dart / sdk.git / refs/tags/2.13.0-60.0.dev / . / tests / language_2 / least_upper_bound / expansive_runtime_test.dart

// TODO(multitest): This was automatically migrated from a multitest and may | |

// contain strange or dead code. | |

// Copyright (c) 2013, 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. | |

// Test least upper bound through type checking of conditionals. | |

class N<T> { | |

T get n => null; | |

} | |

class C1<T> extends N<N<C1<T>>> { | |

T get c1 => null; | |

} | |

class C2<T> extends N<N<C2<N<C2<T>>>>> { | |

T get c2 => null; | |

} | |

/** | |

* Test that we don't try to find the least upper bound by applying the | |

* algorithm for finding the most specific common declaration recursively on | |

* type arguments. | |

* | |

* For C1<int> and N<C1<String>> this would result in this infinite chain of | |

* computations: | |

* | |

* lub(C1<int>, N<C1<String>>) = lub(N<N<C1<int>>>, N<C1<String>>) | |

* => | |

* lub(N<C1<int>>, C1<String>) = lub(N<C1<int>>, N<N<C1<String>>>) | |

* => | |

* lub(C1<int>, N<C1<String>>) = lub(N<N<C1<int>>>, N<C1<String>>>) | |

* => ... | |

*/ | |

void testC1(bool z, C1<int> a, N<C1<String>> b) { | |

if (z) { | |

// The least upper bound of C1<int> and N<C1<String>> is Object since the | |

// supertypes are | |

// {C1<int>, N<N<C1<int>>>, Object} for C1<int> and | |

// {N<C1<String>>, Object} for N<C1<String>> and | |

// Object is the most specific type in the intersection of the supertypes. | |

// Is least upper bound dynamic? | |

// Is least upper bound N<...> ? | |

// Is least upper bound C1<...> ? | |

// Is least upper bound N<dynamic> ? | |

// Is least upper bound N<N<...>> ? | |

// Is least upper bound N<C1<...>> ? | |

} | |

} | |

/** | |

* Test that we don't try to find the least upper bound by applying the | |

* algorithm for finding the most specific common declaration recursively on | |

* type arguments. | |

* | |

* For C1<int> and N<C1<String>> this would result in this infinite and | |

* expanding chain of computations: | |

* | |

* lub(C2<int>, N<C2<String>>) = lub(N<N<C2<N<C2<int>>>>>, N<C2<String>>) | |

* => | |

* lub(N<C2<N<C2<int>>>>, C2<String>) = | |

* lub(N<C2<N<C2<int>>>>, N<N<C2<N<C2<String>>>>>) | |

* => | |

* lub(C2<N<C2<int>>>, N<C2<N<C2<String>>>>) = | |

* lub(N<N<C2<N<C2<int>>>>>, N<C2<N<C2<String>>>>>) | |

* => ... | |

*/ | |

void testC2(bool z, C2<int> a, N<C2<String>> b) { | |

if (z) { | |

// The least upper bound of C2<int> and N<C2<String>> is Object since the | |

// supertypes are | |

// {C2<int>, N<N<C2<N<C2<int>>>>>, Object} for C1<int> and | |

// {N<C2<String>>, Object} for N<C1<String>> and | |

// Object is the most specific type in the intersection of the supertypes. | |

// Is least upper bound dynamic? | |

// Is least upper bound N<...> ? | |

// Is least upper bound C2<...> ? | |

// Is least upper bound N<dynamic> ? | |

// Is least upper bound N<N<...>> ? | |

// Is least upper bound N<C2<...>> ? | |

} | |

} | |

void main() { | |

testC1(false, null, null); | |

testC2(false, null, null); | |

} |