Bug Report
I was eager to try PEP661 support on master, but found what might be an oversight in stubtest. It flags sentinel usage against the stub's parameter type, while it does allow object-style marker objects. Since PEP661's sentinel is now the canonical way to write such a marker, I'd expect it to be allowed in such places:
To Reproduce
# foo.py
from typing_extensions import sentinel
_MISSING = sentinel("_MISSING")
def f(x=_MISSING):
pass# foo.pyi
def f(x: int = ...) -> None: ...
python -m mypy.stubtest foo
Expected Behavior
No errors, the same as with _MISSING = object():
Success: no issues found in 1 module
Actual Behavior
error: foo.f is inconsistent, runtime parameter "x" has a default value of type typing_extensions.sentinel, which is incompatible with stub parameter type int
Stub: in file foo.pyi:1
def (x: int =)
Runtime: in file foo.py:5
def (x=_MISSING)
Found 1 error (checked 1 module)
I get the same on Python 3.15 beta.
As described above, adding the sentinel to the stub's type (x: int | _MISSING = ...) isn't an option.
The exemption seems to be in _verify_arg_default_value:
# Avoid false positives for marker objects
and type(runtime_arg.default) is not object
It could be adjusted to include sentinel the same way.
My Environment
- Mypy version used: master at 8d30064 (2.4.0+dev)
- Mypy command-line flags: none
- Mypy configuration options from
mypy.ini (and other config files): none
- Python version used: 3.14.7 (
typing_extensions 4.16.0)
Bug Report
I was eager to try PEP661 support on
master, but found what might be an oversight instubtest. It flags sentinel usage against the stub's parameter type, while it does allowobject-style marker objects. Since PEP661's sentinel is now the canonical way to write such a marker, I'd expect it to be allowed in such places:To Reproduce
Expected Behavior
No errors, the same as with
_MISSING = object():Actual Behavior
I get the same on Python 3.15 beta.
As described above, adding the sentinel to the stub's type (
x: int | _MISSING = ...) isn't an option.The exemption seems to be in
_verify_arg_default_value:It could be adjusted to include
sentinelthe same way.My Environment
mypy.ini(and other config files): nonetyping_extensions4.16.0)