Visual Shader Arrange Nodes button crashes Godot

[CarlisleJonah]

Godot version

v4.1.1.stable.mono.official [bd6af8e]

System information

Windows 10

Issue description

In the Visual Shader editor, clicking Arrange Nodes crashes Godot.

Steps to reproduce

Click Arrange Nodes in the Visual Shader editor with the reproduction project. Sometimes it works on first click, sometimes it takes a few clicks. Below is an image of the shader I was fiddling with that caused this to happen (I assume).

Minimal reproduction project

Test.zip

[fire]

I want to investigate the Arrange button, but I'm not able for a few days. Help welcome.

[qycyfjy]

The most direct reason is that function _place_block may be called recursively and stack overflow

godot/scene/gui/graph_edit_arranger.cpp

Line 536 in c12d635

_place_block(u, p_delta, r_layers, r_root, r_align, r_node_name, r_inner_shift, r_sink, r_shift, r_node_positions);

By observing the function arguments, I found that there may be something wrong with the r_layers: normally, we only need to know which nodes there are in a certain layer, it is unlikely that duplicate nodes will be needed. But this is not the case, sometimes, there will be repeated elements in a some layers.

By looking at the code before calling function _place_block, r_layers is obtained by calling the following function:

godot/scene/gui/graph_edit_arranger.cpp

Line 106 in c12d635

HashMap<int, Vector<StringName>> layers = _layering(selected_nodes, upper_neighbours);

Assume that layer one includes two nodes, "3" and "13", but in the layers returned by _layering(), the elements of that layer may be "3", "3", "13", which means a "3" is repeated (interesting, if repetition happens, that is the repetition of the first element, I'm not sure if it's always like this, I haven't dug into the algorithm of _layering() carefully).

One dirty workaround is to remove all repeated elements in every entry of the returned HashMap, i.e., Vector("3", "3", "13")->Vector("3", "13")