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1.7.0: Overloaded function with decorator using ParamSpec does not type check #16474
Closed as not planned
Description
Bug Report
Code with overloads with a decorator using a ParamSpec was typechecking fine with mypy 1.6.1 but not with mypy 1.7.0.
To Reproduce
See the following reproducer loosely based on an API client library where I hit this problem.
The library allows optionally parsing the response body into a model class
test_overload.py
import typing
P = typing.ParamSpec("P")
R = typing.TypeVar("R")
def handle_exception(
func: typing.Callable[P, typing.Awaitable[R]]
) -> typing.Callable[P, typing.Awaitable[R]]:
return func
class Response:
pass
class ResponseModel:
pass
ResponseT = typing.TypeVar("ResponseT", bound=ResponseModel)
@typing.overload
async def request(response_model: type[ResponseT]) -> ResponseT:
...
@typing.overload
async def request(response_model: None = ...) -> Response:
...
@handle_exception
async def request(
response_model: type[ResponseT] | None = None,
) -> ResponseT | Response:
raise NotImplementedError()It can be reproduced without async too.
test_overload_sync.py
import typing
P = typing.ParamSpec("P")
R = typing.TypeVar("R")
def handle_exception(
func: typing.Callable[P, R]
) -> typing.Callable[P, R]:
return func
class Response:
pass
class ResponseModel:
pass
ResponseT = typing.TypeVar("ResponseT", bound=ResponseModel)
@typing.overload
def request(response_model: type[ResponseT]) -> ResponseT:
...
@typing.overload
def request(response_model: None = ...) -> Response:
...
@handle_exception
def request(
response_model: type[ResponseT] | None = None,
) -> ResponseT | Response:
raise NotImplementedError()Expected Behavior
No mypy errors.
This works with 1.6.1:
$ mypy --version
mypy 1.6.1 (compiled: yes)
$ mypy test_overload.py
Success: no issues found in 1 source fileActual Behavior
It fails to type check:
$ mypy test_overload.py
test_overload.py:33: error: Argument 1 to "handle_exception" has incompatible type "Callable[[type[ResponseT] | None], Coroutine[Any, Any, ResponseT | Response]]"; expected "Callable[[VarArg(Never), KwArg(Never)], Awaitable[Never]]" [arg-type]
test_overload.py:33: error: Overloaded function implementation does not accept all possible arguments of signature 1 [misc]
test_overload.py:33: error: Overloaded function implementation cannot produce return type of signature 1 [misc]
test_overload.py:33: error: Overloaded function implementation does not accept all possible arguments of signature 2 [misc]
test_overload.py:33: error: Overloaded function implementation cannot produce return type of signature 2 [misc]
Found 5 errors in 1 file (checked 1 source file)Sync version:
$ python3 -m mypy test_overload_sync.py
test_overload.py:33: error: Argument 1 to "handle_exception" has incompatible type "Callable[[type[ResponseT] | None], ResponseT | Response]"; expected "Callable[[VarArg(Never), KwArg(Never)], Never]" [arg-type]
test_overload.py:33: error: Overloaded function implementation does not accept all possible arguments of signature 1 [misc]
test_overload.py:33: error: Overloaded function implementation does not accept all possible arguments of signature 2 [misc]Your Environment
- Mypy version used: 1.7.0 (compiled)
- Mypy command-line flags: mypy test_overload.py, tried with and without a clean cache
- Python version: 3.10.2, 3.11.6
Activity
ilevkivskyi commentedon Nov 13, 2023
This is likely a duplicate of #16451. It should be fixed on latest master (merged few minutes ago). Could you please double-check and re-open if needed?
AlexWaygood commentedon Nov 13, 2023
Both snippets pass for me locally with the latest master (but not before #16461)
thomascellerier commentedon Nov 14, 2023
Thanks!
I tested as well with master and it works.