no error when overriding property with incompatible return type when the overridden property has another decorator
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bug
topic-descriptors
topic-inheritance
- Dominant language
- Python
- Stars
- 20.6k
- Forks
- 3.3k
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Description
from contextlib import contextmanager
from typing import Iterator
@contextmanager
def foo() -> Iterator[None]:
yield
class Bar:
@property
def asdf(self) -> int:
return 2
class Baz(Bar):
@property
def asdf(self) -> str: # no error
return ""
@asdf.setter
@foo()
def asdf(self, new_value): ...
removing the @foo() decorator makes the error appear:
main.py:16: error: Signature of "asdf" incompatible with supertype "Bar" [override]
main.py:16: note: Superclass:
main.py:16: note: int
main.py:16: note: Subclass:
main.py:16: note: str
Found 1 error in 1 file (checked 1 source file)
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.
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- Open a pull request that references the issue number.
Research direction
Run the supplied Python reproducer and compare it with the version where @foo() is removed. Trace how decorated property setters are handled during property override checking; done means mypy reports the incompatible int-to-str override in the decorated case as well.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- python
- Domain
- devtools
- Issue type
- Bug
- Difficulty
- 3/5
- Estimated time
- 1-2 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100