[Regression: 0.470->0.501] Lots of new errors relating to "uninhabited" in Django-based app code #2978

inducer · 2017-03-08T01:02:50Z

git clone https://github.com/inducer/relate
cd relate
./run-mypy.sh

used to work with no warnings in 0.470. Now, it spews this:

course/content.py:877: error: <uninhabited> has no attribute "id"
course/content.py:1445: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/content.py:1446: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/utils.py:179: error: <uninhabited> has no attribute "exam"
course/utils.py:533: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/utils.py:534: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/utils.py:583: error: <uninhabited> has no attribute "permissions"
course/enrollment.py:129: error: <uninhabited> has no attribute "roles"
course/enrollment.py:143: error: <uninhabited> has no attribute "permissions"
course/views.py:156: error: <uninhabited> has no attribute "has_permission"
course/flow.py:416: error: <uninhabited> has no attribute "user"
course/flow.py:633: error: <uninhabited> has no attribute "answer"
course/flow.py:830: error: <uninhabited> has no attribute "get_most_recent_grade"
course/flow.py:848: error: Unsupported left operand type for + (some union)
course/flow.py:855: error: Unsupported left operand type for + (some union)
course/flow.py:862: error: Unsupported left operand type for + (some union)
course/flow.py:923: error: <uninhabited> has no attribute "is_submitted_answer"
course/flow.py:924: error: <uninhabited> has no attribute "save"
course/flow.py:1264: error: <uninhabited> has no attribute "get_most_recent_grade"

Focusing on the first error:

https://github.com/inducer/relate/blob/fed97182f4e8940bb032a224c5cbcd007a8bd722/course/content.py#L877

it should be clear that course is an instance of Course (i.e. not None).

The text was updated successfully, but these errors were encountered:

gvanrossum · 2017-03-08T01:21:32Z

Yeah, I can repro this. @ddfisher The script uses --strict-optional.

I experimented with that one location a bit, and found:

If you replace if course is not None ... with if course ... the error goes away.
Without that change, reveal_type(course) inside the if shows <uninhabited>; with that change it shows Course.
Either way, before the if, reveal_type(course) shows Optional[Course].

Definitely sounds like a binder issue...

gvanrossum · 2017-03-08T01:25:23Z

@inducer If you want to help, maybe you can use git bisect to track down the exact mypy commit that caused this?

inducer · 2017-03-08T01:51:24Z

Would love to, but paper deadline and 12 proposals to review over the next 7 days... Sorry!

refi64 · 2017-03-09T18:15:23Z

Under mypy 0.47, I still get:

course/flow.py:1884: error: Call to untyped function "make_form" in typed context
course/flow.py:1943: error: Call to untyped function "form_to_html" in typed context
course/grading.py:189: error: Call to untyped function "make_form" in typed context
course/grading.py:206: error: Call to untyped function "form_to_html" in typed context
course/grading.py:229: error: Call to untyped function "update_grade_data_from_grading_form_v2" in typed context

refi64 · 2017-03-09T18:25:37Z

Looks like some of the errors were caused by 9496d6f; I'm still trying to locate the others.

refi64 · 2017-03-09T18:35:36Z

Oof, this one's a mess...more of the errors were from 9406886, but there are still some that haven't come up yet...

refi64 · 2017-03-09T18:48:36Z

Around half of the errors were from, bizarrely enough, 3cc5201.

So, to sum it up:

9496d6f started the trouble:

course/content.py:1445: error: object has no attribute "preview_git_commit_sha"
course/content.py:1446: error: object has no attribute "preview_git_commit_sha"
course/utils.py:533: error: object has no attribute "preview_git_commit_sha"
course/utils.py:534: error: object has no attribute "preview_git_commit_sha"
course/utils.py:583: error: object has no attribute "permissions"
course/enrollment.py:129: error: object has no attribute "roles"
course/views.py:156: error: object has no attribute "has_permission"
course/flow.py:1264: error: object has no attribute "get_most_recent_grade"

9406886 changed the objects to <uninhabited>:

course/content.py:1445: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/content.py:1446: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/utils.py:533: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/utils.py:534: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/utils.py:583: error: <uninhabited> has no attribute "permissions"
course/enrollment.py:129: error: <uninhabited> has no attribute "roles"
course/views.py:156: error: <uninhabited> has no attribute "has_permission"
course/flow.py:1264: error: <uninhabited> has no attribute "get_most_recent_grade"

