Close #7051: autodoc: Support instance variables without defaults (PEP-526)

6 files changed, 126 insertions, 13 deletions

diff --git a/CHANGES b/CHANGES
index 1466548e4..14427b3c2 100644
--- a/CHANGES
+++ b/CHANGES
@@ -39,6 +39,7 @@ Features added
 * #2755: autodoc: Support type_comment style (ex. ``# type: (str) -> str``)
   annotation (python3.8+ or `typed_ast <https://github.com/python/typed_ast>`_
   is required)
+* #7051: autodoc: Support instance variables without defaults (PEP-526)
 * SphinxTranslator now calls visitor/departure method for super node class if
   visitor/departure method for original node class not found
 
diff --git a/sphinx/ext/autodoc/__init__.py b/sphinx/ext/autodoc/__init__.py
index 9c4d4ba40..c9eb5207f 100644
--- a/sphinx/ext/autodoc/__init__.py
+++ b/sphinx/ext/autodoc/__init__.py
@@ -24,7 +24,7 @@ from sphinx.deprecation import (
     RemovedInSphinx30Warning, RemovedInSphinx40Warning, deprecated_alias
 )
 from sphinx.environment import BuildEnvironment
-from sphinx.ext.autodoc.importer import import_object, get_object_members
+from sphinx.ext.autodoc.importer import import_object, get_module_members, get_object_members
 from sphinx.ext.autodoc.mock import mock
 from sphinx.locale import _, __
 from sphinx.pycode import ModuleAnalyzer, PycodeError
@@ -32,9 +32,7 @@ from sphinx.util import inspect
 from sphinx.util import logging
 from sphinx.util import rpartition
 from sphinx.util.docstrings import prepare_docstring
-from sphinx.util.inspect import (
-    getdoc, object_description, safe_getattr, safe_getmembers, stringify_signature
-)
+from sphinx.util.inspect import getdoc, object_description, safe_getattr, stringify_signature
 
 if False:
     # For type annotation
@@ -529,7 +527,10 @@ class Documenter:
         # process members and determine which to skip
         for (membername, member) in members:
             # if isattr is True, the member is documented as an attribute
-            isattr = False
+            if member is INSTANCEATTR:
+                isattr = True
+            else:
+                isattr = False
 
             doc = getdoc(member, self.get_attr, self.env.config.autodoc_inherit_docstrings)
 
@@ -793,7 +794,7 @@ class ModuleDocumenter(Documenter):
                     hasattr(self.object, '__all__')):
                 # for implicit module members, check __module__ to avoid
                 # documenting imported objects
-                return True, safe_getmembers(self.object)
+                return True, get_module_members(self.object)
             else:
                 memberlist = self.object.__all__
                 # Sometimes __all__ is broken...
@@ -806,7 +807,7 @@ class ModuleDocumenter(Documenter):
                         type='autodoc'
                     )
                     # fall back to all members
-                    return True, safe_getmembers(self.object)
+                    return True, get_module_members(self.object)
         else:
             memberlist = self.options.members or []
         ret = []
@@ -1251,6 +1252,37 @@ class DataDocumenter(ModuleLevelDocumenter):
             or self.modname
 
 
+class DataDeclarationDocumenter(DataDocumenter):
+    """
+    Specialized Documenter subclass for data that cannot be imported
+    because they are declared without initial value (refs: PEP-526).
+    """
+    objtype = 'datadecl'
+    directivetype = 'data'
+    member_order = 60
+
+    # must be higher than AttributeDocumenter
+    priority = 11
+
+    @classmethod
+    def can_document_member(cls, member: Any, membername: str, isattr: bool, parent: Any
+                            ) -> bool:
+        """This documents only INSTANCEATTR members."""
+        return (isinstance(parent, ModuleDocumenter) and
+                isattr and
+                member is INSTANCEATTR)
+
+    def import_object(self) -> bool:
+        """Never import anything."""
+        # disguise as a data
+        self.objtype = 'data'
+        return True
+
+    def add_content(self, more_content: Any, no_docstring: bool = False) -> None:
+        """Never try to get a docstring from the object."""
+        super().add_content(more_content, no_docstring=True)
+
+
 class MethodDocumenter(DocstringSignatureMixin, ClassLevelDocumenter):  # type: ignore
     """
     Specialized Documenter subclass for methods (normal, static and class).
@@ -1438,7 +1470,9 @@ class InstanceAttributeDocumenter(AttributeDocumenter):
     def can_document_member(cls, member: Any, membername: str, isattr: bool, parent: Any
                             ) -> bool:
         """This documents only INSTANCEATTR members."""
-        return isattr and (member is INSTANCEATTR)
+        return (not isinstance(parent, ModuleDocumenter) and
+                isattr and
+                member is INSTANCEATTR)
 
     def import_object(self) -> bool:
         """Never import anything."""
@@ -1550,6 +1584,7 @@ def setup(app: Sphinx) -> Dict[str, Any]:
     app.add_autodocumenter(ClassDocumenter)
     app.add_autodocumenter(ExceptionDocumenter)
     app.add_autodocumenter(DataDocumenter)
+    app.add_autodocumenter(DataDeclarationDocumenter)
     app.add_autodocumenter(FunctionDocumenter)
     app.add_autodocumenter(DecoratorDocumenter)
     app.add_autodocumenter(MethodDocumenter)
diff --git a/sphinx/ext/autodoc/importer.py b/sphinx/ext/autodoc/importer.py
index 31bc6042d..672d90ec7 100644
--- a/sphinx/ext/autodoc/importer.py
+++ b/sphinx/ext/autodoc/importer.py
@@ -12,7 +12,7 @@ import importlib
 import traceback
 import warnings
 from collections import namedtuple
-from typing import Any, Callable, Dict, List
+from typing import Any, Callable, Dict, List, Tuple
 
 from sphinx.deprecation import RemovedInSphinx40Warning, deprecated_alias
 from sphinx.util import logging
@@ -101,12 +101,35 @@ def import_object(modname: str, objpath: List[str], objtype: str = '',
         raise ImportError(errmsg)
 
