Make struct font_drivers read-only

This simplifies the code a bit, and makes the structs more
shareable and less likely to become corrupt.
* src/alloc.c (cleanup_vector):
* src/font.c (valid_font_driver, font_prepare_cache)
(font_finish_cache, font_get_cache, font_clear_cache)
(register_font_driver, font_update_drivers):
* src/font.h (struct font, struct font_driver_list)
(valid_font_driver):
struct font_drivers are now const.
* src/font.c, src/ftcrfont.c, src/ftfont.c, src/nsfont.m, src/xfont.c:
Omit no-longer-necessary decls.
* src/ftcrfont.c (syms_of_ftcrfont):
* src/ftxfont.c (syms_of_ftxfont):
* src/xftfont.c (syms_of_xftfont):
Omit no-longer-necessary initialization code.
* src/ftcrfont.c (ftcrfont_driver):
* src/ftfont.c (ftfont_driver):
* src/ftxfont.c (ftxfont_driver):
* src/macfont.m (macfont_driver):
* src/nsfont.m (nsfont_driver):
* src/xfont.c (xfont_driver):
* src/xftfont.c (xftfont_driver):
Use C99-style initializer for ease of maintenance, and make it const.
* src/ftcrfont.c, src/ftxfont.c, src/xftfont.c:
Refer to functions like ftfont_text_extents directly.
* src/ftfont.c (ftfont_get_cache, ftfont_list, ftfont_list_family)
(ftfont_has_char, ftfont_encode_char, ftfont_text_extents)
(ftfont_get_bitmap, ftfont_anchor_point, ftfont_otf_capability)
(ftfont_variation_glyphs, ftfont_filter_properties)
(ftfont_combining_capability):
* src/xfont.c (xfont_get_cache):
Now extern, so that other modules’ struct font_drivers can use
them directly.
* src/macfont.m (macfont_descriptor_entity):
* src/nsfont.m (nsfont_open):
Use constant directly; this is clearer.

10 files changed, 251 insertions, 303 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 175dcab2487..ae32400708a 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3201,7 +3201,7 @@ cleanup_vector (struct Lisp_Vector *vector)
       && ((vector->header.size & PSEUDOVECTOR_SIZE_MASK)
           == FONT_OBJECT_MAX))
     {
-      struct font_driver *drv = ((struct font *) vector)->driver;
+      struct font_driver const *drv = ((struct font *) vector)->driver;
 
       /* The font driver might sometimes be NULL, e.g. if Emacs was
          interrupted before it had time to set it up.  */
diff --git a/src/font.c b/src/font.c
index ce632335256..9fe7c26ea9c 100644
--- a/src/font.c
+++ b/src/font.c
@@ -132,7 +132,7 @@ static struct font_driver_list *font_driver_list;
 /* Used to catch bogus pointers in font objects.  */
 
 bool
-valid_font_driver (struct font_driver *drv)
+valid_font_driver (struct font_driver const *drv)
 {
   Lisp_Object tail, frame;
   struct font_driver_list *fdl;
@@ -2543,14 +2543,11 @@ font_match_p (Lisp_Object spec, Lisp_Object font)
    is a number frames sharing this cache, and FONT-CACHE-DATA is a
    cons (FONT-SPEC . [FONT-ENTITY ...]).  */
 
-static void font_prepare_cache (struct frame *, struct font_driver *);
-static void font_finish_cache (struct frame *, struct font_driver *);
-static Lisp_Object font_get_cache (struct frame *, struct font_driver *);
 static void font_clear_cache (struct frame *, Lisp_Object,
-                              struct font_driver *);
+                              struct font_driver const *);
 
 static void
-font_prepare_cache (struct frame *f, struct font_driver *driver)
+font_prepare_cache (struct frame *f, struct font_driver const *driver)
 {
   Lisp_Object cache, val;
 
@@ -2572,7 +2569,7 @@ font_prepare_cache (struct frame *f, struct font_driver *driver)
 
 
 static void
-font_finish_cache (struct frame *f, struct font_driver *driver)
+font_finish_cache (struct frame *f, struct font_driver const *driver)
 {
   Lisp_Object cache, val, tmp;
 
@@ -2593,7 +2590,7 @@ font_finish_cache (struct frame *f, struct font_driver *driver)
 
 
 static Lisp_Object
-font_get_cache (struct frame *f, struct font_driver *driver)
+font_get_cache (struct frame *f, struct font_driver const *driver)
 {
   Lisp_Object val = driver->get_cache (f);
   Lisp_Object type = driver->type;
@@ -2608,7 +2605,8 @@ font_get_cache (struct frame *f, struct font_driver *driver)
 
 
 static void
-font_clear_cache (struct frame *f, Lisp_Object cache, struct font_driver *driver)
+font_clear_cache (struct frame *f, Lisp_Object cache,
+                  struct font_driver const *driver)
 {
   Lisp_Object tail, elt;
   Lisp_Object entity;
@@ -3463,7 +3461,7 @@ font_open_by_name (struct frame *f, Lisp_Object name)
    (e.g. syms_of_xfont).  */
 
 void
-register_font_driver (struct font_driver *driver, struct frame *f)
+register_font_driver (struct font_driver const *driver, struct frame *f)
 {
   struct font_driver_list *root = f ? f->font_driver_list : font_driver_list;
   struct font_driver_list *prev, *list;
@@ -3524,7 +3522,7 @@ font_update_drivers (struct frame *f, Lisp_Object new_drivers)
      drivers.  */
   for (list = f->font_driver_list; list; list = list->next)
     {
-      struct font_driver *driver = list->driver;
+      struct font_driver const *driver = list->driver;
       if ((EQ (new_drivers, Qt) || ! NILP (Fmemq (driver->type, new_drivers)))
           != list->on)
         {
@@ -3587,7 +3585,7 @@ font_update_drivers (struct frame *f, Lisp_Object new_drivers)
              and then use it under w32 or ns.  */
           for (list = f->font_driver_list; list; list = list->next)
             {
-              struct font_driver *driver = list->driver;
+              struct font_driver const *driver = list->driver;
               eassert (! list->on);
               if (! driver->start_for_frame
                   || driver->start_for_frame (f) == 0)
diff --git a/src/font.h b/src/font.h
index c14823bc1eb..af0214c3f23 100644
--- a/src/font.h
+++ b/src/font.h
@@ -380,7 +380,7 @@ struct font
 #endif /* HAVE_WINDOW_SYSTEM */
 
