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.

CHANGES

@@ -77,6 +77,8 @@ Bugs fixed
   contains invalid type comments
 * #8693: autodoc: Default values for overloaded functions are rendered as string
 * #8134: autodoc: crashes when mocked decorator takes arguments
+* #8800: autodoc: Uninitialized attributes in superclass are recognized as
+  undocumented
 * #8306: autosummary: mocked modules are documented as empty page when using
   :recursive: option
 * #8232: graphviz: Image node is not rendered if graph file is in subdirectory

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):
-            # 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)
-
-            # 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()
+            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:
+                    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
+            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
 

tests/roots/test-ext-autodoc/target/uninitialized_attributes.py

@@ -0,0 +1,8 @@
+class Base:
+    attr1: int  #: docstring
+    attr2: str
+
+
+class Derived(Base):
+    attr3: int  #: docstring
+    attr4: str

tests/test_ext_autodoc_autoclass.py

@@ -106,6 +106,73 @@ def test_inherited_instance_variable(app):
     ]
 
 
+@pytest.mark.skipif(sys.version_info < (3, 6), reason='py36+ is available since python3.6.')
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_uninitialized_attributes(app):
+    options = {"members": None,
+               "inherited-members": True}
+    actual = do_autodoc(app, 'class', 'target.uninitialized_attributes.Derived', options)
+    assert list(actual) == [
+        '',
+        '.. py:class:: Derived()',
+        '   :module: target.uninitialized_attributes',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr1',
+        '      :module: target.uninitialized_attributes',
+        '      :type: int',
+        '',
+        '      docstring',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr3',
+        '      :module: target.uninitialized_attributes',
+        '      :type: int',
+        '',
+        '      docstring',
+        '',
+    ]
+
+
+@pytest.mark.skipif(sys.version_info < (3, 6), reason='py36+ is available since python3.6.')
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_undocumented_uninitialized_attributes(app):
+    options = {"members": None,
+               "inherited-members": True,
+               "undoc-members": True}
+    actual = do_autodoc(app, 'class', 'target.uninitialized_attributes.Derived', options)
+    assert list(actual) == [
+        '',
+        '.. py:class:: Derived()',
+        '   :module: target.uninitialized_attributes',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr1',
+        '      :module: target.uninitialized_attributes',
+        '      :type: int',
+        '',
+        '      docstring',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr2',
+        '      :module: target.uninitialized_attributes',
+        '      :type: str',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr3',
+        '      :module: target.uninitialized_attributes',
+        '      :type: int',
+        '',
+        '      docstring',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr4',
+        '      :module: target.uninitialized_attributes',
+        '      :type: str',
+        '',
+    ]
+
+
 def test_decorators(app):
     actual = do_autodoc(app, 'class', 'target.decorator.Baz')
     assert list(actual) == [