Regression test

Closes phpstan/phpstan#4117

tests/PHPStan/Analyser/NodeScopeResolverTest.php

@@ -915,6 +915,7 @@ public function dataFileAsserts(): iterable
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/constant-array-intersect.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-7153.php');
 		yield from $this->gatherAssertTypes(__DIR__ . '/data/in-array-non-empty.php');
+		yield from $this->gatherAssertTypes(__DIR__ . '/data/bug-4117.php');
 	}
 
 	/**

tests/PHPStan/Analyser/data/bug-4117.php

@@ -0,0 +1,54 @@
+<?php
+
+namespace Bug4117Types;
+
+use ArrayIterator;
+use IteratorAggregate;
+use function PHPStan\Testing\assertType;
+
+/**
+ * @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) {
+			assertType("T of mixed~0|0.0|''|'0'|array{}|false|null (class Bug4117Types\GenericList, argument)", $item);
+		} else {
+			assertType("(array{}&T (class Bug4117Types\GenericList, argument))|(0.0&T (class Bug4117Types\GenericList, argument))|(0&T (class Bug4117Types\GenericList, argument))|(''&T (class Bug4117Types\GenericList, argument))|('0'&T (class Bug4117Types\GenericList, argument))|(T (class Bug4117Types\GenericList, argument)&false)|null", $item);
+		}
+
+		assertType("T of mixed~0|0.0|''|'0'|array{}|false|null (class Bug4117Types\GenericList, argument)|null", $item);
+
+		return $item;
+	}
+
+	/**
+	 * @return ?T
+	 */
+	public function works(int $key)
+	{
+		$item = $this->items[$key] ?? null;
+		assertType('T (class Bug4117Types\GenericList, argument)|null', $item);
+
+		return $item;
+	}
+}