Report accessing private properties on non-final classes in ?? condition

Author: ondrejmirtes

src/Rules/Properties/AccessPropertiesCheck.php

@@ -240,6 +240,13 @@ private function processSingleProperty(Scope $scope, PropertyFetch $node, string
 			|| !$write
 			|| (!$propertyReflection->isPrivateSet() && !$propertyReflection->isProtectedSet())
 		) {
+			if (
+				$scope->isUndefinedExpressionAllowed($node)
+				&& !$propertyReflection->getDeclaringClass()->isFinal()
+			) {
+				return [];
+			}
+
 			return [
 				RuleErrorBuilder::message(sprintf(
 					'Access to %s property %s::$%s.',

tests/PHPStan/Rules/Properties/AccessPropertiesRuleTest.php

@@ -1144,4 +1144,25 @@ public function testBug11424(): void
 		]);
 	}
 
+	public function testBug12645(): void
+	{
+		$this->checkThisOnly = false;
+		$this->checkUnionTypes = true;
+		$this->checkDynamicProperties = false;
+		$this->analyse([__DIR__ . '/data/bug-12645.php'], [
+			[
+				'Access to private property Bug12645\Foo::$id.',
+				18,
+			],
+			[
+				'Access to private property Bug12645\Foo::$id.',
+				19,
+			],
+			[
+				'Access to private property Bug12645\Foo::$id.',
+				24,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Properties/data/bug-12645.php

@@ -0,0 +1,25 @@
+<?php
+
+namespace Bug12645;
+
+class Foo
+{
+	private int $id = 1;
+
+	public function getId(): int
+	{
+		return $this->id;
+	}
+}
+
+function (): void {
+	$foo = new Foo();
+
+	var_dump($foo->id ?? 2);
+	var_dump($foo->id);
+};
+
+function (Foo $foo): void {
+	var_dump($foo->id ?? 2);
+	var_dump($foo->id);
+};