Avoid "value can be null" warning for extension method

Question

I am using an extension on Iterable that adds the following two methods

extension MyIterableExt<T> on Iterable<T> {
  bool get isEmptyOrNull => this == null || this.isEmpty;
  bool get isNotEmptyOrNull => this != null && this.isNotEmpty;
}

This works as I expected, but when I try to use it in statements where the receiver can be null, I get a warning in IntelliJ. For example, the following code works and prints true:

List<String> x;
print('${x?.reversed.isEmptyOrNull}');

Is there any way I can make the Dart Analyzer understand that the extension checks if this == null and thus not show the warning?

Please note that I do not want to have to add suppression directives to every file or line where I use this extension!

I know I can add // ignore_for_file: can_be_null_after_null_aware or // ignore: can_be_null_after_null_aware to make the warning go away, but what I'm looking for is a way to make the Dart Analyzer understand that the warning for this particular extension method is not needed.

This is in a non null-safe project, if that matters.

Answer 1

Based on the Flutter docs, you should be able to add a comment at the top of your code that will essentially disable null safety checks:

// @dart=2.9
import 'src/my_app.dart';

main() {
  //...
}

You should be able to put that comment at the top of any specific file you want this behavior. It doesn't have to be in your "main" file.

Answer 2

you can make Iterable Nullable

extension MyIterableExt<T> on Iterable<T>? {
  bool get isEmptyOrNull => this == null || this!.isEmpty;
  bool get isNotEmptyOrNull => this != null && this!.isNotEmpty;
}

Answer 3

Make extension base on Iterable? is the way, if you have to find something to disable the warning but not want to change the code then im sorry cause i never do that before.

void main() {
  Iterable? a = [];
  Iterable b = ['1', '2', '3'];
  
  print('a.isEmptyOrNull: ${a.isEmptyOrNull}');
  print('b.isEmptyOrNull: ${b.isEmptyOrNull}');
  print('a.isNotEmptyOrNull: ${a.isNotEmptyOrNull}');
  print('b.isNotEmptyOrNull: ${b.isNotEmptyOrNull}');
}

extension on Iterable? {
  bool get isEmptyOrNull => this == null || this!.isEmpty;
  bool get isNotEmptyOrNull => this != null && this!.isNotEmpty;
}

result

a.isEmptyOrNull: true
b.isEmptyOrNull: false
a.isNotEmptyOrNull: false
b.isNotEmptyOrNull: true