Bleeding edge - API class const fetch rule

conf/config.level0.neon

@@ -12,6 +12,8 @@ conditionalTags:
 		phpstan.rules.rule: %checkUninitializedProperties%
 	PHPStan\Rules\Methods\ConsistentConstructorRule:
 		phpstan.rules.rule: %featureToggles.consistentConstructor%
+	PHPStan\Rules\Api\ApiClassConstFetchRule:
+		phpstan.rules.rule: %featureToggles.runtimeReflectionRules%
 	PHPStan\Rules\Api\ApiInstanceofRule:
 		phpstan.rules.rule: %featureToggles.runtimeReflectionRules%
 	PHPStan\Rules\Api\RuntimeReflectionFunctionRule:
@@ -82,6 +84,8 @@ rules:
 	- PHPStan\Rules\Whitespace\FileWhitespaceRule
 
 services:
+	-
+		class: PHPStan\Rules\Api\ApiClassConstFetchRule
 	-
 		class: PHPStan\Rules\Api\ApiInstanceofRule
 	-

src/Rules/Api/ApiClassConstFetchRule.php

@@ -0,0 +1,75 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Api;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Reflection\ReflectionProvider;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use function count;
+use function sprintf;
+
+/**
+ * @implements Rule<Node\Expr\ClassConstFetch>
+ */
+class ApiClassConstFetchRule implements Rule
+{
+
+	public function __construct(
+		private ApiRuleHelper $apiRuleHelper,
+		private ReflectionProvider $reflectionProvider,
+	)
+	{
+	}
+
+	public function getNodeType(): string
+	{
+		return Node\Expr\ClassConstFetch::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if (!$node->name instanceof Node\Identifier) {
+			return [];
+		}
+
+		if (!$node->class instanceof Node\Name) {
+			return [];
+		}
+
+		$className = $scope->resolveName($node->class);
+		if (!$this->reflectionProvider->hasClass($className)) {
+			return [];
+		}
+
+		$classReflection = $this->reflectionProvider->getClass($className);
+		if (!$this->apiRuleHelper->isPhpStanCode($scope, $classReflection->getName(), $classReflection->getFileName())) {
+			return [];
+		}
+
+		$ruleError = RuleErrorBuilder::message(sprintf(
+			'Accessing %s::%s is not covered by backward compatibility promise. The class might change in a minor PHPStan version.',
+			$classReflection->getDisplayName(),
+			$node->name->toString(),
+		))->tip(sprintf(
+			"If you think it should be covered by backward compatibility promise, open a discussion:\n   %s\n\n   See also:\n   https://phpstan.org/developing-extensions/backward-compatibility-promise",
+			'https://github.com/phpstan/phpstan/discussions',
+		))->build();
+
+		$docBlock = $classReflection->getResolvedPhpDoc();
+		if ($docBlock === null) {
+			return [$ruleError];
+		}
+
+		foreach ($docBlock->getPhpDocNodes() as $phpDocNode) {
+			$apiTags = $phpDocNode->getTagsByName('@api');
+			if (count($apiTags) > 0) {
+				return [];
+			}
+		}
+
+		return [$ruleError];
+	}
+
+}

tests/PHPStan/Rules/Api/ApiClassConstFetchRuleTest.php

@@ -0,0 +1,41 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Api;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+use function sprintf;
+
+/**
+ * @extends RuleTestCase<ApiClassConstFetchRule>
+ */
+class ApiClassConstFetchRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new ApiClassConstFetchRule(new ApiRuleHelper(), $this->createReflectionProvider());
+	}
+
+	public function testRuleInPhpStan(): void
+	{
+		$this->analyse([__DIR__ . '/data/class-const-fetch-in-phpstan.php'], []);
+	}
+
+	public function testRuleOutOfPhpStan(): void
+	{
+		$tip = sprintf(
+			"If you think it should be covered by backward compatibility promise, open a discussion:\n   %s\n\n   See also:\n   https://phpstan.org/developing-extensions/backward-compatibility-promise",
+			'https://github.com/phpstan/phpstan/discussions',
+		);
+
+		$this->analyse([__DIR__ . '/data/class-const-fetch-out-of-phpstan.php'], [
+			[
+				'Accessing PHPStan\Command\AnalyseCommand::class is not covered by backward compatibility promise. The class might change in a minor PHPStan version.',
+				14,
+				$tip,
+			],
+		]);
+	}
+
+}

tests/PHPStan/Rules/Api/data/class-const-fetch-in-phpstan.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace PHPStan\ClassConstFetch;
+
+use PHPStan\Command\AnalyseCommand;
+use PHPStan\Reflection\ClassReflection;
+
+class Foo
+{
+
+	public function doFoo()
+	{
+		echo ClassReflection::class;
+		echo AnalyseCommand::class;
+	}
+
+}

tests/PHPStan/Rules/Api/data/class-const-fetch-out-of-phpstan.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace App\ClassConstFetch;
+
+use PHPStan\Command\AnalyseCommand;
+use PHPStan\Reflection\ClassReflection;
+
+class Foo
+{
+
+	public function doFoo()
+	{
+		echo ClassReflection::class;
+		echo AnalyseCommand::class;
+	}
+
+}