Fix for bug#3946: Error in LPAD() when padstring is longer than 1 character

mysql-test/r/ctype_ucs.result:
  Test for bug#3946: Error in LPAD() when padstring is longer than 1 character
mysql-test/t/ctype_ucs.test:
  Test for bug#3946: Error in LPAD() when padstring is longer than 1 character

mysql-test/r/ctype_ucs.result

@@ -47,6 +47,15 @@ t1	CREATE TABLE `t1` (
   `r` char(10) character set ucs2 NOT NULL default ''
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1;
+create table t2(f1 Char(30));
+insert into t2 values ("103000"), ("22720000"), ("3401200"), ("78000");
+select lpad(f1, 12, "-o-/") from t2;
+lpad(f1, 12, "-o-/")
+-o-/-o103000
+-o-/22720000
+-o-/-3401200
+-o-/-o-78000
+drop table t2;
 SET NAMES koi8r;
 SET character_set_connection=ucs2;
 create table t1 (a varchar(10) character set ucs2, key(a));

mysql-test/t/ctype_ucs.test

@@ -47,6 +47,16 @@ LPAD(_ucs2 X'0420',10,_ucs2 X'0421') l,
 RPAD(_ucs2 X'0420',10,_ucs2 X'0421') r;
 SHOW CREATE TABLE t1;
 DROP TABLE t1;
+
+
+#
+# BUG3946
+#
+
+create table t2(f1 Char(30));
+insert into t2 values ("103000"), ("22720000"), ("3401200"), ("78000");
+select lpad(f1, 12, "-o-/") from t2;
+drop table t2;
 ######################################################
 #
 # Test of like

sql/item_strfunc.cc

@@ -2097,10 +2097,8 @@ String *Item_func_lpad::val_str(String *str)
     count-= pad_char_length;
   }
   if (count > 0)
-  {
-    pad->length(pad->charpos(count));
-    str->append(*pad);
-  }
+    str->append(pad->ptr(), pad->charpos(count), collation.collation);
+
   str->append(*res);
   null_value= 0;
   return str;