Resource.duplicate(true) also duplicates the script

[mphe]

Godot version

3.4.2 and 4.0 alpha

System information

Arch Linux

Issue description

Calling Resource.duplicate(true) to make a deep copy of a resource will also duplicate the assigned script. This bug exists in both Godot 3 and 4.
However, in Godot 3 it was possible to override the duplicate function to manually handle copying. In Godot 4.0 overriding does not work.

Technically, it behaves correctly as it is supposed to make a deep copy, but I don't think it should include the script.

Steps to reproduce

The reproduction project contains a custom resource CustomResource and a tool node ResourceDuplicator that instantiates one CustomResource and then duplicates it in _ready.

1. Get the reproduction project (made for 4.0)
2. Open main.tscn
3. Add node -> ResourceDuplicator

Immediately after, Godot will log an error of another class hiding CustomResource.

- built-in:3 - Parse Error: Class "CustomResource" hides a global script class.
- modules/gdscript/gdscript.cpp:873 - Method/function failed. Returning: ERR_PARSE_ERROR

This happens because Godot also copies the script. Upon saving you can also see the duplicated script in main.tscn.

[gd_scene load_steps=6 format=3 uid="uid://c4debhsy0cak8"]

[ext_resource type="Script" path="res://ResourceDuplicator.gd" id="1_siepb"]
[ext_resource type="Script" path="res://CustomResource.gd" id="2_gg6uf"]

[sub_resource type="Resource" id="Resource_5rudm"]
script = ExtResource( "2_gg6uf" )

[sub_resource type="GDScript" id="GDScript_bv7cb"]
script/source = "@tool
extends Resource
class_name CustomResource

# Does not seem to get called
func duplicate(deep: bool = false):
    push_warning(\"DUP\")
    return CustomResource.new()
"

[sub_resource type="Resource" id="Resource_v1am0"]
script = SubResource( "GDScript_bv7cb" )

[node name="Node2D" type="Node2D"]

[node name="ResourceDuplicator" type="Node" parent="."]
script = ExtResource( "1_siepb" )
resource = SubResource( "Resource_5rudm" )
resource2 = SubResource( "Resource_v1am0" )

Minimal reproduction project

resource_script_duplication_4.0.zip

[DaGamingWolf]

big oof on this. i was running in circles trying to find the source.

[mphe]

Seems to be fixed in Godot 4.0.
Is it planned to backport this fix to 3.x? Otherwise, this issue can probably be closed.

[akien-mga]

Indeed this was fixed by #71142, and this issue is a duplicate of #33079.

The fix could be backported if needed (without the property usage constant rename and reodering, to preserve compatibility).