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Pylint incorrectly flags as unused-import things that are used as variable type annotations #1063

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fabianhjr opened this issue Aug 6, 2016 · 15 comments
Closed

Pylint incorrectly flags as unused-import things that are used as variable type annotations #1063

fabianhjr opened this issue Aug 6, 2016 · 15 comments
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@fabianhjr
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Steps to reproduce

from typing import Optional

a = None  # type: Optional[str]

Current behavior

pylint flags Optional as an unused-import

Expected behavior

pylint shouldn't flag Optional as unused-import

pylint --version output

pylint 1.6.4,
astroid 1.4.8
Python 3.5.2 (default, Jun 28 2016, 08:46:01)
[GCC 6.1.1 20160602]

Supporting documentation:
https://www.python.org/dev/peps/pep-0484/
@PCManticore
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Yes, we do not currently process type comments. A planned support for PEP 484 is in our roadmap, but I am not sure how fast we will reach it.

@PCManticore PCManticore added this to the 4K milestone Aug 11, 2016
@petrpulc
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Partially fixed in #1231, but only if they are used as a sting annotations for function attributes.

The full support is in question, as I don't personally see a way how to extract comments from AST(eroid) representation of the module... Any help or advice will be very appreciated.

@PCManticore
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You can't extract comments from astroid.

@euresti
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euresti commented Dec 30, 2016

Hi. I built a pylint extension inspired by https://gist.github.com/PCManticore/eca887488248b7594d37 to handle precisely this for our code base. With it all the unused imports go away, and it'll even warn you of stuff you haven't imported.

It also adds some inferences for special typing things like NamedTuple, NewType, TypeVar and handles subscripts on Generic types so that things like Employee = NamedTuple('Employee', [('name', str), ('id', int)]) won't generate an Invalid Constant Name error.

So if you think this is valuable I can work on cleaning up the code and making a pull request. I imagine this would be an extension that users can enable if they want to. Also suggestions on the name are welcome. Mine is called mypy_lint_enhancer.py but that's a really terrible name. Maybe extensions/pep484.py or extensions/typing.py.

Cheers!

@PCManticore
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@euresti That sounds pretty neat! Sure thing, please send a pull request. Depending on the additions, it might be something enabled by default.

euresti pushed a commit to euresti/pylint that referenced this issue Dec 31, 2016
RFC: Implement a new extension for pyling to handle type annotations …
f0302c4 
…as comments.

For now let's call this an RFC don't merge as is.

Basically this adds a plugin that adds a couple of transforms.

   the body as if they were real code. This silences unused-import and
   will trigger undefined-variable on missing imports.  Since these
   lines get inserted in the same line as the happen
   multiple-statements is disable on those lines.

   creating new types by subscripting existing ones.

   intended to silence invalid-name.

Also fixed a small bug in _supports_protocol where only metaclasses
were looked at and not the metaclasses of the base classes.

Tests pass!

Fixes pylint-dev#1063
euresti pushed a commit to euresti/pylint that referenced this issue Dec 31, 2016
RFC: Implement a new extension for pyling to handle type annotations …
d76a51a 
…as comments.

For now let's call this an RFC don't merge as is.

Basically this adds a plugin that adds a couple of transforms.

   the body as if they were real code. This silences unused-import and
   will trigger undefined-variable on missing imports.  Since these
   lines get inserted in the same line as the happen
   multiple-statements is disable on those lines.

   creating new types by subscripting existing ones.

   intended to silence invalid-name.

Also fixed a small bug in _supports_protocol where only metaclasses
were looked at and not the metaclasses of the base classes.

Tests pass!

Fixes pylint-dev#1063
@euresti euresti mentioned this issue Dec 31, 2016
Closed
euresti pushed a commit to euresti/pylint that referenced this issue Dec 31, 2016
RFC: Implement a new extension for pyling to handle type annotations …
d75ef88 
…as comments.

For now let's call this an RFC don't merge as is.

Basically this adds a plugin that adds a couple of transforms.

   the body as if they were real code. This silences unused-import and
   will trigger undefined-variable on missing imports.  Since these
   lines get inserted in the same line as the happen
   multiple-statements is disable on those lines.

   creating new types by subscripting existing ones.

   intended to silence invalid-name.

Also fixed a small bug in _supports_protocol where only metaclasses
were looked at and not the metaclasses of the base classes.

Tests pass!

