Call to Node:duplicate does not trigger duplication

[StillWantTea]

Hello,

I noticed this while actually trying to do some benchmarks but it seems the behaviour for the call to Node:duplicate is not the same as what happens with gdscript, mainly that it doesn't seem to duplicate, the node id that it is given is the same.

You can easily replicate this with:

local luaexample = {
	extends = Node2D,
}

function luaexample:_ready()
	local n = Node:new()
	local d1 = n:duplicate()
	local d2 = n:duplicate()
	print(n, d1, d2)
end

return luaexample

and the gdscript version to compare:

extends Node2D


# Called when the node enters the scene tree for the first time.
func _ready() -> void:
	var n = Node.new()
	var d1 = n.duplicate()
	var d2 = n.duplicate()
	print(n, d1, d2)

If I've just misunderstood how to use the duplicate api then I apologise in advance.

[gilzoide]

Hey @StillWantTea, thanks for the report!

Well, that's a bug, and I think I know what's going on already 😬
So, Godot objects in Lua are represented internally by Variant values, because it makes the implementation a lot smaller and simpler than implementing each Variant type separately. The problem is that calling duplicate in Variants currently always call Variant::duplicate and not the duplicate method from the Node or other classes that might have it (like Resource and StreamPeerBuffer). So what we need to do is change the implementation to call the duplicate method if possible and fallback to Variant::duplicate afterwards. Thankfully this is easy to do =]