Implement AbstractProtectedMethodRule

conf/config.level0.neon

@@ -89,6 +89,7 @@ rules:
 	- PHPStan\Rules\Methods\ExistingClassesInTypehintsRule
 	- PHPStan\Rules\Methods\FinalPrivateMethodRule
 	- PHPStan\Rules\Methods\MethodCallableRule
+	- PHPStan\Rules\Methods\MethodVisibitiliyInInterfaceRule
 	- PHPStan\Rules\Methods\MissingMethodImplementationRule
 	- PHPStan\Rules\Methods\MethodAttributesRule
 	- PHPStan\Rules\Methods\StaticMethodCallableRule

src/Rules/Methods/MethodVisibitiliyInInterfaceRule.php

@@ -0,0 +1,47 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Methods;
+
+use PhpParser\Node;
+use PHPStan\Analyser\Scope;
+use PHPStan\Node\InClassMethodNode;
+use PHPStan\Rules\Rule;
+use PHPStan\Rules\RuleErrorBuilder;
+use function sprintf;
+
+/** @implements Rule<InClassMethodNode> */
+class MethodVisibitiliyInInterfaceRule implements Rule
+{
+
+	public function getNodeType(): string
+	{
+		return InClassMethodNode::class;
+	}
+
+	public function processNode(Node $node, Scope $scope): array
+	{
+		$method = $node->getMethodReflection();
+
+		if ($method->isPublic()) {
+			return [];
+		}
+
+		$classReflection = $scope->getClassReflection();
+		if ($classReflection === null) {
+			return [];
+		}
+
+		if (!$classReflection->isInterface()) {
+			return [];
+		}
+
+		return [
+			RuleErrorBuilder::message(sprintf(
+				'Method %s::%s() cannot use non-public visibility in interface.',
+				$method->getDeclaringClass()->getDisplayName(),
+				$method->getName(),
+			))->nonIgnorable()->build(),
+		];
+	}
+
+}

tests/PHPStan/Rules/Methods/MethodVisibitiliyInInterfaceRuleTest.php

@@ -0,0 +1,31 @@
+<?php declare(strict_types = 1);
+
+namespace PHPStan\Rules\Methods;
+
+use PHPStan\Rules\Rule;
+use PHPStan\Testing\RuleTestCase;
+
+/** @extends RuleTestCase<MethodVisibitiliyInInterfaceRule> */
+class MethodVisibitiliyInInterfaceRuleTest extends RuleTestCase
+{
+
+	protected function getRule(): Rule
+	{
+		return new MethodVisibitiliyInInterfaceRule();
+	}
+
+	public function testRule(): void
+	{
+		$this->analyse([__DIR__ . '/data/visibility-in-interace.php'], [
+			[
+				'Method VisibilityInInterface\FooInterface::sayPrivate() cannot use non-public visibility in interface.',
+				7,
+			],
+			[
+				'Method VisibilityInInterface\FooInterface::sayProtected() cannot use non-public visibility in interface.',
+				8,
+			],
+		]);
+	}
+
+}

tests/PHPStan/Rules/Methods/data/visibility-in-interace.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace VisibilityInInterface;
+
+interface FooInterface
+{
+	private function sayPrivate() : void;
+	protected function sayProtected() : void;
+	public function sayPublic() : void;
+
+	function noVisibility() : void;
+}
+
+trait FooTrait
+{
+	private function sayPrivate() : void {}
+	protected function sayProtected() : void {}
+	public function sayPublic() : void {}
+
+	function noVisibility() : void {}
+}
+
+abstract class AbstractFoo
+{
+	abstract private function sayPrivate() : void;
+	abstract protected function sayProtected() : void;
+	abstract public function sayPublic() : void;
+
+	abstract function noVisibility() : void;
+}