--- mysql-5.0-orig/sql/sql_string.h	Mon Jan 22 12:10:41 2007
+++ mysql-5.0-ucs/sql/sql_string.h	Thu Jun  7 01:07:02 2007
@@ -244,6 +244,7 @@
   bool set_or_copy_aligned(const char *s, uint32 arg_length, CHARSET_INFO *cs);
   bool copy(const char*s,uint32 arg_length, CHARSET_INFO *csfrom,
 	    CHARSET_INFO *csto, uint *errors);
+  bool convert_cs(CHARSET_INFO *cs);
   bool append(const String &s);
   bool append(const char *s);
   bool append(const char *s,uint32 arg_length);
--- mysql-5.0-orig/sql/sql_string.cc	Mon Jan 22 12:10:41 2007
+++ mysql-5.0-ucs/sql/sql_string.cc	Thu Jun  7 02:18:35 2007
@@ -414,6 +414,26 @@
     str_length--;
 }
 
+bool String::convert_cs(CHARSET_INFO *cs)
+{
+  uint32 offset;
+  if (needs_conversion(str_length, str_charset, cs, &offset))
+  {
+    String tmp;
+    uint32 new_length= str_length / str_charset->mbminlen * cs->mbmaxlen;
+    uint dummy_errors;
+    tmp.copy(*this);
+    if (realloc(new_length)) 
+      return TRUE;
+    str_length= copy_and_convert(Ptr, new_length, cs,
+                                 tmp.Ptr, str_length, str_charset,
+                                 &dummy_errors);
+  }
+
+  str_charset= cs;
+  return FALSE;
+}
+
 bool String::append(const String &s)
 {
   if (s.length())
--- mysql-5.0-orig/sql/item_sum.cc	Tue May 22 13:45:56 2007
+++ mysql-5.0-ucs/sql/item_sum.cc	Thu Jun  7 01:46:17 2007
@@ -3209,6 +3209,9 @@
   null_value= 1;
   max_length= thd->variables.group_concat_max_len;
 
+  if (separator->convert_cs(collation.collation))
+    return TRUE;
+
   if (check_sum_func(thd, ref))
     return TRUE;
 
--- mysql-5.0-orig/sql/sql_yacc.yy	Tue Jun  5 22:04:34 2007
+++ mysql-5.0-ucs/sql/sql_yacc.yy	Thu Jun  7 03:08:52 2007
@@ -5420,7 +5420,7 @@
     |DISTINCT   { $$ = 1; };
 
 opt_gconcat_separator:
-    /* empty */        { $$ = new (YYTHD->mem_root) String(",",1,default_charset_info); }
+    /* empty */        { $$ = new (YYTHD->mem_root) String(",", 1, &my_charset_latin1); }
     |SEPARATOR_SYM text_string  { $$ = $2; };
 
 
--- mysql-5.0-orig/mysql-test/t/func_gconcat.test	Tue May 22 13:48:47 2007
+++ mysql-5.0-ucs/mysql-test/t/func_gconcat.test	Thu Jun  7 03:16:31 2007
@@ -552,3 +552,17 @@
 DROP TABLE t1, t2, t3;
 
 --echo End of 5.0 tests
+
+create table t1 (a char(1) character set ucs2);
+insert into t1 values ('a'),('b'),('c');
+select hex(group_concat(a)) from t1;
+select collation(group_concat(a)) from t1;
+DROP TABLE t1;
+
+set names latin1;
+create table t1 (a char(1) character set latin1);
+insert into t1 values ('a'),('b'),('c');
+set character_set_connection=ucs2;
+select hex(group_concat(a separator ',')) from t1;
+select collation(group_concat(a separator ',')) from t1;
+drop table t1;
--- mysql-5.0-orig/mysql-test/r/func_gconcat.result	Tue May 22 13:48:47 2007
+++ mysql-5.0-ucs/mysql-test/r/func_gconcat.result	Thu Jun  7 03:16:44 2007
@@ -811,3 +811,23 @@
 SET group_concat_max_len= DEFAULT;
 DROP TABLE t1, t2, t3;
 End of 5.0 tests
+create table t1 (a char(1) character set ucs2);
+insert into t1 values ('a'),('b'),('c');
+select hex(group_concat(a)) from t1;
+hex(group_concat(a))
+0061002C0062002C0063
+select collation(group_concat(a)) from t1;
+collation(group_concat(a))
+ucs2_general_ci
+DROP TABLE t1;
+set names latin1;
+create table t1 (a char(1) character set latin1);
+insert into t1 values ('a'),('b'),('c');
+set character_set_connection=ucs2;
+select hex(group_concat(a separator ',')) from t1;
+hex(group_concat(a separator ','))
+612C622C63
+select collation(group_concat(a separator ',')) from t1;
+collation(group_concat(a separator ','))
+latin1_swedish_ci
+drop table t1;