Fixes pylint-dev#1063
euresti pushed a commit to euresti/pylint that referenced this issue Jan 1, 2017
RFC: Implement a new extension for pyling to handle type annotations …
9961a48 
…as comments.

For now let's call this an RFC don't merge as is.

Basically this adds a plugin that adds a couple of transforms.

   the body as if they were real code. This silences unused-import and
   will trigger undefined-variable on missing imports.  Since these
   lines get inserted in the same line as the happen
   multiple-statements is disable on those lines.

   creating new types by subscripting existing ones.

   intended to silence invalid-name.

Also fixed a small bug in _supports_protocol where only metaclasses
were looked at and not the metaclasses of the base classes.

Tests pass!

Fixes pylint-dev#1063
euresti pushed a commit to euresti/pylint that referenced this issue Jan 2, 2017
RFC: Implement a new extension for pyling to handle type annotations …
007534a 
…as comments.

For now let's call this an RFC don't merge as is.

Basically this adds a plugin that adds a couple of transforms.

   the body as if they were real code. This silences unused-import and
   will trigger undefined-variable on missing imports.  Since these
   lines get inserted in the same line as the happen
   multiple-statements is disable on those lines.

   creating new types by subscripting existing ones.

   intended to silence invalid-name.

Also fixed a small bug in _supports_protocol where only metaclasses
were looked at and not the metaclasses of the base classes.

Tests pass!

Fixes pylint-dev#1063
@PCManticore PCManticore mentioned this issue Apr 12, 2017
Closed
@PCManticore PCManticore modified the milestones: 1.7.0, 4K Apr 12, 2017
@PCManticore PCManticore mentioned this issue Apr 13, 2017
Closed
@PCManticore PCManticore modified the milestones: 1.8.0, 1.7.0 Apr 13, 2017
@PCManticore PCManticore modified the milestones: 1.8.0, 2.0 Dec 12, 2017
@gaborbernat
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so what's the status with this? @euresti code did make it or not?

@euresti
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euresti commented Mar 21, 2018

It never made it in. My code is here:
#1253
and here
pylint-dev/astroid#392

I don't use pylint anymore nor type comments anymore though. So I don't really have much need for this. Sorry.

@Daenyth
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Daenyth commented Mar 21, 2018

Pyflakes on python3 makes a vastly better experience IMO

@ohemorange
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Certbot would love to see this!

@PCManticore PCManticore modified the milestones: 2.0, 2.1 Apr 25, 2018
@s-kostyuk s-kostyuk mentioned this issue May 1, 2018
Merged
@gsemet
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gsemet commented May 3, 2018

that would be very handy indeed!

@rwrzesien rwrzesien mentioned this issue May 7, 2018
Merged
@PCManticore
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We recently switched to typed_ast from Dropbox, which has support for extracting type comments. This is fixed in the master branch, please give it a go when you get a chance!

@gaborbernat
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@PCManticore thanks, any non-dev release plans for it? 😄

@PCManticore
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Probably right after Python 3.7 comes out. We still have some issues to flesh out until then (check the 2.0 milestone from both pylint and astroid).

ahitrin added a commit to ahitrin/SiebenApp that referenced this issue Aug 27, 2018
@ahitrin
Typing: ignore "unused import" lint warning
6096a0b 
Pylint knows nothing about types used in comments and raises false
warnings about them [1]. A fix probably will not be released until
Python 3.7. Currently, the only way to live with it is to supppress
"unused import" warning.

> gaborbernat commented on 24 May
> @PCManticore thanks, any non-dev release plans for it?
>
> PCManticore commented on 24 May
> Probably right after Python 3.7 comes out. We still have some issues
> to flesh out until then (check the 2.0 milestone from both pylint and
> astroid).

[1]: pylint-dev/pylint#1063
@PCManticore
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@gaborbernat Already launched, forgot to reply.

@ksaaskil ksaaskil mentioned this issue Nov 15, 2018
Merged
2 tasks
@dvogelbacher
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Are there any plans to also fix this for python 2? (pylint 1.9)?

@allieychen allieychen mentioned this issue May 29, 2019
Merged
@chadrik chadrik mentioned this issue Sep 23, 2019
Closed
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RFC: Implement an extension for pyling to handle Type comment euresti/pylint
9 participants
@Daenyth @gsemet @fabianhjr @PCManticore @gaborbernat @euresti @ohemorange @petrpulc @dvogelbacher