isinstance(cls_with_metaclass, non_type) raises KeyError

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Assessment

Difficulty
4/5
Estimated time
3-5 days
Newbie friendliness
25/100
Issue type
Bug
Clarity
Needs clarification
Activity status
Stale
Tech stack
python
Domain
compilers

Research direction

Start by running the attached tem3.py reproducer and confirm that isinstance(cls_with_metaclass, non_type) raises KeyError. Trace the interpreter-core implementation of isinstance and identify the relevant regression-test location. Done means the reproducer no longer raises KeyError and a regression test covers the behavior.

Written by the indexing model from the issue text.

Description

3.7 (EOL) 3.8 (EOL) 3.9 (EOL) interpreter-core type-bug
BPO 40180
Nosy @terryjreedy, @serhiy-storchaka, @isidentical
Files
  • tem3.py
    		•

    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = None
closed_at = None
created_at = <Date 2020-04-04.19:28:49.901>
labels = ['interpreter-core', '3.8', 'type-bug', '3.7', '3.9']
title = 'isinstance(cls_with_metaclass, non_type) raises KeyError'
updated_at = <Date 2020-04-04.22:54:24.596>
user = 'https://github.com/terryjreedy'

    bugs.python.org fields:

    activity = <Date 2020-04-04.22:54:24.596>
actor = 'serhiy.storchaka'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Interpreter Core']
creation = <Date 2020-04-04.19:28:49.901>
creator = 'terry.reedy'
dependencies = []
files = ['49034']
hgrepos = []
issue_num = 40180
keywords = []
message_count = 5.0
messages = ['365774', '365776', '365791', '365797', '365801']
nosy_count = 3.0
nosy_names = ['terry.reedy', 'serhiy.storchaka', 'BTaskaya']
pr_nums = []
priority = 'normal'
resolution = None
stage = 'needs patch'
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue40180'
versions = ['Python 3.7', 'Python 3.8', 'Python 3.9']

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