// Copyright (c) 2019, 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

/// @assertion From the Unified collection Spec:
/// A [spreadElement] starting with [...?] is a constant element if its
/// expression is constant and it evaluates to [null] or a constant [List], [Set]
/// or [Map] instance originally created by a list, set or map literal. It is a
/// potentially constant element if the expression is potentially constant
/// expression.
/// @description: Checks that constant list [...?] spread element can only be
/// potentially constant list or set or [null].
/// @author iarkh@unipro.ru


class A {
  const A();
}

class B extends A {
  const B();
}

class MyClass {
  final String a;
  const MyClass(Object o) : a = o as String;
}


main() {
  const List l1 = [...?(A() is B ? [12345] : [])];
  const List l2 = [...?(A() is A ? [12345] : [0])];
  const List l3 = [...?(MyClass("test") is MyClass ? [12345] : [])];
  const List l4 = [...?(A() is B ? {12345} : {1})];
  const List l5 = [...?(A() is A ? {12345} : {0})];
  const List l6 = [...?(MyClass("test") is MyClass ? {12345} : {1})];
  const List l7  = [...?(A() is B ? [12345] : null)];
}