* string.c (rb_str_dup_frozen): handle tail shared string.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@3165 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,8 +1,10 @@
-Wed Dec 18 02:27:34 2002  Nobuyoshi Nakada  <nobu.nokada@softhome.net>
+Wed Dec 18 03:52:55 2002  Nobuyoshi Nakada  <nobu.nokada@softhome.net>
 
 	* string.c (rb_str_new4): handle tail shared string.
 	  (ruby-bugs-ja:PR#370)
 
+	* string.c (rb_str_dup_frozen): ditto.
+
 Tue Dec 17 21:08:29 2002  Nobuyoshi Nakada  <nobu.nokada@softhome.net>
 
 	* node.h (NODE_ATTRASGN): new node, assignment to attribute.

string.c

@@ -517,8 +517,11 @@ rb_str_dup_frozen(str)
     VALUE str;
 {
     if (FL_TEST(str, ELTS_SHARED)) {
-	OBJ_FREEZE(RSTRING(str)->aux.shared);
-	return RSTRING(str)->aux.shared;
+	VALUE shared = RSTRING(str)->aux.shared;
+	if (RSTRING(shared)->len == RSTRING(str)->len) {
+	    OBJ_FREEZE(shared);
+	    return shared;
+	}
     }
     if (OBJ_FROZEN(str)) return str;
     str = rb_str_dup(str);