From 119765515c58dbd5053fcb702de25fdf4711ef70 Mon Sep 17 00:00:00 2001
From: Richard van Velzen <richard@frank.nl>
Date: Mon, 20 Jun 2022 09:26:05 +0200
Subject: [PATCH] Fix TypeCombinator::union() for intersection of array and
 template type

---
 src/Type/TypeCombinator.php                   |  3 ++
 .../Rules/Methods/ReturnTypeRuleTest.php      |  6 +++
 tests/PHPStan/Rules/Methods/data/bug-4117.php | 47 +++++++++++++++++++
 3 files changed, 56 insertions(+)
 create mode 100644 tests/PHPStan/Rules/Methods/data/bug-4117.php

diff --git a/src/Type/TypeCombinator.php b/src/Type/TypeCombinator.php
index 9ba14f5425..ce77dda2ee 100644
--- a/src/Type/TypeCombinator.php
+++ b/src/Type/TypeCombinator.php
@@ -161,6 +161,9 @@ public static function union(Type ...$types): Type
 				$intermediateArrayType = null;
 				$intermediateAccessoryTypes = [];
 				foreach ($types[$i]->getTypes() as $innerType) {
+					if ($innerType instanceof TemplateType) {
+						continue 2;
+					}
 					if ($innerType instanceof ArrayType) {
 						$intermediateArrayType = $innerType;
 						continue;
diff --git a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
index b3229ae4ee..d7b28fb919 100644
--- a/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
+++ b/tests/PHPStan/Rules/Methods/ReturnTypeRuleTest.php
@@ -706,4 +706,10 @@ public function testBug7460(): void
 		$this->analyse([__DIR__ . '/data/bug-7460.php'], []);
 	}
 
+	public function testBug4117(): void
+	{
+		$this->checkExplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-4117.php'], []);
+	}
+
 }
diff --git a/tests/PHPStan/Rules/Methods/data/bug-4117.php b/tests/PHPStan/Rules/Methods/data/bug-4117.php
new file mode 100644
index 0000000000..7874fb460c
--- /dev/null
+++ b/tests/PHPStan/Rules/Methods/data/bug-4117.php
@@ -0,0 +1,47 @@
+<?php declare(strict_types = 1);
+
+namespace Bug4117;
+
+use ArrayIterator;
+use IteratorAggregate;
+
+/**
+ * @refactor Refactor utils into base library
+ * @template T of mixed
+ * @implements IteratorAggregate<int, T>
+ */
+class GenericList implements IteratorAggregate
+{
+    /** @var array<int, T> */
+    protected $items = [];
+
+    /**
+     * @return ArrayIterator<int, T>
+     */
+    public function getIterator(): ArrayIterator
+    {
+        return new ArrayIterator($this->items);
+    }
+
+    /**
+     * @return ?T
+     */
+	public function broken(int $key)
+    {
+        $item = $this->items[$key] ?? null;
+        if ($item) {
+        }
+
+        return $item;
+    }
+
+    /**
+     * @return ?T
+     */
+	public function works(int $key)
+    {
+        $item = $this->items[$key] ?? null;
+
+        return $item;
+    }
+}