Regression tests

Closes phpstan/phpstan#7880

Author: ondrejmirtes

tests/PHPStan/Rules/Properties/TypesAssignedToPropertiesRuleTest.php

@@ -882,6 +882,20 @@ public function testBug13438e(): void
 		]);
 	}
 
+	public function testBug7880(): void
+	{
+		$this->checkExplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-7880.php'], []);
+	}
+
+	#[RequiresPhp('>= 8.1')]
+	public function testBug7880b(): void
+	{
+		$this->checkExplicitMixed = true;
+		$this->checkImplicitMixed = true;
+		$this->analyse([__DIR__ . '/data/bug-7880b.php'], []);
+	}
+
 	public function testBug13438f(): void
 	{
 		$this->checkExplicitMixed = true;

tests/PHPStan/Rules/Properties/data/bug-7880.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace Bug7880;
+
+class C {
+	/** @var array{a: string, b: string}|null */
+	private $a = null;
+
+	public function foo(): void {
+		if ($this->a !== null) {
+			$this->a['b'] = "baz";
+		}
+	}
+}

tests/PHPStan/Rules/Properties/data/bug-7880b.php

@@ -0,0 +1,23 @@
+<?php // lint >= 8.1
+
+namespace Bug7880b;
+
+enum Undefined: string
+{
+	case VALUE = '!@#$~~UNDEFINED~~$#@!';
+}
+
+class Test1 {}
+
+class Test {
+	/**
+	 * @var Undefined|array<Test1>
+	 */
+	public array|Undefined $property = Undefined::VALUE;
+}
+
+function (): void {
+	$a = new Test();
+	$a->property = [];
+	$a->property[] = new Test1();
+};