Pylint crash on using double underscore function

[hyde-00]

Steps to reproduce

Minimum code to reproduce pylint crash:

from __future__ import absolute_import
from abc import abstractmethod

class ApplianceConfig:

    # Implemented in child class.
    def _get_details(self):
        pass

    def __generate_reponse_file_data(self):
        d = {}
        if len(self._get_details()):
            d['key'] = json.dumps(self._get_details())

Current behavior

Traceback (most recent call last):
  File "/opt/venv/lib64/python3.6/site-packages/astroid/decorators.py", line 135, in raise_if_nothing_inferred
    yield next(generator)
StopIteration: {'node': <Call l.12 at 0x7f734a9b1be0>, 'context': <astroid.context.InferenceContext object at 0x7f734a9bc888>}

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/opt/venv/bin/pylint", line 11, in <module>

▽
    sys.exit(run_pylint())
  File "/opt/venv/lib64/python3.6/site-packages/pylint/__init__.py", line 22, in run_pylint
    PylintRun(sys.argv[1:])
  File "/opt/venv/lib64/python3.6/site-packages/pylint/lint/run.py", line 358, in __init__
    linter.check(args)
  File "/opt/venv/lib64/python3.6/site-packages/pylint/lint/pylinter.py", line 863, in check
    self.get_ast, self._iterate_file_descrs(files_or_modules)
  File "/opt/venv/lib64/python3.6/site-packages/pylint/lint/pylinter.py", line 896, in _check_files
    self._check_file(get_ast, check_astroid_module, name, filepath, modname)
  File "/opt/venv/lib64/python3.6/site-packages/pylint/lint/pylinter.py", line 922, in _check_file
    check_astroid_module(ast_node)
  File "/opt/venv/lib64/python3.6/site-packages/pylint/lint/pylinter.py", line 1055, in check_astroid_module
    ast_node, walker, rawcheckers, tokencheckers
  File "/opt/venv/lib64/python3.6/site-packages/pylint/lint/pylinter.py", line 1099, in _check_astroid_module
    walker.walk(ast_node)
  File "/opt/venv/lib64/python3.6/site-packages/pylint/utils/ast_walker.py", line 75, in walk
    self.walk(child)
  File "/opt/venv/lib64/python3.6/site-packages/pylint/utils/ast_walker.py", line 75, in walk
    self.walk(child)
  File "/opt/venv/lib64/python3.6/site-packages/pylint/utils/ast_walker.py", line 75, in walk
    self.walk(child)
  [Previous line repeated 1 more time]
  File "/opt/venv/lib64/python3.6/site-packages/pylint/utils/ast_walker.py", line 72, in walk
    callback(astroid)
  File "/opt/venv/lib64/python3.6/site-packages/pylint/checkers/refactoring/len_checker.py", line 76, in visit_call
    instance = next(len_arg.infer())
  File "/opt/venv/lib64/python3.6/site-packages/astroid/node_classes.py", line 366, in infer
    yield from self._infer(context, **kwargs)
  File "/opt/venv/lib64/python3.6/site-packages/astroid/decorators.py", line 140, in raise_if_nothing_inferred
    raise exceptions.InferenceError(**error.args[0]) from error
astroid.exceptions.InferenceError: Inference failed for <Call l.12 at 0x7f734a9b1be0>.

Expected behavior

Pylint should not crash. I was using pylint==2.6.0 earlier and this crash was not observed.

Result of pylint --version output:

vpylint --version
pylint 2.7.2
astroid 2.5.1
Python 3.6.8 (default, Sep 26 2019, 11:57:09)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-39)]

[cdce8p]

I believe this is a duplicate of #4215 which is already fixed in the current master. Will be included in the next release.

[hippo91]

@hyde-00 thanks for your report. I confirm that the bug does not occur anymore with the master branch and as it seems to be a duplicate i close this issue.