   /* Font-driver for the font.  */
-  struct font_driver *driver;
+  struct font_driver const *driver;
 
   /* There are more members in this structure, but they are private
      to the font-driver.  */
@@ -783,7 +783,7 @@ struct font_driver_list
      font driver list.*/
   bool on;
   /* Pointer to the font driver.  */
-  struct font_driver *driver;
+  struct font_driver const *driver;
   /* Pointer to the next element of the chain.  */
   struct font_driver_list *next;
 };
@@ -841,13 +841,13 @@ extern void font_parse_family_registry (Lisp_Object family,
 extern int font_parse_xlfd (char *name, ptrdiff_t len, Lisp_Object font);
 extern ptrdiff_t font_unparse_xlfd (Lisp_Object font, int pixel_size,
                                     char *name, int bytes);
-extern void register_font_driver (struct font_driver *driver, struct frame *f);
+extern void register_font_driver (struct font_driver const *, struct frame *);
 extern void free_font_driver_list (struct frame *f);
 #ifdef ENABLE_CHECKING
-extern bool valid_font_driver (struct font_driver *);
+extern bool valid_font_driver (struct font_driver const *);
 #else
 INLINE bool
-valid_font_driver (struct font_driver *d)
+valid_font_driver (struct font_driver const *d)
 {
   return true;
 }
@@ -874,18 +874,37 @@ extern void font_filter_properties (Lisp_Object font,
 extern void font_drop_xrender_surfaces (struct frame *f);
 
 #ifdef HAVE_FREETYPE
-extern struct font_driver ftfont_driver;
+extern int ftfont_anchor_point (struct font *, unsigned int, int,
+                                int *, int *);
+extern int ftfont_get_bitmap (struct font *, unsigned int,
+                              struct font_bitmap *, int);
+extern int ftfont_has_char (Lisp_Object, int);
+extern int ftfont_variation_glyphs (struct font *, int, unsigned[256]);
+extern Lisp_Object ftfont_combining_capability (struct font *);
+extern Lisp_Object ftfont_get_cache (struct frame *);
+extern Lisp_Object ftfont_list (struct frame *, Lisp_Object);
+extern Lisp_Object ftfont_list_family (struct frame *);
+extern Lisp_Object ftfont_match (struct frame *, Lisp_Object);
+extern Lisp_Object ftfont_open (struct frame *, Lisp_Object, int);
+extern Lisp_Object ftfont_otf_capability (struct font *);
+extern Lisp_Object ftfont_shape (Lisp_Object);
+extern unsigned ftfont_encode_char (struct font *, int);
+extern void ftfont_close (struct font *);
+extern void ftfont_filter_properties (Lisp_Object, Lisp_Object);
+extern void ftfont_text_extents (struct font *, unsigned *, int,
+                                 struct font_metrics *);
 extern void syms_of_ftfont (void);
 #endif  /* HAVE_FREETYPE */
 #ifdef HAVE_X_WINDOWS
-extern struct font_driver xfont_driver;
+extern struct font_driver const xfont_driver;
+extern Lisp_Object xfont_get_cache (struct frame *);
 extern void syms_of_xfont (void);
 extern void syms_of_ftxfont (void);
 #ifdef HAVE_XFT
-extern struct font_driver xftfont_driver;
+extern struct font_driver const xftfont_driver;
 #endif
 #if defined HAVE_FREETYPE || defined HAVE_XFT
-extern struct font_driver ftxfont_driver;
+extern struct font_driver const ftxfont_driver;
 extern void syms_of_xftfont (void);
 #endif
 #ifdef HAVE_BDFFONT
@@ -898,12 +917,12 @@ extern struct font_driver uniscribe_font_driver;
 extern void syms_of_w32font (void);
 #endif  /* HAVE_NTGUI */
 #ifdef HAVE_NS
-extern struct font_driver nsfont_driver;
+extern struct font_driver const nsfont_driver;
 extern void syms_of_nsfont (void);
 extern void syms_of_macfont (void);
 #endif  /* HAVE_NS */
 #ifdef USE_CAIRO
-extern struct font_driver ftcrfont_driver;
+extern struct font_driver const ftcrfont_driver;
 extern void syms_of_ftcrfont (void);
 #endif
 
diff --git a/src/ftcrfont.c b/src/ftcrfont.c
index 2676502705d..f62b40f41c4 100644
--- a/src/ftcrfont.c
+++ b/src/ftcrfont.c
@@ -65,8 +65,6 @@ enum metrics_status
 #define METRICS_SET_STATUS(metrics, status) \
   ((metrics)->ascent = 0, (metrics)->descent = (status))
 
