*args type checking

[max-sixty]

Environment data

• Language Server version: 2020.6.1
• OS and version: MacOS
• Python version (& distribution if applicable, e.g. Anaconda): Python3.7

Expected behaviour

@jakebailey suggested I open a new issue based on #15 (comment)

From that issue:

The dims issue is a third thing (separate again), as it's saying that you can't unpack Hashable into a *args parameter, which is true from a type checking point of view. If you believe that message to be wrong, I'd file a separate issue for that one as well, especially if you have the type checking mode set to "off".

I'm not sure this is correct. mypy & the pep seems fairly explicit that *args: Hashable should expect each of the args to Hashable, not args itself to be Hashable:
https://www.python.org/dev/peps/pep-0484/#arbitrary-argument-lists-and-default-argument-values

Copying the requested screenshot from the attached issue for convenience

Let me know if logs etc would be helpful.

Thank you!

[jakebailey]

Yes, dims should have type Tuple[Hashable] or Iterable[Hashable] (or similar, I can't recall the exact one used for variadic args as I'm typing this).

I'll likely clone this to check for myself, as this codebase seems to be very annotated (yay!), but if you remove that if block entirely, does the issue go away?

[max-sixty]

I'm not sure that's the case, though. Here's a screenshot of the link above:

Removing the if block does fix it. Why is that? Presumably entering the if block means that dims must be a tuple, which is iterable?

[erictraut]

This is definitely a bug in pyright/pylance. I'm debugging it now. In some code path (not yet determined) it's not treating the type of args as a Tuple. In other code paths it does. Stay tuned for a fix. And thanks for reporting the problem.

[jakebailey]

When I said "should have type Tuple[Hashable]", I meant the actual type of the dims variable within the function scope, not that you should annotate it as such. *dims: Hashable is a valid annotation.

[max-sixty]

When I said "should have type Tuple[Hashable]", I meant the actual type of the dims variable within the function scope, not that you should annotate it as such. *dims: Hashable is a valid annotation.

Great, I see, thanks

[erictraut]

I found and fixed the bug and added some additional unit tests. It will be fixed in the next release. Thanks again for the bug report.

[max-sixty]

Thank you! Feel free to close!

[jakebailey]

This issue has been fixed in version 2020.7.0, which we've just released. You can find the changelog here: https://github.com/microsoft/pylance-release/blob/master/CHANGELOG.md#202070-9-july-2020