LanguageFeatures/Patterns/execution_pattern_for_in_element_A01_t04.dart

// Copyright (c) 2023, 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
/// A collection element of the form:
///
/// for (<keyword> <pattern> in <expression>) <element>
///
/// Where <keyword> is var or final is treated like so:
/// 1. Let I be the static type of <expression>, inferred using context type
///   schema Iterable<P> where P is the context type schema of <pattern>.
/// 2. Calculate the element type of I:
///     i. If I implements Iterable<T> for some T then E is T.
///     ii. Else if I is dynamic then E is dynamic.
///     iii. Else it is a compile-time error.
/// 3. Type check <pattern> with matched value type E.
/// 4. If there are no compile-time errors, then execution proceeds as the
///   following code, where id1 and id2 are fresh identifiers and append() is
///   an operation to add an element to the surrounding collection being built:
/// ```dart
/// I id1 = <expression>;
/// Iterator<E> id2 = id1.iterator;
/// while (id2.moveNext()) {
///   <keyword> <pattern> = id2.current;
///   append(<element>);
/// }
/// ```
/// @description Checks that it is a compile-time error if `I` doesn't implement
/// `Iterable<T>` and in not `dynamic`
/// @author sgrekhov22@gmail.com

import "patterns_lib.dart";

main() {
  [
    for (var (int v1) in 42) v1
//                       ^
// [analyzer] unspecified
// [cfe] unspecified
  ];
  [
    for (final <int>[v2] in "42") v2
//                          ^
// [analyzer] unspecified
// [cfe] unspecified
  ];
  [
    for (var <String, int>{"k1": v3} in 42) v3
//                                      ^
// [analyzer] unspecified
// [cfe] unspecified
  ];
  [
    for (final (int v4,) in "42") v4
//                          ^
// [analyzer] unspecified
// [cfe] unspecified
  ];
  [
    for (var (n: v5) in 42) v5
//                      ^
// [analyzer] unspecified
// [cfe] unspecified
  ];
  [
    for (final Square(area: v6) in "42") v6
//                                 ^
// [analyzer] unspecified
// [cfe] unspecified
  ];
}