extern int composition_gstring_width (Lisp_Object, ptrdiff_t, ptrdiff_t,
struct font_metrics *);
extern void composition_compute_stop_pos (struct composition_it *,
ptrdiff_t, ptrdiff_t, ptrdiff_t,
Lisp_Object);
extern int composition_gstring_width (Lisp_Object, ptrdiff_t, ptrdiff_t,
struct font_metrics *);
extern void composition_compute_stop_pos (struct composition_it *,
ptrdiff_t, ptrdiff_t, ptrdiff_t,
Lisp_Object);