networkx 2.6: TypeError by passing None as closure to types.FunctionType()

[fumitoh]

Hi, I tried to import networkx and encountered an error:

>>> import networkx as nx
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/fumito/nogil/nogil_build/lib/python3.9/site-packages/networkx/__init__.py", line 79, in <module>
    from networkx import algorithms
  File "/home/fumito/nogil/nogil_build/lib/python3.9/site-packages/networkx/algorithms/__init__.py", line 74, in <module>
    from networkx.algorithms import isomorphism
  File "/home/fumito/nogil/nogil_build/lib/python3.9/site-packages/networkx/algorithms/isomorphism/__init__.py", line 3, in <module>
    from networkx.algorithms.isomorphism.matchhelpers import *
  File "/home/fumito/nogil/nogil_build/lib/python3.9/site-packages/networkx/algorithms/isomorphism/matchhelpers.py", line 194, in <module>
    numerical_edge_match = copyfunc(numerical_node_match, "numerical_edge_match")
  File "/home/fumito/nogil/nogil_build/lib/python3.9/site-packages/networkx/algorithms/isomorphism/matchhelpers.py", line 22, in copyfunc
    return types.FunctionType(
TypeError: arg 5 (closure) must be tuple

numerical_node_match.__closure__ is None, so None is passed to copyfunc instead of a tuple. The original CPython doesn't rasie the error.

[colesbury]

Thanks for the bug report @fumitoh. networkx 2.6+ expose some issues with the nogil interpreter that aren't easy to resolve. In particular, there are some complicated cases involving modifying __kwdefaults__ and __code__ attributes on functions. I'll need to think a bit on how to handle those issues.

In the meantime, I think networkx 2.5.1 is compatible with nogil Python.