Fix #8460: autodoc: Support custom types defined by typing.NewType

A custom type defined by typing.NewType was rendered as a function
because the generated type is a function having special attributes.
This renders it as a variable.

Note: The module name where the NewType object defined is lost on
generating it.  So it is hard to make cross-reference for these custom
types.

CHANGES

@@ -30,6 +30,7 @@ Features added
   value equal to None is set.
 * #8209: autodoc: Add ``:no-value:`` option to :rst:dir:`autoattribute` and
   :rst:dir:`autodata` directive to suppress the default value of the variable
+* #8460: autodoc: Support custom types defined by typing.NewType
 * #6914: Add a new event :event:`warn-missing-reference` to custom warning
   messages when failed to resolve a cross-reference
 * #6914: Emit a detailed warning when failed to resolve a ``:ref:`` reference

sphinx/ext/autodoc/__init__.py

@@ -1714,7 +1714,12 @@ class DataDocumenter(ModuleLevelDocumenter):
     def add_directive_header(self, sig: str) -> None:
         super().add_directive_header(sig)
         sourcename = self.get_sourcename()
-        if not self.options.annotation:
+        if self.options.annotation is SUPPRESS or inspect.isNewType(self.object):
+            pass
+        elif self.options.annotation:
+            self.add_line('   :annotation: %s' % self.options.annotation,
+                          sourcename)
+        else:
             # obtain annotation for this data
             annotations = get_type_hints(self.parent, None, self.config.autodoc_type_aliases)
             if self.objpath[-1] in annotations:
@@ -1734,11 +1739,6 @@ class DataDocumenter(ModuleLevelDocumenter):
                     self.add_line('   :value: ' + objrepr, sourcename)
             except ValueError:
                 pass
-        elif self.options.annotation is SUPPRESS:
-            pass
-        else:
-            self.add_line('   :annotation: %s' % self.options.annotation,
-                          sourcename)
 
     def document_members(self, all_members: bool = False) -> None:
         pass
@@ -1753,8 +1753,18 @@ class DataDocumenter(ModuleLevelDocumenter):
             # suppress docstring of the value
             super().add_content(more_content, no_docstring=True)
         else:
+            if not more_content:
+                more_content = StringList()
+
+            if inspect.isNewType(self.object):
+                self.update_content_for_NewType(more_content)
             super().add_content(more_content, no_docstring=no_docstring)
 
+    def update_content_for_NewType(self, more_content: StringList) -> None:
+        supertype = restify(self.object.__supertype__)
+        more_content.append(_('alias of %s') % supertype, '')
+        more_content.append('', '')
+
 
 class DataDeclarationDocumenter(DataDocumenter):
     """
@@ -1800,6 +1810,24 @@ class GenericAliasDocumenter(DataDocumenter):
         super().add_content(content)
 
 
+class NewTypeDataDocumenter(DataDocumenter):
+    """
+    Specialized Documenter subclass for NewTypes.
+
+    Note: This must be invoked before FunctionDocumenter because NewType is a kind of
+    function object.
+    """
+
+    objtype = 'newtypedata'
+    directivetype = 'data'
+    priority = FunctionDocumenter.priority + 1
+
+    @classmethod
+    def can_document_member(cls, member: Any, membername: str, isattr: bool, parent: Any
+                            ) -> bool:
+        return inspect.isNewType(member) and isattr
+
+
 class TypeVarDocumenter(DataDocumenter):
     """
     Specialized Documenter subclass for TypeVars.
@@ -2307,6 +2335,7 @@ def setup(app: Sphinx) -> Dict[str, Any]:
     app.add_autodocumenter(ExceptionDocumenter)
     app.add_autodocumenter(DataDocumenter)
     app.add_autodocumenter(GenericAliasDocumenter)
+    app.add_autodocumenter(NewTypeDataDocumenter)
     app.add_autodocumenter(TypeVarDocumenter)
     app.add_autodocumenter(FunctionDocumenter)
     app.add_autodocumenter(DecoratorDocumenter)

sphinx/ext/autosummary/generate.py

@@ -89,11 +89,12 @@ def setup_documenters(app: Any) -> None:
                                     DecoratorDocumenter, ExceptionDocumenter,
                                     FunctionDocumenter, GenericAliasDocumenter,
                                     InstanceAttributeDocumenter, MethodDocumenter,
-                                    ModuleDocumenter, PropertyDocumenter,
-                                    SingledispatchFunctionDocumenter, SlotsAttributeDocumenter)
+                                    ModuleDocumenter, NewTypeDataDocumenter,
+                                    PropertyDocumenter, SingledispatchFunctionDocumenter,
+                                    SlotsAttributeDocumenter)
     documenters = [
         ModuleDocumenter, ClassDocumenter, ExceptionDocumenter, DataDocumenter,
-        FunctionDocumenter, MethodDocumenter, AttributeDocumenter,
+        FunctionDocumenter, MethodDocumenter, NewTypeDataDocumenter, AttributeDocumenter,
         InstanceAttributeDocumenter, DecoratorDocumenter, PropertyDocumenter,
         SlotsAttributeDocumenter, GenericAliasDocumenter, SingledispatchFunctionDocumenter,
     ]  # type: List[Type[Documenter]]

sphinx/util/inspect.py

@@ -174,6 +174,16 @@ def getslots(obj: Any) -> Optional[Dict]:
         raise ValueError
 
 
+def isNewType(obj: Any) -> bool:
+    """Check the if object is a kind of NewType."""
+    __module__ = safe_getattr(obj, '__module__', None)
+    __qualname__ = safe_getattr(obj, '__qualname__', None)
+    if __module__ == 'typing' and __qualname__ == 'NewType.<locals>.new_type':
+        return True
+    else:
+        return False
+
+
 def isenumclass(x: Any) -> bool:
     """Check if the object is subclass of enum."""
     return inspect.isclass(x) and issubclass(x, enum.Enum)

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

@@ -1,4 +1,4 @@
-from typing import TypeVar
+from typing import NewType, TypeVar
 
 #: T1
 T1 = TypeVar("T1")
@@ -13,3 +13,6 @@ T4 = TypeVar("T4", covariant=True)
 
 #: T5
 T5 = TypeVar("T5", contravariant=True)
+
+#: T6
+T6 = NewType("T6", int)

tests/test_ext_autodoc.py

@@ -1758,6 +1758,14 @@ def test_autodoc_TypeVar(app):
         '   T5',
         '',
         "   alias of TypeVar('T5', contravariant=True)",
+        '',
+        '.. py:data:: T6',
+        '   :module: target.typevar',
+        '',
+        '   T6',
+        '',
+        '   alias of :class:`int`',
+        '',
     ]
 
 

tests/test_ext_autodoc_autodata.py

@@ -73,3 +73,18 @@ def test_autodata_type_comment(app):
         '   attr3',
         '',
     ]
+
+
+@pytest.mark.sphinx('html', testroot='ext-autodoc')
+def test_autodata_NewType(app):
+    actual = do_autodoc(app, 'data', 'target.typevar.T6')
+    assert list(actual) == [
+        '',
+        '.. py:data:: T6',
+        '   :module: target.typevar',
+        '',
+        '   T6',
+        '',
+        '   alias of :class:`int`',
+        '',
+    ]