python / python/cpython

ABCMeta.__subclasscheck__() doesn't support duck typing.

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3.10 3.9 (EOL) stdlib type-bug
Dominant language
Python
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Forks
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Description

BPO 44847

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 2021-08-06.06:56:59.358>
labels = ['type-bug', 'library', '3.9', '3.10']
title = "ABCMeta.__subclasscheck__() doesn't support duck typing."
updated_at = <Date 2021-08-06.06:56:59.358>
user = 'https://bugs.python.org/grahamd'

bugs.python.org fields:

activity = <Date 2021-08-06.06:56:59.358>
actor = 'grahamd'
assignee = 'none'
closed = False
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2021-08-06.06:56:59.358>
creator = 'grahamd'
dependencies = []
files = []
hgrepos = []
issue_num = 44847
keywords = []
message_count = 1.0
messages = ['399060']
nosy_count = 1.0
nosy_names = ['grahamd']
pr_nums = []
priority = 'normal'
resolution = None
stage = None
status = 'open'
superseder = None
type = 'behavior'
url = 'https://bugs.python.org/issue44847'
versions = ['Python 3.9', 'Python 3.10']

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

The issue identifies ABCMeta.subclasscheck and the Library (Lib) component, but names no source file or test. Start by locating that implementation and its existing tests, then reproduce the duck-typing behavior and establish the expected subclass-checking result before adding coverage.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
backend
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Needs clarification
Newbie friendliness
32/100

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