Passing a PyGraph into copy.copy raises a `PanicException`

[mr-jakey]

Information

• rustworkx version:0.17.1
• Python version: 3.12.10
• Rust version: -
• Operating system: MacOS

What is the current behavior?

If I run copy.copy on a graph that has been previously operated on by PyGraph.contract_nodes, a PanicException is raised.

What is the expected behavior?

The graph should be copied? If PyGraph is known to not be copy/deepcopy safe, sorry! PyGraph.copy works fine, but I'm more concerned about a possible issue with contract_nodes.

Steps to reproduce the problem

from copy import copy
from rustworkx.visualization import graphviz_draw
from rustworkx import PyGraph

graph = PyGraph()
graph.add_nodes_from(['a', 'b', 'c', 'd'])
graph.add_edge(0, 1, "_")
graph.add_edge(1, 2, "_")
graph.add_edge(2, 3, "_")

_idx = graph.contract_nodes(nodes=(1, 2), obj='G')

_ = copy(graph)

Thanks!

[IvanIsCoding]

I think this bug is legitimate, it seems related to #1505. contract_nodes leaves PyGraph in a weird state.

In the meantime, rustworkx.PyGraph.copy seems to be working, can you check if it fits your use case? I think graph.copy() uses our custom logic and just works.

I still think we just make copy.copy and copy.deepcopy work, so I will keep this open

[mr-jakey]

Nice - PyGraph copy does work for my use case. And yes, it does seem related to #1505. I'm using a temporary placeholder contract function just to be safe until that issue is resolved. Thanks for taking a look!