No disconnect when changing node type with less joints in visual shader editor

[timkrief]

Godot version

4.1.stable

System information

Ubuntu 22.04

Issue description

Visual shader editor should disconnect (at least visually) when we change the number of joints

before changing the type

after

this one break things

Steps to reproduce

You can see what to do to reproduce the bug in the screenshot

Minimal reproduction project

A visual shader, two nodes.

[EddieBreeg]

I'd like to give this one a shot if no one is working on it

[EddieBreeg]

I found the source of the issue, however I really am not sure about how to fix it.
When you change a compose/decompose type, the set_op_type method of the relevant node class gets called.

godot/scene/resources/visual_shader_nodes.cpp

Line 4767 in 60f3b79

void VisualShaderNodeVectorCompose::set_op_type(OpType p_op_type) {

godot/scene/resources/visual_shader_nodes.cpp

Line 4946 in 60f3b79

void VisualShaderNodeVectorDecompose::set_op_type(OpType p_op_type) {

These methods just set the new vector type, and emit a signal to the editor. This signal gets handled by this method:

godot/editor/plugins/visual_shader_editor_plugin.cpp

Lines 180 to 186 in 60f3b79

	void VisualShaderGraphPlugin::update_node(VisualShader::Type p_type, int p_node_id) {
	if (p_type != visual_shader->get_shader_type() || !links.has(p_node_id)) {
	return;
	}
	remove_node(p_type, p_node_id, true);
	add_node(p_type, p_node_id, true);
	}

As far as I can see, the update method has no way of knowing the number of ports has changed, so it can't take care of removing the extra connections when needed.

The simplest solution I can think of would be to handle the signal with another method, similar to _expand_output_port.

[EddieBreeg]

Another solution would be to compare the number of input/output ports between the start and the end of the update method.
If this number has changed we can then find the connections we should remove. It works, but I don't know how I feel about doing this in the update method.

[EddieBreeg]

I sort of managed to fix the issue, but unfortunately it created an even weirder bug.

Here if I changed the vector compose node to vector2, it will correctly disconnected the ports.

But if I then switch the node back to 3D, and then try to recreate that EXACT same connection, it won't allow me: nothing happens. The connection doesn't register. If I now try to create a different connection to that port, it works as expected and everything goes back to normal.

[EddieBreeg]

#79417 (comment)

This is now fixed, it was in fact caused by my original code not fully fixing the problem