LanguageFeatures/nnbd/flow-analysis/reachability_A01_t04.dart

/*
 * Copyright (c) 2020, 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 Variable or getter: If N is an expression of the form x where the
 * type of x is T then:
 *
 * If T <: Never then:
 *  Let null(N) = unreachable(before(N)).
 *  Let notNull(N) = unreachable(before(N)).
 * Otherwise if T <: Null then:
 *  Let null(N) = before(N).
 *  Let notNull(N) = unreachable(before(N)).
 * Otherwise if T is non-nullable then:
 *  Let null(N) = unreachable(before(N)).
 *  Let notNull(N) = before(N).
 *
 * @description Checks reachability after variable or getter. Test variable of
 * type Null
 *
 * @author sgrekhov@unipro.ru
 * @issue 41985
 */
// Requirements=nnbd-strong

main() {
  int i;
  Null n = null;
  if (n == null) {
    i = 42; // condition is always true therefore `i` must be definitely assigned
  }
  i; // It's not an error to read local non-nullable variable if it is definitely assigned
}