 
+def get_module_members(module: Any) -> List[Tuple[str, Any]]:
+    """Get members of target module."""
+    from sphinx.ext.autodoc import INSTANCEATTR
+
+    members = {}  # type: Dict[str, Tuple[str, Any]]
+    for name in dir(module):
+        try:
+            value = safe_getattr(module, name, None)
+            members[name] = (name, value)
+        except AttributeError:
+            continue
+
+    # annotation only member (ex. attr: int)
+    if hasattr(module, '__annotations__'):
+        for name in module.__annotations__:
+            if name not in members:
+                members[name] = (name, INSTANCEATTR)
+
+    return sorted(list(members.values()))
+
+
 Attribute = namedtuple('Attribute', ['name', 'directly_defined', 'value'])
 
 
 def get_object_members(subject: Any, objpath: List[str], attrgetter: Callable,
                        analyzer: Any = None) -> Dict[str, Attribute]:
     """Get members and attributes of target object."""
+    from sphinx.ext.autodoc import INSTANCEATTR
+
     # the members directly defined in the class
     obj_dict = attrgetter(subject, '__dict__', {})
 
@@ -140,10 +163,14 @@ def get_object_members(subject: Any, objpath: List[str], attrgetter: Callable,
         except AttributeError:
             continue
 
+    # annotation only member (ex. attr: int)
+    if hasattr(subject, '__annotations__'):
+        for name in subject.__annotations__:
+            if name not in members:
+                members[name] = Attribute(name, True, INSTANCEATTR)
+
     if analyzer:
         # append instance attributes (cf. self.attr1) if analyzer knows
-        from sphinx.ext.autodoc import INSTANCEATTR
-
         namespace = '.'.join(objpath)
         for (ns, name) in analyzer.find_attr_docs():
             if namespace == ns and name not in members:
diff --git a/sphinx/ext/autosummary/generate.py b/sphinx/ext/autosummary/generate.py
index cf7f52f33..57082c943 100644
--- a/sphinx/ext/autosummary/generate.py
+++ b/sphinx/ext/autosummary/generate.py
@@ -71,13 +71,13 @@ def setup_documenters(app: Any) -> None:
         ModuleDocumenter, ClassDocumenter, ExceptionDocumenter, DataDocumenter,
         FunctionDocumenter, MethodDocumenter, AttributeDocumenter,
         InstanceAttributeDocumenter, DecoratorDocumenter, PropertyDocumenter,
-        SlotsAttributeDocumenter,
+        SlotsAttributeDocumenter, DataDeclarationDocumenter,
     )
     documenters = [
         ModuleDocumenter, ClassDocumenter, ExceptionDocumenter, DataDocumenter,
         FunctionDocumenter, MethodDocumenter, AttributeDocumenter,
         InstanceAttributeDocumenter, DecoratorDocumenter, PropertyDocumenter,
-        SlotsAttributeDocumenter,
+        SlotsAttributeDocumenter, DataDeclarationDocumenter,
     ]  # type: List[Type[Documenter]]
     for documenter in documenters:
         app.registry.add_documenter(documenter.objtype, documenter)
diff --git a/tests/roots/test-ext-autodoc/target/typed_vars.py b/tests/roots/test-ext-autodoc/target/typed_vars.py
new file mode 100644
index 000000000..9c71cd55b
--- /dev/null
+++ b/tests/roots/test-ext-autodoc/target/typed_vars.py
@@ -0,0 +1,9 @@
+#: attr1
+attr1: str = ''
+#: attr2
+attr2: str
+
+
+class Class:
+    attr1: int = 0
+    attr2: int
diff --git a/tests/test_autodoc.py b/tests/test_autodoc.py
index 6ee2c6ea9..05cc8bc74 100644
--- a/tests/test_autodoc.py
+++ b/tests/test_autodoc.py
@@ -1388,6 +1388,47 @@ def test_partialmethod_undoc_members(app):
     assert list(actual) == expected
 
 
+@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_instance_variables(app):
+    options = {"members": None,
+               "undoc-members": True}
+    actual = do_autodoc(app, 'module', 'target.typed_vars', options)
+    assert list(actual) == [
+        '',
+        '.. py:module:: target.typed_vars',
+        '',
+        '',
+        '.. py:class:: Class',
+        '   :module: target.typed_vars',
+        '',
+        '   ',
+        '   .. py:attribute:: Class.attr1',
+        '      :module: target.typed_vars',
+        '      :annotation: = 0',
+        '   ',
+        '   ',
+        '   .. py:attribute:: Class.attr2',
+        '      :module: target.typed_vars',
+        '      :annotation: = None',
+        '   ',
+        '',
+        '.. py:data:: attr1',
+        '   :module: target.typed_vars',
+        "   :annotation: = ''",
+        '',
+        '   attr1',
+        '   ',
+        '',
+        '.. py:data:: attr2',
+        '   :module: target.typed_vars',
+        "   :annotation: = None",
+        '',
+        '   attr2',
+        '   '
+    ]
+
+
 @pytest.mark.sphinx('html', testroot='pycode-egg')
 def test_autodoc_for_egged_code(app):
     options = {"members": None,