Bug report

Bug description:

This issue was originally reported in thebeartype library (Ref:beartype/beartype#610), but investigation suggests it may stem from a change in Python’sannotationlib.ForwardRef implementation.

Starting with Python 3.14.1, deferred annotations (PEP 649) involving self-referential return type is raising:TypeError: unhashable type: 'cell' at decoration time.This worked correctly in Python 3.14.0 and the issue appears to persist in 3.14.2, suggesting a regression.

The error originates fromannotationlib.ForwardRef.__hash__, which attempts to hash internal state containing non-hashable cell objects. Although observed via beartype, this may affects any downstream library that hashes ForwardRef objects. The following code seems to be raising the issue:
tuple(sorted(self.__cell__.items())) if isinstance(self.__cell__, dict) else self.__cell__,

Code:

#!pip install beartype==0.22.9frombeartypeimportbeartypeclassMyClass:@beartypedeffoo(self)->MyClass:returnMyClass()print(MyClass().foo())

Observed behavior:

The program fails during decoration with the error:TypeError: unhashable type: 'cell'

File".../beartype/_check/metadata/hint/hintsane.py", line 242,in __init__    self._hash = hash((hint, hint_recursable_to_depth, typearg_to_hint))File".../python3.14/annotationlib.py", line 291,in __hash__return hash((..., tuple(sorted(self.__extra_names__.items()))))TypeError: unhashable type:'cell'

Inspection shows:

>>>self.__cell__{'__classdict__':<cellat0x...:dictobject>}>>>tuple(sorted(self.__cell__.items()))(('__classdict__',<cellat0x...>),)

Since cell objects are not hashable, this causeshash to fail.

Affected Versions:

Python3.14.1 and3.14.2
OS Tested on: MacOS

CPython versions tested on:

3.14

Operating systems tested on:

macOS

Linked PRs

• gh-143831: Compare cells by identity in forward references #143848
• [3.14] gh-143831: Compare cells by identity in forward references (GH-143848) #144020