Buffer support for re

[JelleZijlstra]

No description provided.

[JelleZijlstra]

Also showed up in python/mypy#12661. Replaces #7158.

[github-actions]

Diff from mypy_primer, showing the effect of this PR on open source code:

paroxython (https://github.com/laowantong/paroxython)
+ paroxython/map_taxonomy.py:223: error: Argument 1 to "append" of "list" has incompatible type "str"; expected "TaxonName"
core (https://github.com/home-assistant/core)
+ homeassistant/components/huawei_lte/device_tracker.py:170: error: On Python 3 formatting "b'abc'" with "{}" produces "b'abc'", not "abc"; use "{!r}" if this is desired behavior [str-bytes-safe]

[Akuli]

Maybe we should update the third-party regex stubs too.

[hauntsaninja]

Thanks! The homeassistant one looks like a false positive to me, probably a mypy bug, although we should be able to work around it if we wanted by using self types for Match.group

[JelleZijlstra]

@Akuli sure, I'll do that in a separate PR.

@hauntsaninja yes that one is weird to me. Not sure where mypy gets bytes from in this code: https://github.com/home-assistant/core/blob/859dcb396a6f7a1712a188fc67060019aea24e9c/homeassistant/components/huawei_lte/device_tracker.py#L170. I don't understand how self types would help either.

(Also, the paroxython one looks like a true positive. I don't know why mypy didn't catch it before.)

[hauntsaninja]

I filed python/mypy#12666 for it