Creating and Saving Mono Nodes Fails

[shartte]

Godot version:
3.1

Issue description:
Given a C# class "NodeScript" which inherits from Node, I expected the following to work:

var node = new NodeScript();
        
var packedScene = new PackedScene();
packedScene.Pack(node);

var restoredNode = (NodeScript) packedScene.Instance();

But the restoredNode loses the association with NodeScript upon being loaded. When I save the PackedScene to a file (my actual intent), I also see that the Node is saved with a CSharpScript association, but no actual association to the subclass.

I think the saved scene exhibits #17689, but the underlying issue is that the Ctor of NodeScript doesn't actually associate the right script with the node.

Minimal project:
ScriptChange.zip

[shartte]

After debugging this a little further, CSharpScript::create_for_managed_type does not set the path of the created Script instance. Indeed at runtime, it really can't.
A proper fix probably requires #15661.

[raulsntos]

Can anyone still reproduce this issue in Godot 3.5 or any later release?

I've been unable to reproduce with the provided MRP in v3.5.stable.mono.official [991bb6a].

[neikeq]

I would be surprised if this was fixed in 3.x as the presumed cause of the bug should still be there: scripts created from C# (new Class()) don't have a path assigned.
This should be fixed in master already, though, as we re-use the same script that's loaded from disk: 67db899.

[raulsntos]

Oh, I misunderstood the reproduction steps. It's still happening in 3.x indeed. It results in the following scene:

[gd_scene load_steps=2 format=2]

[sub_resource type="CSharpScript" id=1]

[node name="" type="Node"]
script = SubResource( 1 )

I can confirm it's fixed in master and it results in the following scene:

[gd_scene load_steps=2 format=3]

[ext_resource type="Script" path="res://NodeScript.cs" id="1_yfurm"]

[node name="" type="Node"]
script = ExtResource("1_yfurm")