(🐞) false negative with `dataclass` "non-default argument follows default argument"
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bug
topic-dataclasses
- Dominant language
- Python
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Description
from dataclasses import dataclass
@dataclass
class A:
a: int = 0
@dataclass
class B(A):
a: int
b: str
Mypy shows no error but this fails at runtime with TypeError: non-default argument 'b' follows default argument
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First steps
- Read the whole issue, then the project's contributing guide.
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- Open a pull request that references the issue number.
Research direction
Start with the dataclass inheritance reproducer in the issue and run it through mypy with the linked playground configuration. Trace how the checker handles inherited dataclass fields and default ordering; done means mypy reports the runtime-invalid non-default argument ordering shown by the example.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100