LanguageFeatures/Records/record_type_annotations_A04_t02.dart

// Copyright (c) 2022, 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 a record type has any of:
///
/// The same field name more than once. This is true even if one or both of the
/// colliding fields is positional. We could permit collisions with positional
/// field names since they are only used for documentation, but we disallow it
/// because it's confusing and not useful.
///
/// Only one positional field and no trailing comma. This isn't ambiguous, since
/// there are no parenthesized type expressions in Dart. But prohibiting this is
/// symmetric with record expressions and leaves the potential for later support
/// for parentheses for grouping in type expressions.
///
/// A field named hashCode, runtimeType, noSuchMethod, or toString.
///
/// A field name that starts with an underscore.
///
/// A field name that collides with the synthesized getter name of a positional
/// field. For example: (int, $1: int) since the named field '$1' collides with
/// the getter for the first positional field.
///
/// @description Checks that it is no error if a record type has no named fields
/// and only one positional field but with a trailing comma
/// @author sgrekhov22@gmail.com

typedef R1 = (int i,);

typedef (int,) R2();

typedef void R3((String s,) r);

(int,) foo() => (42,);

Record bar((int i,) r) => r;

main() {
  (int,) r1 = (42,);

  (double d,) r2 = (3.14,);

  ((int,),) r3 = ((42,),);

  dynamic d = (1,);
  if (d is (int i,)) {
  }

  d as (int,);
}