Some Tweeners are leaking references

[KoBeWi]

Godot version

32f8f74

System information

W10

Issue description

Related to #51231

Tween and Tweeners had a circular reference, which prevented them from being freed properly (this was fixed by #51237)

However, Tween is still not being destroyed. Also if you use typed variable for tween, some Tweeners aren't destroyed too, which makes me think it's some GDScript bug. Here's test code:

extends Node2D
func _input(event):
	if event is InputEventKey and event.pressed:
		var tween = create_tween()
#		var tween: Tween = create_tween()
		tween.tween_property(self, "modulate", Color.RED, 1)
		tween.tween_interval(0.1)
		tween.tween_method(func(v): print(v), 0, 1, 0.1)
		tween.tween_callback(func(): print("finished"))

Run the scene, press any key and check the object Monitor. When animation starts, 5 objects are created and only 4 are destroyed when it ends; 1 object leaks (the Tween). When you switch to the commented line (so the tween is typed), 3 objects are leaked (Tween, IntervalTweener and CallbackTweener).

Steps to reproduce

See above.

Minimal reproduction project

You can compile engine with this patch for easier debugging:
0001-Add-Tween-destructor-prints.txt

[briansemrau]

@KoBeWi Are you checking for Tween destructor calls before or after the scene tree is destructed? After some investigation it seems that the SceneTree keeps a list of created tweens to supply SceneTree::get_processed_tweens. This keeps a reference to them and prevents them from being destructed.

godot/scene/main/scene_tree.cpp

Line 1126 in 98a7bf3

Ref<Tween> SceneTree::create_tween() {

[briansemrau]

Disregard my question above.

I've reproduced this issue.

extends Node2D

var tween1: Tween
var tween2: Tween

func _ready():
    tween1 = create_tween()
    tween2 = create_tween()
    tween1 = create_tween()

WARNING: ObjectDB instances leaked at exit (run with --verbose for details).
     at: ObjectDB::cleanup (core\object\object.cpp:2022)
Leaked instance: Tween:-9222416011494424091
Leaked instance: Tween:-9222415461738610202
Leaked instance: Tween:-9222416561250237972

[Richard74Huang]

Just a report,
I've noticed that create_tween and create_timer still cause leaking with in 4.0 build [41edfc8]

OS: macOS 12.3/arm64