Found the following significant warnings:
  atkClasses.c:1050:25: warning: assignment to ‘void (*)(AtkObject *, guint,  void *)’ {aka ‘void (*)(struct _AtkObject *, unsigned int,  void *)’} from incompatible pointer type ‘void (*)(AtkObject *, guint,  AtkObject *)’ {aka ‘void (*)(struct _AtkObject *, unsigned int,  struct _AtkObject *)’} [-Wincompatible-pointer-types]
  atkClasses.c:1058:34: warning: assignment to ‘void (*)(AtkObject *, void **)’ {aka ‘void (*)(struct _AtkObject *, void **)’} from incompatible pointer type ‘void (*)(AtkObject *, AtkObject *)’ {aka ‘void (*)(struct _AtkObject *, struct _AtkObject *)’} [-Wincompatible-pointer-types]
  atkClasses.c:1397:51: warning: passing argument 2 of ‘object_class->active_descendant_changed’ from incompatible pointer type [-Wincompatible-pointer-types]
  gdkFuncs.c:6000:36: warning: passing argument 2 of ‘gdk_window_get_user_data’ from incompatible pointer type [-Wincompatible-pointer-types]
  gioClasses.c:1948:17: warning: assignment to ‘gssize (*)(GOutputStream *, const void *, gsize,  GCancellable *, GError **)’ {aka ‘long int (*)(struct _GOutputStream *, const void *, long unsigned int,  struct _GCancellable *, struct _GError **)’} from incompatible pointer type ‘gssize (*)(GOutputStream *, const guchar *, gsize,  GCancellable *, GError **)’ {aka ‘long int (*)(struct _GOutputStream *, const unsigned char *, long unsigned int,  struct _GCancellable *, struct _GError **)’} [-Wincompatible-pointer-types]
  gioClasses.c:1964:20: warning: assignment to ‘void (*)(GOutputStream *, const void *, gsize,  int,  GCancellable *, void (*)(GObject *, GAsyncResult *, void *), void *)’ {aka ‘void (*)(struct _GOutputStream *, const void *, long unsigned int,  int,  struct _GCancellable *, void (*)(struct _GObject *, struct _GAsyncResult *, void *), void *)’} from incompatible pointer type ‘void (*)(GOutputStream *, const guchar *, gsize,  int,  GCancellable *, void (*)(GObject *, GAsyncResult *, void *), void *)’ {aka ‘void (*)(struct _GOutputStream *, const unsigned char *, long unsigned int,  int,  struct _GCancellable *, void (*)(struct _GObject *, struct _GAsyncResult *, void *), void *)’} [-Wincompatible-pointer-types]
  gtkClasses.c:8665:28: warning: assignment to ‘gboolean (*)(GtkNotebook *, gint)’ {aka ‘int (*)(struct _GtkNotebook *, int)’} from incompatible pointer type ‘void (*)(GtkNotebook *, gint)’ {aka ‘void (*)(struct _GtkNotebook *, int)’} [-Wincompatible-pointer-types]
  gtkClasses.c:11110:21: warning: assignment to ‘gboolean (*)(GtkScrolledWindow *, GtkScrollType,  gboolean)’ {aka ‘int (*)(struct _GtkScrolledWindow *, enum <anonymous>,  int)’} from incompatible pointer type ‘void (*)(GtkScrolledWindow *, GtkScrollType,  gboolean)’ {aka ‘void (*)(struct _GtkScrolledWindow *, enum <anonymous>,  int)’} [-Wincompatible-pointer-types]
See ‘/home/hornik/tmp/R.check/r-devel-gcc/Work/PKGS/RGtk2.Rcheck/00install.out’ for details.