detect override of deprecated method

Author: Khartir

Diff for: rules.neon

@@ -6,6 +6,8 @@ services:
         class: PHPStan\Rules\Deprecations\DeprecatedClassHelper
     -
         class: PHPStan\Rules\Deprecations\OverrideDeprecatedPropertyRule
+    -
+        class: PHPStan\Rules\Deprecations\OverrideDeprecatedMethodRule
 
 rules:
 	- PHPStan\Rules\Deprecations\AccessDeprecatedPropertyRule
@@ -28,3 +30,5 @@ 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/DeprecatedScopeHelper.php

@@ -7,7 +7,7 @@
 class DeprecatedScopeHelper
 {
 
-	public static function isScopeDeprecated(Scope $scope): bool
+	public static function isScopeDeprecated(Scope $scope, bool $skipMethod = false): bool
 	{
 		$class = $scope->getClassReflection();
 		if ($class !== null && $class->isDeprecated()) {
@@ -19,6 +19,10 @@ public static function isScopeDeprecated(Scope $scope): bool
 			return true;
 		}
 
+		if ($skipMethod) {
+			return false;
+		}
+
 		$function = $scope->getFunction();
 		if ($function !== null && $function->isDeprecated()->yes()) {
 			return true;

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

@@ -0,0 +1,64 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Deprecations;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Node\InClassMethodNode;
+use PHPStan\Rules\Rule;
+use function sprintf;
+
+/**
+ * @implements Rule<InClassMethodNode>
+ */
+class OverrideDeprecatedMethodRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return InClassMethodNode::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		if (DeprecatedScopeHelper::isScopeDeprecated($scope, true)) {
+			return [];
+		}
+
+		if (!$scope->isInClass()) {
+			return [];
+		}
+
+		if ($node->getMethodReflection()->isPrivate()) {
+			return [];
+		}
+
+		$class = $scope->getClassReflection();
+
+		$parents = $class->getParents();
+
+		$methodName = $node->getMethodReflection()->getName();
+
+		foreach ($parents as $parent) {
+			if (!$parent->hasMethod($methodName)) {
+				continue;
+			}
+
+			$parentMethod = $parent->getMethod($methodName, $scope);
+
+			if (!$parentMethod->isDeprecated()->yes()) {
+				return [];
+			}
+
+			return [sprintf(
+				'Class %s overrides deprecated method %s of class %s.',
+				$class->getName(),
+				$methodName,
+				$parent->getName()
+			)];
+		}
+
+		return [];
+	}
+
+}

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

@@ -0,0 +1,32 @@
+<?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();
+	}
+
+	public function testDeprecatedMethodOverride(): void
+	{
+		$this->analyse(
+			[__DIR__ . '/data/override-deprecated-method.php'],
+			[
+				[
+					'Class OverrideDeprecatedMethod\Child overrides deprecated method foo of class OverrideDeprecatedMethod\Foo.',
+					22,
+				],
+			]
+		);
+	}
+
+}

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

@@ -0,0 +1,27 @@
+<?php
+
+namespace OverrideDeprecatedMethod;
+
+class Foo
+{
+	/**
+	 * @deprecated
+	 */
+	public function foo(): void
+	{}
+
+	/**
+	 * @deprecated
+	 */
+	private function bar(): void
+	{}
+}
+
+class Child extends Foo
+{
+	public function foo(): void
+	{}
+
+	private function bar(): void
+	{}
+}