mypy should check qualname (and other special dunders)
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bug
topic-runtime-semantics
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
- PR merge metrics
- PR metrics pending
Description
Bug Report
Noticed when playing with https://github.com/python/mypy/issues/20819. When you assign an int to __qualname__, Python raises a TypeError but mypy itself doesn't.
To Reproduce
class X:
__qualname__ = 5
Expected Behavior
Error.
Actual Behavior
No error.
Your Environment
Reproduced in mypy-play
- Mypy version used: 1.19.1
- Mypy command-line flags: N/A
- Mypy configuration options from
mypy.ini(and other config files): N/A - Python version used: 3.12
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the provided reproducer in mypy and inspect how assignments to special dunder attributes are checked. Done means mypy reports an error for assigning an int to qualname, with coverage for the other special dunders included by the change.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- compilers, devtools
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100