Fix sphinx-doc#9756: autodoc: Crashed if classmethod does not have __func__ attribute

Author: tk0miya

CHANGES

@@ -60,6 +60,7 @@ Bugs fixed
 * #9657: autodoc: The base class for a subclass of mocked object is incorrect
 * #9607: autodoc: Incorrect base class detection for the subclasses of the
   generic class
+* #9756: autodoc: Crashed if classmethod does not have __func__ attribute
 * #9630: autosummary: Failed to build summary table if :confval:`primary_domain`
   is not 'py'
 * #9670: html: Fix download file with special characters

sphinx/util/inspect.py

@@ -865,7 +865,7 @@ def getdoc(obj: Any, attrgetter: Callable = safe_getattr,
     if cls and name and isclassmethod(obj, cls, name):
         for basecls in getmro(cls):
             meth = basecls.__dict__.get(name)
-            if meth:
+            if meth and hasattr(meth, '__func__'):
                 return getdoc(meth.__func__)
 
     doc = attrgetter(obj, '__doc__', None)