Pylint-Django: AttributeError: 'Subscript' object has no attribute 'name'

It's been a while I've been experiencing an issue when running Pylint with pylint_django. I include the error traceback and details on my environment.

I think I've found a solution and submitted a push request, but I publish the question here in case other people are facing the same issue.

The issue is publish in GitHub: https://github.com/PyCQA/pylint-django/issues/284

Traceback:

Traceback (most recent call last):
  File "D:\DevTools\Python38-32\lib\runpy.py", line 193, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "D:\DevTools\Python38-32\lib\runpy.py", line 86, in _run_code
    exec(code, run_globals)
  File "D:\DevRepo\dex\venv\Scripts\pylint.exe\__main__.py", line 9, in <module>
  File "d:\devrepo\dex\venv\lib\site-packages\pylint\__init__.py", line 22, in run_pylint
    PylintRun(sys.argv[1:])
  File "d:\devrepo\dex\venv\lib\site-packages\pylint\lint\run.py", line 344, in __init__
    linter.check(args)
  File "d:\devrepo\dex\venv\lib\site-packages\pylint\lint\pylinter.py", line 870, in check
    self._check_files(
  File "d:\devrepo\dex\venv\lib\site-packages\pylint\lint\pylinter.py", line 904, in _check_files
    self._check_file(get_ast, check_astroid_module, name, filepath, modname)
  File "d:\devrepo\dex\venv\lib\site-packages\pylint\lint\pylinter.py", line 930, in _check_file
    check_astroid_module(ast_node)
  File "d:\devrepo\dex\venv\lib\site-packages\pylint\lint\pylinter.py", line 1062, in check_astroid_module 
    retval = self._check_astroid_module(
  File "d:\devrepo\dex\venv\lib\site-packages\pylint\lint\pylinter.py", line 1107, in _check_astroid_module
    walker.walk(ast_node)
  File "d:\devrepo\dex\venv\lib\site-packages\pylint\utils\ast_walker.py", line 75, in walk
    self.walk(child)
  File "d:\devrepo\dex\venv\lib\site-packages\pylint\utils\ast_walker.py", line 72, in walk
    callback(astroid)
  File "d:\devrepo\dex\venv\lib\site-packages\pylint_django\checkers\forms.py", line 47, in visit_classdef
    if child.targets[0].name == 'exclude':
AttributeError: 'Subscript' object has no attribute 'name'

After having completely cleaned the file forms.py giving the error I think I've managed to isolate the problematic line. The file, still giving the error, now contains only this:

from django import forms

from dex import models


class DataSelectionForm(forms.ModelForm):
    """
    Form
    """
    class Meta:
        model = models.DataSelection
        fields = [
            "field",
        ]
        widgets = {}
        widgets["field"] = forms.CheckboxSelectMultiple

Of course, I've overly simplified that form class. It seems the error is caused by widgets["field"] = forms.CheckboxSelectMultiple, which in the real code is adding a different widget to a specific field after a loop creates the widgets dict.

If I use instead widgets = {"field": forms.CheckboxSelectMultiple} then everything is fine.

A few details about my configuration:

• OS: Windows 10 Pro x64
• Pip: 19.2.3
• Python: 3.8.2

Result of pip freeze:

astroid==2.4.2
certifi==2020.6.20
chardet==3.0.4
colorama==0.4.3
Django==2.2.14
django-activity-stream==0.9.0
django-annoying==0.10.6
django-filter==2.3.0
django-formtools==2.2
django-jsonstore==0.4.1
django-material==1.6.7
django-simple-history==2.11.0
django-viewflow==1.6.1
docutils==0.16
gunicorn==20.0.4
idna==2.10
isort==4.3.21
lazy-object-proxy==1.4.3
mccabe==0.6.1
oauthlib==3.1.0
Pillow==7.2.0
psycopg2==2.8.5
pyasn1==0.4.8
pyasn1-modules==0.2.8
pylint==2.5.3
pylint-django==2.2.0
pylint-plugin-utils==0.6
python-ldap==3.3.1
python-magic==0.4.18
python-magic-bin==0.4.14
pytz==2020.1
PyYAML==5.3.1
requests==2.24.0
requests-oauthlib==1.3.0
rope==0.17.0
six==1.15.0
sqlparse==0.3.1
toml==0.10.1
urllib3==1.25.10
wrapt==1.12.1