Do not check variance validity in private methods

src/Rules/Generics/FunctionSignatureVarianceRule.php

@@ -40,6 +40,7 @@ public function processNode(Node $node, Scope $scope): array
 			sprintf('in return type of function %s()', $functionName),
 			sprintf('in function %s()', $functionName),
 			false,
+			false,
 		);
 	}
 

src/Rules/Generics/MethodSignatureVarianceRule.php

@@ -39,6 +39,7 @@ public function processNode(Node $node, Scope $scope): array
 			sprintf('in return type of method %s::%s()', $method->getDeclaringClass()->getDisplayName(), $method->getName()),
 			sprintf('in method %s::%s()', $method->getDeclaringClass()->getDisplayName(), $method->getName()),
 			$method->getName() === '__construct' || $method->isStatic(),
+			$method->isPrivate(),
 		);
 	}
 

src/Rules/Generics/VarianceCheck.php

@@ -20,21 +20,11 @@ public function checkParametersAcceptor(
 		string $returnTypeMessage,
 		string $generalMessage,
 		bool $isStatic,
+		bool $isPrivate,
 	): array
 	{
 		$errors = [];
 
-		foreach ($parametersAcceptor->getParameters() as $parameterReflection) {
-			$variance = $isStatic
-				? TemplateTypeVariance::createStatic()
-				: TemplateTypeVariance::createContravariant();
-			$type = $parameterReflection->getType();
-			$message = sprintf($parameterTypeMessage, $parameterReflection->getName());
-			foreach ($this->check($variance, $type, $message) as $error) {
-				$errors[] = $error;
-			}
-		}
-
 		foreach ($parametersAcceptor->getTemplateTypeMap()->getTypes() as $templateType) {
 			if (!$templateType instanceof TemplateType
 				|| $templateType->getScope()->getFunctionName() === null
@@ -50,6 +40,21 @@ public function checkParametersAcceptor(
 			))->build();
 		}
 
+		if ($isPrivate) {
+			return $errors;
+		}
+
+		foreach ($parametersAcceptor->getParameters() as $parameterReflection) {
+			$variance = $isStatic
+				? TemplateTypeVariance::createStatic()
+				: TemplateTypeVariance::createContravariant();
+			$type = $parameterReflection->getType();
+			$message = sprintf($parameterTypeMessage, $parameterReflection->getName());
+			foreach ($this->check($variance, $type, $message) as $error) {
+				$errors[] = $error;
+			}
+		}
+
 		$variance = TemplateTypeVariance::createCovariant();
 		$type = $parametersAcceptor->getReturnType();
 		foreach ($this->check($variance, $type, $returnTypeMessage) as $error) {

tests/PHPStan/Rules/Generics/data/method-signature-variance-contravariant.php

@@ -69,4 +69,7 @@ function l() {}
 
 	/** @return Invariant<Out<X>> */
 	function m() {}
+
+	/** @return X */
+	private function n() {}
 }

tests/PHPStan/Rules/Generics/data/method-signature-variance-covariant.php

@@ -69,4 +69,7 @@ function l() {}
 
 	/** @return Invariant<Out<X>> */
 	function m() {}
+
+	/** @param X $n */
+	private function n($n) {}
 }