tests/language_2/abstract/override_adds_optional_args_concrete_test.dart

// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

// @dart = 2.9

class A {
  void foo() {}
}

class B extends A {
  // This class declaration violates soundness, since it allows `new
  // B().foo(42)`, which would lead to invalid arguments being passed to A.foo.
  void /*@compile-error=unspecified*/ foo([x]);
}

void f(B b) {
  b.foo();
}

main() {
  f(new B());
}