Final constant rule

conf/config.level0.neon

@@ -50,6 +50,7 @@ rules:
 	- PHPStan\Rules\Classes\NewStaticRule
 	- PHPStan\Rules\Classes\NonClassAttributeClassRule
 	- PHPStan\Rules\Classes\TraitAttributeClassRule
+	- PHPStan\Rules\Constants\FinalConstantRule
 	- PHPStan\Rules\Exceptions\ThrowExpressionRule
 	- PHPStan\Rules\Functions\ArrowFunctionAttributesRule
 	- PHPStan\Rules\Functions\ArrowFunctionReturnNullsafeByRefRule

src/Php/PhpVersion.php

@@ -132,4 +132,9 @@ public function isInterfaceConstantImplicitlyFinal(): bool
 		return $this->versionId < 80100;
 	}
 
+	public function supportsFinalConstants(): bool
+	{
+		return $this->versionId >= 80100;
+	}
+
 }

src/Rules/Constants/FinalConstantRule.php

@@ -0,0 +1,43 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Constants;
+
+use PhpParser\Node;
+use PhpParser\Node\Stmt\ClassConst;
+use PHPStan\Analyser\Scope;
+use PHPStan\Php\PhpVersion;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+
+/** @implements Rule<ClassConst> */
+class FinalConstantRule implements Rule
+{
+
+	private PhpVersion $phpVersion;
+
+	public function __construct(PhpVersion $phpVersion)
+	{
+		$this->phpVersion = $phpVersion;
+	}
+
+	public function getNodeType(): string
+	{
+		return ClassConst::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if (!$node->isFinal()) {
+			return [];
+		}
+
+		if ($this->phpVersion->supportsFinalConstants()) {
+			return [];
+		}
+
+		return [
+			RuleErrorBuilder::message('Final class constants are supported only on PHP 8.1 and later.')->nonIgnorable()->build(),
+		];
+	}
+
+}

tests/PHPStan/Rules/Constants/FinalConstantRuleTest.php

@@ -0,0 +1,57 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Constants;
+
+use PHPStan\Php\PhpVersion;
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/**
+ * @extends RuleTestCase<FinalConstantRule>
+ */
+class FinalConstantRuleTest extends RuleTestCase
+{
+
+	/** @var int */
+	private $phpVersionId;
+
+	protected function getRule(): Rule
+	{
+		return new FinalConstantRule(new PhpVersion($this->phpVersionId));
+	}
+
+	public function dataRule(): array
+	{
+		return [
+			[
+				80000,
+				[
+					[
+						'Final class constants are supported only on PHP 8.1 and later.',
+						9,
+					],
+				],
+			],
+			[
+				80100,
+				[],
+			],
+		];
+	}
+
+	/**
+	 * @dataProvider dataRule
+	 * @param int $phpVersionId
+	 * @param mixed[] $errors
+	 */
+	public function testRule(int $phpVersionId, array $errors): void
+	{
+		if (!self::$useStaticReflectionProvider) {
+			$this->markTestSkipped('Test requires static reflection.');
+		}
+
+		$this->phpVersionId = $phpVersionId;
+		$this->analyse([__DIR__ . '/data/final-constant.php'], $errors);
+	}
+
+}

tests/PHPStan/Rules/Constants/data/final-constant.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace FinalConstant;
+
+class Foo
+{
+
+	const TEST = 1;
+	final const BAR = 2;
+
+}