infinite recursion in pylint (new case 2020-12)

[arielf]

This case is different than similar cases reported before.

Is your issue fixed on the preview release?: pip install pylint astroid --pre -U
NO, I'm on latest: see below.

Steps to reproduce

python3 in env is 3.7.9

Put the following python code in a file li.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# vim: ts=4 sw=4 expandtab
"""
This causes an infinite recursion in pylint:

    % pylint --version
    pylint 2.6.0
    astroid 2.4.2
    Python 3.7.9 (default, Aug 18 2020, 06:22:45)
    [GCC 7.5.0]
"""
import pandas as pd
from addict import Dict

class Validator(Dict):
    """validator class"""
    def __init__(self, sep=',', filename=None):
        self.sep = sep
        self.filename = filename
        self.df = None

    def fubar(self, **kwargs):
        """
        reproduce pylint inf-recursion
        """
        self.df = pd.read_csv(self.filename, sep=self.sep, **kwargs)

        # problem is triggered here:
        # This doesn't crash:
        #   for fieldname in self.df:
        # But this crashes ('columns' member added by pandas):
        for fieldname in self.df.columns:
            pass

Current behavior

% pylint li.py
Traceback (most recent call last):
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 32, in cached
    return cache[func]
KeyError: <bound method ClassDef._get_assign_nodes of <ClassDef.DatetimeIndex l.72 at 0x7f9850c228d0>>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 32, in cached
    return cache[func]
KeyError: <bound method MultiLineBlockMixin._get_assign_nodes of <FunctionDef.get_loc l.577 at 0x7f9850328910>>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 32, in cached
    return cache[func]
KeyError: <bound method MultiLineBlockMixin._get_assign_nodes of <If l.592 at 0x7f9850240990>>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 32, in cached
    return cache[func]
KeyError: <bound method MultiLineBlockMixin._get_assign_nodes of <If l.596 at 0x7f9850240e90>>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 32, in cached
    return cache[func]
KeyError: <bound method MultiLineBlockMixin._get_assign_nodes of <If l.607 at 0x7f9850247190>>

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/user/.local/bin/pylint", line 8, in <module>
    sys.exit(run_pylint())
  File "/home/user/.local/lib/python3.7/site-packages/pylint/__init__.py", line 22, in run_pylint
    PylintRun(sys.argv[1:])
  File "/home/user/.local/lib/python3.7/site-packages/pylint/lint/run.py", line 349, in __init__
    linter.check(args)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/lint/pylinter.py", line 863, in check
    self.get_ast, self._iterate_file_descrs(files_or_modules)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/lint/pylinter.py", line 896, in _check_files
    self._check_file(get_ast, check_astroid_module, name, filepath, modname)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/lint/pylinter.py", line 922, in _check_file
    check_astroid_module(ast_node)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/lint/pylinter.py", line 1055, in check_astroid_module
    ast_node, walker, rawcheckers, tokencheckers
  File "/home/user/.local/lib/python3.7/site-packages/pylint/lint/pylinter.py", line 1099, in _check_astroid_module
    walker.walk(ast_node)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/utils/ast_walker.py", line 75, in walk
    self.walk(child)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/utils/ast_walker.py", line 75, in walk
    self.walk(child)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/utils/ast_walker.py", line 75, in walk
    self.walk(child)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/utils/ast_walker.py", line 72, in walk
    callback(astroid)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/checkers/typecheck.py", line 1825, in visit_for
    self._check_iterable(node.iter)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/checkers/typecheck.py", line 1806, in _check_iterable
    inferred = safe_infer(node)
  File "/home/user/.local/lib/python3.7/site-packages/pylint/checkers/utils.py", line 1143, in safe_infer
    value = next(infer_gen)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 132, in raise_if_nothing_inferred
    yield next(generator)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 96, in wrapped
    res = next(generator)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/inference.py", line 293, in infer_attribute
    for owner in self.expr.infer(context):
  File "/home/user/.local/lib/python3.7/site-packages/astroid/util.py", line 160, in limit_inference
    yield from islice(iterator, size)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/context.py", line 113, in cache_generator
    for result in generator:
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 142, in raise_if_nothing_inferred
    yield from generator
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 96, in wrapped
    res = next(generator)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/inference.py", line 319, in infer_attribute
    yield from owner.igetattr(self.attrname, context)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/bases.py", line 222, in igetattr
    self._wrap_attr(get_attr, context), context, frame=self
  File "/home/user/.local/lib/python3.7/site-packages/astroid/bases.py", line 136, in _infer_stmts
    for inferred in stmt.infer(context=context):
  File "/home/user/.local/lib/python3.7/site-packages/astroid/util.py", line 160, in limit_inference
    yield from islice(iterator, size)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/context.py", line 113, in cache_generator
    for result in generator:
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 142, in raise_if_nothing_inferred
    yield from generator
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 96, in wrapped
    res = next(generator)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/bases.py", line 136, in _infer_stmts
    for inferred in stmt.infer(context=context):
  File "/home/user/.local/lib/python3.7/site-packages/astroid/util.py", line 160, in limit_inference
    yield from islice(iterator, size)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/context.py", line 113, in cache_generator
    for result in generator:
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 142, in raise_if_nothing_inferred
    yield from generator
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 96, in wrapped
    res = next(generator)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/inference.py", line 233, in infer_call
    yield from callee.infer_call_result(caller=self, context=callcontext)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/scoped_nodes.py", line 1722, in infer_call_result
    yield from returnnode.value.infer(context)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/util.py", line 160, in limit_inference

