gh-125618: Make FORWARDREF format succeed more often

[JelleZijlstra]

Fixes#125618.

cc @DavidCEllis

• Issue: [3.14] annotationlib - get_annotations returns an empty annotations dict if an AttributeError is raised when __annotations__ is accessed #125618

[DavidCEllis]

Looks like this works in the case where the object is defined globally, but this still manages to fail if the object used in the annotation is defined (or even potentially redefined) within the function.

Repro:

fromannotationlibimportget_annotations, Formatdefboom():
obj=object()
classRaisesAttributeError:
attriberr: obj.missingget_annotations(RaisesAttributeError, format=Format.FORWARDREF)
boom()

Output:

Traceback (mostrecentcalllast):
File"C:\Users\ducks\Source\cpython\.cache\annotation_examine.py", line9, in<module>boom()
~~~~^^File"C:\Users\ducks\Source\cpython\.cache\annotation_examine.py", line7, inboomget_annotations(RaisesAttributeError, format=Format.FORWARDREF)
~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^File"C:\Users\ducks\Source\cpython\Lib\annotationlib.py", line778, inget_annotationsann=_get_and_call_annotate(obj, format)
File"C:\Users\ducks\Source\cpython\Lib\annotationlib.py", line902, in_get_and_call_annotateann=call_annotate_function(annotate, format, owner=obj)
File"C:\Users\ducks\Source\cpython\Lib\annotationlib.py", line629, incall_annotate_functionresult=func(Format.VALUE_WITH_FAKE_GLOBALS)
File"C:\Users\ducks\Source\cpython\.cache\annotation_examine.py", line6, in__annotate__attriberr: obj.missing^^^^^^^^^^^File"C:\Users\ducks\Source\cpython\Lib\annotationlib.py", line380, in__getattr__returnself.__make_new(ast.Attribute(self.__get_ast(), attr))
~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^File"C:\Users\ducks\Source\cpython\Lib\annotationlib.py", line358, in__make_newself.__stringifier_dict__.stringifiers.append(stringifier)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^AttributeError: 'builtin_function_or_method'objecthasnoattribute'stringifiers'

This came up because this is how I'd written my test case for this (writing the test case was actually as far as I'd gone, because the first test case raised the other issue).

deftest_attributeerror_handled(self):
classMissingAttrib:
passclassRaisesAttributeError:
attriberr: MissingAttrib.missingwithself.assertRaises(AttributeError):
get_annotations(RaisesAttributeError, format=Format.VALUE)
self.assertEqual(
get_annotations(RaisesAttributeError, format=Format.FORWARDREF),
{
"attriberr": support.EqualToForwardRef(
"MissingAttrib.missing", owner=RaisesAttributeError,
is_class=True,
)
}
)
self.assertEqual(
get_annotations(RaisesAttributeError, format=Format.STRING),
{"attriberr": "MissingAttrib.missing"}
)

[JelleZijlstra]

Thanks! This was a silly bug that also broke test_pydoc, I will add your case as a test case so we catch this.