Language/Expressions/Conditional/type_t08.dart

// Copyright (c) 2011, 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 conditional expression c of the form e1 ? e2 : e3.
 * If all of the following hold:
 * • e1 shows that a variable v has type T.
 * • v is not potentially mutated in e2 or within a closure.
 * • If the variable v is accessed by a closure in e2 then the variable v is
 *   not potentially mutated anywhere in the scope of v .
 * then the type of v is known to be T in e2.
 * @description Checks that if e1 shows that v has type T, v2 is not potentially
 * mutated in e2, but potentially mutated within a closure, then the type of v
 * is not known to be T in e2.
 * @author ilya
 */

import '../../../Utils/expect.dart';

var closure;

class C {}
class D extends C {
  f() => closure();
}

f(var x) {
  closure = () => x = new C();

  x is D ? [x.f(), x.f() /*throws*/] : null;
}

main() {
  Expect.throws(() => f(new D()));
}