[TRACKER] Cyclic dependencies related issues

[dalexeev]

Godot version

4.2 dev

Issue description

Anything related to cyclic dependencies/requirements of resources. Note that cyclic references (RefCounted) can be a slightly different issue.

Bugs

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1. Memory leak with circular reference in GDscript #7038
   discussion enhancement topic:core topic:gdscript +4
   
2. export var PackedScene crash when having circular references #24146
   bug confirmed crash topic:core +4
3. Cyclic dependencies between References, even without any static typing, cause memory leaks / errors on exit #38768
   bug topic:gdscript +2
4. Editor destroys scene or sometimes crashes through cyclic reference #39153
   bug crash topic:editor +3
5. Node self-reference leaks on quit if it is typed #39294
   bug topic:gdscript +2
6. Using a class_name reference doesn't work when preload() on the class that tries to use the class_name #55615
   bug topic:gdscript +2
7. Renaming gdscript with class_name can cause cyclic error. #56628
   bug confirmed topic:gdscript +3
8. Godot editor sometimes crashes when resources are moved into another folder #59116
   bug crash needs testing topic:editor +4
9. Parse Error: [ext_resource] referenced non-loaded resource when loading a specific scene #64330
   bug confirmed topic:3d topic:import +4
10. Saving custom resources using the ResourceSaver.FLAG_BUNDLE_RESOURCES flag causes crash on load. #65393
    bug discussion topic:core +3
11. Setting a custom resource's exported resource variable to an instance of itself crashes the editor #69508
    bug crash topic:editor +3
12. Circular dependencies of scenes (by preload) cause a script can not be loaded #70985
    bug topic:gdscript +2
13. [4.0] Circular references in @export node vars cause error on breakpoint only "Potential infinite recursion detected. Bailing." #73589
    bug topic:core +2
14. Type casting of certain resources fails unexpectedly #73615
    bug topic:gdscript +2
15. "Bad address index" error is printed when there is a cyclic reference in a script #74253
    bug confirmed topic:gdscript +3
16. Godot 4 is making scenes corrupt (Failing to load multiple child scenes from the same parent scene) #74806
    bug needs testing topic:editor +3
17. Some complex cyclical dependency seems to silently prevent resources from being loaded as correct class #74837
    bug confirmed topic:core topic:gdscript +4
18. Saving embedded resource to overwrite previously used resource file causes error "possible cyclic resource inclusion" and fails to update resource reference, keeping embedded data #74915
    bug topic:editor +2
19. Game crashes immediately without error message #75268
    bug crash topic:gdscript +3
20. Potential infinite recursion detected while setting a breakpoint after instantiating a scene with circular reference #76019
    bug topic:core +2
21. Script removed from node upon preload scene in cyclic reference. #76641
    bug confirmed topic:editor +3
    
22. Nonexistent resource error when trying to use change_scene_to_packed() to change the scene to a PackedScene via an exported variable when the target scene also has a reference to the first scene #77090
    documentation topic:core +2
23. preload cause ' cyclic resource inclusion' error #77436
    archived +1
24. GDScript resources are not unloaded due to an extra reference #77513
    bug topic:core topic:gdscript +3
25. Autocompletion breaks until the editor is restarted when a cyclic reference occurs #78074
    bug confirmed topic:editor topic:gdscript +4
26. Scenes unable to be opened upon cylic preload() in script #78128
    archived bug topic:core topic:gdscript +4
27. Scene keeps having its root class's script removed when project is loaded #78211
    bug needs testing topic:editor +3
28. Using ResourceSaver to save Resource with cross/circle reference crashed the game #79197
    bug crash topic:core topic:gdscript +4
29. Scene is invalid/corrupt according to the Godot editor, but works normally ingame #79545
    bug topic:core +2
30. Getting error when scenes are set using PackedScene among each other #79625
    discussion topic:core +2
31. Broken Scene / Error Reporting #80043
    bug needs testing topic:core +3
32. Scene file became corrupted/invalid. #80324
    bug topic:editor +2
33. Scene becomes corrupted or Godot crashes when renaming a scene that involves dependencies #80379
    bug topic:editor +2
34. Cyclic reference error with autoload, preload and ordering #80645
    bug topic:gdscript +2
35. Bad address index. #80714
    archived bug topic:gdscript +3
36. @export PackedScene scene corruption #80981
    bug confirmed discussion topic:core +4
37. Static Instance Preload Scene read corruption #81462
    bug topic:core topic:gdscript +3
38. Preload target scene got corrupted when attached script has reference of preload-caller script #81685
    bug topic:core topic:gdscript +3
39. Scene file invalid/corrupt on circular dependencies #83539
    bug needs testing topic:core +3
40. Script parsing fails when two scenes reference eachother #83803
    bug topic:core topic:gdscript +3
41. Resource loaded without being associated with script class name #87397
    bug topic:gdscript +2
42. Saved resource loses data when duplicated #94242
    bug topic:core topic:gdscript +3
43. Preloading resources with cyclic dependencies fail #98551
    archived bug confirmed topic:gdscript +4
44. Error Cannot get class ''. Parameter "obj" is null. under specific conditions #100100
    needs testing topic:gdscript +2

PRs

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1. Better error reporting for cyclic loads #80854
   bug needs work topic:core +3
2. Fix loading of cyclic scenes from GDScript #92326
   archived bug topic:core topic:gdscript +4
3. GDScript: Enhance handling of cyclic dependencies #93346
   bug topic:core topic:gdscript +3

[Maran23]

One more issue with cyclic dependencies:
#87397

[yoont4]

This tracker is nice to have, but is there also a place that aggregates design suggestions for avoiding this in the first place? I've got a fairly large project, and even slight changes, like referencing a type can suddenly cause a series of seemingly unrelated files to become corrupted. e.g. I have a global PlayerState autoload, and referencing something as simple as a resource type will suddenly make my units become corrupted with errors like:

E 0:00:01:0779   ResourceLoaderText::_parse_ext_resource: res://core/units/unit.tscn:502 - Parse Error: [ext_resource] referenced non-existent resource at: res://core/components/drag_and_drop/drag_component_2d.gd
  <C++ Source>   scene\resources\resource_format_text.cpp:163 @ ResourceLoaderText::_parse_ext_resource()

This is after referencing an ItemBlueprint type, which has nothing to do with my Units! I literally have no idea how to make forward progress on my projects anymore, because I have no idea when something is just going to blow up.

[dalexeev]

This tracker is nice to have, but is there also a place that aggregates design suggestions for avoiding this in the first place?

@yoont4 No, trackers are usually not intended for general discussion, only for grouping/classifying related issues. You can write a comment if you notice missing issues, and a maintainer will add them to the first post.

For general discussion, please use the appropriate Godot Contributors Chat channel (in this case #gdscript) or the issue most relevant to your topic from the list, if any (in this case it is quite difficult to do since there are a lot of issues).

[vibrunazo]

Should #78074 be added here?

[vvvvvvitor]

#92326 was superseded by #93346.

[p10tr3k]

Another one: #99333