Fixing reference return

[BastiaanOlij]

Investigating various issues around using reference, adding use cases to the test project to test them and fixing them.

Note, things are currently broken on the Godot side until godotengine/godot#55282 is merged.
You can work around that issue by commenting out the print statements in the constructors of Example and ExampleRef.

[BastiaanOlij]

At this point in time I'm getting a crash when closing the editor after loading the project.
Seems to work in runtime.

Also property inspector stopped working again.

[BastiaanOlij]

The crash I mention here is caused by our issues with initialization, because we have our print in our construct the editor starts constructing additional object and that messes everything up. Groud is working on a rewrite of that. We have a workaround by moving the line initializing_with_extension = true; in class_db.cpp down till after setting our pointers in godot itself.

[kb173]

Although we already wrote about this in the gdextension Godot chat, I'm summarizing it again here so it doesn't get lost there:

I was getting the following compile error when compiling my GDExtension with this PR (both on your branch and on origin/master with this commit cherry-picked):

godot-cpp/include/godot_cpp/classes/ref.hpp: In instantiation of 'godot::Ref<T>::Ref(godot::Ref<T_Other>&&) [with T_Other = godot::GeoPoint; T = godot::GeoFeature]':
src/geodata.cpp:109:16:   required from here
godot-cpp/include/godot_cpp/classes/ref.hpp:198:40: error: 'godot::GeoPoint* godot::Ref<godot::GeoPoint>::reference' is private within this context
  198 |                 T *swap = (T *)p_other.reference;
      |                                ~~~~~~~~^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp:50:12: note: declared private here
   50 |         T *reference = nullptr;
      |            ^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp:199:25: error: 'godot::GeoPoint* godot::Ref<godot::GeoPoint>::reference' is private within this context
  199 |                 p_other.reference = (T_Other *)reference;
      |                 ~~~~~~~~^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp:50:12: note: declared private here
   50 |         T *reference = nullptr;
      |            ^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp: In instantiation of 'godot::Ref<T>::Ref(godot::Ref<T_Other>&&) [with T_Other = godot::GeoLine; T = godot::GeoFeature]':
src/geodata.cpp:118:16:   required from here
godot-cpp/include/godot_cpp/classes/ref.hpp:198:40: error: 'godot::GeoLine* godot::Ref<godot::GeoLine>::reference' is private within this context
  198 |                 T *swap = (T *)p_other.reference;
      |                                ~~~~~~~~^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp:50:12: note: declared private here
   50 |         T *reference = nullptr;
      |            ^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp:199:25: error: 'godot::GeoLine* godot::Ref<godot::GeoLine>::reference' is private within this context
  199 |                 p_other.reference = (T_Other *)reference;
      |                 ~~~~~~~~^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp:50:12: note: declared private here
   50 |         T *reference = nullptr;
      |            ^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp: In instantiation of 'godot::Ref<T>::Ref(godot::Ref<T_Other>&&) [with T_Other = godot::GeoPolygon; T = godot::GeoFeature]':
src/geodata.cpp:127:16:   required from here
godot-cpp/include/godot_cpp/classes/ref.hpp:198:40: error: 'godot::GeoPolygon* godot::Ref<godot::GeoPolygon>::reference' is private within this context
  198 |                 T *swap = (T *)p_other.reference;
      |                                ~~~~~~~~^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp:50:12: note: declared private here
   50 |         T *reference = nullptr;
      |            ^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp:199:25: error: 'godot::GeoPolygon* godot::Ref<godot::GeoPolygon>::reference' is private within this context
  199 |                 p_other.reference = (T_Other *)reference;
      |                 ~~~~~~~~^~~~~~~~~
godot-cpp/include/godot_cpp/classes/ref.hpp:50:12: note: declared private here
   50 |         T *reference = nullptr;
      |            ^~~~~~~~~
scons: *** [src/geodata.os] Error 1
scons: building terminated because of errors.

Note that GeoPoint, GeoLine, and GeoPolygon all inherit from GeoFeature, which inherits from Resource. Seems to be related to this additional layer of inheritance.

I could work around this error by manually making all members of Ref (in godot-cpp/include/godot_cpp/classes/ref.hpp) public.

[BastiaanOlij]

Now basing this on including godotengine/godot#57968 for an upstream fix, so mostly just test cases left.

[akien-mga]

Did this mean to say "extended" instead of "example"?

[Zylann]

I think this was a second attempt at fixing #652 (other PR was #660) but this PR doesnt mention any issue number nor the previous PR so... here they are, unless I'm mistaken.

I wonder if it could be related to #751 as well.

[Faless]

Superseded by #958.