Allow reinitialization of a readonly property in __clone since PHP8.3

Closes phpstan/phpstan#11495

Author: takaram

src/Php/PhpVersion.php

@@ -327,4 +327,9 @@ public function hasDateTimeExceptions(): bool
 		return $this->versionId >= 80300;
 	}
 
+	public function supportsReadonlyPropertyReinitializationOnClone(): bool
+	{
+		return $this->versionId >= 80300;
+	}
+
 }

src/Rules/Properties/ReadOnlyPropertyAssignRule.php

@@ -5,6 +5,7 @@
 use PhpParser\Node;
 use PHPStan\Analyser\Scope;
 use PHPStan\Node\PropertyAssignNode;
+use PHPStan\Php\PhpVersion;
 use PHPStan\Reflection\ConstructorsHelper;
 use PHPStan\Reflection\MethodReflection;
 use PHPStan\Rules\Rule;
@@ -24,6 +25,7 @@ class ReadOnlyPropertyAssignRule implements Rule
 	public function __construct(
 		private PropertyReflectionFinder $propertyReflectionFinder,
 		private ConstructorsHelper $constructorsHelper,
+		private PhpVersion $phpVersion,
 	)
 	{
 	}
@@ -76,9 +78,11 @@ public function processNode(Node $node, Scope $scope): array
 				throw new ShouldNotHappenException();
 			}
 
+			$methodName = $scopeMethod->getName();
 			if (
-				in_array($scopeMethod->getName(), $this->constructorsHelper->getConstructors($scopeClassReflection), true)
-				|| strtolower($scopeMethod->getName()) === '__unserialize'
+				in_array($methodName, $this->constructorsHelper->getConstructors($scopeClassReflection), true)
+				|| strtolower($methodName) === '__unserialize'
+				|| ($this->phpVersion->supportsReadonlyPropertyReinitializationOnClone() && strtolower($methodName) === '__clone')
 			) {
 				if (TypeUtils::findThisType($scope->getType($propertyFetch->var)) === null) {
 					$errors[] = RuleErrorBuilder::message(sprintf('Readonly property %s::$%s is not assigned on $this.', $declaringClass->getDisplayName(), $propertyReflection->getName()))

tests/PHPStan/Rules/Properties/ReadOnlyPropertyAssignRuleTest.php

@@ -2,6 +2,7 @@
 
 namespace PHPStan\Rules\Properties;
 
+use PHPStan\Php\PhpVersion;
 use PHPStan\Reflection\ConstructorsHelper;
 use PHPStan\Rules\Rule;
 use PHPStan\Testing\RuleTestCase;
@@ -23,6 +24,7 @@ protected function getRule(): Rule
 					'ReadonlyPropertyAssign\\TestCase::setUp',
 				],
 			),
+			new PhpVersion(PHP_VERSION_ID),
 		);
 	}
 
@@ -154,4 +156,21 @@ public function testBug6773(): void
 		]);
 	}
 
+	public function testBug11495(): void
+	{
+		if (PHP_VERSION_ID < 80100) {
+			$this->markTestSkipped('Test requires PHP 8.1.');
+		}
+
+		$errors = [];
+		if (PHP_VERSION_ID < 80300) {
+			$errors[] = [
+				'Readonly property Bug11495\HelloWorld::$foo is assigned outside of the constructor.',
+				17,
+			];
+		}
+
+		$this->analyse([__DIR__ . '/data/bug-11495.php'], $errors);
+	}
+
 }

tests/PHPStan/Rules/Properties/data/bug-11495.php

@@ -0,0 +1,24 @@
+<?php // lint >= 8.1
+declare(strict_types = 1);
+
+namespace Bug11495;
+
+class HelloWorld
+{
+	private readonly string $foo;
+
+	public function __construct()
+	{
+		$this->foo = 'bar';
+	}
+
+	public function __clone()
+	{
+		$this->foo = 'baz';
+	}
+
+	public function getFoo(): string
+	{
+		return $this->foo;
+	}
+}