LanguageFeatures/Records/record_type_annotations_A04_t06.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 only one
/// named field with no trailing comma
/// @author sgrekhov22@gmail.com

typedef R1 = ({int i});

typedef ({int j}) R2();

typedef void R3(({String s}) r);

({int i}) foo() => (i: 42);

void bar(({int i}) r) {}

main() {
  ({int j}) r1 = (j: 42);

  dynamic d = (x: 42);
  if (d is ({int i})) {
  }

  d as ({int x});
}