Don't emit Liskov violations w.r.t. grandparent class if the violation cannot be fixed without breaking Liskov w.r.t. the parent class #2000
Description
Question
I have the following code:
from typing import Iterable
from collections import UserList
class Errors(UserList[str]):
def __init__(self, initlist=None):
super().__init__(initlist)
def append(self, item: str) -> None:
super().append(item)
def extend(self, other: Iterable[str]) -> None:
for item in other:
self.append(item)This fails with an error similar to
uv run ty check
error[invalid-method-override]: Invalid override of method `append`
--> error.py:8:9
|
6 | super().__init__(initlist)
7 |
8 | def append(self, item: str) -> None:
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `MutableSequence.append`
9 | super().append(item)
|
::: stdlib/typing.pyi:1112:9
|
1110 | def __delitem__(self, index: slice) -> None: ...
1111 | # Mixin methods
1112 | def append(self, value: _T) -> None:
| ------------------------------- `MutableSequence.append` defined here
1113 | """S.append(value) -- append value to the end of the sequence"""
|
info: This violates the Liskov Substitution Principle
info: rule `invalid-method-override` is enabled by default
error[invalid-method-override]: Invalid override of method `extend`
--> error.py:11:9
|
9 | super().append(item)
10 |
11 | def extend(self, other: Iterable[str]) -> None:
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Definition is incompatible with `MutableSequence.extend`
12 | for item in other:
13 | self.append(item)
|
::: stdlib/typing.pyi:1118:9
|
1116 | """S.clear() -> None -- remove all items from S"""
1117 |
1118 | def extend(self, values: Iterable[_T]) -> None:
| ------------------------------------------ `MutableSequence.extend` defined here
1119 | """S.extend(iterable) -- extend sequence by appending elements from the iterable"""
|
info: This violates the Liskov Substitution Principle
info: rule `invalid-method-override` is enabled by default
Found 2 diagnostics
What am I missing?
Forgive me, if there is an obvious error hidden in plain sight. I havent written a lot of python lately..
Version
ty 0.0.2