-struct font_driver ftcrfont_driver;
-
 static int
 ftcrfont_glyph_extents (struct font *font,
                         unsigned glyph,
@@ -101,7 +99,7 @@ ftcrfont_glyph_extents (struct font *font,
   cache = ftcrfont_info->metrics[row] + col;
 
   if (METRICS_STATUS (cache) == METRICS_INVALID)
-    ftfont_driver.text_extents (font, &glyph, 1, cache);
+    ftfont_text_extents (font, &glyph, 1, cache);
 
   if (metrics)
     *metrics = *cache;
@@ -112,7 +110,7 @@ ftcrfont_glyph_extents (struct font *font,
 static Lisp_Object
 ftcrfont_list (struct frame *f, Lisp_Object spec)
 {
-  Lisp_Object list = ftfont_driver.list (f, spec), tail;
+  Lisp_Object list = ftfont_list (f, spec), tail;
 
   for (tail = list; CONSP (tail); tail = XCDR (tail))
     ASET (XCAR (tail), FONT_TYPE_INDEX, Qftcr);
@@ -122,15 +120,13 @@ ftcrfont_list (struct frame *f, Lisp_Object spec)
 static Lisp_Object
 ftcrfont_match (struct frame *f, Lisp_Object spec)
 {
-  Lisp_Object entity = ftfont_driver.match (f, spec);
+  Lisp_Object entity = ftfont_match (f, spec);
 
   if (VECTORP (entity))
     ASET (entity, FONT_TYPE_INDEX, Qftcr);
   return entity;
 }
 
-extern FT_Face ftfont_get_ft_face (Lisp_Object);
-
 static Lisp_Object
 ftcrfont_open (struct frame *f, Lisp_Object entity, int pixel_size)
 {
@@ -181,7 +177,7 @@ ftcrfont_close (struct font *font)
   cairo_font_face_destroy (ftcrfont_info->cr_font_face);
   unblock_input ();
 
-  ftfont_driver.close (font);
+  ftfont_close (font);
 }
 
 static void
@@ -282,6 +278,34 @@ ftcrfont_draw (struct glyph_string *s,
 
 
 
+struct font_driver const ftcrfont_driver =
+  {
+  type: LISPSYM_INITIALLY (Qftcr),
+  get_cache: ftfont_get_cache,
+  list: ftcrfont_list,
+  match: ftcrfont_match,
+  list_family: ftfont_list_family,
+  open: ftcrfont_open,
+  close: ftcrfont_close,
+  has_char: ftfont_has_char,
+  encode_char: ftfont_encode_char,
+  text_extents: ftcrfont_text_extents,
+  draw: ftcrfont_draw,
+  get_bitmap: ftfont_get_bitmap,
+  anchor_point: ftfont_anchor_point,
+#ifdef HAVE_LIBOTF
+  otf_capability: ftfont_otf_capability,
+#endif
+#if defined HAVE_M17N_FLT && defined HAVE_LIBOTF
+  shape: ftfont_shape,
+#endif
+#ifdef HAVE_OTF_GET_VARIATION_GLYPHS
+  get_variation_glyphs: ftfont_variation_glyphs,
+#endif
+  filter_properties: ftfont_filter_properties,
+  combining_capability: ftfont_combining_capability,
+  };
+
 void
 syms_of_ftcrfont (void)
 {
@@ -289,14 +313,5 @@ syms_of_ftcrfont (void)
     abort ();
 
   DEFSYM (Qftcr, "ftcr");
-
-  ftcrfont_driver = ftfont_driver;
-  ftcrfont_driver.type = Qftcr;
-  ftcrfont_driver.list = ftcrfont_list;
-  ftcrfont_driver.match = ftcrfont_match;
-  ftcrfont_driver.open = ftcrfont_open;
-  ftcrfont_driver.close = ftcrfont_close;
-  ftcrfont_driver.text_extents = ftcrfont_text_extents;
-  ftcrfont_driver.draw = ftcrfont_draw;
   register_font_driver (&ftcrfont_driver, NULL);
 }
diff --git a/src/ftfont.c b/src/ftfont.c
index 17fe66828fa..768b524f0a6 100644
--- a/src/ftfont.c
+++ b/src/ftfont.c
@@ -35,6 +35,8 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include "font.h"
 #include "ftfont.h"
 
+static struct font_driver const ftfont_driver;
+
 /* Flag to tell if FcInit is already called or not.  */
 static bool fc_initialized;
 
@@ -73,17 +75,9 @@ enum ftfont_cache_for
     FTFONT_CACHE_FOR_ENTITY
   };
 
-static Lisp_Object ftfont_pattern_entity (FcPattern *, Lisp_Object);
-
-static Lisp_Object ftfont_resolve_generic_family (Lisp_Object,
-                                                  FcPattern *);
 static Lisp_Object ftfont_lookup_cache (Lisp_Object,
                                         enum ftfont_cache_for);
 
-static void ftfont_filter_properties (Lisp_Object font, Lisp_Object alist);
-
-static Lisp_Object ftfont_combining_capability (struct font *);
-
 #define SYMBOL_FcChar8(SYM) (FcChar8 *) SDATA (SYMBOL_NAME (SYM))
 
 static struct
@@ -480,83 +474,7 @@ ftfont_get_otf (struct ftfont_info *ftfont_info)
 }
 #endif  /* HAVE_LIBOTF */
 
