Bug Report
Mypy allows an instance variable annotation on a subclass to restrict the variable’s type in a way that’s incompatible with the superclass. This is unsound and should be forbidden.
To Reproduce
class A:
def __init__(self, x: object) -> None:
self.x = x
class B(A):
x: int
B("string").x + 1https://mypy-play.net/?mypy=latest&python=3.10&gist=00ef5dbb43039cac3d1672b3ece3029a&flags=strict
Mypy doesn’t give any errors, but should, because this fails at runtime with TypeError: can only concatenate str (not "int") to str.
Expected Behavior
mypy should complain about x: int.
Actual Behavior
No mypy errors.
Your Environment
- Mypy version used: 0.981
- Mypy command-line flags:
--strict
- Python version used: 3.10.7
Bug Report
Mypy allows an instance variable annotation on a subclass to restrict the variable’s type in a way that’s incompatible with the superclass. This is unsound and should be forbidden.
To Reproduce
https://mypy-play.net/?mypy=latest&python=3.10&gist=00ef5dbb43039cac3d1672b3ece3029a&flags=strict
Mypy doesn’t give any errors, but should, because this fails at runtime with
TypeError: can only concatenate str (not "int") to str.Expected Behavior
mypy should complain about
x: int.Actual Behavior
No mypy errors.
Your Environment
--strict