fix: prevent ClassVar override with instance property
#18853
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shenyih0ng
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shenyih0ng
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Mar 29, 2025
Comment on lines
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| self.fail( | ||
| message_registry.CANNOT_OVERRIDE_CLASS_VAR.format(base.name), | ||
| decorator_func, | ||
| ) |
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wondering if the error code OVERRIDE should be attached to this error message? left it as misc to keep behaviour consistent with existing error message:
Line 3722 in f2f8a98
Contributor
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Diff from mypy_primer, showing the effect of this PR on open source code: django-stubs (https://github.com/typeddjango/django-stubs)
+ django-stubs/db/migrations/operations/special.pyi:38: error: Cannot override class variable (previously declared on base class "Operation") with instance variable [misc]
+ django-stubs/db/migrations/operations/special.pyi:38: note: Error code "misc" not covered by "type: ignore" comment
+ django-stubs/db/migrations/operations/special.pyi:59: error: Cannot override class variable (previously declared on base class "Operation") with instance variable [misc]
+ django-stubs/db/migrations/operations/special.pyi:59: note: Error code "misc" not covered by "type: ignore" comment
|
sterliakov
reviewed
Mar 29, 2025
| from typing import ClassVar | ||
|
|
||
| class A: | ||
| x: ClassVar[int] |
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Could you add a testcase with ClassVar[property]? I suspect that isn't supported even without this PR (#18504) and don't know if it is important enough, but better be explicit about this.
class Parent:
foo: ClassVar[property]
class Child(Parent):
@property
def foo(self) -> None: ...
@foo.setter
def foo(self, _: None) -> None: ...
(this should ideally be accepted, but probably isn't yet)
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Fixes #18790
This PR adds a new override check to prevent instance properties (defined using
@property) from overriding inherited class variables.