LanguageFeatures/Extension-methods/explicit_extension_member_invocation_A20_t04.dart

// Copyright (c) 2019, 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.

/// @assertion It is a compile-time error if an extension application occurs in a
/// place where it is not the target expression of a simple or composite member
/// invocation. That is, the only valid use of an extension application is to
/// invoke members on it. This is similar to how prefix names can also only be
/// used as member invocation targets. The main difference is that extensions can
/// also declare operators.
///
/// @description Check that it is no compile-time error if null-aware member
/// access like E(o)?[v] is used for explicit extension invocation
/// @issue 39326
/// https://github.com/dart-lang/language/issues/677
/// @author sgrekhov@unipro.ru
/// @issue 43217


import "../../Utils/expect.dart";

class C {
}

extension Ext on C {
  int operator [](int index) => index;
}

main() {
  C c = C();
  Expect.equals(42, Ext(c)?[42]);
//                        ^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
//                      ^
// [cfe] Operand of null-aware operation '?.' has type 'C' which excludes null.
}