[hundreds of similar lines trimmed for brevity]

  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 34, in cached
    cache[func] = result = func(*args, **kwargs)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/mixins.py", line 153, in _get_assign_nodes
    return list(itertools.chain.from_iterable(children_assign_nodes))
  File "/home/user/.local/lib/python3.7/site-packages/astroid/mixins.py", line 151, in <genexpr>
    for child_node in block
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 34, in cached
    cache[func] = result = func(*args, **kwargs)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/mixins.py", line 153, in _get_assign_nodes
    return list(itertools.chain.from_iterable(children_assign_nodes))
  File "/home/user/.local/lib/python3.7/site-packages/astroid/mixins.py", line 151, in <genexpr>
    for child_node in block
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 34, in cached
    cache[func] = result = func(*args, **kwargs)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/mixins.py", line 150, in _get_assign_nodes
    for block in self._multi_line_blocks
  File "/home/user/.local/lib/python3.7/site-packages/astroid/decorators.py", line 72, in __get__
    val = self.wrapped(inst)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/mixins.py", line 130, in _multi_line_blocks
    return tuple(getattr(self, field) for field in self._multi_line_block_fields)
  File "/home/user/.local/lib/python3.7/site-packages/astroid/mixins.py", line 130, in <genexpr>
    return tuple(getattr(self, field) for field in self._multi_line_block_fields)
RecursionError: maximum recursion depth exceeded while calling a Python object

Expected behavior

pylint issues lint errors but completes without a RecursionError + crash.

pylint --version output

% pylint --version
pylint 2.6.0
astroid 2.4.2
Python 3.7.9 (default, Aug 18 2020, 06:22:45)
[GCC 7.5.0]

[Pierre-Sassoulas]

I can't reproduce with pandas==1.2.2 and astroid 2.4.2 or 2.5.0 with current pylint or with pylint 2.6.0 or 2.6.2. (except by changing the limit with init-hook='import sys; sys.setrecursionlimit(600)' ). I'm using python 3.8, I'll check with python 3.7 later.

[Pierre-Sassoulas]

Look like it's fixed with 2.7.2, if you encounter a maximum recursion depth exceeded on pylint > 2.7 with astroid > 2.5.1, please open a new issue.