added regression test

Author: staabm

tests/PHPStan/Rules/Properties/TypesAssignedToPropertiesRuleTest.php

@@ -918,4 +918,11 @@ public function testBug2888(): void
 		]);
 	}
 
+	public function testBug11777(): void
+	{
+		$this->checkExplicitMixed = true;
+		$this->checkImplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-11777.php'], []);
+	}
+
 }

tests/PHPStan/Rules/Properties/data/bug-11777.php

@@ -0,0 +1,12 @@
+<?php
+
+namespace Bug11777;
+
+class HelloWorld {
+	/** @var array<int, resource> */
+	private array $pipes;
+
+	public function sayHello(string $cmd): void {
+		proc_open($cmd, [0 => ['pipe', 'r']], $this->pipes);
+	}
+}