Pycodestyle: FutureWarning: Possible nested set for EXTRANEOUS_WHITESPACE_REGEX

[The-Compiler]

When running pycodestyle 2.3.1 with Python 3.7, I get:

/home/florian/proj/qutebrowser/git/.tox/flake8/lib/python3.7/site-packages/pycodestyle.py:113: FutureWarning: Possible nested set at position 1
  EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')

[adiroiban]

See https://docs.python.org/dev/whatsnew/3.7.html

Support of nested sets and set operations in regular expressions as ..... To avoid a warning escape them with a backslash.

Let me see if I can fix this :)

[RawrBear]

Getting the same thing in Atom while using Python 3.7.
Installed linter-flake8 and got
python37\lib\site-packages\pycodestyle.py:113: FutureWarning: Possible nested set at position 1 EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')
As a python noob, I really don't know what else to add :(

[Arcanemagus]

@RawrBear Make sure that your pycodestyle version is v2.4.0 or higher as that was the first release that included the fix.

[RawrBear]

@Arcanemagus I didn't get notified about your message until now.
Thanks for the fix. I updated pycodestyle through pip which worked but broke flake8 because apparently its only compatible with version 2.3.1. so linter-flake8 is a no go right now :/

Fix one problem, find another ten lol

[jeidsath]

@RawrBear I had the same problem, so I just copied the escaped version of the line to my code:

Fixed version: https://github.com/PyCQA/pycodestyle/blob/master/pycodestyle.py#L133

[declantraynor]

@RawrBear I've found in the meantime that installing flake8 from master works around the problem:

pip install -e git+https://gitlab.com/pycqa/flake8#egg=flake8

Hope this helps.

[ghost]

@declantraynor Maybe I'm nitpicking but pip install -e without a specific commit is prone to changes and breakage. I think it's a good idea to pin a specific commit, the newest is 9631dac5 as of time of writing

pip install -e git+https://gitlab.com/pycqa/flake8@9631dac5#egg=flake8

[matthieugouel]

In addition you can specify the directory where flake8 will be installed with the option --src. So personally I used this command to install flake8 in my global site package :

pip3 install -e git+https://gitlab.com/pycqa/flake8@9631dac5#egg=flake
8 --src /usr/local/lib/python3.7/site-packages

[nomoon]

The workaround doesn't seem to function in Pipenv-based projects, where the specified flake8 dependency gets discarded and 3.5.0 is used regardless.

[bsergean]

Should we open a ticket on the flake8 repo? It is still broken for me.
The workaround ... doesn't work, as I cannot access gitlab.

$ pip install -e git+https://gitlab.com/pycqa/flake8@9631dac5#egg=flake8
Obtaining flake8 from git+https://gitlab.com/pycqa/flake8@9631dac5#egg=flake8
  Cloning https://gitlab.com/pycqa/flake8 (to revision 9631dac5) to ./venv/src/flake8
fatal: unable to access 'https://gitlab.com/pycqa/flake8/': LibreSSL SSL_connect: SSL_ERROR_SYSCALL in connection to gitlab.com:443 
Command "git clone -q https://gitlab.com/pycqa/flake8 /xxx/venv/src/flake8" failed with error code 128 in None

But I can reach gitlab at port 443 though.

$ telnet gitlab.com 443
Trying 52.167.219.168...
Connected to gitlab.com.
Escape character is '^]'.

[PiDelport]

Downstream flake8 issue: https://gitlab.com/pycqa/flake8/issues/437

[JayRizzo]

FYI if you want to fix this yourself modify the file, as it is a simple problem with the regex.

my error:

   flake8 --select=F test.py 
    /Users/jkirchoff/Documents/GitHub/test/venv/lib/python3.7/site-packages/pep8.py:110: 
    FutureWarning: Possible nested set at position 1
      EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')

I modified the regex, to my best guess until this is resolved by escaping the literals.

EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[\[\(\{]\s|\s\[\]\}\)\,\;\:]')

My understanding of this is that there is a self-defining-loop that causes this error.

anyway if you modify the line 110, this fixes the error.
=)

UPDATE:

@hongqn , you are correct the exact path on my machine is

/usr/local/lib/python3.7/site-packages/pycodestyle.py

Hi All,

I know this is closed but anyone that used my regex, cc: @VarunDelft
please update using this one.
This finds the intended targets, any spaces after ({[ and before ]}),:;

EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'((\(|\[|\{) | (\}|\]|\)|\;|\:|\,))')

Request: As I am unaware of your PR process please pass along to whom it concerns. =)

Have a great day all!

[hoylemd]

@JayRizzo Thanks for the workaround! Just to clarify, it should be pep8.py in your environment's site-packages where you make that edit?

[VarunDelft]

Thanks @JayRizzo

[bsergean]

Given that flake8 is still stuck at 3.5.0, because of an incompatibly change in pycodestyle==2.4.0, could there be a release of pycodestyle==2.3.2 with just that regex fix ?

Editing /usr/local/lib/python3.7/site-packages/pycodestyle.py in place feels like a hack ... I guess I should make a PR, but I don't know if there are branches or infrastructure in place to release a 2.3.2; is there a branch for 2.3 or something like that ?

[CoreyCole]

Here is a tag for 2.3.1 (it is the latest with a tag before 2.4.0) https://github.com/PyCQA/pycodestyle/tree/2.3.1

[bsergean]

Thanks for the link / I tried to use 2.3.1 explicitly, but it doesn't have that regex fix.

flake8 `find src -name '*.py'`
/xxx/venv/lib/python3.7/site-packages/pycodestyle.py:113: FutureWarning: Possible nested set at position 1
  EXTRANEOUS_WHITESPACE_REGEX = re.compile(r'[[({] | []}),;:]')
(venv) $ pip freeze | grep pycodes
pycodestyle==2.3.1
(venv) $ pip freeze | grep flake8
flake8==3.5.0

[CoreyCole]

I opened a PR, but I'm not sure what branch to target with it- it is at master for now https://github.com/PyCQA/pycodestyle/pull/796

[sobolevn]

If you are using pytest-flake8 you can disable this warning with:

filterwarnings =
  ignore::FutureWarning

Place these two lines in your setup.cfg or similar file. Full example: https://github.com/wemake-services/wemake-python-styleguide/blob/master/setup.cfg#L35-L38

[airhorns]

FYI flake8 3.6.0 has been released which includes support for pycodestyle 2.4.0 and thus removes this warning if you're using flake8! Just make sure to upgrade to 3.6.0. 🎉