gistfile1.c

/* gtkwidget.h */
gboolean gtk_widget_get_visible (GtkWidget *w);

/* gtkwidget-private.h */
struct _GtkWidgetPrivate
{
  ...
};

#ifdef GTK_COMPILATION
#define gtk_widget_get_visible(w)    get_visible ((w))

static inline gboolean
get_visible (GtkWidget *w)
{
  return w->priv->visible;
}
#else
#define gtk_widget_get_visible(w)    (gtk_widget_get_visible) ((w))
#endif

/* gtkwidget.c */

#ifdef GTK_COMPILATION
gboolean
(gtk_widget_get_visible) (GtkWidget *w)
{
  return gtk_widget_get_visible (w);
}
#else
gboolean
(gtk_widget_get_visible) (GtkWidget *w)
{
  g_return_val_if_fail (GTK_IS_WIDGET (w), FALSE);

  return w->priv->visible;
}
#endif