Mypy: New "module has no attribute" errors in 0.710

[gregbedwell]

This is a change in behaviour I've noticed in 0.710. I can't help but think it's so simple that I'm obviously doing something very wrong, but I can't obviously see what. My apologies for wasting your time if it is user error! None of the other checking/linting tools I've tried warn about any issues here.

Here's a reproducer for what I'm seeing:

(py3.6) e:\tmp\mypy-issue>cat foo.py
from bar import qaz

print(qaz())

(py3.6) e:\tmp\mypy-issue>cat bar\__init__.py
from bar.baz import qaz

__all__ = [
    'qaz',
]

(py3.6) e:\tmp\mypy-issue>cat bar\baz.py
def qaz() -> int:
    return 42

(py3.6) e:\tmp\mypy-issue>python --version
Python 3.6.4

(py3.6) e:\tmp\mypy-issue>python foo.py
42

(py3.6) e:\tmp\mypy-issue>pip install -q "mypy<0.710"

(py3.6) e:\tmp\mypy-issue>mypy --version
mypy 0.701

(py3.6) e:\tmp\mypy-issue>mypy --strict .

(py3.6) e:\tmp\mypy-issue>pip install -q "mypy==0.710"

(py3.6) e:\tmp\mypy-issue>mypy --version
mypy 0.710

(py3.6) e:\tmp\mypy-issue>mypy --strict .
foo.py:1: error: Module 'bar' has no attribute 'qaz'

(py3.6) e:\tmp\mypy-issue>

Let me know if you need any more information.

Thanks!

[msullivan]

This is a result of the new --no-implicit-reexports flag, which is part of
--strict. See
https://mypy.readthedocs.io/en/latest/command_line.html#miscellaneous-strictness-flags

It can be fixed by doing import qaz as qaz.

On Thu, Jun 20, 2019, 11:03 Greg Bedwell [e-mail] wrote:

This is a change in behaviour I've noticed in 0.710. I can't help but
think it's so simple that I'm obviously doing something very wrong, but I
can't obviously see what. My apologies for wasting your time if it is user
error! None of the other checking/linting tools I've tried warn about any
issues here.

Here's a reproducer for what I'm seeing:

(py3.6) e:\tmp\mypy-issue>cat foo.py
from bar import qaz

print(qaz())

(py3.6) e:\tmp\mypy-issue>cat bar__init__.py
from bar.baz import qaz

__all__ = [
'qaz',
]

(py3.6) e:\tmp\mypy-issue>cat bar\baz.py
def qaz() -> int:
return 42

(py3.6) e:\tmp\mypy-issue>python --version
Python 3.6.4

(py3.6) e:\tmp\mypy-issue>python foo.py
42

(py3.6) e:\tmp\mypy-issue>pip install -q "mypy<0.710"

(py3.6) e:\tmp\mypy-issue>mypy --version
mypy 0.701

(py3.6) e:\tmp\mypy-issue>mypy --strict .

(py3.6) e:\tmp\mypy-issue>pip install -q "mypy==0.710"

(py3.6) e:\tmp\mypy-issue>mypy --version
mypy 0.710

(py3.6) e:\tmp\mypy-issue>mypy --strict .
foo.py:1: error: Module 'bar' has no attribute 'qaz'

(py3.6) e:\tmp\mypy-issue>

Let me know if you need any more information.

Thanks!

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[gregbedwell]

Ah. Brilliant. Thanks! Sorry for the noise

[pcorpet]

@msullivan this is blocking when this happens in a dependency (I want to access init from https://github.com/getsentry/sentry-python/blob/master/sentry_sdk/__init__.py).

Should I just run mypy with --implicit-reexport then?

And/or should I ask the lib to export it using init as init?