annotationlib.get_annotations() infinite loop on __wrapped__ cycle (eval_str=True)

[raminfp]

Bug report

Bug description:

annotationlib.get_annotations() hangs indefinitely when called with eval_str=True on a callable that has a circular __wrapped__ reference chain.

Reproducer

import annotationlib

def f(x: 'int') -> 'str': pass
f.__wrapped__ = f # self-referential cycle

# Hangs forever, never returns
annotationlib.get_annotations(f, eval_str=True)

Two-node cycle also triggers it:

def g(): pass
f.__wrapped__ = g
g.__wrapped__ = f
annotationlib.get_annotations(f, eval_str=True) # hangs

Root Cause

In Lib/annotationlib.py, get_annotations() has an early-return guard at line 1010:

if not eval_str:
 return dict(ann) # fast path, skips unwrap entirely for default eval_str=False

When eval_str=True the code falls through to a while True: loop (lines 1039–1048)
that unwraps __wrapped__ chains with no cycle detection:

if unwrap is not None:
 while True:
 if hasattr(unwrap, "__wrapped__"):
 unwrap = unwrap.__wrapped__ # no cycle detection
 continue
 if functools := sys.modules.get("functools"):
 if isinstance(unwrap, functools.partial):
 unwrap = unwrap.func # also no cycle detection
 continue
 break

Fix

Apply the same cycle-detection pattern used by inspect.unwrap() (visited id-set):

if unwrap is not None:
 seen = {id(unwrap)}
 while True:
 if hasattr(unwrap, "__wrapped__"):
 candidate = unwrap.__wrapped__
 if id(candidate) in seen:
 break
 seen.add(id(candidate))
 unwrap = candidate
 continue
 if functools := sys.modules.get("functools"):
 if isinstance(unwrap, functools.partial):
 candidate = unwrap.func
 if id(candidate) in seen:
 break
 seen.add(id(candidate))
 unwrap = candidate
 continue
 break
 if hasattr(unwrap, "__globals__"):
 obj_globals = unwrap.__globals__

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux

Linked PRs

• gh-146556: Fix infinite loop in annotationlib.get_annotations() on circular __wrapped__ #146557
• [3.14] gh-146556: Fix infinite loop in annotationlib.get_annotations() on circular __wrapped__ (GH-146557) #146622