Fixed CallableType::getReferencedClasses()

src/Type/CallableType.php

@@ -56,7 +56,12 @@ public function __construct(
 	 */
 	public function getReferencedClasses(): array
 	{
-		return [];
+		$classes = [];
+		foreach ($this->parameters as $parameter) {
+			$classes = array_merge($classes, $parameter->getType()->getReferencedClasses());
+		}
+
+		return array_merge($classes, $this->returnType->getReferencedClasses());
 	}
 
 	public function accepts(Type $type, bool $strictTypes): TrinaryLogic

tests/PHPStan/Rules/Methods/ExistingClassesInTypehintsRuleTest.php

@@ -116,6 +116,14 @@ public function testExistingClassInTypehint(): void
 				'Parameter $array of method TestMethodTypehints\FooMethodTypehints::unknownTypesInArrays() has invalid typehint type TestMethodTypehints\AnotherNonexistentClass.',
 				102,
 			],
+			[
+				'Parameter $cb of method TestMethodTypehints\CallableTypehints::doFoo() has invalid typehint type TestMethodTypehints\Bla.',
+				113,
+			],
+			[
+				'Parameter $cb of method TestMethodTypehints\CallableTypehints::doFoo() has invalid typehint type TestMethodTypehints\Ble.',
+				113,
+			],
 		]);
 	}
 

tests/PHPStan/Rules/Methods/data/typehints.php

@@ -105,3 +105,14 @@ function unknownTypesInArrays(array $array)
 	}
 
 }
+
+class CallableTypehints
+{
+
+	/** @param callable(Bla): Ble $cb */
+	public function doFoo(callable $cb): void
+	{
+
+	}
+
+}