-static Lisp_Object ftfont_get_cache (struct frame *);
-static Lisp_Object ftfont_list (struct frame *, Lisp_Object);
-static Lisp_Object ftfont_match (struct frame *, Lisp_Object);
-static Lisp_Object ftfont_list_family (struct frame *);
-static Lisp_Object ftfont_open (struct frame *, Lisp_Object, int);
-static void ftfont_close (struct font *);
-static int ftfont_has_char (Lisp_Object, int);
-static unsigned ftfont_encode_char (struct font *, int);
-static void ftfont_text_extents (struct font *, unsigned *, int,
-                                 struct font_metrics *);
-static int ftfont_get_bitmap (struct font *, unsigned,
-                              struct font_bitmap *, int);
-static int ftfont_anchor_point (struct font *, unsigned, int,
-                                int *, int *);
-#ifdef HAVE_LIBOTF
-static Lisp_Object ftfont_otf_capability (struct font *);
-# ifdef HAVE_M17N_FLT
-static Lisp_Object ftfont_shape (Lisp_Object);
-# endif
-#endif
-
-#ifdef HAVE_OTF_GET_VARIATION_GLYPHS
-static int ftfont_variation_glyphs (struct font *, int c,
-                                    unsigned variations[256]);
-#endif /* HAVE_OTF_GET_VARIATION_GLYPHS */
-
-struct font_driver ftfont_driver =
-  {
-    LISPSYM_INITIALLY (Qfreetype),
-    0,                          /* case insensitive */
-    ftfont_get_cache,
-    ftfont_list,
-    ftfont_match,
-    ftfont_list_family,
-    NULL,                       /* free_entity */
-    ftfont_open,
-    ftfont_close,
-    /* We can't draw a text without device dependent functions.  */
-    NULL,                       /* prepare_face */
-    NULL,                       /* done_face */
-    ftfont_has_char,
-    ftfont_encode_char,
-    ftfont_text_extents,
-    /* We can't draw a text without device dependent functions.  */
-    NULL,                       /* draw */
-    ftfont_get_bitmap,
-    NULL,                       /* free_bitmap */
-    ftfont_anchor_point,
-#ifdef HAVE_LIBOTF
-    ftfont_otf_capability,
-#else  /* not HAVE_LIBOTF */
-    NULL,
-#endif  /* not HAVE_LIBOTF */
-    NULL,                       /* otf_drive */
-    NULL,                       /* start_for_frame */
-    NULL,                       /* end_for_frame */
-#if defined (HAVE_M17N_FLT) && defined (HAVE_LIBOTF)
-    ftfont_shape,
-#else  /* not (HAVE_M17N_FLT && HAVE_LIBOTF) */
-    NULL,
-#endif  /* not (HAVE_M17N_FLT && HAVE_LIBOTF) */
-    NULL,                       /* check */
-
-#ifdef HAVE_OTF_GET_VARIATION_GLYPHS
-    ftfont_variation_glyphs,
-#else
-    NULL,
-#endif
-
-    ftfont_filter_properties, /* filter_properties */
-
-    NULL,                       /* cached_font_ok */
-
-    ftfont_combining_capability,
-  };
-
-static Lisp_Object
+Lisp_Object
 ftfont_get_cache (struct frame *f)
 {
   return freetype_font_cache;
@@ -873,7 +791,7 @@ ftfont_spec_pattern (Lisp_Object spec, char *otlayout, struct OpenTypeSpec **ots
   return pattern;
 }
 
-static Lisp_Object
+Lisp_Object
 ftfont_list (struct frame *f, Lisp_Object spec)
 {
   Lisp_Object val = Qnil, family, adstyle;
@@ -1072,7 +990,7 @@ ftfont_list (struct frame *f, Lisp_Object spec)
   return val;
 }
 
-static Lisp_Object
+Lisp_Object
 ftfont_match (struct frame *f, Lisp_Object spec)
 {
   Lisp_Object entity = Qnil;
@@ -1122,7 +1040,7 @@ ftfont_match (struct frame *f, Lisp_Object spec)
   return entity;
 }
 
-static Lisp_Object
+Lisp_Object
 ftfont_list_family (struct frame *f)
 {
   Lisp_Object list = Qnil;
@@ -1301,7 +1219,7 @@ ftfont_open2 (struct frame *f,
   return font_object;
 }
 
-static Lisp_Object
+Lisp_Object
 ftfont_open (struct frame *f, Lisp_Object entity, int pixel_size)
 {
   Lisp_Object font_object;
@@ -1314,7 +1232,7 @@ ftfont_open (struct frame *f, Lisp_Object entity, int pixel_size)
   return ftfont_open2 (f, entity, pixel_size, font_object);
 }
 
-static void
+void
 ftfont_close (struct font *font)
 {
   /* FIXME: Although this function can be called while garbage-collecting,
@@ -1344,7 +1262,7 @@ ftfont_close (struct font *font)
     FT_Done_Size (ftfont_info->ft_size);
 }
 
-static int
+int
 ftfont_has_char (Lisp_Object font, int c)
 {
   struct charset *cs = NULL;
@@ -1374,7 +1292,7 @@ ftfont_has_char (Lisp_Object font, int c)
     }
 }
 
-static unsigned
+unsigned
 ftfont_encode_char (struct font *font, int c)
 {
   struct ftfont_info *ftfont_info = (struct ftfont_info *) font;
@@ -1385,7 +1303,7 @@ ftfont_encode_char (struct font *font, int c)
   return (code > 0 ? code : FONT_INVALID_CODE);
 }
 
-static void
+void
 ftfont_text_extents (struct font *font, unsigned int *code,
                      int nglyphs, struct font_metrics *metrics)
 {
@@ -1429,7 +1347,7 @@ ftfont_text_extents (struct font *font, unsigned int *code,
   metrics->width = width;
 }
 
-static int
+int
 ftfont_get_bitmap (struct font *font, unsigned int code, struct font_bitmap *bitmap, int bits_per_pixel)
 {
   struct ftfont_info *ftfont_info = (struct ftfont_info *) font;
@@ -1472,7 +1390,7 @@ ftfont_get_bitmap (struct font *font, unsigned int code, struct font_bitmap *bit
   return 0;
 }
 
