Bug report

Bug description:

Theinspect.ismethoddescriptor() function reports descriptor objects which implement__delete__() but not__set__() asmethod descriptors, even though they are, in fact,data descriptors:

Actual behavior example:

>>>importinspect>>>classDescriptor:...def__get__(self,*_):pass...def__delete__(self,*_):pass# Note: `__set__()` *not* defined....>>>inspect.ismethoddescriptor(Descriptor())# Wrong result:True

Expected result:

>>>inspect.ismethoddescriptor(Descriptor())# Correct result:False

See also:https://discuss.python.org/t/inspect-ismethoddescriptor-checks-for-the-lack-of-set-but-ignores-delete-should-it-be-fixed/55039

There is an additional question:to which Python versions should the fix be applied?

IMHO, the fix can be safely applied to the branches 3.14 (main) and 3.13 (still in the beta phase). Backporting it to the earlier versions might be considered too disruptive. Obviously, the decision will need to be made by a core developer, not me.

CPython versions tested on:

3.8, 3.9, 3.10, 3.11, 3.12, 3.13, CPython main branch

Linked PRs

• gh-120381: Fix inspect.ismethoddescriptor() #120383
• [3.13] gh-120381: Fix inspect.ismethoddescriptor() (GH-120383) #120684