* ext/json/lib/json/pure/generator.rb (utf8_to_json):

force_encoding before gsub.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@19704 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,8 @@
+Tue Oct  7 16:43:51 2008  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* ext/json/lib/json/pure/generator.rb (utf8_to_json):
+	  force_encoding before gsub.
+
 Tue Oct  7 16:35:41 2008  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* ext/json/lib/json/pure/generator.rb (utf8_to_json):

ext/json/lib/json/pure/generator.rb

@@ -40,8 +40,8 @@ module JSON
   # Convert a UTF8 encoded Ruby string _string_ to a JSON string, encoded with
   # UTF16 big endian characters as \u????, and return it.
   def utf8_to_json(string) # :nodoc:
-    string = string.gsub(/["\\\/\x0-\x1f]/) { MAP[$&] }
-    string.force_encoding(Encoding::ASCII_8BIT)
+    string = string.dup.force_encoding(Encoding::ASCII_8BIT)
+    string.gsub!(/["\\\/\x0-\x1f]/) { MAP[$&] }
     string.gsub!(/(
                     (?:
                       [\xc2-\xdf][\x80-\xbf]    |