Fixed false positive about unreferenced template type in a parameter with nested generics

Author: ondrejmirtes

src/Rules/FunctionDefinitionCheck.php

@@ -324,7 +324,7 @@ private function checkParametersAcceptor(
 					TypeTraverser::map($parameter->getType(), static function (Type $type, callable $traverse) use (&$templateTypes): Type {
 						if ($type instanceof TemplateType) {
 							unset($templateTypes[$type->getName()]);
-							return $type;
+							return $traverse($type);
 						}
 
 						return $traverse($type);

tests/PHPStan/Rules/Methods/ExistingClassesInTypehintsRuleTest.php

@@ -247,4 +247,14 @@ public function testRequiredParameterAfterOptional(int $phpVersionId, array $err
 		$this->analyse([__DIR__ . '/data/required-parameter-after-optional.php'], $errors);
 	}
 
+	public function testBug4641(): void
+	{
+		$this->analyse([__DIR__ . '/data/bug-4641.php'], [
+			[
+				'Template type U of method Bug4641\I::getRepository() is not referenced in a parameter.',
+				26,
+			],
+		]);
+	}
+
 }

tests/PHPStan/Rules/Methods/data/bug-4641.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Bug4641;
+
+interface IEntity
+{
+
+}
+
+/** @template E of IEntity */
+interface IRepository
+{
+
+}
+
+interface I
+{
+
+	/**
+	 * @template E of IEntity
+	 * @template T of IRepository<E>
+	 * @template U
+	 * @phpstan-param class-string<T> $className
+	 * @phpstan-return T
+	 */
+	function getRepository(string $className): IRepository;
+
+}