Uninitializing engine singletons makes the engine try to call free callbacks to GDExtensions that are already uninitialized

[adamscott]

Tested versions

Reproducible in: Godot v4.4.dev (5b52b4b)

System information

Godot v4.4.dev (5b52b4b) - macOS Sequoia (15.2.0) - Multi-window, 1 monitor - OpenGL 3 (Compatibility) - Apple M3 Max - Apple M3 Max (16 threads)

Issue description

The editor (and the games, surely) crash when exiting when having some GDExtensions that have callbacks.

The issue stems from this code in Object::~Object() (core/object/object.cpp) when it tries to run callbacks to GDExtensions when they have already been uninitialized.

godot/core/object/object.cpp

Lines 2207 to 2214 in 5b52b4b

	if (_instance_bindings != nullptr) {
	for (uint32_t i = 0; i < _instance_binding_count; i++) {
	if (_instance_bindings[i].free_callback) {
	_instance_bindings[i].free_callback(_instance_bindings[i].token, this, _instance_bindings[i].binding);
	}
	}
	memfree(_instance_bindings);
	}

I experienced it about the Time singleton being deleted. That memdelete comes from #87635.

Steps to reproduce

1. Create a new project
2. Install DebugDraw3D (https://godotengine.org/asset-library/asset/1766)
3. Quit the project.

Minimal reproduction project (MRP)

gh#101465.zip

[dsnopek]

Thanks!

This issue seems to be the same as godotengine/godot-cpp#889, for which we made PR godotengine/godot-cpp#1458 for godot-cpp.

Do you know if DebugDraw3D is using a version of godot-cpp that includes that fix? If not, then I think it'll be fixed when they update.

In any case, this is a really tricky problem, that took a lot of discussion to find an acceptable fix for. I really hope that it isn't back, and that it's just a matter of that GDExtension being on an old version of godot-cpp. :-)

[DmitriySalnikov]

Do you know if DebugDraw3D is using a version of godot-cpp that includes that fix?

The asset-library version still uses godot-cpp 4.1-cherrypicks-12 (latest 13).
And this version seems to crash not only in 4.4, but also in 4.3.

The latest (not yet released) version of the library with godot-cpp 4.1-cherrypicks-13 does not crash for me.