Use NullPool for _hb_set_nil and _hb_map_nil

src/hb-map.cc

@@ -50,16 +50,6 @@ hb_map_create (void)
   return map;
 }
 
-static const hb_map_t _hb_map_nil = {
-  HB_OBJECT_HEADER_STATIC,
-  false, /* successful */
-  0, /* population */
-  0, /* occupancy */
-  0, /* mask */
-  0, /* prime */
-  nullptr /* items */
-};
-
 /**
  * hb_map_get_empty:
  *
@@ -70,7 +60,7 @@ static const hb_map_t _hb_map_nil = {
 hb_map_t *
 hb_map_get_empty (void)
 {
-  return const_cast<hb_map_t *> (&_hb_map_nil);
+  return const_cast<hb_map_t *> (&Null(hb_map_t));
 }
 
 /**

src/hb-private.hh

@@ -545,7 +545,7 @@ _hb_ceil_to_4 (unsigned int v)
 
 /* Global nul-content Null pool.  Enlarge as necessary. */
 
-#define HB_NULL_POOL_SIZE 264
+#define HB_NULL_POOL_SIZE 384
 static_assert (HB_NULL_POOL_SIZE % sizeof (void *) == 0, "Align HB_NULL_POOL_SIZE.");
 
 #ifdef HB_NO_VISIBILITY

src/hb-set.cc

@@ -50,12 +50,6 @@ hb_set_create (void)
   return set;
 }
 
-static const hb_set_t _hb_set_nil = {
-  HB_OBJECT_HEADER_STATIC,
-  false, /* successful */
-  0, /* population */
-};
-
 /**
  * hb_set_get_empty:
  *
@@ -66,7 +60,7 @@ static const hb_set_t _hb_set_nil = {
 hb_set_t *
 hb_set_get_empty (void)
 {
-  return const_cast<hb_set_t *> (&_hb_set_nil);
+  return const_cast<hb_set_t *> (&Null(hb_set_t));
 }
 
 /**