Fixes counting bug with Ref<T>.

[zombietype]

Ref would lose count during return from plugin - either dangling when
directly returned, or double deleted if a Ref is stored.
Fixing by increasing the count before encode.

Fixes: #652

[BastiaanOlij]

Just commenting here as well so it's recorded instead of just adding my feedback on godot chat.

I think your logic is sound as you've explained in 652, the core issue seems to be that we just copy the pointer into the reference object on the godot side instead of calling the proper setter logic.

What I'm wondering about is if this is good/safe enough. This will only work if the reference we're assigning is currently unset. If it is set that means we're just overwriting the current pointer and that object will become dangling.

What is should be doing is calling ref (https://github.com/godotengine/godot/blob/master/core/object/ref_counted.h#L61), but we can't call that from within Godot.

I wonder if this fix should be on the godot side instead of on the godot-cpp side, if that is even possible. Else we may have to enhance this logic to check if there is a current value set on the reference and unref that first.

[akien-mga]

Style issue (spaces vs tabs).

[BastiaanOlij]

Talking some more on Godot chat we're looking at adding a method to the API that allows us to set a reference on the Godot side properly so the full logic runs.

[BastiaanOlij]

@kidrigger I don't have a good test case to test it with but this should improve your solution to make it a little more safer:
godotengine/godot#55277

This should change your code to:

_FORCE_INLINE_ static void encode(Ref<T> p_val, const void *p_ptr) {
	godot::internal::gdn_interface->reference_assign((GDNativeObjectPtr) p_ptr, (GDNativeObjectPtr)p_val->_owner);
}

This way we're sure that if a reference object is re-used it will properly clear the previous reference.