3cc5201 somehow just made it all worse:

course/content.py:877: error: <uninhabited> has no attribute "id"
course/content.py:1445: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/content.py:1446: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/utils.py:179: error: <uninhabited> has no attribute "exam"
course/utils.py:533: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/utils.py:534: error: <uninhabited> has no attribute "preview_git_commit_sha"
course/utils.py:583: error: <uninhabited> has no attribute "permissions"
course/enrollment.py:129: error: <uninhabited> has no attribute "roles"
course/enrollment.py:143: error: <uninhabited> has no attribute "permissions"
course/views.py:156: error: <uninhabited> has no attribute "has_permission"
course/flow.py:416: error: <uninhabited> has no attribute "user"
course/flow.py:633: error: <uninhabited> has no attribute "answer"
course/flow.py:830: error: <uninhabited> has no attribute "get_most_recent_grade"
course/flow.py:848: error: Unsupported left operand type for + (some union)
course/flow.py:855: error: Unsupported left operand type for + (some union)
course/flow.py:862: error: Unsupported left operand type for + (some union)
course/flow.py:923: error: <uninhabited> has no attribute "is_submitted_answer"
course/flow.py:924: error: <uninhabited> has no attribute "save"
course/flow.py:1264: error: <uninhabited> has no attribute "get_most_recent_grade"

refi64 · 2017-03-09T19:52:14Z

Also, I can confirm that 9496d6f was the root cause; temporarily reverting it made the errors go away.

gvanrossum · 2017-03-09T20:24:04Z

Thanks for the great investigation! Hopefully Jukka knows how to fix it.

refi64 · 2017-03-09T20:35:35Z

Reduced test case:

# Run mypy with --strict-optional
from typing import Any, Optional

class A(Any): pass

def f(a: Optional[A]):
    if a is not None:
        reveal_type(a)

(The Any stemmed from a class inside of a non-existent import, since --ignore-missing-imports was passed).

Ironically enough, the bad commit's message says:

In particular, this helps with classes that have Any base classes.

:/

refi64 · 2017-03-09T23:06:35Z

Also, this was caused by the same commit:

from typing import Any, Union

class A(Any): pass
class B: pass

def f(a: Union[A, B]):
    if not isinstance(a, B):
        reveal_type(a)  # Union[<ERROR>, <ERROR>]

JukkaL · 2017-03-10T12:05:54Z

Oh well, I knew that the bad commit was only a partial fix, but I didn't foresee these problems. A more complete fix that I was working on caused many problems with internal Dropbox code. The bad commit fixed other urgent issues so just reverting it is not a good option. I'll look at finishing up the more complete fix.

ddfisher · 2017-03-14T18:26:00Z

Well, one problem is we need to kill this:

         if any(isinstance(typ, AnyType) for typ in items):
              return AnyType()

JukkaL · 2017-03-14T18:38:18Z

@ddfisher Yup, that's gone in my private branch.

The main change is that unions containing Any are no longer simplified to just Any. Also union simplification now has a deterministic result unlike previously, when result could depend on the order of items in a union (this is true modulo remaining bugs). This required changes in various other places to keep the existing semantics, and resulted in some fixes to existing test cases. I also had to fix some tangentially related minor bugs that were triggered by the other changes. We generally don't have fully constructed TypeInfos so we can't do proper union simplification during semantic analysis. Just implement simple-minded simplification that deals with the cases we care about. Fixes #2978. Fixes #1914.

JukkaL · 2017-04-04T11:08:03Z

I think that this is still open because the fix was reverted.

gvanrossum added the topic-strict-optional label Mar 8, 2017

gvanrossum added the bug mypy got something wrong label Mar 8, 2017

JukkaL self-assigned this Mar 10, 2017

JukkaL added a commit that referenced this issue Mar 19, 2017

Fix #2978.

c6fd9a6

JukkaL mentioned this issue Mar 19, 2017

[Reverted] Fixes to union simplification, isinstance and more #3025

Merged

JukkaL added a commit that referenced this issue Mar 21, 2017

Fix #2978.

dc62a99

JukkaL closed this as completed in #3025 Mar 29, 2017

JukkaL reopened this Apr 4, 2017

ilevkivskyi closed this as completed in 4141d20 Apr 4, 2017

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[Regression: 0.470->0.501] Lots of new errors relating to "uninhabited" in Django-based app code #2978

[Regression: 0.470->0.501] Lots of new errors relating to "uninhabited" in Django-based app code #2978

inducer commented Mar 8, 2017

gvanrossum commented Mar 8, 2017

gvanrossum commented Mar 8, 2017

inducer commented Mar 8, 2017

refi64 commented Mar 9, 2017

refi64 commented Mar 9, 2017

refi64 commented Mar 9, 2017

refi64 commented Mar 9, 2017

refi64 commented Mar 9, 2017

gvanrossum commented Mar 9, 2017

refi64 commented Mar 9, 2017 •

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refi64 commented Mar 9, 2017

JukkaL commented Mar 10, 2017

ddfisher commented Mar 14, 2017

JukkaL commented Mar 14, 2017

JukkaL commented Apr 4, 2017

[Regression: 0.470->0.501] Lots of new errors relating to "uninhabited" in Django-based app code #2978

[Regression: 0.470->0.501] Lots of new errors relating to "uninhabited" in Django-based app code #2978

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inducer commented Mar 8, 2017

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