FlowBox#bind_model results in an invalid memory access

[BigBoyBarney]

Hi!
I'm sorry for opening so many issues in succession 😩

The following snippet results in an invalid memory access.

flowbox = Gtk::FlowBox.new
create_flow_box_widget = ->(item : GObject::Object) : Gtk::Widget { Gtk::Label.new(label: "hello") }
string_list = Gtk::StringList.new("")
flowbox.bind_model(model: string_list, create_widget_func: create_flow_box_widget)

I looked at the generated bindings too, which make perfect sense I think.

def bind_model(model : Gio::ListModel?, create_widget_func : Gtk::FlowBoxCreateWidgetFunc) : Nil
  # gtk_flow_box_bind_model: (Method)
  # @model: (nullable)
  # @create_widget_func:
  # @user_data: (nullable)
  # @user_data_free_func:
  # Returns: (transfer none)
 
  # Generator::NullableArrayPlan
  model = if model.nil?
            Pointer(Void).null
          else
            model.to_unsafe
          end
  # Generator::CallbackArgPlan
  if create_widget_func
    _box = ::Box.box(create_widget_func)
    create_widget_func = ->(lib_item : Pointer(Void), lib_user_data : Pointer(Void)) {
      # Generator::BuiltInTypeArgPlan
      item = GObject::Object.new(lib_item, GICrystal::Transfer::None)
      ::Box(Proc(GObject::Object, Gtk::Widget)).unbox(lib_user_data).call(item)
    }.pointer
    user_data = GICrystal::ClosureDataManager.register(_box)
    user_data_free_func = ->GICrystal::ClosureDataManager.deregister(Pointer(Void)).pointer
  else
    create_widget_func = user_data = user_data_free_func = Pointer(Void).null
  end

  # C call
  LibGtk.gtk_flow_box_bind_model(to_unsafe, model, create_widget_func, user_data, user_data_free_func)

  # Return value handling
end

Here is the error message as well.

Invalid memory access (signal 11) at address 0x0      
[0x430136] *Exception::CallStack::print_backtrace:Nil +118 in /home/barney/.cache/crystal/crystal-run-window.tmp
[0x41d736] ~procProc(Int32, Pointer(LibC::SiginfoT), Pointer(Void), Nil) +310 in /home/barney/.cache/crystal/crystal-run-window.tmp
[0x7f9d4d8d7090] ?? +140313587708048 in /lib64/libc.so.6
[0x7f9d4de49e34] ?? +140313593421364 in /lib64/libgtk-4.so.1
[0x7f9d4de636e5] ?? +140313593525989 in /lib64/libgtk-4.so.1
[0x7f9d4de65821] ?? +140313593534497 in /lib64/libgtk-4.so.1
[0x7f9d4de65961] ?? +140313593534817 in /lib64/libgtk-4.so.1
[0x7f9d4de47937] ?? +140313593411895 in /lib64/libgtk-4.so.1
[0x7f9d4e66ef27] g_type_create_instance +599 in /lib64/libgobject-2.0.so.0
[0x7f9d4e6541c4] ?? +140313601851844 in /lib64/libgobject-2.0.so.0
[0x7f9d4e6557de] g_object_new_with_properties +574 in /lib64/libgobject-2.0.so.0
[0x7f9d4e656801] g_object_new +193 in /lib64/libgobject-2.0.so.0
[0x7f9d4dde6dee] ?? +140313593015790 in /lib64/libgtk-4.so.1
[0x7f9d4e66ef27] g_type_create_instance +599 in /lib64/libgobject-2.0.so.0
[0x7f9d4e6541c4] ?? +140313601851844 in /lib64/libgobject-2.0.so.0
[0x7f9d4e6557de] g_object_new_with_properties +574 in /lib64/libgobject-2.0.so.0
[0x7f9d4e656801] g_object_new +193 in /lib64/libgobject-2.0.so.0
[0x4e9676] *Gtk::FlowBox::new:Gtk::FlowBox +6 in /home/barney/.cache/crystal/crystal-run-window.tmp
[0x401e0f] __crystal_main +1055 in /home/barney/.cache/crystal/crystal-run-window.tmp
[0x46f2b6] *Crystal::main_user_code<Int32, Pointer(Pointer(UInt8))>:Nil +6 in /home/barney/.cache/crystal/crystal-run-window.tmp
[0x46f22a] *Crystal::main<Int32, Pointer(Pointer(UInt8))>:Int32 +58 in /home/barney/.cache/crystal/crystal-run-window.tmp
[0x40f4f6] main +6 in /home/barney/.cache/crystal/crystal-run-window.tmp
[0x7f9d4d8c0248] ?? +140313587614280 in /lib64/libc.so.6
[0x7f9d4d8c030b] __libc_start_main +139 in /lib64/libc.so.6
[0x401925] _start +37 in /home/barney/.cache/crystal/crystal-run-window.tmp
[0x0] ???

There's a relatively high chance that this issue is self-inflicted and I'm misusing the method, in which case I would like to apologise.

[BlobCodes]

I think the create_widget_func returns the crystal wrapper to gtk and not the widget
Also I think gtk wants a full transfer

- ::Box(Proc(GObject::Object, Gtk::Widget)).unbox(lib_user_data).call(item)
+ tmp = ::Box(Proc(GObject::Object, Gtk::Widget)).unbox(lib_user_data).call(item)
+ GICrystal.ref(tmp)
+ tmp.to_unsafe