LanguageFeatures/Records/type_promotion_A01_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 Type inference and promotion flows through records in much the 
/// same way it does for instances of generic classes (which are covariant in 
/// Dart just like record fields are) and collection literals.
///
/// @description Checks type promotion for records. Test records with named
/// fields only
/// @author sgrekhov22@gmail.com

typedef R1 = ({int i, String s})?;
typedef R2 = ({num? n, Object? o});

main() {
  R1 r1;
  if (2 > 1) {
    r1 = (i: 42, s: "answer");
  }
  if (r1 != null) {
    r1.i;
    r1.s;
  } else {
    r1?.i;
    r1?.s;
  }

  R2 r2 = (n: 42, o: "answer");
  if (r2 is ({int? n, String o})) {
    r2.n?.isOdd;
    r2.o.substring(0);
  }

  ({Object o}) r3 = (o: 42);
  if (r3 is ({int o})) {
    r3.o.isOdd;
  }

  ({String s})? r4 = null;
  if (2 > 1) {
    r4 = (s: "Lily was here",);
  }
  if (r4 != null) {
    r4.s.substring(0);
  }

  Record r5 = (i: 42);
  if (r5 is ({int i})) {
    r5.i.isOdd;
  }
}