struct RString member should not be mrb_value

include/mruby/string.h

@@ -29,7 +29,7 @@ struct RString {
   long len;
   union {
     size_t capa;
-    mrb_value shared;
+    struct RString *shared;
   } aux;
   char *buf;
 };

src/gc.c

@@ -351,8 +351,9 @@ gc_mark_children(mrb_state *mrb, struct RBasic *obj)
     {
       struct RString *s = (struct RString*)obj;
 
-      if (s->flags & MRB_STR_SHARED) {
-        mrb_gc_mark_value(mrb, s->aux.shared)
+      while (s->flags & MRB_STR_SHARED) {
+	s = s->aux.shared;
+	if (!s) break;
       }
     }
     break;

src/string.c

@@ -492,13 +492,13 @@ str_new4(mrb_state *mrb, enum mrb_vtype ttype, mrb_value str)
   RSTRING(str2)->buf = RSTRING_PTR(str);
 
   if (MRB_STR_SHARED_P(str)) {
-    mrb_value shared = RSTRING_SHARED(str);
+    struct RString *shared = RSTRING_SHARED(str);
     FL_SET(str2, MRB_STR_SHARED);
     RSTRING_SHARED(str2) = shared;
   }
   else {
     FL_SET(str, MRB_STR_SHARED);
-    RSTRING_SHARED(str) = str2;
+    RSTRING_SHARED(str) = mrb_str_ptr(str2);
   }
   mrb_enc_cr_str_exact_copy(mrb, str2, str);
   return str2;
@@ -2185,7 +2185,7 @@ str_replace_shared(mrb_state *mrb, mrb_value str2, mrb_value str)
   str = mrb_str_new_frozen(mrb, str);
   RSTRING(str2)->len = RSTRING_LEN(str);
   RSTRING(str2)->buf = RSTRING_PTR(str);
-  RSTRING_SHARED(str2) = str;
+  RSTRING_SHARED(str2) = mrb_str_ptr(str);
   FL_SET(str2, MRB_STR_SHARED);
   mrb_enc_cr_str_exact_copy(mrb, str2, str);
 
@@ -2220,9 +2220,9 @@ mrb_str_new_frozen(mrb_state *mrb, mrb_value orig)
 
   klass = mrb_obj_class(mrb, orig);
 
-  if (MRB_STR_SHARED_P(orig) && !mrb_nil_p(RSTRING_SHARED(orig))) {
+  if (MRB_STR_SHARED_P(orig) && RSTRING_SHARED(orig)) {
     long ofs;
-    ofs = RSTRING_LEN(str) - RSTRING_LEN(orig);
+    ofs = RSTRING_LEN(str) - RSTRING_SHARED(orig)->len;
 #ifdef INCLUDE_ENCODING
     if ((ofs > 0) || (klass != RBASIC(str)->c) ||
         ENCODING_GET(mrb, str) != ENCODING_GET(mrb, orig)) {
@@ -2776,9 +2776,9 @@ str_replace(mrb_state *mrb, mrb_value str, mrb_value str2)
 
   len = RSTRING_LEN(str2);
   if (MRB_STR_SHARED_P(str2)) {
-    mrb_value shared = RSTRING_SHARED(str2);
+    struct RString *shared = RSTRING_SHARED(str2);
     RSTRING_LEN(str) = len;
-    RSTRING_PTR(str) = RSTRING_PTR(str2);
+    RSTRING_PTR(str) = shared->buf;
     FL_SET(str, MRB_STR_SHARED);
     RSTRING_SHARED(str) = shared;
   }