merge-pyi: async def given `coroutine` type, but requires the inner return type?

[crwilcox]

I ran pytype and then merge-pyi on an existing codebase. In a few places, the following was added.

async def _commit(self) -> Coroutine[Any, Any, list]:
    ...
    ...
    return list()

However, this will result in an error when running pytype, as the expected type is list. This can be resolved with a Union, though this seems off?

async def _commit(self) -> Union[Coroutine[Any, Any, list], list]:
    ...
    ...
    return list()

PR with this staged: https://github.com/googleapis/python-firestore/pull/134/files#diff-b966babc1b8a5b217e6e2c88fad8c38bR133

[rchen152]

Adding a Union doesn't seem right. If the only problem with the list annotation is that it doesn't match what merge-pyi inserted and it otherwise works for type-checking, I'd go with that. If the Coroutine annotation is the right one, you can add # pytype: disable=bad-return-type on the return list() line to silence the error. Either way, I agree that this seems like a bug.

[crwilcox]

@rchen152 yeah. I think these should all be the inner type, not a coroutine type (list in this case)

I was cautious that maybe they can look like both (based on if awaited maybe?) but I think you have the right of it.