From dcd8ff544aadbd75a6357457462be15e17fa2e67 Mon Sep 17 00:00:00 2001
From: Takeshi KOMIYA <i.tkomiya@gmail.com>
Date: Thu, 19 Nov 2020 00:32:49 +0900
Subject: [PATCH] Fix #8443: autoattribute does not support uninitialized ivars

---
 CHANGES                                 |  2 ++
 sphinx/ext/autodoc/__init__.py          | 20 ++++++++++++++++-
 tests/test_ext_autodoc_autoattribute.py | 30 +++++++++++++++++++++++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/CHANGES b/CHANGES
index 5639d032f..44f63a357 100644
--- a/CHANGES
+++ b/CHANGES
@@ -45,6 +45,8 @@ Bugs fixed
   and attributes
 * #8443: autodoc: autodata directive can't create document for PEP-526 based
   type annotated variables
+* #8443: autodoc: autoattribute directive can't create document for PEP-526
+  based uninitalized variables
 * #8419: html search: Do not load ``language_data.js`` in non-search pages
 
 Testing
diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index 79a3c78fc..a73b67f92 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -2045,6 +2045,22 @@ class AttributeDocumenter(DocstringStripSignatureMixin, ClassLevelDocumenter):
 
     def isinstanceattribute(self) -> bool:
         """Check the subject is an instance attribute."""
+        # uninitialized instance variable (PEP-526)
+        with mock(self.config.autodoc_mock_imports):
+            try:
+                ret = import_object(self.modname, self.objpath[:-1], 'class',
+                                    attrgetter=self.get_attr,
+                                    warningiserror=self.config.autodoc_warningiserror)
+                self.parent = ret[3]
+                annotations = get_type_hints(self.parent, None,
+                                             self.config.autodoc_type_aliases)
+                if self.objpath[-1] in annotations:
+                    self.object = UNINITIALIZED_ATTR
+                    return True
+            except ImportError:
+                pass
+
+        # An instance variable defined inside __init__().
         try:
             analyzer = ModuleAnalyzer.for_module(self.modname)
             attr_docs = analyzer.find_attr_docs()
@@ -2055,7 +2071,9 @@ class AttributeDocumenter(DocstringStripSignatureMixin, ClassLevelDocumenter):
 
             return False
         except PycodeError:
-            return False
+            pass
+
+        return False
 
     def import_object(self, raiseerror: bool = False) -> bool:
         try:
diff --git a/tests/test_ext_autodoc_autoattribute.py b/tests/test_ext_autodoc_autoattribute.py
index ca74f9aeb..31dccbd03 100644
--- a/tests/test_ext_autodoc_autoattribute.py
+++ b/tests/test_ext_autodoc_autoattribute.py
@@ -9,6 +9,8 @@
     :license: BSD, see LICENSE for details.
 """
 
+import sys
+
 import pytest
 from test_ext_autodoc import do_autodoc
 
@@ -39,3 +41,31 @@ def test_autoattribute_novalue(app):
         '   should be documented -- süß',
         '',
     ]
+
+
+@pytest.mark.skipif(sys.version_info < (3, 6), reason='python 3.6+ is required.')
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_autoattribute_typed_variable(app):
+    actual = do_autodoc(app, 'attribute', 'target.typed_vars.Class.attr2')
+    assert list(actual) == [
+        '',
+        '.. py:attribute:: Class.attr2',
+        '   :module: target.typed_vars',
+        '   :type: int',
+        '',
+    ]
+
+
+@pytest.mark.skipif(sys.version_info < (3, 6), reason='python 3.6+ is required.')
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_autoattribute_instance_variable(app):
+    actual = do_autodoc(app, 'attribute', 'target.typed_vars.Class.attr4')
+    assert list(actual) == [
+        '',
+        '.. py:attribute:: Class.attr4',
+        '   :module: target.typed_vars',
+        '   :type: int',
+        '',
+        '   attr4',
+        '',
+    ]