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prefer-specifying-future-value-type

v1.30.0
warning
effort: 2m
teams+

Warns when a Future.value invocation gets a nullable argument, but the expected type is not nullable.

If such Future.value invocation receives null at runtime, it will throw an exception because the expected type it not nullable.

Example​

❌ Bad:

void fn(int? nullable) {
  // LINT: This Future can throw at runtime because the provided value is nullable, but the expected type is not.
  //  Try specifying the type argument as nullable or passing a non-nullable value.
  final int value = Future.value(nullable);

  // LINT: This Future can throw at runtime because the provided value is nullable, but the expected type is not.
  //  Try specifying the type argument as nullable or passing a non-nullable value.
  final value = Future<int>.value(nullable);
}

✅ Good:

void fn(int? nullable) {
  final value = Future.value(1);
  final value = Future<int?>.value(nullable);
}

Additional Resources​

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