"Undefined name" on using `six`, which is in typeshed

[gnprice]

Trying to run Pyre on Zulip, I get the following errors (among many others):

zthumbor/loaders/helpers.py:64:11 Undefined name [18]: Global name `six` is undefined.
zthumbor/loaders/helpers.py:64:20 Undefined name [18]: Global name `six` is undefined.
zthumbor/loaders/helpers.py:70:11 Undefined name [18]: Global name `six` is undefined.
zthumbor/loaders/helpers.py:70:20 Undefined name [18]: Global name `six` is undefined.

This puzzles me because six is in typeshed -- which Pyre is supposed to refer to, right? In fact, here's the relevant import line:

from six.moves.urllib.parse import urlparse, parse_qs

and indeed that module, and those names within it, are there in typeshed.

I don't have any good ideas for what's going wrong in this instance. If there isn't an obvious (to you as the Pyre developers) thing that this could be, I can try refining out a minimal repro case.

[sinancepel]

@gnprice by default, pyre only pulls in the stdlib stubs from typeshed. You can add the third party directory to your .pyre_configuration by adding the line `"search_path": ["/path/to/typeshed/third_party"]. I'll see if we can make the documentation clearer with respect to this.

[PeterJCLaw]

@sinancepel I've hit (and was about to report, but found this issue first) errors from pyre indicating that it's not finding third party stubs from typeshed. To me this is quite surprising, as I'd very much expect those stubs to be being found by default.

Since most users of pyre will be installing via pip install pyre-check, they most likely won't know where their typeshed is without looking for it. I see this as a good motivation for making it easier to enable use of typeshed third party stubs.

Would you be open to either or both:

• making it so that pyre picks up the third party stubs from the typeshed by default
• providing an option which enables third party stubs to be picked up from the typeshed (perhaps --[no-]third-party-stubs-from-typeshed?)

I'd also be curious to understand why the default is what it is (as noted, I find it surprising that the default is to ignore part of the typeshed), so maybe covering that explicitly in the docs would be useful.

Meta: I'm assuming from this issue having been closed that the documentation change you alluded to has happened. If not, I'd be happy to review whether this is needed after that clarification is in place.

[dark]

The main reason to initially support only stdlib was simplicity. As the project grows, we will start looking into 3rd-party as well.
As a matter of fact, I am working on this feature, so I am going to reopen this issue and self-assign it for clarity.