In Godot 4.3 @export setters referencing nodes are called twice in nested scenes

[graydoubt]

In Godot 4.3 @export setters referencing nodes are called twice in nested scenes

[KoBeWi]

Indeed, this is caused by default values being stored in the scene for Node properties. This was already reported and will be fixed in beta2: #91591

[graydoubt]

This may be related to how the .tscn files are stored in 4.3.

In Godot 4.2, the main.tscn would contain:

[gd_scene load_steps=2 format=3 uid="uid://d1bdwhmo0dn6f"]

[ext_resource type="PackedScene" uid="uid://bkucqgqglk6k1" path="res://ui.tscn" id="1_aniqm"]

[node name="Main" type="Node"]

[node name="UI" parent="." instance=ExtResource("1_aniqm")]

But in Godot 4.3, the main scene file redundantly stores the same properties already defined in the ui scene file:

[gd_scene load_steps=2 format=3 uid="uid://d1bdwhmo0dn6f"]

[ext_resource type="PackedScene" uid="uid://bkucqgqglk6k1" path="res://ui.tscn" id="1_aniqm"]

[node name="Main" type="Node"]

[node name="UI" parent="." node_paths=PackedStringArray("my_button", "my_label", "my_label2") instance=ExtResource("1_aniqm")]
my_button = NodePath("Button")
my_label = NodePath("Label")
my_label2 = NodePath("Label2")

It appears that this is why the setters are called twice. If the setter does any heavy work, it will perform it twice. If it connects signals, it'll try to connect them twice. This seems like a regression.

The full debug output from the MRP is:

<CanvasLayer#28571600128>: setting button path
<CanvasLayer#28571600128>: setting int
<CanvasLayer#28571600128>: setting string
<Button#28588377345>: setting icon
UI:<CanvasLayer#28571600128>: setting button
UI:<CanvasLayer#28571600128>: setting label
UI:<CanvasLayer#28571600128>: setting label2
UI:<CanvasLayer#28571600128>: setting button
UI:<CanvasLayer#28571600128>: setting label
UI:<CanvasLayer#28571600128>: setting label2