LanguageFeatures/Extension-methods/syntax_member_declarations_t02.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 an extension declaration is a top-level declaration with a grammar
/// similar to:
/// <extension> ::=
///   `extension' <identifier>? <typeParameters>? `on' <type> `?'? `{'
///     memberDeclaration*
///   `}'
/// ...
/// The member declarations can be any non-abstract static or instance member
/// declaration except for instance variables and constructors, and they cannot
/// have the same name as a member declared by Object (==, hashCode , toString,
/// runtimeType or noSuchMethod)
///
/// @description Check that it is a compile error if extension declares an
/// instance variable, constructor or abstract method
/// @author sgrekhov@unipro.ru



extension ExtendedList<T> on List<T> {
  int instanceVar;
//    ^^^^^^^^^^^
// [analyzer] unspecified
// [cfe] unspecified
  String _privateInstanceVar;
//       ^^^^^^^^^^^^^^^^^^^
// [analyzer] unspecified
// [cfe] unspecified
  ExtendedList() {}
//^^^^^^^^^^^^
// [analyzer] SYNTACTIC_ERROR.EXTENSION_DECLARES_CONSTRUCTOR
// [cfe] Extensions can't declare constructors.
  ExtendedList.named(int i) {}
//^^^^^^^^^^^^
// [analyzer] SYNTACTIC_ERROR.EXTENSION_DECLARES_CONSTRUCTOR
// [cfe] Extensions can't declare constructors.
  void abstractMethod(String v);
  //   ^^^^^^^^^^^^^^
  // [analyzer] SYNTACTIC_ERROR.EXTENSION_DECLARES_ABSTRACT_MEMBER
  // [cfe] Extensions can't declare abstract members.
}

main() {
  List<String> list = ["Lily", "was", "here"];
}