Uses StringName in GDExtension perf critical instance creation & method/properties setter/getter

[touilleMan]

related to godotengine/godot#67750

[bruvzg]

Looks really good.

A few missing things:

• _alloc_and_copy_cstr helper functions can be removed from wrapper.hpp, class_db.hpp and method_bind.hpp.
• There's GDNativeExtensionScriptInstanceToString which is defined to return const char *, but in the engine its return is assigned to String, probably should be changed as well.
• Also, you have missed __constant_get_bitfield_name (in the type_info.hpp).

[touilleMan]

@bruvzg thanks for the quick feedbacks 😃

I've updated the PR with your remarks

[touilleMan]

@bruvzg While I'm at at it, I wonder why in Godot the ScriptInstance have a get_property_list/get_property_type/get_method_list method instead of letting them in Script
https://github.com/godotengine/godot/blob/0d04e7ec914ff609dfbdfff3dca04ed12a21e600/core/object/script_language.h#L173-L174

I suspect this is not really intended, but it creates the impression two instances of the same script can have different property/methods.
This is something possible in dynamic language such as Python (where a class basically a dictionary that can be updated at anytime), but I don't think this is used in Godot (GDScript doesn't allow to modify the class at runtime as far as I know).

I think it's a good thing to consider a script can never change once loaded (this is the kind of assertion that is expected, so you can be sure plenty of things will break in subtile way if an extension starts to do that)

So my guess is we should correct this (or at least add comment on GDNativeExtensionInstanceInfo in gdnative_interface.h) to make sure GDExtension user won't get mislead by this

[touilleMan]

This PR is running fine with the demo project, so I guess this is ready for review & merge \o/

[bruvzg]

This is something possible in dynamic language such as Python (where a class basically a dictionary that can be updated at anytime), but I don't think this is used in Godot (GDScript doesn't allow to modify the class at runtime as far as I know).

I think it's a bind for the get_property_list of Object instance which have script attached, not for the Script itself.

[groud]

@touilleMan I believe this PR might have caused #921 to happen. Could you confirm whether it's likely ?

[touilleMan]

@groud that's most likely the case !

I'll try to have an eye on this before our Thursday meeting 🤠