'literalInt' => [
+            '<?php
+                $min = min(1, 2);
+                $max = max(3, 4);
+            ',
+            [
+                '$min' => 'int',
+                '$max' => 'int',
+            ],
+        ];
+        yield 'nonInt' => [
+            '<?php
+                $min = min("a", "b");
+                $max = max("x", "y");
+            ',
+            [
+                '$min' => 'string',
+                '$max' => 'string',
+            ],
+        ];
+        yield 'maxIntRange' => [
+            '<?php
+                $headers = fgetcsv(fopen("test.txt", "r"));
+                $h0 = $h1 = null;
+                foreach($headers as $i => $v) {
+                    if ($v === "") $h0 = $i;
+                    if ($v === "") $h1 = $i;
+                }
+                if ($h0 === null || $h1 === null) throw new \Exception();
+
+                $min = min($h0, $h1);
+                $max = max($h0, $h1);
+            ',
+            [
+                '$min' => 'int<0, max>',
+                '$max' => 'int<0, max>',
+            ],
+        ];
+    }
+}