* insns.def (concatstrings): don't use initial ASCII-8BIT string.

[ruby-core:38635] [Bug #5126]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32791 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Mon Aug  1 12:00:35 2011  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* insns.def (concatstrings): don't use initial ASCII-8BIT string.
+	  [ruby-core:38635] [Bug #5126]
+
 Sun Jul 31 22:57:16 2011  Yuki Sonoda (Yugui)  <yugui@yugui.jp>
 
 	* enc/Makefile.in (ECHO1): Same as the recent fix in common.mk.

insns.def

@@ -392,9 +392,9 @@ concatstrings
 (...)
 (VALUE val) // inc += 1 - num;
 {
-    rb_num_t i = num;
+    rb_num_t i = num - 1;
 
-    val = rb_str_new(0, 0);
+    val = rb_str_resurrect(TOPN(i));
     while (i-- > 0) {
 	const VALUE v = TOPN(i);
 	rb_str_append(val, v);