pylint 1.9.5 is broken because of isort 5

[abitrolly]

pylint is used by this project that is #not-so-trivial to port to Python 3 yet.

Finished processing dependencies for pylint==1.9.5
Traceback (most recent call last):
  File "build/bin/pylint", line 11, in <module>
    load_entry_point('pylint==1.9.5', 'console_scripts', 'pylint')()
...
  File "/Users/travis/gopath/src/github.com/grumpyhome/grumpy/grumpy-runtime-src/build/lib/python2.7/site-packages/pylint-1.9.5-py2.7.egg/pylint/utils.py", line 1033, in register_plugins
    module = modutils.load_module_from_file(join(directory, filename))
  File "/Users/travis/gopath/src/github.com/grumpyhome/grumpy/grumpy-runtime-src/build/lib/python2.7/site-packages/astroid-1.6.6-py2.7.egg/astroid/modutils.py", line 272, in load_module_from_file
    return load_module_from_modpath(modpath, path, use_sys)
  File "/Users/travis/gopath/src/github.com/grumpyhome/grumpy/grumpy-runtime-src/build/lib/python2.7/site-packages/astroid-1.6.6-py2.7.egg/astroid/modutils.py", line 233, in load_module_from_modpath
    module = imp.load_module(curname, mp_file, mp_filename, mp_desc)
  File "/Users/travis/gopath/src/github.com/grumpyhome/grumpy/grumpy-runtime-src/build/lib/python2.7/site-packages/pylint-1.9.5-py2.7.egg/pylint/checkers/imports.py", line 40, in <module>
    import isort
  File "/Users/travis/gopath/src/github.com/grumpyhome/grumpy/grumpy-runtime-src/build/lib/python2.7/site-packages/isort-5.6.4-py2.7.egg/isort/__init__.py", line 2, in <module>
    from . import settings
  File "/Users/travis/gopath/src/github.com/grumpyhome/grumpy/grumpy-runtime-src/build/lib/python2.7/site-packages/isort-5.6.4-py2.7.egg/isort/settings.py", line 36
    FILE_SKIP_COMMENTS: Tuple[str, ...] = (
                      ^
SyntaxError: invalid syntax

Expected behavior

1.9.x to still work for Python 2.

[dbaty]

pylint 1.9.5 had a relatively loose requirement on isort: isort >= 4.2.5. It was fine when 1.9.5 was released.

But now that pulls isort 5, which is not compatible with Python 2 anymore. (That is, it can read Python 2 code, but you need to run isort with Python 3.6+, cf. its documentation for further details.)

In your case, I would suggest adding isort<5 before pylint==1.9.5 in your project requirements. That should get you isort 4, which is compatible with Python 2.

If that's all right, you may close this issue.

[abitrolly]

@dbaty I expect there are many legacy projects, where porting efforts would benefit from having working pylint out of the box. If it is possible to release a mainenance update for 1.9.x, I'd rather wait for that.

[PCManticore]

My opinion is that the best course of action here is to pin the isort version in 1.9.6. This won't get you isort 5 but at least pylint would still be able to work. We won't port the isort 4+5 support that was added in pylint 2.6 though.

[abitrolly]

Pinning isort in 1.9.6 seems fine with me.

[Pierre-Sassoulas]

Meanwhile, if you encounter the problem in your CI you can pin isort yourself. Pylint has isort >= 4.2.5 in 1.9.5, if you add isort <5 in your own requirements, 1.9.5 will work again before we release 1.9.6 (@PCManticore I could do it, but I would need to have maintainer right on pypi.).

[abitrolly]

I'll be waiting for the new release. Thanks for the hint, though.

[jacobtylerwalls]

This issue is useful as a google-indexed reference for folks needing to manage their dependencies on legacy projects.

Although it was worthy of discussion at the time, 1.9.5 is almost three years old, and I know of no plans to maintain it here (and I wouldn't be in favor of doing so). I hope that makes sense.