Merge pull request #5308 from tk0miya/5306_warning_for_invalid_typehints

Fix #5306: autodoc: emit a warning for invalid typehints

CHANGES

@@ -197,6 +197,7 @@ Features added
 * #5246: Add :confval:`singlehtml_sidebars` to configure sidebars for singlehtml
   builder
 * #5273: doctest: Skip doctest conditionally
+* #5306: autodoc: emit a warning for invalid typehints
 
 Bugs fixed
 ----------

sphinx/util/inspect.py

@@ -20,12 +20,15 @@
 from six.moves import builtins
 
 from sphinx.util import force_decode
+from sphinx.util import logging
 from sphinx.util.pycompat import NoneType
 
 if False:
     # For type annotation
     from typing import Any, Callable, Dict, List, Tuple, Type  # NOQA
 
+logger = logging.getLogger(__name__)
+
 memory_address_re = re.compile(r' at 0x[0-9a-f]{8,16}(?=>)', re.IGNORECASE)
 
 
@@ -339,7 +342,8 @@ def __init__(self, subject, bound_method=False, has_retval=True):
 
         try:
             self.annotations = typing.get_type_hints(subject)  # type: ignore
-        except Exception:
+        except Exception as exc:
+            logger.warning('Invalid type annotation found on %r. Ingored: %r', subject, exc)
             self.annotations = {}
 
         if bound_method: