Fixed formatting of parametrized IO annotation

Fixes #142.

Author: agronholm

CHANGELOG.rst

@@ -2,6 +2,8 @@ UNRELEASED
 ==========
 
 * Dropped support for Sphinx < 3.0
+* Fixed ``TypeError`` when formatting a parametrized ``typing.IO`` annotation
+
 
 1.10.3
 ======

sphinx_autodoc_typehints.py

@@ -42,7 +42,8 @@ def get_annotation_class_name(annotation, module: str) -> str:
         return annotation.__qualname__
     elif getattr(annotation, '_name', None):  # Required for generic aliases on Python 3.7+
         return annotation._name
-    elif getattr(annotation, 'name', None) and module in ('typing', 'typing_extensions'):
+    elif (module in ('typing', 'typing_extensions')
+            and isinstance(getattr(annotation, 'name', None), str)):
         # Required for at least Pattern and Match
         return annotation.name
 

tests/test_sphinx_autodoc_typehints.py

@@ -143,6 +143,7 @@ def test_parse_annotation(annotation, module, class_name, args):
     (Pattern,                       ':py:class:`~typing.Pattern`'),
     (Pattern[str],                  ':py:class:`~typing.Pattern`\\[:py:class:`str`]'),
     (IO,                            ':py:class:`~typing.IO`'),
+    (IO[str],                       ':py:class:`~typing.IO`\\[:py:class:`str`]'),
     (Metaclass,                     ':py:class:`~%s.Metaclass`' % __name__),
     (A,                             ':py:class:`~%s.A`' % __name__),
     (B,                             ':py:class:`~%s.B`' % __name__),
@@ -483,7 +484,7 @@ class dummy_module.DataClass
 
            Class docstring.
 
-           __init__() -> None
+           __init__()
 
               {dataclass_docstring}