Hooked properties cannot be unset()

src/Reflection/Php/PhpPropertyReflection.php

@@ -256,6 +256,11 @@ public function hasHook(string $hookType): bool
 		return $this->setHook !== null;
 	}
 
+	public function isHooked(): bool
+	{
+		return $this->getHook !== null || $this->setHook !== null;
+	}
+
 	public function getHook(string $hookType): ExtendedMethodReflection
 	{
 		if ($hookType === 'get') {

src/Rules/Variables/UnsetRule.php

@@ -4,6 +4,7 @@
 
 use PhpParser\Node;
 use PHPStan\Analyser\Scope;
+use PHPStan\Php\PhpVersion;
 use PHPStan\Rules\IdentifierRuleError;
 use PHPStan\Rules\Properties\PropertyReflectionFinder;
 use PHPStan\Rules\Rule;
@@ -20,6 +21,7 @@ final class UnsetRule implements Rule
 
 	public function __construct(
 		private PropertyReflectionFinder $propertyReflectionFinder,
+		private PhpVersion $phpVersion,
 	)
 	{
 	}
@@ -103,6 +105,36 @@ private function canBeUnset(Node $node, Scope $scope): ?IdentifierRuleError
 					->identifier($propertyReflection->isReadOnly() ? 'unset.readOnlyProperty' : 'unset.readOnlyPropertyByPhpDoc')
 					->build();
 			}
+
+			if ($propertyReflection->isHooked()) {
+				return RuleErrorBuilder::message(
+					sprintf(
+						'Cannot unset hooked %s::$%s property.',
+						$propertyReflection->getDeclaringClass()->getDisplayName(),
+						$foundPropertyReflection->getName(),
+					),
+				)
+					->line($node->getStartLine())
+					->identifier('unset.hookedProperty')
+					->build();
+			} elseif ($this->phpVersion->supportsPropertyHooks()) {
+				if (
+					!$propertyReflection->isPrivate()
+					&& !$propertyReflection->isFinal()->yes()
+					&& !$propertyReflection->getDeclaringClass()->isFinal()
+				) {
+					return RuleErrorBuilder::message(
+						sprintf(
+							'Cannot unset property %s::$%s because it might have hooks in a subclass.',
+							$propertyReflection->getDeclaringClass()->getDisplayName(),
+							$foundPropertyReflection->getName(),
+						),
+					)
+						->line($node->getStartLine())
+						->identifier('unset.possiblyHookedProperty')
+						->build();
+				}
+			}
 		}
 
 		return null;

tests/PHPStan/Rules/Variables/UnsetRuleTest.php

@@ -2,9 +2,12 @@
 
 namespace PHPStan\Rules\Variables;
 
+use PHPStan\Php\PhpVersion;
 use PHPStan\Rules\Properties\PropertyReflectionFinder;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
+use function array_merge;
+use const PHP_VERSION_ID;
 
 /**
  * @extends RuleTestCase<UnsetRule>
@@ -14,7 +17,10 @@ class UnsetRuleTest extends RuleTestCase
 
 	protected function getRule(): Rule
 	{
-		return new UnsetRule(self::getContainer()->getByType(PropertyReflectionFinder::class));
+		return new UnsetRule(
+			self::getContainer()->getByType(PropertyReflectionFinder::class),
+			self::getContainer()->getByType(PhpVersion::class),
+		);
 	}
 
 	public function testUnsetRule(): void
@@ -55,7 +61,18 @@ public function testBug2752(): void
 
 	public function testBug4289(): void
 	{
-		$this->analyse([__DIR__ . '/data/bug-4289.php'], []);
+		$errors = [];
+
+		if (PHP_VERSION_ID >= 80400) {
+			$errors = [
+				[
+					'Cannot unset property Bug4289\BaseClass::$fields because it might have hooks in a subclass.',
+					25,
+				],
+			];
+		}
+
+		$this->analyse([__DIR__ . '/data/bug-4289.php'], $errors);
 	}
 
 	public function testBug5223(): void
@@ -94,7 +111,15 @@ public function testBug4565(): void
 
 	public function testBug12421(): void
 	{
-		$this->analyse([__DIR__ . '/data/bug-12421.php'], [
+		$errors = [];
+		if (PHP_VERSION_ID >= 80400) {
+			$errors[] = [
+				'Cannot unset property Bug12421\RegularProperty::$y because it might have hooks in a subclass.',
+				7,
+			];
+		}
+
+		$errors = array_merge($errors, [
 			[
 				'Cannot unset readonly Bug12421\NativeReadonlyClass::$y property.',
 				11,
@@ -120,6 +145,38 @@ public function testBug12421(): void
 				34,
 			],
 		]);
+
+		$this->analyse([__DIR__ . '/data/bug-12421.php'], $errors);
+	}
+
+	public function testUnsetHookedProperty(): void
+	{
+		if (PHP_VERSION_ID < 80400) {
+			$this->markTestSkipped('Test requires PHP 8.4 or later.');
+		}
+
+		$this->analyse([__DIR__ . '/data/unset-hooked-property.php'], [
+			[
+				'Cannot unset hooked UnsetHookedProperty\User::$name property.',
+				6,
+			],
+			[
+				'Cannot unset hooked UnsetHookedProperty\User::$fullName property.',
+				7,
+			],
+			[
+				'Cannot unset hooked UnsetHookedProperty\Foo::$ii property.',
+				9,
+			],
+			[
+				'Cannot unset hooked UnsetHookedProperty\Foo::$iii property.',
+				10,
+			],
+			[
+				'Cannot unset property UnsetHookedProperty\NonFinalClass::$publicProperty because it might have hooks in a subclass.',
+				13,
+			],
+		]);
 	}
 
 }

tests/PHPStan/Rules/Variables/data/unset-hooked-property.php

@@ -0,0 +1,66 @@
+<?php // lint >= 8.4
+
+namespace UnsetHookedProperty;
+
+function doUnset(Foo $foo, User $user, NonFinalClass $nonFinalClass, FinalClass $finalClass): void {
+	unset($user->name);
+	unset($user->fullName);
+
+	unset($foo->ii);
+	unset($foo->iii);
+
+	unset($nonFinalClass->publicFinalProperty);
+	unset($nonFinalClass->publicProperty);
+
+	unset($finalClass->publicFinalProperty);
+	unset($finalClass->publicProperty);
+}
+
+class User
+{
+	public string $name {
+		set {
+			if (strlen($value) === 0) {
+				throw new \ValueError("Name must be non-empty");
+			}
+			$this->name = $value;
+		}
+	}
+
+	public string $fullName {
+		get {
+			return "Yennefer of Vengerberg";
+		}
+	}
+
+	public function __construct(string $name) {
+		$this->name = $name;
+	}
+}
+
+abstract class Foo
+{
+	abstract protected int $ii { get; }
+
+	abstract public int $iii { get; }
+}
+
+class NonFinalClass {
+	private string $privateProperty;
+	public string $publicProperty;
+	final public string $publicFinalProperty;
+
+	function doFoo() {
+		unset($this->privateProperty);
+	}
+}
+
+final class FinalClass {
+	private string $privateProperty;
+	public string $publicProperty;
+	final public string $publicFinalProperty;
+
+	function doFoo() {
+		unset($this->privateProperty);
+	}
+}