-static int
+int
 ftfont_anchor_point (struct font *font, unsigned int code, int idx,
                      int *x, int *y)
 {
@@ -1538,7 +1456,7 @@ ftfont_otf_features (OTF_GSUB_GPOS *gsub_gpos)
 }
 
 
-static Lisp_Object
+Lisp_Object
 ftfont_otf_capability (struct font *font)
 {
   struct ftfont_info *ftfont_info = (struct ftfont_info *) font;
@@ -2701,7 +2619,7 @@ ftfont_shape (Lisp_Object lgstring)
 
 #ifdef HAVE_OTF_GET_VARIATION_GLYPHS
 
-static int
+int
 ftfont_variation_glyphs (struct font *font, int c, unsigned variations[256])
 {
   struct ftfont_info *ftfont_info = (struct ftfont_info *) font;
@@ -2759,14 +2677,14 @@ static const char *const ftfont_non_booleans [] = {
   NULL,
 };
 
-static void
+void
 ftfont_filter_properties (Lisp_Object font, Lisp_Object alist)
 {
   font_filter_properties (font, alist, ftfont_booleans, ftfont_non_booleans);
 }
 
 
-static Lisp_Object
+Lisp_Object
 ftfont_combining_capability (struct font *font)
 {
 #ifdef HAVE_M17N_FLT
@@ -2776,6 +2694,34 @@ ftfont_combining_capability (struct font *font)
 #endif
 }
 
+static struct font_driver const ftfont_driver =
+  {
+  /* We can't draw a text without device dependent functions.  */
+  type: LISPSYM_INITIALLY (Qfreetype),
+  get_cache: ftfont_get_cache,
+  list: ftfont_list,
+  match: ftfont_match,
+  list_family: ftfont_list_family,
+  open: ftfont_open,
+  close: ftfont_close,
+  has_char: ftfont_has_char,
+  encode_char: ftfont_encode_char,
+  text_extents: ftfont_text_extents,
+  get_bitmap: ftfont_get_bitmap,
+  anchor_point: ftfont_anchor_point,
+#ifdef HAVE_LIBOTF
+  otf_capability: ftfont_otf_capability,
+#endif
+#if defined HAVE_M17N_FLT && defined HAVE_LIBOTF
+  shape: ftfont_shape,
+#endif
+#ifdef HAVE_OTF_GET_VARIATION_GLYPHS
+  get_variation_glyphs: ftfont_variation_glyphs,
+#endif
+  filter_properties: ftfont_filter_properties,
+  combining_capability: ftfont_combining_capability,
+  };
+
 void
 syms_of_ftfont (void)
 {
diff --git a/src/ftxfont.c b/src/ftxfont.c
index bfdeb4051b9..d8792ac27bd 100644
--- a/src/ftxfont.c
+++ b/src/ftxfont.c
@@ -31,8 +31,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 /* FTX font driver.  */
 
-struct font_driver ftxfont_driver;
-
 struct ftxfont_frame_data
 {
   /* Background and foreground colors.  */
@@ -125,7 +123,7 @@ ftxfont_draw_bitmap (struct frame *f, GC gc_fore, GC *gcs, struct font *font,
   unsigned char *b;
   int i, j;
 
-  if (ftfont_driver.get_bitmap (font, code, &bitmap, size > 0x100 ? 1 : 8) < 0)
+  if (ftfont_get_bitmap (font, code, &bitmap, size > 0x100 ? 1 : 8) < 0)
     return 0;
   if (size > 0x100)
     {
@@ -188,8 +186,7 @@ ftxfont_draw_bitmap (struct frame *f, GC gc_fore, GC *gcs, struct font *font,
         }
     }
 
-  if (ftfont_driver.free_bitmap)
-    ftfont_driver.free_bitmap (font, &bitmap);
+  /* There is no ftfont_free_bitmap, so do not try to free BITMAP.  */
 
   return bitmap.advance;
 }
@@ -211,7 +208,7 @@ ftxfont_draw_background (struct frame *f, struct font *font, GC gc, int x, int y
 static Lisp_Object
 ftxfont_list (struct frame *f, Lisp_Object spec)
 {
-  Lisp_Object list = ftfont_driver.list (f, spec), tail;
+  Lisp_Object list = ftfont_list (f, spec), tail;
 
   for (tail = list; CONSP (tail); tail = XCDR (tail))
     ASET (XCAR (tail), FONT_TYPE_INDEX, Qftx);
@@ -221,7 +218,7 @@ ftxfont_list (struct frame *f, Lisp_Object spec)
 static Lisp_Object
 ftxfont_match (struct frame *f, Lisp_Object spec)
 {
-  Lisp_Object entity = ftfont_driver.match (f, spec);
+  Lisp_Object entity = ftfont_match (f, spec);
 
   if (VECTORP (entity))
     ASET (entity, FONT_TYPE_INDEX, Qftx);
@@ -231,13 +228,10 @@ ftxfont_match (struct frame *f, Lisp_Object spec)
 static Lisp_Object
 ftxfont_open (struct frame *f, Lisp_Object entity, int pixel_size)
 {
-  Lisp_Object font_object;
-  struct font *font;
-
-  font_object = ftfont_driver.open (f, entity, pixel_size);
+  Lisp_Object font_object = ftfont_open (f, entity, pixel_size);
   if (NILP (font_object))
     return Qnil;
-  font = XFONT_OBJECT (font_object);
+  struct font *font = XFONT_OBJECT (font_object);
   font->driver = &ftxfont_driver;
   return font_object;
 }
@@ -245,7 +239,7 @@ ftxfont_open (struct frame *f, Lisp_Object entity, int pixel_size)
 static void
 ftxfont_close (struct font *font)
 {
-  ftfont_driver.close (font);
+  ftfont_close (font);
 }
 
 static int
@@ -345,18 +339,39 @@ ftxfont_end_for_frame (struct frame *f)
 
