Returning promise from non-async function doesn't work

[sergejostir]

What version of async are you using?
3.2.0

Which environment did the issue occur in (Node/browser/Babel/Typescript version)
Node

What did you do? Please include a minimal reproducible case illustrating issue.

async.waterfall([
  () => Promise.resolve(),
  async () => {
    console.log('not called');
  },
]);

What did you expect to happen?
I would expect this snippet to work properly. Async function is just a normal function that 100% returns Promise. If I return promise from the non-async function the result is exactly the same, so I do not understand why async package fails in this case.

What was the actual result?
The code did not execute properly.

[aearly]

Async function is just a normal function that 100% returns Promise.

This is not entirely true, async functions have a detectable AsyncFunction type we can handle separately. If you're going to return a promise, it must explicitly use the async keyword so the library can handle it properly (and also not pass a callback).

[sergejostir]

I see. It confused me because I expected to get the same result for using native async function and simply returning a promise. I found an explanation here now: #1386