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Incompatible signature error when there are overloads that split a Literal union in a subclass #11762
Description
Bug Report
When I try to overload the method foo() in B, I get an incompatible signature error from mypy and I think it's a bug.
To Reproduce
- Write this code in a file
from typing import Literal, overload
class A:
def foo(self, bar: Literal["X"] | Literal["Y"]) -> int | bool:
if bar == "X":
return 1
else:
return True
class B(A):
@overload
def foo(self, bar: Literal["X"]) -> int:
...
@overload
def foo(self, bar: Literal["Y"]) -> bool:
...
def foo(self, bar: Literal["X"] | Literal["Y"]) -> int | bool:
return super().foo(bar)- Run
mypy <filename>
Expected Behavior
In a similar case (below), it does not produce an error so I think it's a bug.
class C:
def foo(self, bar: bool | float) -> int | str:
if isinstance(bar, bool):
return 1
else:
return "A"
class D(C):
@overload
def foo(self, bar: bool) -> int:
...
@overload
def foo(self, bar: float) -> str:
...
def foo(self, bar: bool | float) -> int | str:
return super().foo(bar)Actual Behavior
mypy produces the following error:
d.py:13: error: Signature of "foo" incompatible with supertype "A"
d.py:13: note: Superclass:
d.py:13: note: def foo(self, bar: Union[Literal['X'], Literal['Y']]) -> Union[int, bool]
d.py:13: note: Subclass:
d.py:13: note: @overload
d.py:13: note: def foo(self, bar: Literal['X']) -> int
d.py:13: note: @overload
d.py:13: note: def foo(self, bar: Literal['Y']) -> bool
Found 1 error in 1 file (checked 1 source file)Your Environment
- Mypy version used: 0.920
- Mypy command-line flags: None
- Mypy configuration options from
mypy.ini(and other config files): None - Python version used: 3.10.0
- Operating system and version: Windows 10
Activity