detect override of deprecated property

Author: Khartir

rules.neon

@@ -15,6 +15,8 @@ services:
 		class: PHPStan\Rules\Deprecations\DefaultDeprecatedScopeResolver
 		tags:
 			- phpstan.deprecations.deprecatedScopeResolver
+	-
+		class: PHPStan\Rules\Deprecations\OverrideDeprecatedPropertyRule
 
 rules:
 	- PHPStan\Rules\Deprecations\AccessDeprecatedPropertyRule
@@ -33,3 +35,7 @@ rules:
 	- PHPStan\Rules\Deprecations\TypeHintDeprecatedInFunctionSignatureRule
 	- PHPStan\Rules\Deprecations\UsageOfDeprecatedCastRule
 	- PHPStan\Rules\Deprecations\UsageOfDeprecatedTraitRule
+
+conditionalTags:
+    PHPStan\Rules\Deprecations\OverrideDeprecatedPropertyRule:
+        phpstan.rules.rule: %featureToggles.bleedingEdge%

src/Rules/Deprecations/OverrideDeprecatedPropertyRule.php

@@ -0,0 +1,79 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Deprecations;
+
+use PhpParser\Node;
+use PhpParser\Node\Stmt\Property;
+use PHPStan\Analyser\Scope;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use function sprintf;
+
+/**
+ * @implements Rule<Property>
+ */
+class OverrideDeprecatedPropertyRule implements Rule
+{
+
+	/** @var DeprecatedScopeHelper */
+	private $deprecatedScopeHelper;
+
+	public function __construct(DeprecatedScopeHelper $deprecatedScopeHelper)
+	{
+		$this->deprecatedScopeHelper = $deprecatedScopeHelper;
+	}
+
+	public function getNodeType(): string
+	{
+		return Property::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();
+
+		$parents = $class->getParents();
+
+		$propertyName = (string) $node->props[0]->name;
+
+		$property = $class->getProperty($propertyName, $scope);
+
+		if ($property->isDeprecated()->no()) {
+			return [];
+		}
+
+		foreach ($parents as $parent) {
+			if (!$parent->hasProperty($propertyName)) {
+				continue;
+			}
+
+			$parentProperty = $parent->getProperty($propertyName, $scope);
+
+			if (!$parentProperty->isDeprecated()->yes()) {
+				return [];
+			}
+
+			return [RuleErrorBuilder::message(sprintf(
+				'Class %s overrides deprecated property %s of class %s.',
+				$class->getName(),
+				$propertyName,
+				$parent->getName()
+			))->identifier('property.deprecated')->build()];
+		}
+
+		return [];
+	}
+
+}

tests/Rules/Deprecations/OverrideDeprecatedPropertyRuleTest.php

@@ -0,0 +1,32 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Deprecations;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/**
+ * @extends RuleTestCase<OverrideDeprecatedPropertyRule>
+ */
+class OverrideDeprecatedPropertyRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new OverrideDeprecatedPropertyRule(new DeprecatedScopeHelper([new DefaultDeprecatedScopeResolver()]));
+	}
+
+	public function testDeprecatedPropertyOverride(): void
+	{
+		$this->analyse(
+			[__DIR__ . '/data/override-deprecated-property.php'],
+			[
+				[
+					'Class OverrideDeprecatedProperty\Child overrides deprecated property deprecatedProperty of class OverrideDeprecatedProperty\Ancestor.',
+					25,
+				],
+			]
+		);
+	}
+
+}

tests/Rules/Deprecations/data/override-deprecated-property.php

@@ -0,0 +1,38 @@
+<?php
+
+namespace OverrideDeprecatedProperty;
+
+class Ancestor
+{
+	/**
+	 * @deprecated
+	 */
+	public $deprecatedProperty;
+
+	/**
+	 * @deprecated
+	 */
+	private $privateDeprecatedProperty;
+
+	/**
+	 * @deprecated
+	 */
+	public $explicitlyNotDeprecated;
+}
+
+class Child extends Ancestor
+{
+	public $deprecatedProperty;
+
+	private $privateDeprecatedProperty;
+
+	/**
+	 * @not-deprecated
+	 */
+	public $explicitlyNotDeprecated;
+}
+
+class GrandChild extends Child
+{
+	public $explicitlyNotDeprecated;
+}