Added regression test

Author: staabm

tests/PHPStan/Rules/Functions/ReturnTypeRuleTest.php

@@ -322,4 +322,16 @@ public function testBug11549(): void
 		$this->analyse([__DIR__ . '/data/bug-11549.php'], []);
 	}
 
+	public function testBug11301(): void
+	{
+		$this->checkExplicitMixed = true;
+		$this->checkNullables = true;
+		$this->analyse([__DIR__ . '/data/bug-11301.php'], [
+			[
+				'Function Bug11301\cString() should return array<string, string> but returns array<int, string>.',
+				35,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Functions/data/bug-11301.php

@@ -0,0 +1,48 @@
+<?php
+
+namespace Bug11301;
+
+/**
+ * @return array<int, string>
+ */
+function cInt(): array
+{
+	$a = ['12345'];
+	$b = ['abc'];
+
+	return array_combine($a, $b);
+}
+
+/**
+ * @return array<int, string>
+ */
+function cInt2(): array
+{
+	$a = ['12345', 123];
+	$b = ['abc', 'def'];
+
+	return array_combine($a, $b);
+}
+
+/**
+ * @return array<string, string>
+ */
+function cString(): array
+{
+	$a = ['12345'];
+	$b = ['abc'];
+
+	return array_combine($a, $b);
+}
+
+
+/**
+ * @return array<int|string, string>
+ */
+function cString2(): array
+{
+	$a = ['12345', 123, 'a'];
+	$b = ['abc', 'def', 'xy'];
+
+	return array_combine($a, $b);
+}