Fix #7983: autodoc: Generator type annotation is wrongly rendered in py36

This adds a special handler (if-branch) for Generator type to stringify
them correctly.  So far, they have been considered as a kind of Callable.

1 files changed, 3 insertions, 1 deletions

diff --git a/sphinx/util/typing.py b/sphinx/util/typing.py
index 86f9c6e5c..d71ca1b2d 100644
--- a/sphinx/util/typing.py
+++ b/sphinx/util/typing.py
@@ -10,7 +10,7 @@
 
 import sys
 import typing
-from typing import Any, Callable, Dict, List, Tuple, TypeVar, Union
+from typing import Any, Callable, Dict, Generator, List, Tuple, TypeVar, Union
 
 from docutils import nodes
 from docutils.parsers.rst.states import Inliner
@@ -164,6 +164,8 @@ def _stringify_py36(annotation: Any) -> str:
             # for Python 3.5.2+
             if annotation.__args__ is None or len(annotation.__args__) <= 2:  # type: ignore  # NOQA
                 params = annotation.__args__  # type: ignore
+            elif annotation.__origin__ == Generator:  # type: ignore
+                params = annotation.__args__  # type: ignore
             else:  # typing.Callable
                 args = ', '.join(stringify(arg) for arg
                                  in annotation.__args__[:-1])  # type: ignore