Fix #8800: autodoc: Uninitialized attributes in superclass are recognized as undocumented

Unintentionally, uninitialized attributes defined at superclasses are
recognized as undocumented in the filtering step.  Therefore, they are
filtered if `:undoc-members:` option given.

1 files changed, 19 insertions, 8 deletions

diff --git a/sphinx/ext/autodoc/importer.py b/sphinx/ext/autodoc/importer.py
index 477aae247..b792b1a5f 100644
--- a/sphinx/ext/autodoc/importer.py
+++ b/sphinx/ext/autodoc/importer.py
@@ -294,24 +294,35 @@ def get_class_members(subject: Any, objpath: List[str], attrgetter: Callable
 
     try:
         for cls in getmro(subject):
+            try:
+                modname = safe_getattr(cls, '__module__')
+                qualname = safe_getattr(cls, '__qualname__')
+                analyzer = ModuleAnalyzer.for_module(modname)
+                analyzer.analyze()
+            except AttributeError:
+                qualname = None
+                analyzer = None
+            except PycodeError:
+                analyzer = None
+
             # annotation only member (ex. attr: int)
             for name in getannotations(cls):
                 name = unmangle(cls, name)
                 if name and name not in members:
-                    members[name] = ObjectMember(name, INSTANCEATTR, class_=cls)
+                    if analyzer and (qualname, name) in analyzer.attr_docs:
+                        docstring = '\n'.join(analyzer.attr_docs[qualname, name])
+                    else:
+                        docstring = None
+
+                    members[name] = ObjectMember(name, INSTANCEATTR, class_=cls,
+                                                 docstring=docstring)
 
             # append instance attributes (cf. self.attr1) if analyzer knows
-            try:
-                modname = safe_getattr(cls, '__module__')
-                qualname = safe_getattr(cls, '__qualname__')
-                analyzer = ModuleAnalyzer.for_module(modname)
-                analyzer.analyze()
+            if analyzer:
                 for (ns, name), docstring in analyzer.attr_docs.items():
                     if ns == qualname and name not in members:
                         members[name] = ObjectMember(name, INSTANCEATTR, class_=cls,
                                                      docstring='\n'.join(docstring))
-            except (AttributeError, PycodeError):
-                pass
     except AttributeError:
         pass