Created attachment 302562 [details]
main.cpp sample file.

Compile the attached file with the following command line (I have gcc 5.1 here and glib 2.44.0)

g++ main.cpp `pkg-config gtk+-3.0 --cflags --libs` -Wcast-qual

I cause excessive warnings.

In file included from /usr/include/glib-2.0/gobject/gobject.h:24:0,
                 from /usr/include/glib-2.0/gobject/gbinding.h:29,
                 from /usr/include/glib-2.0/glib-object.h:23,
                 from /usr/include/glib-2.0/gio/gioenums.h:28,
                 from /usr/include/glib-2.0/gio/giotypes.h:28,
                 from /usr/include/glib-2.0/gio/gio.h:26,
                 from /usr/include/gtk-3.0/gdk/gdkapplaunchcontext.h:28,
                 from /usr/include/gtk-3.0/gdk/gdk.h:32,
                 from /usr/include/gtk-3.0/gtk/gtk.h:30,
                 from main.cpp:1:
/usr/include/glib-2.0/gio/glistmodel.h: In function ‘GListModel* G_LIST_MODEL(gconstpointer)’:
/usr/include/glib-2.0/gobject/gtype.h:479:88: warning: cast from type ‘gconstpointer {aka const void*}’ to type ‘GTypeInstance* {aka _GTypeInstance*}’ casts away qualifiers [-Wcast-qual]
 #define G_TYPE_CHECK_INSTANCE_CAST(instance, g_type, c_type)    (_G_TYPE_CIC ((instance), (g_type), c_type))
                                                                                        ^
/usr/include/glib-2.0/gobject/gtype.h:2186:57: note: in definition of macro ‘_G_TYPE_CIC’
     ((ct*) g_type_check_instance_cast ((GTypeInstance*) ip, gt))
                                                         ^
/usr/include/glib-2.0/gobject/gtype.h:1565:12: note: in expansion of macro ‘G_TYPE_CHECK_INSTANCE_CAST’
     return G_TYPE_CHECK_INSTANCE_CAST (ptr, module_obj_name##_get_type (), ModuleObjName); }               \
            ^
/usr/include/glib-2.0/gio/glistmodel.h:36:1: note: in expansion of macro ‘G_DECLARE_INTERFACE’
 G_DECLARE_INTERFACE(GListModel, g_list_model, G, LIST_MODEL, GObject)
 ^
/usr/include/glib-2.0/gio/glistmodel.h: In function ‘gboolean G_IS_LIST_MODEL(gconstpointer)’:
/usr/include/glib-2.0/gobject/gtype.h:491:88: warning: cast from type ‘gconstpointer {aka const void*}’ to type ‘GTypeInstance* {aka _GTypeInstance*}’ casts away qualifiers [-Wcast-qual]
 #define G_TYPE_CHECK_INSTANCE_TYPE(instance, g_type)            (_G_TYPE_CIT ((instance), (g_type)))
                                                                                        ^
/usr/include/glib-2.0/gobject/gtype.h:2200:44: note: in definition of macro ‘_G_TYPE_CIT’
   GTypeInstance *__inst = (GTypeInstance*) ip; GType __t = gt; gboolean __r; \
                                            ^
/usr/include/glib-2.0/gobject/gtype.h:1567:12: note: in expansion of macro ‘G_TYPE_CHECK_INSTANCE_TYPE’
     return G_TYPE_CHECK_INSTANCE_TYPE (ptr, module_obj_name##_get_type ()); }                              \
            ^
/usr/include/glib-2.0/gio/glistmodel.h:36:1: note: in expansion of macro ‘G_DECLARE_INTERFACE’
 G_DECLARE_INTERFACE(GListModel, g_list_model, G, LIST_MODEL, GObject)
 ^
/usr/include/glib-2.0/gio/glistmodel.h: In function ‘GListModelInterface* G_LIST_MODEL_GET_IFACE(gconstpointer)’:
