The Updating Scene popup pops up constantly when switching scenes

[Rindbee]

Godot version

v4.2.dev.custom_build [ec395516e]

System information

Linux Mint 21.1 (Vera) - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1050 Ti (nvidia; 515.105.01) - Intel(R) Core(TM) i5-7300HQ CPU @ 2.50GHz (4 Threads)

Issue description

When the sub-scene is saved and closed, if it automatically switches to the main scene, then opens the sub-scene again. Later, every time you switch to the main scene, the Updating Scene popup will pop up.

diff --git a/editor/editor_data.cpp b/editor/editor_data.cpp
index af7163eec1..3e08b2f02f 100644
--- a/editor/editor_data.cpp
+++ b/editor/editor_data.cpp
@@ -662,6 +662,7 @@ bool EditorData::_find_updated_instances(Node *p_root, Node *p_node, HashSet<Str
                if (!checked_paths.has(path)) {
                        uint64_t modified_time = FileAccess::get_modified_time(path);
                        if (modified_time != ss->get_last_modified_time()) {
+                               print_line(p_root, p_node, ss, ss->get_last_modified_time(), modified_time);
                                return true; //external scene changed
                        }

In later switches, ss->get_last_modified_time() keeps returning 0.

Main:<Node2D#1762429819445> Sub:<Node2D#1762446543234> <SceneState#-9223370274575945336> 1688862627 1688863516
Main:<Node2D#2462106842463> Sub:<Node2D#2462123619739> <SceneState#-9223369575788120694> 0 1688863516
Main:<Node2D#2677157197217> Sub:<Node2D#2677173974273> <SceneState#-9223369575788120694> 0 1688863516
Main:<Node2D#2781830246877> Sub:<Node2D#2781847025065> <SceneState#-9223369575788120694> 0 1688863516

Steps to reproduce

1. Open MRP, and make sure the main scene and sub scene are opened;
2. Switch to sub scene, save the scene, and close;
3. With switching to the main scene, the Updating Scene pop-up window will appear automatically;
4. Open the sub scene again, and switch between the main scene and the sub scene. Whenever you switch to the main scene, the Updating Scene pop-up window will appear.

0.mp4

Minimal reproduction project

update-scene-issue.zip

[Rindbee]

godot/editor/editor_node.cpp

Lines 3710 to 3716 in 83cc5d4

	// Used from somewhere else? No problem! Update state and replace sdata.
	Ref<PackedScene> ps = ResourceCache::get_ref(lpath);
	if (ps.is_valid()) {
	ps->replace_state(sdata->get_state());
	ps->set_last_modified_time(sdata->get_last_modified_time());
	sdata = ps;
	}

godot/core/io/resource.h

Lines 127 to 128 in 83cc5d4

	virtual void set_last_modified_time(uint64_t p_time) { last_modified_time = p_time; }
	uint64_t get_last_modified_time() const { return last_modified_time; }

The PackedScene class overrides set_last_modified_time() but not get_last_modified_time(). So get_last_modified_time() always returns 0.

godot/scene/resources/packed_scene.h

Lines 257 to 259 in 83cc5d4

	virtual void set_last_modified_time(uint64_t p_time) override {
	state->set_last_modified_time(p_time);
	}