detect override of deprecated method

Author: Khartir

Diff for: rules.neon

@@ -17,6 +17,8 @@ services:
 			- phpstan.deprecations.deprecatedScopeResolver
 	-
 		class: PHPStan\Rules\Deprecations\OverrideDeprecatedPropertyRule
+	-
+		class: PHPStan\Rules\Deprecations\OverrideDeprecatedMethodRule
 
 rules:
 	- PHPStan\Rules\Deprecations\AccessDeprecatedPropertyRule
@@ -39,3 +41,5 @@ rules:
 conditionalTags:
     PHPStan\Rules\Deprecations\OverrideDeprecatedPropertyRule:
         phpstan.rules.rule: %featureToggles.bleedingEdge%
+    PHPStan\Rules\Deprecations\OverrideDeprecatedMethodRule:
+        phpstan.rules.rule: %featureToggles.bleedingEdge%

Diff for: src/Rules/Deprecations/OverrideDeprecatedMethodRule.php

@@ -0,0 +1,84 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Deprecations;
+
+use PhpParser\Node;
+use PhpParser\Node\Stmt\ClassMethod;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use function sprintf;
+
+/**
+ * @implements Rule<ClassMethod>
+ */
+class OverrideDeprecatedMethodRule implements Rule
+{
+
+	/** @var DeprecatedScopeHelper */
+	private $deprecatedScopeHelper;
+
+	public function __construct(DeprecatedScopeHelper $deprecatedScopeHelper)
+	{
+		$this->deprecatedScopeHelper = $deprecatedScopeHelper;
+	}
+
+	public function getNodeType(): string
+	{
+		return ClassMethod::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if ($this->deprecatedScopeHelper->isScopeDeprecated($scope)) {
+			return [];
+		}
+
+		if (!$scope->isInClass()) {
+			return [];
+		}
+
+		if ($node->isPrivate()) {
+			return [];
+		}
+
+		$class = $scope->getClassReflection();
+
+		$ancestors = $class->getAncestors();
+
+		$methodName = (string) $node->name;
+
+		$method = $class->getMethod($methodName, $scope);
+
+		if ($method->isDeprecated()->no()) {
+			return [];
+		}
+
+		foreach ($ancestors as $ancestor) {
+			if ($ancestor === $class) {
+				continue;
+			}
+
+			if (!$ancestor->hasMethod($methodName)) {
+				continue;
+			}
+
+			$ancestorMethod = $ancestor->getMethod($methodName, $scope);
+
+			if (!$ancestorMethod->isDeprecated()->yes()) {
+				return [];
+			}
+
+			return [RuleErrorBuilder::message(sprintf(
+				'Class %s overrides deprecated method %s of %s %s.',
+				$class->getName(),
+				$methodName,
+				$ancestor->isInterface() ? 'interface' : 'class',
+				$ancestor->getName()
+			))->identifier('method.deprecated')->build()];
+		}
+
+		return [];
+	}
+
+}

Diff for: tests/Rules/Deprecations/OverrideDeprecatedMethodRuleTest.php

@@ -0,0 +1,37 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Deprecations;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/**
+ * @extends RuleTestCase<OverrideDeprecatedMethodRule>
+ */
+class OverrideDeprecatedMethodRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new OverrideDeprecatedMethodRule(new DeprecatedScopeHelper([new DefaultDeprecatedScopeResolver()]));
+	}
+
+	public function testDeprecatedMethodOverride(): void
+	{
+		$this->analyse(
+			[__DIR__ . '/data/override-deprecated-method.php'],
+			[
+				[
+					'Class OverrideDeprecatedMethod\Child overrides deprecated method deprecatedMethod of class OverrideDeprecatedMethod\Ancestor.',
+					36,
+				],
+
+				[
+					'Class OverrideDeprecatedMethod\Child overrides deprecated method deprecatedInInterface of interface OverrideDeprecatedMethod\Deprecated.',
+					48,
+				],
+			]
+		);
+	}
+
+}

Diff for: tests/Rules/Deprecations/data/override-deprecated-method.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace OverrideDeprecatedMethod;
+
+class Ancestor
+{
+	/**
+	 * @deprecated
+	 */
+	public function deprecatedMethod(): void
+	{}
+
+	/**
+	 * @deprecated
+	 */
+	private function privateDeprecatedMethod(): void
+	{}
+
+	/**
+	 * @deprecated
+	 */
+	public function explicitlyNotDeprecatedMethod(): void
+	{}
+}
+
+interface Deprecated
+{
+	/**
+	 * @deprecated
+	 */
+	public function deprecatedInInterface(): void;
+}
+
+class Child extends Ancestor implements Deprecated
+{
+	public function deprecatedMethod(): void
+	{}
+
+	private function privateDeprecatedMethod(): void
+	{}
+
+	/**
+	 * @not-deprecated
+	 */
+	public function explicitlyNotDeprecatedMethod(): void
+	{}
+
+	public function deprecatedInInterface(): void
+	{}
+}
+
+class GrandChild extends Child
+{
+	public function explicitlyNotDeprecatedMethod(): void
+	{}
+}