functools.update_wrapper() will not accept descriptor (decorator) as wrapper

Description:

The type stub for functools.update_wrapper() does not permit a descriptor for the wrapper (first) argument, a legitimate case arising when defining a descriptor-type decorator (like @property is).
https://github.com/python/typeshed/blob/main/stdlib/functools.pyi#L83

@erictraut While perhaps not exactly a regression, this used to work up until this commit of yours here (last week): https://github.com/python/typeshed/commit/9c4bfd5d11b47677e128452baa8ac7eeb1903a8e#diff-02c51ed45b741b6765c365fb5d6578c586510bbbd57b10a1dba10aeba37ae157L70-R84. I say not exactly a regression because the prior constraint introduced here was perhaps overly loose: https://github.com/python/typeshed/pull/4627/files

Example
As an example, the following (pyright) typing error is detected in the lazyproperty descriptor-type decorator defined here: https://gist.github.com/scanny/255f16339b74b2b59e896d67bd459d6b

lazyproperty.py|65 col 34-38 error| Argument of type "Self@lazyproperty[T@lazyproperty]"
  cannot be assigned to parameter "wrapper"
  of type "(**_PWrapper@update_wrapper) -> _RWapper@update_wrapper"
  in function "update_wrapper"
 Type "Self@lazyproperty[T@lazyproperty]" cannot be assigned to
 type "(**_PWrapper@update_wrapper) -> _RWapper@update_wrapper"

To Reproduce
The gist referenced above has no dependencies other than the stdlib so can be type-checked directly (using pyright v1.1.296):

$ pyright lazyproperty.py

Analysis

The type definition at work constrains wrapper to be a Callable[_PWrapper, _RWapper]. I believe it also needs to permit Descriptor, although I'm not completely sure what that type definition is. My best guess is something like this:

class HasDunderGet(Protocol):
    def __get__(self, obj: Any, type: type = None) -> Any: ...
class HasDunderSet(Protocol):
    def __set__(self, obj: Any, value: Any) -> None: ...
class HasDunderDelete(Protocol):
    def __delete__(self, obj: Any) -> None: ...

Descriptor = Union[HasDunderGet, HasDunderSet, HasDunderDelete]

Expected behavior
As far as I can tell, this is a legitimate usage of functools.update_wrapper() and decorators that produce a descriptor (like @property does) are also legitimate Python. It has certainly worked for a long time and also even typechecked with pyright previously (v1.1.273), maybe six months ago. So I would expect it to be accepted as written.

Beginne mit stdlib/functools.pyi ungefähr in den Zeilen 82–87 und vergleiche die Wrapper-Annotation mit der Deskriptorverwendung im verlinkten lazyproperty.py-Gist. Führe pyright v1.1.296 für lazyproperty.py aus, um den Fehler zu reproduzieren, und untersuche anschließend den referenzierten typeshed-Commit und den früheren Pull Request als Kontext. Als erledigt gilt die Aufgabe, wenn der legitime Deskriptor-Decorator die Typprüfung besteht, ohne die Typisierung von update_wrapper in nicht verwandten Bereichen abzuschwächen.