Fix for the bug #3089: SUBSTRING bug when mixed with CONCAT and ORDER BY

mysql-test/r/func_str.result

@@ -624,3 +624,13 @@ Note	1003	select high_priority md5(_latin1'hello') AS `md5('hello')`,sha(_latin1
 SELECT lpad(12345, 5, "#");
 lpad(12345, 5, "#")
 12345
+create table t1 (id int(1), str varchar(10)) DEFAULT CHARSET=utf8;
+insert into t1 values (1,'aaaaaaaaaa'), (2,'bbbbbbbbbb');
+create table t2 (id int(1), str varchar(10)) DEFAULT CHARSET=utf8;
+insert into t2 values (1,'cccccccccc'), (2,'dddddddddd');
+select substring(concat(t1.str, t2.str), 1, 15) "name" from t1, t2 
+where t2.id=t1.id order by name;
+name
+aaaaaaaaaaccccc
+bbbbbbbbbbddddd
+drop table t1, t2;

mysql-test/t/func_str.test

@@ -360,3 +360,16 @@ explain extended select md5('hello'), sha('abc'), sha1('abc'), soundex(''), 'moo
 #
 
 SELECT lpad(12345, 5, "#");
+
+
+#
+# Bug #3089
+#
+
+create table t1 (id int(1), str varchar(10)) DEFAULT CHARSET=utf8;
+insert into t1 values (1,'aaaaaaaaaa'), (2,'bbbbbbbbbb');
+create table t2 (id int(1), str varchar(10)) DEFAULT CHARSET=utf8;
+insert into t2 values (1,'cccccccccc'), (2,'dddddddddd');
+select substring(concat(t1.str, t2.str), 1, 15) "name" from t1, t2 
+where t2.id=t1.id order by name;
+drop table t1, t2;

sql/item_strfunc.cc

@@ -1033,7 +1033,7 @@ void Item_func_substr::fix_length_and_dec()
   }
   if (arg_count == 3 && args[2]->const_item())
   {
-    int32 length= (int32) args[2]->val_int() * default_charset_info->mbmaxlen;
+    int32 length= (int32) args[2]->val_int() * collation.collation->mbmaxlen;
     if (length <= 0)
       max_length=0; /* purecov: inspected */
     else