value.h: introduce `MRB_TT_STRUCT` for `mruby-struct`.

include/mruby/value.h

@@ -150,6 +150,7 @@ static const unsigned int IEEE754_INFINITY_BITS_SINGLE = 0x7F800000;
   f(MRB_TT_ENV,         struct REnv,        "env") \
   f(MRB_TT_DATA,        struct RData,       "Data") \
   f(MRB_TT_FIBER,       struct RFiber,      "Fiber") \
+  f(MRB_TT_STRUCT,      struct RArray,      "Struct") \
   f(MRB_TT_ISTRUCT,     struct RIStruct,    "istruct") \
   f(MRB_TT_BREAK,       struct RBreak,      "break") \
   f(MRB_TT_COMPLEX,     struct RComplex,    "Complex") \

mrbgems/mruby-os-memsize/src/memsize.c

@@ -88,6 +88,7 @@ os_memsize_of_object(mrb_state* mrb, mrb_value obj)
               mrb_hash_memsize(obj);
       break;
     }
+    case MRB_TT_STRUCT:
     case MRB_TT_ARRAY: {
       mrb_int len = RARRAY_LEN(obj);
       /* Arrays that do not fit within an RArray perform a heap allocation

mrbgems/mruby-struct/src/struct.c

@@ -18,6 +18,8 @@
 #define RSTRUCT_LEN(st) RARRAY_LEN(st)
 #define RSTRUCT_PTR(st) RARRAY_PTR(st)
 
+#define mrb_struct_p(o) (mrb_type(o) == MRB_TT_STRUCT)
+
 static struct RClass *
 struct_class(mrb_state *mrb)
 {
@@ -58,19 +60,14 @@ static mrb_value
 struct_members(mrb_state *mrb, mrb_value s)
 {
   mrb_value members = struct_s_members(mrb, mrb_obj_class(mrb, s));
-  if (!mrb_array_p(s)) {
+  if (!mrb_struct_p(s) || RSTRUCT_LEN(s) == 0) {
     mrb_raise(mrb, E_TYPE_ERROR, "corrupted struct");
   }
   if (RSTRUCT_LEN(s) != RARRAY_LEN(members)) {
-    if (RSTRUCT_LEN(s) == 0) {  /* probably uninitialized */
-      mrb_ary_resize(mrb, s, RARRAY_LEN(members));
-    }
-    else {
     mrb_raisef(mrb, E_TYPE_ERROR,
                "struct size differs (%i required %i given)",
                RARRAY_LEN(members), RSTRUCT_LEN(s));
   }
-  }
   return members;
 }
 
@@ -213,7 +210,7 @@ make_struct(mrb_state *mrb, mrb_value name, mrb_value members, struct RClass *kl
     }
     c = mrb_define_class_under(mrb, klass, RSTRING_PTR(name), klass);
   }
-  MRB_SET_INSTANCE_TT(c, MRB_TT_ARRAY);
+  MRB_SET_INSTANCE_TT(c, MRB_TT_STRUCT);
   nstr = mrb_obj_value(c);
   mrb_iv_set(mrb, nstr, MRB_SYM(__members__), members);
 
@@ -362,7 +359,7 @@ mrb_struct_init_copy(mrb_state *mrb, mrb_value copy)
   if (!mrb_obj_is_instance_of(mrb, s, mrb_obj_class(mrb, copy))) {
     mrb_raise(mrb, E_TYPE_ERROR, "wrong argument class");
   }
-  if (!mrb_array_p(s)) {
+  if (!mrb_struct_p(s)) {
     mrb_raise(mrb, E_TYPE_ERROR, "corrupted struct");
   }
   mrb_ary_replace(mrb, copy, s);

src/gc.c

@@ -742,6 +742,7 @@ gc_mark_children(mrb_state *mrb, mrb_gc *gc, struct RBasic *obj)
     }
     break;
 
+  case MRB_TT_STRUCT:
   case MRB_TT_ARRAY:
     {
       struct RArray *a = (struct RArray*)obj;
@@ -857,6 +858,7 @@ obj_free(mrb_state *mrb, struct RBasic *obj, int end)
     }
     break;
 
+  case MRB_TT_STRUCT:
   case MRB_TT_ARRAY:
     if (ARY_SHARED_P(obj))
       mrb_ary_decref(mrb, ((struct RArray*)obj)->as.heap.aux.shared);
@@ -1041,6 +1043,7 @@ gc_gray_counts(mrb_state *mrb, mrb_gc *gc, struct RBasic *obj)
     }
     break;
 
+  case MRB_TT_STRUCT:
   case MRB_TT_ARRAY:
     {
       struct RArray *a = (struct RArray*)obj;