pkg/front_end/testcases/inference/promotion_subtype_check.dart

// Copyright (c) 2017, 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.
// @dart=2.9
/*@testedFeatures=inference*/
library test;

void f(Object x) {
  if (x is int) {
    if (/*@ promotedType=int* */ x is String) {
      // Promotion blocked; String is not a subtype of int.
      var /*@ type=int* */ y = /*@ promotedType=int* */ x;
    }
  }
}

void g(int x) {
  if (x is String) {
    // Promotion blocked; String is not a subtype of int.
    var /*@ type=int* */ y = x;
  }
}

main() {}