"No overload variant of sub" Issue with re.compile after upgrading to mypy 0.4

[timabbott]

On upgrading to mypy 0.4 I get this new error:

/home/tabbott/foo.py:4: error: No overload variant of "sub" matches argument types [typing.Pattern[builtins.str*], builtins.str, builtins.str]

when using a compiled regular expression:

content = "test"
import re
quote_re = re.compile(r'{quote}(.*?){quote}', re.DOTALL)
content = re.sub(quote_re, r'~~~ quote\n\1\n~~~', content)

Haven't had a chance to investigate whether this is caused be a change in typeshed or mypy itself.

[gvanrossum]

That's strange. Assuming you're using --py2 mode (there's no overload in the Python 3 stub for re.pyi). The stdlib/2.7/re.pyi hasn't changed since your change 21c90d5 in January. It looks like the spec for sub() is wrong, it doesn't allow Pattern[AnyStr] for the pattern arg. I'm guessing that some bug in overload checking was fixed that surfaced this. The stub needs to be fixed.

[rwbarton]

Oh, I think one of my changes made it so that type variables with value restriction in overloads would only match types that are a subtype of the union of the possible values of the type variable. So Pattern[str] no longer matches Union[str, unicode]. Not sure why the statement type checked in the first place, maybe #1322?

[timabbott]

OK, I think this turned out to be just a stub issue, so we can close it, right?

[gvanrossum]

Yup.