Fix #5480: autodoc: unable to find type hints for unresolvable Forward references

CHANGES

@@ -24,6 +24,7 @@ Bugs fixed
 * #5495: csv-table directive with file option in included file is broken (refs:
   #4821)
 * #5498: autodoc: unable to find type hints for a ``functools.partial``
+* #5480: autodoc: unable to find type hints for unresolvable Forward references
 
 Testing
 --------

sphinx/util/inspect.py

@@ -358,19 +358,12 @@ class Signature(object):
             self.argspec = getargspec(subject)
 
         try:
-            if ispartial(subject):
-                # get_type_hints() does not support partial objects
-                self.annotations = {}  # type: Dict[str, Any]
-            else:
-                self.annotations = typing.get_type_hints(subject)  # type: ignore
-        except Exception as exc:
-            if (3, 5, 0) <= sys.version_info < (3, 5, 3) and isinstance(exc, AttributeError):
-                # python 3.5.2 raises ValueError for classmethod-ized partial objects.
-                self.annotations = {}
-            else:
-                logger.warning('Invalid type annotation found on %r. Ignored: %r',
-                               subject, exc)
-                self.annotations = {}
+            self.annotations = typing.get_type_hints(subject)  # type: ignore
+        except Exception:
+            # get_type_hints() does not support some kind of objects like partial,
+            # ForwardRef and so on.  For them, it raises an exception. In that case,
+            # we try to build annotations from argspec.
+            self.annotations = {}
 
         if bound_method:
             # client gives a hint that the subject is a bound method

tests/test_util_inspect.py

@@ -232,7 +232,7 @@ def test_Signature_partialmethod():
                     reason='type annotation test is available on py34 or above')
 def test_Signature_annotations():
     from typing_test_data import (
-        f0, f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11, f12, f13, f14, Node)
+        f0, f1, f2, f3, f4, f5, f6, f7, f8, f9, f10, f11, f12, f13, f14, f15, Node)
 
     # Class annotations
     sig = inspect.Signature(f0).format_args()
@@ -297,6 +297,10 @@ def test_Signature_annotations():
     sig = inspect.Signature(f14).format_args()
     assert sig == '() -> Any'
 
+    # ForwardRef
+    sig = inspect.Signature(f15).format_args()
+    assert sig == '(x: Unknown, y: int) -> Any'
+
     # type hints by string
     sig = inspect.Signature(Node.children).format_args()
     if (3, 5, 0) <= sys.version_info < (3, 5, 3):

tests/typing_test_data.py

@@ -76,6 +76,10 @@ def f14() -> Any:
     pass
 
 
+def f15(x: "Unknown", y: "int") -> Any:
+    pass
+
+
 class Node:
     def __init__(self, parent: Optional['Node']) -> None:
         pass