Running pylint on class with duplicate bases raises DuplicateBasesError exception in astroid #3247
Description
Steps to reproduce
Minimal code to reproduce the error (running pylint on a file with this contents will error out):
import asyncio from typing import AsyncContextManager, Awaitable class _ReproCtxManager(Awaitable[None], AsyncContextManager[None]): def __init__(self): pass def __await__(self): return self.__aenter__().__await__() async def __aenter__(self): return "test" async def __aexit__(self, exc_type, exc, tb): return None async def main(): async with _ReproCtxManager() as x: print(x) print(await _ReproCtxManager()) loop = asyncio.get_event_loop() loop.run_until_complete(main())Current behavior
I get this traceback when running pylint min_bug.py
Traceback
************* Module min_bug min_bug.py:1:0: C0114: Missing module docstring (missing-module-docstring) min_bug.py:5:0: E0241: Duplicate bases for class '_ReproCtxManager' (duplicate-b ases) min_bug.py:10:15: E1101: Instance of 'str' has no '__await__' member (no-member) min_bug.py:15:4: C0103: Argument name "tb" doesn't conform to snake_case naming style (invalid-name) min_bug.py:19:0: C0116: Missing function or method docstring (missing-function-d ocstring) Traceback (most recent call last): File "c:\python37\lib\runpy.py", line 193, in _run_module_as_main "__main__", mod_spec) File "c:\python37\lib\runpy.py", line 85, in _run_code exec(code, run_globals) File "C:\Python37\Scripts\pylint.exe\__main__.py", line 7, in <module> File "c:\python37\lib\site-packages\pylint\__init__.py", line 23, in run_pylin t PylintRun(sys.argv[1:]) File "c:\python37\lib\site-packages\pylint\lint.py", line 1731, in __init__ linter.check(args) File "c:\python37\lib\site-packages\pylint\lint.py", line 1004, in check self._do_check(files_or_modules) File "c:\python37\lib\site-packages\pylint\lint.py", line 1165, in _do_check self.check_astroid_module(ast_node, walker, rawcheckers, tokencheckers) File "c:\python37\lib\site-packages\pylint\lint.py", line 1252, in check_astro id_module walker.walk(ast_node) File "c:\python37\lib\site-packages\pylint\utils\ast_walker.py", line 77, in w alk self.walk(child) File "c:\python37\lib\site-packages\pylint\utils\ast_walker.py", line 77, in w alk self.walk(child) File "c:\python37\lib\site-packages\pylint\utils\ast_walker.py", line 74, in w alk callback(astroid) File "c:\python37\lib\site-packages\pylint\checkers\async.py", line 56, in vis it_asyncwith inferred = checker_utils.safe_infer(ctx_mgr) File "c:\python37\lib\site-packages\pylint\checkers\utils.py", line 1084, in s afe_infer value = next(inferit) File "c:\python37\lib\site-packages\astroid\decorators.py", line 131, in raise _if_nothing_inferred yield next(generator) File "c:\python37\lib\site-packages\astroid\decorators.py", line 95, in wrappe d res = next(generator) File "c:\python37\lib\site-packages\astroid\inference.py", line 227, in infer_ call yield from callee.infer_call_result(caller=self, context=callcontext) File "c:\python37\lib\site-packages\astroid\scoped_nodes.py", line 2136, in in fer_call_result if any(cls.name in EXCEPTION_BASE_CLASSES for cls in self.mro()): File "c:\python37\lib\site-packages\astroid\scoped_nodes.py", line 2813, in mr o return self._compute_mro(context=context) File "c:\python37\lib\site-packages\astroid\scoped_nodes.py", line 2802, in _c ompute_mro unmerged_mro = list(clean_duplicates_mro(unmerged_mro, self, context)) File "c:\python37\lib\site-packages\astroid\scoped_nodes.py", line 104, in cle an_duplicates_mro context=context, astroid.exceptions.DuplicateBasesError: Duplicates found in MROs (_ReproCtxManag er), (_GenericAlias, object), (_GenericAlias, object), (_GenericAlias, _GenericA lias) for <ClassDef._ReproCtxManager l.5 at 0x2554c696988>. Expected behavior
I would expect no exception raised and just have the E0241/duplicate-bases warning shown without the exception. I wasn't sure if I should put this issue here on astroid repo so I'm going with this one first.
pylint --version output
pylint 2.4.4 astroid 2.3.3 Python 3.7.5 (tags/v3.7.5:5c02a39a0b, Oct 15 2019, 00:11:34) [MSC v.1916 64 bit (AMD64)] This issue also happens on latest commit of master.