PopupMenu ID 0 is replaced by its index position.

[Ketei]

Tested versions

• Reproducible in: v4.3.stable.official [77dcf97]

System information

Godot v4.3.stable - Windows 10.0.19045 - GLES3 (Compatibility)

Issue description

When using a PopupMenu (via MenuButton) and trying to use the assigned ID, if that ID is 0 it'll be replaced by the index.

GodotPopMenuBug.mp4

Steps to reproduce

1. Create MenuButton.
2. Create 2 or more items each with a unique ID.
3. Move item with ID 0 to any index but 0.
4. Connect id_pressed signal.
5. That menu item ID 0 will be replaced by its index on the call.

Minimal reproduction project (MRP)

popupmenubug.zip

[kleonc]

This is a regression from #88306. cc @KoBeWi

id = 0 is no longer force-saved within the scene file (same for e.g. OptionButton).

After saving a scene with:

.tscn contents:

• v4.2.2.stable.official [15073af]

...
popup/item_0/text = "ID 1"
popup/item_0/id = 1
popup/item_1/text = "ID 0"
popup/item_1/id = 0
popup/item_2/text = "ID 2"
popup/item_2/id = 2
...

• v4.3.stable.official [77dcf97]

...
popup/item_0/text = "ID 1"
popup/item_0/id = 1
popup/item_1/text = "ID 0"
popup/item_2/text = "ID 2"
popup/item_2/id = 2
...