 
 
+struct font_driver const ftxfont_driver =
+  {
+  /* We can't draw a text without device dependent functions.  */
+  type: LISPSYM_INITIALLY (Qftx),
+  get_cache: ftfont_get_cache,
+  list: ftxfont_list,
+  match: ftxfont_match,
+  list_family: ftfont_list_family,
+  open: ftxfont_open,
+  close: ftxfont_close,
+  has_char: ftfont_has_char,
+  encode_char: ftfont_encode_char,
+  text_extents: ftfont_text_extents,
+  draw: ftxfont_draw,
+  get_bitmap: ftfont_get_bitmap,
+  anchor_point: ftfont_anchor_point,
+#ifdef HAVE_LIBOTF
+  otf_capability: ftfont_otf_capability,
+#endif
+  end_for_frame: ftxfont_end_for_frame,
+#if defined HAVE_M17N_FLT && defined HAVE_LIBOTF
+  shape: ftfont_shape,
+#endif
+#ifdef HAVE_OTF_GET_VARIATION_GLYPHS
+  get_variation_glyphs: ftfont_variation_glyphs,
+#endif
+  filter_properties: ftfont_filter_properties,
+  combining_capability: ftfont_combining_capability,
+  };
+
 void
 syms_of_ftxfont (void)
 {
   DEFSYM (Qftx, "ftx");
-
-  ftxfont_driver = ftfont_driver;
-  ftxfont_driver.type = Qftx;
-  ftxfont_driver.list = ftxfont_list;
-  ftxfont_driver.match = ftxfont_match;
-  ftxfont_driver.open = ftxfont_open;
-  ftxfont_driver.close = ftxfont_close;
-  ftxfont_driver.draw = ftxfont_draw;
-  ftxfont_driver.end_for_frame = ftxfont_end_for_frame;
   register_font_driver (&ftxfont_driver, NULL);
 }
diff --git a/src/macfont.m b/src/macfont.m
index b3a2fb84205..b2f3dff3097 100644
--- a/src/macfont.m
+++ b/src/macfont.m
@@ -38,8 +38,6 @@ Original author: YAMAMOTO Mitsuharu
 
 #include <libkern/OSByteOrder.h>
 
-static struct font_driver macfont_driver;
-
 static double mac_font_get_advance_width_for_glyph (CTFontRef, CGGlyph);
 static CGRect mac_font_get_bounding_rect_for_glyph (CTFontRef, CGGlyph);
 static CFArrayRef mac_font_create_available_families (void);
@@ -893,7 +891,7 @@ macfont_descriptor_entity (CTFontDescriptorRef desc, Lisp_Object extra,
 
   entity = font_make_entity ();
 
-  ASET (entity, FONT_TYPE_INDEX, macfont_driver.type);
+  ASET (entity, FONT_TYPE_INDEX, Qmac_ct);
   ASET (entity, FONT_REGISTRY_INDEX, Qiso10646_1);
 
   macfont_store_descriptor_attributes (desc, entity);
@@ -1663,34 +1661,23 @@ static int macfont_variation_glyphs (struct font *, int c,
                                      unsigned variations[256]);
 static void macfont_filter_properties (Lisp_Object, Lisp_Object);
 
-static struct font_driver macfont_driver =
+static struct font_driver const macfont_driver =
   {
-    LISPSYM_INITIALLY (Qmac_ct),
-    0,                          /* case insensitive */
-    macfont_get_cache,
-    macfont_list,
-    macfont_match,
-    macfont_list_family,
-    macfont_free_entity,
-    macfont_open,
-    macfont_close,
-    NULL,                       /* prepare_face */
-    NULL,                       /* done_face */
-    macfont_has_char,
-    macfont_encode_char,
-    macfont_text_extents,
-    macfont_draw,
-    NULL,                       /* get_bitmap */
-    NULL,                       /* free_bitmap */
-    NULL,                       /* anchor_point */
-    NULL,                       /* otf_capability */
-    NULL,                       /* otf_drive */
-    NULL,                       /* start_for_frame */
-    NULL,                       /* end_for_frame */
-    macfont_shape,
-    NULL,                       /* check */
-    macfont_variation_glyphs,
-    macfont_filter_properties,
+  type: LISPSYM_INITIALLY (Qmac_ct),
+  get_cache: macfont_get_cache,
+  list: macfont_list,
+  match: macfont_match,
+  list_family: macfont_list_family,
+  free_entity: macfont_free_entity,
+  open: macfont_open,
+  close: macfont_close,
+  has_char: macfont_has_char,
+  encode_char: macfont_encode_char,
+  text_extents: macfont_text_extents,
+  draw: macfont_draw,
+  shape: macfont_shape,
+  get_variation_glyphs: macfont_variation_glyphs,
+  filter_properties: macfont_filter_properties,
   };
 
 static Lisp_Object
diff --git a/src/nsfont.m b/src/nsfont.m
index c4c3c8dce7e..d14c362eddf 100644
--- a/src/nsfont.m
+++ b/src/nsfont.m
@@ -610,43 +610,6 @@ ns_findfonts (Lisp_Object font_spec, BOOL isMatch)
    ========================================================================== */
 
