Analyzer: Future<void> requiring return statement?

[matanlurey]

As of dev-6.0:

Future<void> doThing() async {
  return;
}

... lints the return statement with:

warning: Missing return value after 'return'. (return_without_value at [...])

If I change it to return null;, the warning goes away. Interestingly enough, Future<Null> is fine:

Future<Null> doThing() async {
  return;
}

---

On a related note - what is the status of Future<void>? I didn't try compiling/running the code.

EDIT: Thanks @munificent - I see that full support is not planned until after the FE migration.

[lrhn]

You should probably be allowed to not return, or use return; , with a return type of either void or FutureOr<void> (or FutureOr<FutureOr<void>>, etc).

Maybe something like:

A type is "voidable" if it is void or it is FutureOr<T> and T is voidable. It's an error if a function body contains return; or can reach the end of the body without throwing or returning, unless the function's return type is voidable. It is an error if a function body contains return expr; and the function's return type is void.

The FutureOr<void> type is a little tricky. Any value can be assigned to it, so it's not that different from dynamic, void or Object, and it's not void. There are operations you can do on it - it's just that if it\s not Future<void>, you're not supposed to use it.