LanguageFeatures/Primary-constructors/static_processing_A12_t06.dart

// Copyright (c) 2026, 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 The semantics of the primary constructor is found in the
/// following steps, where `D` is the class, mixin class, extension type, or
/// enum declaration in the program that includes a primary constructor `k`, and
/// `D2` is the result of the derivation of the semantics of `D`. The derivation
/// step will delete elements that amount to the primary constructor.
/// Semantically, it will add a new constructor `k2`, and it will add zero or
/// more instance variable declarations.
///
/// Where no processing is mentioned below, `D2` is identical to `D`. Changes
/// occur as follows:
///
/// Let `p` be a formal parameter in `k` which has the modifier `var` or the
/// modifier `final` (that is, `p` is a declaring parameter).
///
/// Consider the situation where `p` has no type annotation:
/// ...
/// - otherwise, if `p` does not have a default value then `p` has declared type
///   `Object?`.
///
/// @description Checks that, in an extension type, if `p` does not have a
/// declared type, its type is `Object?` because of the implicit `final`
/// modifier.
/// @author sgrekhov22@gmail.com

// SharedOptions=--enable-experiment=primary-constructors

import '../../Utils/static_type_helper.dart';

extension type ET1(x) {
  this {
    x.expectStaticType<Exactly<Object?>>();
  }
}

extension type ET2([x]) {
  this {
    x.expectStaticType<Exactly<Object?>>();
  }
}

extension type ET3({x}) {
  this {
    x.expectStaticType<Exactly<Object?>>();
  }
}

extension type ET4({required x}) {
  this {
    x.expectStaticType<Exactly<Object?>>();
  }
}

main() {
  ET1(1);
  ET2(2);
  ET3(x: 3);
  ET4(x: 4);
}