Fix non const animation node _process virtual function

[GuilhermeGSousa]

Quick fix for #74807

I'm working on a motion matching implementation, and am currently improving its API. I currently think the best way to do this by extending AnimationRootNode, but the docs mention the _process method is deprecated, and that many APIs are missing to be able to extend animation nodes. I guess my question is, is this the case? If so, is there anything planned to support this in coming releases?

• Bugsquad edit, closes: Should custom animation node make "_process" as a const function?  #74807

[GuilhermeGSousa]

I'm not seeing how I can register compatibility methods for GDVIRTUAL functions, is that implementer?

Also, how do changes to the C++ bindings work? Is extension_api.json automatically updated, or should I open a PR for that?

[dsnopek]

I'm not seeing how I can register compatibility methods for GDVIRTUAL functions, is that implementer?

There is no way to safely change a virtual method in a binary compatible way. Instead, you need to add a new virtual method under a new name, and then selectively call whichever one is implemented (usually preferring the new one first). You can check if a virtual method is implemented via the GDVIRTUAL_IS_OVERRIDDEN() macro

[dsnopek]

Actually, looking at the PR in more detail, I'm not sure changing const-ness actually breaks compatibility. It may be fine. Someone should test if a GDExtension that overrides this virtual method compiled for Godot 4.3 works fine when loaded into Godot compiled with this PR.

[GuilhermeGSousa]

@dsnopek Thanks for your reply, sorry I got to this so late. I can give that a try as I'm working on one such GDExtension, I'll get back to you on that.

[GuilhermeGSousa]

@dsnopek just tested what you suggested, loading a GDExtension that overrides the const version of this method, on godot compiled with these changes. Works great, no errors!

[dsnopek]

Seems fine from the perspective of GDExtension!

[Repiteo]

The commits will need to be squashed before this can be merged.

[Repiteo]

Thanks!