[Astroid 2.5] astroid.exceptions.DuplicateBasesError: Duplicates found in MROs (OrderedSet)

[Toilal]

Steps to reproduce

1. git clone https://github.com/inetum-orleans/docker-devbox-ddb
2. cd docker-devbox-ddb
3. pylint ddb
4. 💥

Current behavior

Pylint crash with the following stack

Traceback (most recent call last):
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/decorators.py", line 34, in cached
    return cache[func]
KeyError: <bound method ClassDef.slots of <ClassDef.OrderedSet l.55 at 0x7f75735663d0>>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/toilal/.pyenv/versions/3.8.7-ddb/bin/pylint", line 8, in <module>
    sys.exit(run_pylint())
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/__init__.py", line 22, in run_pylint
    PylintRun(sys.argv[1:])
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/lint/run.py", line 349, in __init__
    linter.check(args)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/lint/pylinter.py", line 862, in check
    self._check_files(
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/lint/pylinter.py", line 896, in _check_files
    self._check_file(get_ast, check_astroid_module, name, filepath, modname)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/lint/pylinter.py", line 922, in _check_file
    check_astroid_module(ast_node)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/lint/pylinter.py", line 1054, in check_astroid_module
    retval = self._check_astroid_module(
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/lint/pylinter.py", line 1099, in _check_astroid_module
    walker.walk(ast_node)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/utils/ast_walker.py", line 75, in walk
    self.walk(child)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/utils/ast_walker.py", line 72, in walk
    callback(astroid)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/pylint/checkers/variables.py", line 1203, in visit_importfrom
    module = node.do_import_module(name_parts[0])
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/mixins.py", line 99, in do_import_module
    return mymodule.import_module(
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/scoped_nodes.py", line 646, in import_module
    return MANAGER.ast_from_module_name(absmodname)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/manager.py", line 191, in ast_from_module_name
    return self.ast_from_file(found_spec.location, modname, fallback=False)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/manager.py", line 100, in ast_from_file
    return AstroidBuilder(self).file_build(filepath, modname)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/builder.py", line 139, in file_build
    return self._post_build(module, encoding)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/builder.py", line 159, in _post_build
    self.delayed_assattr(delayed)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/builder.py", line 235, in delayed_assattr
    if not _can_assign_attr(inferred, node.attrname):
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/builder.py", line 60, in _can_assign_attr
    slots = node.slots()
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/decorators.py", line 36, in cached
    cache[func] = result = func(*args, **kwargs)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/scoped_nodes.py", line 2838, in slots
    slots = list(grouped_slots())
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/scoped_nodes.py", line 2823, in grouped_slots
    for cls in self.mro()[:-1]:
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/scoped_nodes.py", line 2909, in mro
    return self._compute_mro(context=context)
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/scoped_nodes.py", line 2898, in _compute_mro
    unmerged_mro = list(clean_duplicates_mro(unmerged_mro, self, context))
  File "/home/toilal/.pyenv/versions/3.8.7/envs/3.8.7-ddb/lib/python3.8/site-packages/astroid/scoped_nodes.py", line 110, in clean_duplicates_mro
    raise exceptions.DuplicateBasesError(
astroid.exceptions.DuplicateBasesError: Duplicates found in MROs (OrderedSet), (_GenericAlias, _Final, object), (_GenericAlias, _Final, object), (_GenericAlias, _GenericAlias) for <ClassDef.OrderedSet l.55 at 0x7f75735663d0>.

Expected behavior

It should lint as usual.

pylint --version output

pylint 2.6.0
astroid 2.5
Python 3.8.7 (default, Jan 19 2021, 12:16:28) 
[GCC 9.3.0]

Problem occurs after upgrading astroid to 2.5. pip install "astroid<2.5" to workaround the issue.

[Pierre-Sassoulas]

@hippo91 maybe pylint 2.6.0 needs to specify astroid < 2.5 ? If that's the case we could release 2.6.1with just a dependency change.

[cdce8p]

Hmm, I can't seem to reproduce it. I wanted to check if the error also occurs with the current pylint master branch and astroid 2.5, but it even ran without issues the first time. Here is what I did

git clone git@github.com:inetum-orleans/docker-devbox-ddb.git
# develop branch, last commit: bcf04b523482de438742e51d47198464d00f0553

cd docker-devbox-ddb.git
python3.8 -m venv venv
source venv/bin/activate
pip install pylint
pylint ddb

pylint 2.6.0
astroid 2.5
Python 3.8.7 (v3.8.7:6503f05dd5, Dec 21 2020, 12:45:15) 
[Clang 6.0 (clang-600.0.57)]
--
macOS Catalina (10.15.7)

--

@Toilal Could you provide more details (operating system, the exact commit you tested, any other useful information)? Would be great if you could also try the current master branch.

# In a new environment, run
pip install -U git+git://github.com/PyCQA/pylint.git@e48946f0b4bd385fcd93b6ef920d092f0d8d7424

If that works, we would know that the pining the astroid version as @Pierre-Sassoulas suggested would be enough to fix it.

[Toilal]

• Ubuntu 20.04
• python 3.8.7 installed with pyenv
• develop branch of https://github.com/inetum-orleans/docker-devbox-ddb
• edit setup.py to remove <2.5 constraint on astroid (current workaround)
• pip install -e .[dev]
• pylint ddb

I have tried current master branch, problem still occurs.

[Toilal]

Also, it works properly with pylint master and astroid<2.5

[Pierre-Sassoulas]

Should be fixed in 2.6.1, I just released. We had astroid>=2.4.0,<=2.5, it should have been astroid>=2.4.0,<2.5.

[Pierre-Sassoulas]

Thank you @Toilal for reporting the issue so fast!