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Arithmetic with type variables fails to typecheck ("Unsupported operand types") #18203
Description
To Reproduce
from typing import Protocol, TypeVar
from typing_extensions import Self
class A(Protocol):
def __add__(self, other: int | Self) -> Self: ...
def __radd__(self, other: int | Self) -> Self: ...
AT = TypeVar("AT", bound=int | A)
# OK:
# AT = TypeVar("AT", int, A)
def f(a: AT) -> None:
a + ahttps://mypy-play.net/?mypy=latest&python=3.12&gist=13a490c6b5b075de398e0c84736fd194
Expected Behavior
It's a little weird that there is a lone type variable, but all cases of the operator application should be covered, so IMO this should typecheck OK. pyright agrees:
WARNING: there is a new pyright version available (v1.1.388 -> v1.1.389).
Please install the new version or set PYRIGHT_PYTHON_FORCE_VERSION to `latest`
/home/andreas/tmp/mypy-arith.py
/home/andreas/tmp/mypy-arith.py:14:10 - warning: TypeVar "AT" appears only once in generic function signature
Use "int | A" instead (reportInvalidTypeVarUse)
/home/andreas/tmp/mypy-arith.py:15:5 - warning: Expression value is unused (reportUnusedExpression)
0 errors, 2 warnings, 0 informations
Actual Behavior
mypy-arith.py:15: error: Unsupported operand types for + (likely involving Union) [operator]
Your Environment
- Mypy version used: 1.13
- Mypy command-line flags: None
- Mypy configuration options from None
- Python version used: 3.13
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