pkg/front_end/testcases/extension_types/issue54649.dart.textual_outline.expect

extension type N(Future<int> _) {}

extension type F(Future<int> _) implements Future<int> {}

void test<X, XN extends N, XF extends F>(
    N n, F f, X x, XN xn, XF xf, N? nq, F? fq, XN? xnq, XF? xfq) async {}