Saving a scene containing a tool node will call PREDELETE notification, while not being deleted

[Zylann]

Godot 3.0.2

Is this behavior intented? I thought NOTIFICATION_PREDELETE would be sent only before the node to be deleted, but it happens anyways when I save the scene, while no node gets deleted (at least I see no reason for this to happen in this situation).

Not only it calls PREDELETE, but also _init() gets called too, BEFORE the predelete... why is all this even done?
I'm saving a scene containing a terrain, which is quite heavy. These steps seem to be unnecessary.

Test project:
PluginPredeleteCalledOnSave.zip

1. Open the main scene, notice the log prints:

Init
Enter world
Enter tree
Ready

2. Save the scene right away, notice this gets printed:

Init
Predelete

[santouits]

This seems to be the reason for the notifications.

godot/editor/editor_node.cpp

Lines 1165 to 1172 in 1bbe95b

	// force creation of node path cache
	// (hacky but needed for the tree to update properly)
	Node *dummy_scene = sdata->instance(PackedScene::GEN_EDIT_STATE_INSTANCE);
	if (!dummy_scene) {
	show_accept(TTR("Couldn't save scene. Likely dependencies (instances or inheritance) couldn't be satisfied."), TTR("OK"));
	return;
	}
	memdelete(dummy_scene);

[KoBeWi]

Still valid in aeccd1e

[KoBeWi]

Ok so I encountered a similar issue, caused probably by the same thing:

tool
extends Node2D

export var test: int setget setest

func setest(t):
	test = t
	prints("test", get_instance_id())

Change test to 1 in the inspector and save the scene. With each save, the script will print with different ID each time.

[KoBeWi]

This is caused by the dummy node created when saving scene (this is the one that calls the method). See #47828