ReadOnlyClassRule

conf/config.level0.neon

@@ -56,6 +56,7 @@ rules:
 	- PHPStan\Rules\Classes\LocalTypeTraitAliasesRule
 	- PHPStan\Rules\Classes\NewStaticRule
 	- PHPStan\Rules\Classes\NonClassAttributeClassRule
+	- PHPStan\Rules\Classes\ReadOnlyClassRule
 	- PHPStan\Rules\Classes\TraitAttributeClassRule
 	- PHPStan\Rules\Constants\DynamicClassConstantFetchRule
 	- PHPStan\Rules\Constants\FinalConstantRule

src/Php/PhpVersion.php

@@ -262,4 +262,14 @@ public function supportsDynamicClassConstantFetch(): bool
 		return $this->versionId >= 80300;
 	}
 
+	public function supportsReadOnlyClasses(): bool
+	{
+		return $this->versionId >= 80200;
+	}
+
+	public function supportsReadOnlyAnonymousClasses(): bool
+	{
+		return $this->versionId >= 80300;
+	}
+
 }

src/Rules/Classes/ReadOnlyClassRule.php

@@ -0,0 +1,58 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Classes;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Node\InClassNode;
+use PHPStan\Php\PhpVersion;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+
+/**
+ * @implements Rule<InClassNode>
+ */
+class ReadOnlyClassRule implements Rule
+{
+
+	public function __construct(private PhpVersion $phpVersion)
+	{
+	}
+
+	public function getNodeType(): string
+	{
+		return InClassNode::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		$classReflection = $node->getClassReflection();
+		if (!$classReflection->isReadOnly()) {
+			return [];
+		}
+		if ($classReflection->isAnonymous()) {
+			if ($this->phpVersion->supportsReadOnlyAnonymousClasses()) {
+				return [];
+			}
+
+			return [
+				RuleErrorBuilder::message('Anonymous readonly classes are supported only on PHP 8.3 and later.')
+					->identifier('classConstant.nativeTypeNotSupported')
+					->nonIgnorable()
+					->build(),
+			];
+		}
+
+		if ($this->phpVersion->supportsReadOnlyClasses()) {
+			return [];
+		}
+
+		return [
+			RuleErrorBuilder::message('Readonly classes are supported only on PHP 8.2 and later.')
+				->identifier('classConstant.nativeTypeNotSupported')
+				->nonIgnorable()
+				->build(),
+		];
+	}
+
+}

tests/PHPStan/Rules/Classes/ReadOnlyClassRuleTest.php

@@ -0,0 +1,42 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Classes;
+
+use PHPStan\Php\PhpVersion;
+use PHPStan\Rules\Rule as TRule;
+use PHPStan\Testing\RuleTestCase;
+use const PHP_VERSION_ID;
+
+/**
+ * @extends RuleTestCase<ReadOnlyClassRule>
+ */
+class ReadOnlyClassRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): TRule
+	{
+		return new ReadOnlyClassRule(self::getContainer()->getByType(PhpVersion::class));
+	}
+
+	public function testRule(): void
+	{
+		$errors = [];
+		if (PHP_VERSION_ID < 80200) {
+			$errors = [
+				[
+					'Readonly classes are supported only on PHP 8.2 and later.',
+					5,
+				],
+			];
+		} elseif (PHP_VERSION_ID < 80300) {
+			$errors = [
+				[
+					'Anonymous readonly classes are supported only on PHP 8.3 and later.',
+					15,
+				],
+			];
+		}
+		$this->analyse([__DIR__ . '/data/readonly-class.php'], $errors);
+	}
+
+}

tests/PHPStan/Rules/Classes/data/readonly-class.php

@@ -0,0 +1,20 @@
+<?php // lint >= 8.3
+
+namespace ReadonlyClass;
+
+readonly class Foo
+{
+
+}
+
+class Bar
+{
+
+	public function doFoo(): void
+	{
+		$c = new readonly class () {
+
+		};
+	}
+
+}