LanguageFeatures/nnbd/static_errors_A32_t13.dart

/*
 * 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.
 */
/**
 * @assertion It is a warning to use a null aware operator (?., ?.., ??, ??=,
 * or ...?) on an expression of type T if T is strictly non-nullable.
 *
 * @description Check it is a warning to use a null aware operator (?., ?.., ??,
 * ??=, or ...?) on a strictly non-nullable receiver. Test if (t is Object) {…}
 * @author sgrekhov@unipro.ru
 * @issue 39598
 * @issue 39714
 */

class A {
}
class C extends A {}

test(var a, C c) {
  if (a is Object) {
    a?.toString();
//  ^
// [cfe] Operand of null-aware operation '?.' has type 'Object' which excludes null.
//   ^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
    a?..toString();
//  ^
// [cfe] Operand of null-aware operation '?..' has type 'Object' which excludes null.
//   ^^^
// [analyzer] STATIC_WARNING.INVALID_NULL_AWARE_OPERATOR
    a ?? c;
//  ^
// [cfe] Operand of null-aware operation '??' has type 'Object' which excludes null.
//       ^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
    a ??= c;
//  ^
// [cfe] Operand of null-aware operation '??=' has type 'Object' which excludes null.
//        ^
// [analyzer] STATIC_WARNING.DEAD_NULL_AWARE_EXPRESSION
  }
}

main() {
  A? a = A();
  C c = C();
  test(a, c);
}