Add MRB_TT_HAS_BASIC_P macro to check whether a typetag has MRB_OBJECT_HEADER.

include/mruby.h

@@ -298,11 +298,11 @@ int mrb_gc_arena_save(mrb_state*);
 void mrb_gc_arena_restore(mrb_state*,int);
 void mrb_gc_mark(mrb_state*,struct RBasic*);
 #define mrb_gc_mark_value(mrb,val) do {\
-  if (mrb_type(val) >= MRB_TT_HAS_BASIC) mrb_gc_mark((mrb), mrb_basic_ptr(val));\
+  if (MRB_TT_HAS_BASIC_P(mrb_type(val))) mrb_gc_mark((mrb), mrb_basic_ptr(val)); \
 } while (0)
 void mrb_field_write_barrier(mrb_state *, struct RBasic*, struct RBasic*);
 #define mrb_field_write_barrier_value(mrb, obj, val) do{\
-  if ((val.tt >= MRB_TT_HAS_BASIC)) mrb_field_write_barrier((mrb), (obj), mrb_basic_ptr(val));\
+  if (MRB_TT_HAS_BASIC_P(val.tt)) mrb_field_write_barrier((mrb), (obj), mrb_basic_ptr(val)); \
 } while (0)
 void mrb_write_barrier(mrb_state *, struct RBasic*);
 

include/mruby/value.h

@@ -469,6 +469,8 @@ mrb_cptr_value(struct mrb_state *mrb, void *p)
 #define mrb_voidp(o) mrb_cptr(o)
 #define mrb_voidp_p(o) mrb_cptr_p(o)
 
+#define MRB_TT_HAS_BASIC_P(tt) ((tt) >= MRB_TT_HAS_BASIC)
+
 static inline mrb_value
 mrb_false_value(void)
 {