 
-static Lisp_Object nsfont_get_cache (struct frame *frame);
-static Lisp_Object nsfont_list (struct frame *, Lisp_Object);
-static Lisp_Object nsfont_match (struct frame *, Lisp_Object);
-static Lisp_Object nsfont_list_family (struct frame *);
-static Lisp_Object nsfont_open (struct frame *f, Lisp_Object font_entity,
-                                 int pixel_size);
-static void nsfont_close (struct font *font);
-static int nsfont_has_char (Lisp_Object entity, int c);
-static unsigned int nsfont_encode_char (struct font *font, int c);
-static void nsfont_text_extents (struct font *font, unsigned int *code,
-                                 int nglyphs, struct font_metrics *metrics);
-static int nsfont_draw (struct glyph_string *s, int from, int to, int x, int y,
-                        bool with_background);
-
-struct font_driver nsfont_driver =
-  {
-    LISPSYM_INITIALLY (Qns),
-    1,                          /* case sensitive */
-    nsfont_get_cache,
-    nsfont_list,
-    nsfont_match,
-    nsfont_list_family,
-    NULL,                       /*free_entity */
-    nsfont_open,
-    nsfont_close,
-    NULL,                       /* prepare_face */
-    NULL,                       /* done_face */
-    nsfont_has_char,
-    nsfont_encode_char,
-    nsfont_text_extents,
-    nsfont_draw,
-    /* excluded: get_bitmap, free_bitmap,
-                 anchor_point, otf_capability, otf_driver,
-                 start_for_frame, end_for_frame, shape */
-  };
-
-
 /* Return a cache of font-entities on FRAME.  The cache must be a
    cons whose cdr part is the actual cache area.  */
 static Lisp_Object
@@ -788,7 +751,7 @@ nsfont_open (struct frame *f, Lisp_Object font_entity, int pixel_size)
 
   font_object = font_make_object (VECSIZE (struct nsfont_info),
                                   font_entity, pixel_size);
-  ASET (font_object, FONT_TYPE_INDEX, nsfont_driver.type);
+  ASET (font_object, FONT_TYPE_INDEX, Qns);
   font_info = (struct nsfont_info *) XFONT_OBJECT (font_object);
   font = (struct font *) font_info;
   if (!font)
@@ -1520,6 +1483,21 @@ ns_dump_glyphstring (struct glyph_string *s)
   fprintf (stderr, "\n");
 }
 
+struct font_driver const nsfont_driver =
+  {
+  type: LISPSYM_INITIALLY (Qns),
+  case_sensitive: true,
+  get_cache: nsfont_get_cache,
+  list: nsfont_list,
+  match: nsfont_match,
+  list_family: nsfont_list_family,
+  open: nsfont_open,
+  close: nsfont_close,
+  has_char: nsfont_has_char,
+  encode_char: nsfont_encode_char,
+  text_extents: nsfont_text_extents,
+  draw: nsfont_draw,
+  };
 
 void
 syms_of_nsfont (void)
diff --git a/src/xfont.c b/src/xfont.c
index ccb8f070626..5999f6715cc 100644
--- a/src/xfont.c
+++ b/src/xfont.c
@@ -113,44 +113,7 @@ xfont_get_pcm (XFontStruct *xfont, XChar2b *char2b)
           ? NULL : pcm);
 }
 
-static Lisp_Object xfont_get_cache (struct frame *);
-static Lisp_Object xfont_list (struct frame *, Lisp_Object);
-static Lisp_Object xfont_match (struct frame *, Lisp_Object);
-static Lisp_Object xfont_list_family (struct frame *);
-static Lisp_Object xfont_open (struct frame *, Lisp_Object, int);
-static void xfont_close (struct font *);
-static void xfont_prepare_face (struct frame *, struct face *);
-static int xfont_has_char (Lisp_Object, int);
-static unsigned xfont_encode_char (struct font *, int);
-static void xfont_text_extents (struct font *, unsigned *, int,
-                                struct font_metrics *);
-static int xfont_draw (struct glyph_string *, int, int, int, int, bool);
-static int xfont_check (struct frame *, struct font *);
-
-struct font_driver xfont_driver =
-  {
-    LISPSYM_INITIALLY (Qx),
-    false,                      /* case insensitive */
-    xfont_get_cache,
-    xfont_list,
-    xfont_match,
-    xfont_list_family,
-    NULL,
-    xfont_open,
-    xfont_close,
-    xfont_prepare_face,
-    NULL,
-    xfont_has_char,
-    xfont_encode_char,
-    xfont_text_extents,
-    xfont_draw,
-    NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
-    xfont_check,
-    NULL, /* get_variation_glyphs */
-    NULL, /* filter_properties */
-  };
-
-static Lisp_Object
+Lisp_Object
 xfont_get_cache (struct frame *f)
 {
   Display_Info *dpyinfo = FRAME_DISPLAY_INFO (f);
@@ -1113,6 +1076,24 @@ xfont_check (struct frame *f, struct font *font)
 }
 
 
+
+struct font_driver const xfont_driver =
+  {
+  type: LISPSYM_INITIALLY (Qx),
+  get_cache: xfont_get_cache,
+  list: xfont_list,
+  match: xfont_match,
+  list_family: xfont_list_family,
+  open: xfont_open,
+  close: xfont_close,
+  prepare_face: xfont_prepare_face,
+  has_char: xfont_has_char,
+  encode_char: xfont_encode_char,
+  text_extents: xfont_text_extents,
+  draw: xfont_draw,
+  check: xfont_check,
+  };
+
 void
 syms_of_xfont (void)
 {
diff --git a/src/xftfont.c b/src/xftfont.c
index 861ad80da5c..74f5ec66e74 100644
--- a/src/xftfont.c
+++ b/src/xftfont.c
@@ -125,15 +125,12 @@ xftfont_get_colors (struct frame *f, struct face *face, GC gc,
     }
 }
 
