Re: compiling gtkmm with atkmm support fails in implementor.cc

[codekiddy <codekiddy gmail com>]

Why should it call Glib::Object::~Object()? Atk::Implementor does not inherit from Glib::Object.

Oh, Yes you are correct, but see this:

Gtk::Widget

class Widget : public Object, public Buildable

#ifdef GTKMM_ATKMM_ENABLED

  ,public Atk::Implementor

{

  //...

}

Gtk::Widget inherits Gtk::Object, which in turn inherits Glib::Object which in turn inherits Glib::ObjectBase

Gtk::Widget also inherits Atk::Implementor which in turn inherits Glib::Interface which in turn inherits Glib::ObjectBase

This is the *only* place where Atk::Implementor gets inherited in entry gtkmm project.

I searched entry gtkmm sources ( CTRL + F ) for "public Atk::Implementor" and only Gtk::Widget inherits Atk::Implementor.

I believe this is the place where we should continue this silly research.

On Wed, Nov 18, 2015 at 8:24 PM, Kjell Ahlstedt <kjell ahlstedt bredband net> wrote:

Den 2015-11-18 kl. 19:23, skrev codekiddy:

Hey guys,

I compiled gtkmm with GTKMM_ATKMM_ENABLED 1

Applied a simple fix, run an example gtkmm program and it works just fine!

Here is how classes inherit destructors in order: ( I marked important code with bold )

Glib::ObjectBase

class ObjectBase : virtual public sigc::trackable

{

  protected:

        virtual ~ObjectBase() noexcept = 0; // pure virtual dtor, any derived class dtor won't throw.

}

Glib::Object

class Object : virtual public ObjectBase

{

  protected:

       virtual ~Object() noexcept;

}

Glib::Interface

class Interface : virtual public Glib::ObjectBase

{

   public:

       virtual ~Interface() noexcept;

}

Atk::Implementor

class Implementor : public Glib::Interface

{

    public:

         virtual ~Implementor() noexcept; // I think this is bad, you'll see why ...

}

Gtk::Widget

class Widget : public Object, public Buildable

#ifdef GTKMM_ATKMM_ENABLED

  ,public Atk::Implementor

{

  //...

}

Now let's see the implementation of Atk::~Implementor()

Implementor::~Implementor() noexcept { }  // do you see why this is bad ?

Atk::~Implementor is defined but it can't call Glib::Object::~Object()

because Glib::Object::~Object() is declared protected

Why should it call Glib::Object::~Object()? Atk::Implementor does not inherit from Glib::Object.

I have removed ~Implementor() destructor and let the compiler generate one.

recompiled atkmm and it now it works just fine!

Interesting, but I don't understand what's the difference between
  Implementor::~Implementor() noexcept { }
and a compiler-generated destructor. Is noexcept bad here? Gtk::Buildable::~Buildable() and many other destructors look the same.

The preprocessor may replace noexcept by _NOEXCEPT because of these lines in glibmmconfig.h:

#if (_MSC_VER < 1900) && !defined (noexcept)
#define _ALLOW_KEYWORD_MACROS 1
#define noexcept _NOEXCEPT
#endif

Please give your opinion, did I do the right thing? I'm not 100% sure.