/usr/include/glib-2.0/gobject/gtype.h:533:88: warning: cast from type ‘gconstpointer {aka const void*}’ to type ‘GTypeInstance* {aka _GTypeInstance*}’ casts away qualifiers [-Wcast-qual]
 #define G_TYPE_INSTANCE_GET_INTERFACE(instance, g_type, c_type) (_G_TYPE_IGI ((instance), (g_type), c_type))
                                                                                        ^
/usr/include/glib-2.0/gobject/gtype.h:2196:89: note: in definition of macro ‘_G_TYPE_IGI’
 #define _G_TYPE_IGI(ip, gt, ct)         ((ct*) g_type_interface_peek (((GTypeInstance*) ip)->g_class, gt))
                                                                                         ^
/usr/include/glib-2.0/gobject/gtype.h:1569:12: note: in expansion of macro ‘G_TYPE_INSTANCE_GET_INTERFACE’
     return G_TYPE_INSTANCE_GET_INTERFACE (ptr, module_obj_name##_get_type (), ModuleObjName##Interface); } \
            ^
/usr/include/glib-2.0/gio/glistmodel.h:36:1: note: in expansion of macro ‘G_DECLARE_INTERFACE’
 G_DECLARE_INTERFACE(GListModel, g_list_model, G, LIST_MODEL, GObject)
 ^
/usr/include/glib-2.0/gio/gliststore.h: In function ‘GListStore* G_LIST_STORE(gconstpointer)’:
/usr/include/glib-2.0/gobject/gtype.h:479:88: warning: cast from type ‘gconstpointer {aka const void*}’ to type ‘GTypeInstance* {aka _GTypeInstance*}’ casts away qualifiers [-Wcast-qual]
 #define G_TYPE_CHECK_INSTANCE_CAST(instance, g_type, c_type)    (_G_TYPE_CIC ((instance), (g_type), c_type))
                                                                                        ^
/usr/include/glib-2.0/gobject/gtype.h:2186:57: note: in definition of macro ‘_G_TYPE_CIC’
     ((ct*) g_type_check_instance_cast ((GTypeInstance*) ip, gt))
                                                         ^
/usr/include/glib-2.0/gobject/gtype.h:1396:12: note: in expansion of macro ‘G_TYPE_CHECK_INSTANCE_CAST’
     return G_TYPE_CHECK_INSTANCE_CAST (ptr, module_obj_name##_get_type (), ModuleObjName); }             \
            ^
/usr/include/glib-2.0/gio/gliststore.h:36:1: note: in expansion of macro ‘G_DECLARE_FINAL_TYPE’
 G_DECLARE_FINAL_TYPE(GListStore, g_list_store, G, LIST_STORE, GObject)
 ^
/usr/include/glib-2.0/gio/gliststore.h: In function ‘gboolean G_IS_LIST_STORE(gconstpointer)’:
/usr/include/glib-2.0/gobject/gtype.h:491:88: warning: cast from type ‘gconstpointer {aka const void*}’ to type ‘GTypeInstance* {aka _GTypeInstance*}’ casts away qualifiers [-Wcast-qual]
 #define G_TYPE_CHECK_INSTANCE_TYPE(instance, g_type)            (_G_TYPE_CIT ((instance), (g_type)))
                                                                                        ^
/usr/include/glib-2.0/gobject/gtype.h:2200:44: note: in definition of macro ‘_G_TYPE_CIT’
   GTypeInstance *__inst = (GTypeInstance*) ip; GType __t = gt; gboolean __r; \
                                            ^
/usr/include/glib-2.0/gobject/gtype.h:1398:12: note: in expansion of macro ‘G_TYPE_CHECK_INSTANCE_TYPE’
     return G_TYPE_CHECK_INSTANCE_TYPE (ptr, module_obj_name##_get_type ()); }                            \
            ^
/usr/include/glib-2.0/gio/gliststore.h:36:1: note: in expansion of macro ‘G_DECLARE_FINAL_TYPE’
 G_DECLARE_FINAL_TYPE(GListStore, g_list_store, G, LIST_STORE, GObject)