-
-struct font_driver xftfont_driver;
-
 static Lisp_Object
 xftfont_list (struct frame *f, Lisp_Object spec)
 {
-  Lisp_Object list = ftfont_driver.list (f, spec), tail;
+  Lisp_Object list = ftfont_list (f, spec);
 
-  for (tail = list; CONSP (tail); tail = XCDR (tail))
+  for (Lisp_Object tail = list; CONSP (tail); tail = XCDR (tail))
     ASET (XCAR (tail), FONT_TYPE_INDEX, Qxft);
   return list;
 }
@@ -141,7 +138,7 @@ xftfont_list (struct frame *f, Lisp_Object spec)
 static Lisp_Object
 xftfont_match (struct frame *f, Lisp_Object spec)
 {
-  Lisp_Object entity = ftfont_driver.match (f, spec);
+  Lisp_Object entity = ftfont_match (f, spec);
 
   if (! NILP (entity))
     ASET (entity, FONT_TYPE_INDEX, Qxft);
@@ -542,7 +539,7 @@ xftfont_has_char (Lisp_Object font, int c)
     return (ENCODE_CHAR (cs, c) != CHARSET_INVALID_CODE (cs));
 
   if (FONT_ENTITY_P (font))
-    return ftfont_driver.has_char (font, c);
+    return ftfont_has_char (font, c);
   xftfont_info = (struct xftfont_info *) XFONT_OBJECT (font);
   return (XftCharExists (xftfont_info->display, xftfont_info->xftfont,
                          (FcChar32) c) == FcTrue);
@@ -668,12 +665,9 @@ xftfont_shape (Lisp_Object lgstring)
 {
   struct font *font = CHECK_FONT_GET_OBJECT (LGSTRING_FONT (lgstring));
   struct xftfont_info *xftfont_info = (struct xftfont_info *) font;
-  FT_Face ft_face;
-  Lisp_Object val;
-
-  ft_face = XftLockFace (xftfont_info->xftfont);
+  FT_Face ft_face = XftLockFace (xftfont_info->xftfont);
   xftfont_info->ft_size = ft_face->size;
-  val = ftfont_driver.shape (lgstring);
+  Lisp_Object val = ftfont_shape (lgstring);
   XftUnlockFace (xftfont_info->xftfont);
   return val;
 }
@@ -697,6 +691,10 @@ xftfont_end_for_frame (struct frame *f)
   return 0;
 }
 
+/* When using X double buffering, the XftDraw structure we build
+   seems to be useless once a frame is resized, so recreate it on
+   ConfigureNotify and in some other cases.  */
+
 static void
 xftfont_drop_xrender_surfaces (struct frame *f)
 {
@@ -751,6 +749,40 @@ xftfont_cached_font_ok (struct frame *f, Lisp_Object font_object,
   return ok;
 }
 
+struct font_driver const xftfont_driver =
+  {
+    /* We can't draw a text without device dependent functions.  */
+  type: LISPSYM_INITIALLY (Qxft),
+  get_cache: xfont_get_cache,
+  list: xftfont_list,
+  match: xftfont_match,
+  list_family: ftfont_list_family,
+  open: xftfont_open,
+  close: xftfont_close,
+  prepare_face: xftfont_prepare_face,
+  done_face: xftfont_done_face,
+  has_char: xftfont_has_char,
+  encode_char: xftfont_encode_char,
+  text_extents: xftfont_text_extents,
+  draw: xftfont_draw,
+  get_bitmap: ftfont_get_bitmap,
+  anchor_point: ftfont_anchor_point,
+#ifdef HAVE_LIBOTF
+  otf_capability: ftfont_otf_capability,
+#endif
+  end_for_frame: xftfont_end_for_frame,
+#if defined HAVE_M17N_FLT && defined HAVE_LIBOTF
+  shape: xftfont_shape,
+#endif
+#ifdef HAVE_OTF_GET_VARIATION_GLYPHS
+  get_variation_glyphs: ftfont_variation_glyphs,
+#endif
+  filter_properties: ftfont_filter_properties,
+  cached_font_ok: xftfont_cached_font_ok,
+  combining_capability: ftfont_combining_capability,
+  drop_xrender_surfaces: xftfont_drop_xrender_surfaces,
+  };
+
 void
 syms_of_xftfont (void)
 {
@@ -770,28 +802,5 @@ This is needed with some fonts to correct vertical overlap of glyphs.  */);
 
   ascii_printable[0] = 0;
 
-  xftfont_driver = ftfont_driver;
-  xftfont_driver.type = Qxft;
-  xftfont_driver.get_cache = xfont_driver.get_cache;
-  xftfont_driver.list = xftfont_list;
-  xftfont_driver.match = xftfont_match;
-  xftfont_driver.open = xftfont_open;
-  xftfont_driver.close = xftfont_close;
-  xftfont_driver.prepare_face = xftfont_prepare_face;
-  xftfont_driver.done_face = xftfont_done_face;
-  xftfont_driver.has_char = xftfont_has_char;
-  xftfont_driver.encode_char = xftfont_encode_char;
-  xftfont_driver.text_extents = xftfont_text_extents;
-  xftfont_driver.draw = xftfont_draw;
-  xftfont_driver.end_for_frame = xftfont_end_for_frame;
-  xftfont_driver.cached_font_ok = xftfont_cached_font_ok;
-#if defined (HAVE_M17N_FLT) && defined (HAVE_LIBOTF)
-  xftfont_driver.shape = xftfont_shape;
-#endif
-  /* When using X double buffering, the XftDraw structure we build
-   seems to be useless once a frame is resized, so recreate it on
-   ConfigureNotify and in some other cases.  */
-  xftfont_driver.drop_xrender_surfaces = xftfont_drop_xrender_surfaces;
-
   register_font_driver (&xftfont_driver, NULL);
 }