Fix #8032: autodoc: A typehint for inherited ivars is not shown

This tries to import the parent object for the instance attribute
to get type annotations for the variable.

CHANGES

@@ -61,6 +61,8 @@ Bugs fixed
 * #7983: autodoc: Generator type annotation is wrongly rendered in py36
 * #8030: autodoc: An uninitialized annotated instance variable is not documented
   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
 * #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

@@ -2020,11 +2020,22 @@ class InstanceAttributeDocumenter(AttributeDocumenter):
                 isattr and
                 member is INSTANCEATTR)
 
+    def import_parent(self) -> Any:
+        try:
+            parent = importlib.import_module(self.modname)
+            for name in self.objpath[:-1]:
+                parent = self.get_attr(parent, name)
+
+            return parent
+        except (ImportError, AttributeError):
+            return None
+
     def import_object(self, raiseerror: bool = False) -> bool:
         """Never import anything."""
         # disguise as an attribute
         self.objtype = 'attribute'
         self.object = INSTANCEATTR
+        self.parent = self.import_parent()
         self._datadescriptor = False
         return True
 

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

@@ -25,3 +25,7 @@ class Class:
         self.attr5: int         #: attr5
         self.attr6 = 0          # type: int
         """attr6"""
+
+
+class Derived(Class):
+    pass

tests/test_ext_autodoc.py

@@ -1576,6 +1576,20 @@ def test_autodoc_typed_instance_variables(app):
         '      This is descr4',
         '',
         '',
+        '.. py:class:: Derived()',
+        '   :module: target.typed_vars',
+        '',
+        '',
+        '   .. py:attribute:: Derived.attr2',
+        '      :module: target.typed_vars',
+        '      :type: int',
+        '',
+        '',
+        '   .. py:attribute:: Derived.descr4',
+        '      :module: target.typed_vars',
+        '      :type: int',
+        '',
+        '',
         '.. py:data:: attr1',
         '   :module: target.typed_vars',
         '   :type: str',