Fix #8545: autodoc: a __slots__ attribute is not documented even having docstring

To avoid filtering __slots__ attributes having docstring at
filter_members(), this passes docstring captured at get_class_members()
to the filter_members() via ObjectMember.

CHANGES

@@ -79,6 +79,7 @@ Bugs fixed
 * #8522: autodoc:  ``__bool__`` method could be called
 * #8067: autodoc: A typehint for the instance variable having type_comment on
   super class is not displayed
+* #8545: autodoc: a __slots__ attribute is not documented even having docstring
 * #8477: autosummary: non utf-8 reST files are generated when template contains
   multibyte characters
 * #8501: autosummary: summary extraction splits text after "el at." unexpectedly

sphinx/ext/autodoc/__init__.py

@@ -275,9 +275,11 @@ class ObjectMember(tuple):
     def __new__(cls, name: str, obj: Any, **kwargs: Any) -> Any:
         return super().__new__(cls, (name, obj))  # type: ignore
 
-    def __init__(self, name: str, obj: Any, skipped: bool = False) -> None:
+    def __init__(self, name: str, obj: Any, docstring: Optional[str] = None,
+                 skipped: bool = False) -> None:
         self.__name__ = name
         self.object = obj
+        self.docstring = docstring
         self.skipped = skipped
 
 
@@ -709,6 +711,11 @@ class Documenter:
                 cls_doc = self.get_attr(cls, '__doc__', None)
                 if cls_doc == doc:
                     doc = None
+
+            if isinstance(obj, ObjectMember) and obj.docstring:
+                # hack for ClassDocumenter to inject docstring via ObjectMember
+                doc = obj.docstring
+
             has_doc = bool(doc)
 
             metadata = extract_metadata(doc)
@@ -1585,16 +1592,18 @@ class ClassDocumenter(DocstringSignatureMixin, ModuleLevelDocumenter):  # type:
             selected = []
             for name in self.options.members:  # type: str
                 if name in members:
-                    selected.append((name, members[name].value))
+                    selected.append(ObjectMember(name, members[name].value,
+                                                 docstring=members[name].docstring))
                 else:
                     logger.warning(__('missing attribute %s in object %s') %
                                    (name, self.fullname), type='autodoc')
             return False, selected
         elif self.options.inherited_members:
-            return False, [(m.name, m.value) for m in members.values()]
+            return False, [ObjectMember(m.name, m.value, docstring=m.docstring)
+                           for m in members.values()]
         else:
-            return False, [(m.name, m.value) for m in members.values()
-                           if m.class_ == self.object]
+            return False, [ObjectMember(m.name, m.value, docstring=m.docstring)
+                           for m in members.values() if m.class_ == self.object]
 
     def get_doc(self, encoding: str = None, ignore: int = None) -> List[List[str]]:
         if encoding is not None:

sphinx/ext/autodoc/importer.py

@@ -310,9 +310,10 @@ def get_class_members(subject: Any, objpath: List[str], attrgetter: Callable,
     if analyzer:
         # append instance attributes (cf. self.attr1) if analyzer knows
         namespace = '.'.join(objpath)
-        for (ns, name) in analyzer.find_attr_docs():
+        for (ns, name), docstring in analyzer.attr_docs.items():
             if namespace == ns and name not in members:
-                members[name] = ClassAttribute(subject, name, INSTANCEATTR)
+                members[name] = ClassAttribute(subject, name, INSTANCEATTR,
+                                               '\n'.join(docstring))
 
     return members
 

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

@@ -1,8 +1,12 @@
 class Foo:
+    """docstring"""
+
     __slots__ = ['attr']
 
 
 class Bar:
+    """docstring"""
+
     __slots__ = {'attr1': 'docstring of attr1',
                  'attr2': 'docstring of attr2',
                  'attr3': None}
@@ -12,4 +16,6 @@ class Bar:
 
 
 class Baz:
+    """docstring"""
+
     __slots__ = 'attr'

tests/test_ext_autodoc.py

@@ -1172,6 +1172,8 @@ def test_slots(app):
         '.. py:class:: Bar()',
         '   :module: target.slots',
         '',
+        '   docstring',
+        '',
         '',
         '   .. py:attribute:: Bar.attr1',
         '      :module: target.slots',
@@ -1192,6 +1194,8 @@ def test_slots(app):
         '.. py:class:: Baz()',
         '   :module: target.slots',
         '',
+        '   docstring',
+        '',
         '',
         '   .. py:attribute:: Baz.attr',
         '      :module: target.slots',
@@ -1200,6 +1204,8 @@ def test_slots(app):
         '.. py:class:: Foo()',
         '   :module: target.slots',
         '',
+        '   docstring',
+        '',
         '',
         '   .. py:attribute:: Foo.attr',
         '      :module: target.slots',

tests/test_ext_autodoc_autoclass.py

@@ -77,6 +77,32 @@ def test_decorators(app):
     ]
 
 
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_slots_attribute(app):
+    options = {"members": None}
+    actual = do_autodoc(app, 'class', 'target.slots.Bar', options)
+    assert list(actual) == [
+        '',
+        '.. py:class:: Bar()',
+        '   :module: target.slots',
+        '',
+        '   docstring',
+        '',
+        '',
+        '   .. py:attribute:: Bar.attr1',
+        '      :module: target.slots',
+        '',
+        '      docstring of attr1',
+        '',
+        '',
+        '   .. py:attribute:: Bar.attr2',
+        '      :module: target.slots',
+        '',
+        '      docstring of instance attr2',
+        '',
+    ]
+
+
 @pytest.mark.skipif(sys.version_info < (3, 7), reason='python 3.7+ is required.')
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_show_inheritance_for_subclass_of_generic_type(app):