Fix #8041: autodoc: An ivar on super class is not shown unexpectedly

An annotated instance variable on super class is not documented when
derived class has also other annotated instance variables because
`obj.__annotations__` is overrided by derived class's type hints.

To get annotations of the target class correctly, this scans MRO to
get all of annotated instance variables.

CHANGES

@@ -71,6 +71,8 @@ Bugs fixed
   when ``:inherited-members:`` option given
 * #8032: autodoc: A type hint for the instance variable defined at parent class
   is not shown in the document of the derived class
+* #8041: autodoc: An annotated instance variable on super class is not
+  documented when derived class has other annotated instance variables
 * #7839: autosummary: cannot handle umlauts in function names
 * #7865: autosummary: Failed to extract summary line when abbreviations found
 * #7866: autosummary: Failed to extract correct summary line when docstring

sphinx/ext/autodoc/__init__.py

@@ -18,6 +18,7 @@
 from typing import (
     Any, Callable, Dict, Iterator, List, Optional, Sequence, Set, Tuple, Type, TypeVar, Union
 )
+from typing import get_type_hints
 
 from docutils.statemachine import StringList
 
@@ -1605,8 +1606,12 @@ def add_directive_header(self, sig: str) -> None:
         sourcename = self.get_sourcename()
         if not self.options.annotation:
             # obtain annotation for this data
-            annotations = getattr(self.parent, '__annotations__', {})
-            if annotations and self.objpath[-1] in annotations:
+            try:
+                annotations = get_type_hints(self.parent)
+            except TypeError:
+                annotations = {}
+
+            if self.objpath[-1] in annotations:
                 objrepr = stringify_typehint(annotations.get(self.objpath[-1]))
                 self.add_line('   :type: ' + objrepr, sourcename)
             else:
@@ -1971,8 +1976,12 @@ def add_directive_header(self, sig: str) -> None:
         sourcename = self.get_sourcename()
         if not self.options.annotation:
             # obtain type annotation for this attribute
-            annotations = getattr(self.parent, '__annotations__', {})
-            if annotations and self.objpath[-1] in annotations:
+            try:
+                annotations = get_type_hints(self.parent)
+            except TypeError:
+                annotations = {}
+
+            if self.objpath[-1] in annotations:
                 objrepr = stringify_typehint(annotations.get(self.objpath[-1]))
                 self.add_line('   :type: ' + objrepr, sourcename)
             else:

sphinx/ext/autodoc/importer.py

@@ -18,6 +18,10 @@
 from sphinx.util import logging
 from sphinx.util.inspect import isclass, isenumclass, safe_getattr
 
+if False:
+    # For type annotation
+    from typing import Type  # NOQA
+
 logger = logging.getLogger(__name__)
 
 
@@ -158,6 +162,24 @@ def get_module_members(module: Any) -> List[Tuple[str, Any]]:
                                      ('value', Any)])
 
 
+def _getmro(obj: Any) -> Tuple["Type", ...]:
+    """Get __mro__ from given *obj* safely."""
+    __mro__ = safe_getattr(obj, '__mro__', None)
+    if isinstance(__mro__, tuple):
+        return __mro__
+    else:
+        return tuple()
+
+
+def _getannotations(obj: Any) -> Mapping[str, Any]:
+    """Get __annotations__ from given *obj* safely."""
+    __annotations__ = safe_getattr(obj, '__annotations__', None)
+    if isinstance(__annotations__, Mapping):
+        return __annotations__
+    else:
+        return {}
+
+
 def get_object_members(subject: Any, objpath: List[str], attrgetter: Callable,
                        analyzer: ModuleAnalyzer = None) -> Dict[str, Attribute]:
     """Get members and attributes of target object."""
@@ -199,11 +221,11 @@ def get_object_members(subject: Any, objpath: List[str], attrgetter: Callable,
             continue
 
     # annotation only member (ex. attr: int)
-    if hasattr(subject, '__annotations__') and isinstance(subject.__annotations__, Mapping):
-        for name in subject.__annotations__:
-            name = unmangle(subject, name)
+    for i, cls in enumerate(_getmro(subject)):
+        for name in _getannotations(cls):
+            name = unmangle(cls, name)
             if name and name not in members:
-                members[name] = Attribute(name, True, INSTANCEATTR)
+                members[name] = Attribute(name, i == 0, INSTANCEATTR)
 
     if analyzer:
         # append instance attributes (cf. self.attr1) if analyzer knows

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

@@ -28,4 +28,4 @@ def __init__(self):
 
 
 class Derived(Class):
-    pass
+    attr7: int

tests/test_ext_autodoc.py

@@ -1580,12 +1580,7 @@ def test_autodoc_typed_instance_variables(app):
         '   :module: target.typed_vars',
         '',
         '',
-        '   .. py:attribute:: Derived.attr2',
-        '      :module: target.typed_vars',
-        '      :type: int',
-        '',
-        '',
-        '   .. py:attribute:: Derived.descr4',
+        '   .. py:attribute:: Derived.attr7',
         '      :module: target.typed_vars',
         '      :type: int',
         '',
@@ -1615,6 +1610,47 @@ def test_autodoc_typed_instance_variables(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_autodoc_typed_inherited_instance_variables(app):
+    options = {"members": None,
+               "undoc-members": True,
+               "inherited-members": True}
+    actual = do_autodoc(app, 'class', 'target.typed_vars.Derived', options)
+    assert list(actual) == [
+        '',
+        '.. py:class:: Derived()',
+        '   :module: target.typed_vars',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr1',
+        '      :module: target.typed_vars',
+        '      :type: int',
+        '      :value: 0',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr2',
+        '      :module: target.typed_vars',
+        '      :type: int',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr3',
+        '      :module: target.typed_vars',
+        '      :value: 0',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr7',
+        '      :module: target.typed_vars',
+        '      :type: int',
+        '',
+        '',
+        '   .. py:attribute:: Derived.descr4',
+        '      :module: target.typed_vars',
+        '      :type: int',
+        '',
+    ]
+
+
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 def test_autodoc_GenericAlias(app):
     options = {"members": None,