Fix sphinx-doc#8157: autodoc: TypeError is raised when annotation has…

… invalid __args__

Typically, the __args__ attribute of type annotations is a tuple
containing arguments for the types (ex. The __args__ of `List[int]` is
`(int,)`).  But some kind of types has non tuple __args__ attribute.
For example, `nptyping.NDArray` is one of them.

This fixes the TypeError when the invalid __args__ attribute found.

CHANGES

@@ -34,6 +34,7 @@ Bugs fixed
   by string not ending with blank lines
 * #8142: autodoc: Wrong constructor signature for the class derived from
   typing.Generic
+* #8157: autodoc: TypeError is raised when annotation has invalid __args__
 * #8192: napoleon: description is disappeared when it contains inline literals
 * #8142: napoleon: Potential of regex denial of service in google style docs
 * #8169: LaTeX: pxjahyper loaded even when latex_engine is not platex

sphinx/util/inspect.py

@@ -9,6 +9,7 @@
 """
 
 import builtins
+import collections.abc
 import contextlib
 import enum
 import inspect
@@ -302,6 +303,11 @@ def iscoroutinefunction(obj: Any) -> bool:
         return False
 
 
+def isiterable(obj: Any) -> bool:
+    """Check if the object is iterable."""
+    return isinstance(obj, collections.abc.Iterable)
+
+
 def isproperty(obj: Any) -> bool:
     """Check if the object is property."""
     if sys.version_info > (3, 8):

sphinx/util/typing.py

@@ -15,6 +15,8 @@
 from docutils import nodes
 from docutils.parsers.rst.states import Inliner
 
+from sphinx.util.inspect import isiterable
+
 
 if sys.version_info > (3, 7):
     from typing import ForwardRef
@@ -105,7 +107,10 @@ def _stringify_py37(annotation: Any) -> str:
         return repr(annotation)
 
     if getattr(annotation, '__args__', None):
-        if qualname == 'Union':
+        if not isiterable(annotation.__args__):
+            # broken __args__ found
+            qualname = repr(annotation)
+        elif qualname == 'Union':
             if len(annotation.__args__) > 1 and annotation.__args__[-1] is NoneType:
                 if len(annotation.__args__) > 2:
                     args = ', '.join(stringify(a) for a in annotation.__args__[:-1])