Recursive self-references that trigger a RecursionError

[cdzhan]

Error Message

(pt) fooooo@bjys1095:/projs/framework/fooooo/test$ python test_dump.py 
/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py:414: PicklingWarning: Cannot locate reference to <class '__main__.test_dump.<locals>.MyFunc'>.
  StockPickler.save(self, obj, save_persistent_id)
/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py:414: PicklingWarning: Cannot pickle <class '__main__.test_dump.<locals>.MyFunc'>: __main__.test_dump.<locals>.MyFunc has recursive self-references that trigger a RecursionError.
  StockPickler.save(self, obj, save_persistent_id)
Traceback (most recent call last):
  File "/projs/framework/fooooo/test/test_dump.py", line 17, in <module>
    test_dump()
  File "/projs/framework/fooooo/test/test_dump.py", line 14, in test_dump
    dumps(a)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 280, in dumps
    dump(obj, file, protocol, byref, fmode, recurse, **kwds)#, strictio)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 252, in dump
    Pickler(file, protocol, **_kwds).dump(obj)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 420, in dump
    StockPickler.dump(self, obj)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 487, in dump
    self.save(obj)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 414, in save
    StockPickler.save(self, obj, save_persistent_id)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 1832, in save_type
    _save_with_postproc(pickler, (_create_type, (
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 1098, in _save_with_postproc
    pickler.save_reduce(*reduction, obj=obj)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 692, in save_reduce
    save(args)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 414, in save
    StockPickler.save(self, obj, save_persistent_id)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 902, in save_tuple
    save(element)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 414, in save
    StockPickler.save(self, obj, save_persistent_id)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 1217, in save_module_dict
    StockPickler.save_dict(pickler, obj)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 972, in save_dict
    self._batch_setitems(obj.items())
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 998, in _batch_setitems
    save(v)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 414, in save
    StockPickler.save(self, obj, save_persistent_id)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 1832, in save_type
    _save_with_postproc(pickler, (_create_type, (
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 1098, in _save_with_postproc
    pickler.save_reduce(*reduction, obj=obj)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 692, in save_reduce
    save(args)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 414, in save
    StockPickler.save(self, obj, save_persistent_id)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 902, in save_tuple
    save(element)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 414, in save
    StockPickler.save(self, obj, save_persistent_id)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 1217, in save_module_dict
    StockPickler.save_dict(pickler, obj)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 972, in save_dict
    self._batch_setitems(obj.items())
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 998, in _batch_setitems
    save(v)
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 414, in save
    StockPickler.save(self, obj, save_persistent_id)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 560, in save
    f(self, obj)  # Call unbound method with explicit self
  File "/projs/framework/fooooo/venv/pt/lib/python3.10/site-packages/dill/_dill.py", line 1869, in save_type
    StockPickler.save_global(pickler, obj, name=obj_name)
  File "/usr/local/python3.10/lib/python3.10/pickle.py", line 1071, in save_global
    raise PicklingError(
_pickle.PicklingError: Can't pickle <class '__main__.test_dump.<locals>.MyFunc'>: it's not found as __main__.test_dump.<locals>.MyFunc

How To Reproduce

import torch
from dill import dumps

class MyTest:
  def forward(self,):
    class MyFunc(torch.autograd.Function):
      pass
   
def test_dump():
  class MyFunc(torch.autograd.Function):
    pass
  a = MyFunc
  dumps(a)

if __name__ == '__main__':
  test_dump()    # fail
  #dumps(MyTest)    # success, why this case pass?

My Env

dill == 0.3.8