LibTest/js_interop/staticInterop_A01_t05.dart

// Copyright (c) 2025, 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 `staticInterop` enables the JS annotated class to be treated as
/// a "static" interop class.
///
/// These classes implicitly all erase to the internal interceptor
/// `JavaScriptObject`, so they can be freely casted to and from other
/// [staticInterop] types, `dart:html` types, and `JSObject` from
/// `dart:js_interop`. Non-[staticInterop] `package:js` types can be casted to
/// [staticInterop] types, but the reverse can fail if the underlying value is a
/// `@Native`-reserved type (like `dart:html` types).
///
/// [staticInterop] classes have the following restrictions:
///  - They must contain a [JS] annotation, either from this library or from
///    `dart:js_interop`.
///  - They should not contain any instance members, inherited or otherwise, and
///    should instead use static extension members, which can be external or
///    non-external.
///  - They can only contain factories and `static` members. They can be
///    combined with [anonymous] to make external factories create new
///    JavaScript object literals instead.
///  - They should not implement, extend, or mixin non-[staticInterop] classes
///    and vice-versa.
///  - The annotation should only be applied to non-mixin classes and no other
///    declarations.
///
/// @description Checks that it is a warning if an extension type is annotated
/// with `@staticInterop`.
/// @author sgrekhov22@gmail.com
/// @issue 61124

import 'dart:js_interop';

@staticInterop
extension type ET1(JSObject o) {}
//             ^^^
// [analyzer] unspecified
// [web] unspecified

@staticInterop
@JS()
extension type ET2(JSObject o) {}
//             ^^^
// [analyzer] unspecified
// [web] unspecified

@staticInterop
extension type ET3(JSObject o) implements JSObject {}
//             ^^^
// [analyzer] unspecified
// [web] unspecified

@staticInterop
@JS()
extension type ET4(JSObject o) implements JSObject {}
//             ^^^
// [analyzer] unspecified
// [web] unspecified

main() {
  print(ET1);
  print(ET2);
  print(ET3);
  print(ET4);
}