MDEV-13118 Wrong results with LOWER and UPPER and subquery

This problem is similar to MDEV-10306.

1. Fixing Item_str_conv::val_str(String *str) to return the result in "str",
   and to use tmp_value only as a temporary buffer for args[0]->val_str().
   The new code version now guarantees that the result is always returned in
   "str". The trick with copy_if_not_alloced() is not used any more.

2. The change #1 revealed the same problem in SUBSTRING_INDEX(),
   so some tests with combinations of UPPER()/LOWER() and SUBSTRING_INDEX()
   started to fail. Fixing Item_func_substr_index::val_str() the same way,
   to return the result in "str" and use tmp_value as a temporary buffer
   for args[0]->val_str().

mysql-test/include/ctype_mdev13118.inc

+--echo #
+--echo # MDEV-13118 Wrong results with LOWER and UPPER and subquery
+--echo #
+
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+--sorted_result
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+--sorted_result
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;

mysql-test/r/ctype_binary.result

@@ -3022,6 +3022,29 @@ DROP TABLE t1;
 SELECT _binary 0x7E, _binary X'7E', _binary B'01111110';
 _binary 0x7E	_binary X'7E'	_binary B'01111110'
 ~	~	~
+SET NAMES utf8, character_set_connection=binary;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varbinary(10) NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+abcdefghi-abcdefghi
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 #
 # End of 10.0 tests
 #

mysql-test/r/ctype_eucjpms.result

@@ -33636,6 +33636,29 @@ HEX(a)	CHAR_LENGTH(a)
 DROP TABLE t1;
 SELECT _eucjpms 0x8EA0;
 ERROR HY000: Invalid eucjpms character string: '8EA0'
+SET NAMES eucjpms;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET eucjpms NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 #
 # End of 10.0 tests
 #

mysql-test/r/ctype_euckr.result

@@ -25274,3 +25274,32 @@ A1A1A1A1A1A120202020202020202020202020202020202020
 #
 # End of 5.6 tests
 #
+#
+# Start of 10.0 tests
+#
+SET NAMES utf8, character_set_connection=euckr;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET euckr NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
+#
+# End of 10.0 tests
+#

mysql-test/r/ctype_gbk.result

@@ -4943,6 +4943,29 @@ E05C5B
 E05B
 DROP TABLE t1;
 # Start of ctype_E05C.inc
+SET NAMES utf8, character_set_connection=gbk;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET gbk NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 #
 # MDEV-9886 Illegal mix of collations with a view comparing a field to a binary constant
 #

mysql-test/r/ctype_latin1.result

@@ -7939,6 +7939,29 @@ a
 0
 DROP VIEW v1;
 DROP TABLE t1;
+SET NAMES latin1;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 #
 # End of 10.0 tests
 #

mysql-test/r/ctype_ucs.result

@@ -5629,6 +5629,29 @@ c2
 YWJjZGVmZ2hp-YWJjZGVmZ2hp
 DROP TABLE t1;
 SET optimizer_switch=@save_optimizer_switch;
+SET NAMES utf8, character_set_connection=ucs2;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET ucs2 NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 #
 # End of 10.0 tests
 #

mysql-test/r/ctype_ujis.result

@@ -25942,6 +25942,29 @@ HEX(a)	CHAR_LENGTH(a)
 DROP TABLE t1;
 SELECT _ujis 0x8EA0;
 ERROR HY000: Invalid ujis character string: '8EA0'
+SET NAMES ujis;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET ujis NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 #
 # End of 10.0 tests
 #

mysql-test/r/ctype_utf16.result

@@ -2134,6 +2134,29 @@ EXECUTE stmt USING @arg00;
 CONCAT(_utf16'a' COLLATE utf16_unicode_ci, ?)
 aÿ
 DEALLOCATE PREPARE stmt;
+SET NAMES utf8, character_set_connection=utf16;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET utf16 NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 #
 # End of 10.0 tests
 #

mysql-test/r/ctype_utf16le.result

@@ -2319,3 +2319,32 @@ DFFFFFDFFFFF9CFFFF9DFFFF9EFFFF
 #
 # End of 5.6 tests
 #
+#
+# Start of 10.0 tests
+#
+SET NAMES utf8, character_set_connection=utf16le;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET utf16le NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
+#
+# Start of 10.0 tests
+#

mysql-test/r/ctype_utf32.result

@@ -2231,6 +2231,29 @@ EXECUTE stmt USING @arg00;
 CONCAT(_utf32'a' COLLATE utf32_unicode_ci, ?)
 aÿ
 DEALLOCATE PREPARE stmt;
+SET NAMEs utf8, character_set_connection=utf32;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET utf32 NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 #
 # End of 10.0 tests
 #

mysql-test/r/ctype_utf8.result

@@ -10127,6 +10127,29 @@ SELECT * FROM v1;
 c
 ß
 DROP VIEW v1;
+SET NAMES utf8;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET utf8 NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 #
 # End of 10.0 tests
 #

mysql-test/r/ctype_utf8mb4.result

@@ -3427,6 +3427,29 @@ t1	CREATE TABLE `t1` (
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
 DROP TABLE t1;
 SET NAMES default;
+SET NAMES utf8mb4;
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET @save_optimizer_switch=@@optimizer_switch;
+SET optimizer_switch=_latin1'derived_merge=on';
+CREATE TABLE t1 AS SELECT REPEAT('a', 10) AS t LIMIT 0;
+SHOW CREATE TABLE t1;
+Table	Create Table
+t1	CREATE TABLE `t1` (
+  `t` varchar(10) CHARACTER SET utf8mb4 NOT NULL DEFAULT ''
+) ENGINE=MyISAM DEFAULT CHARSET=latin1
+INSERT INTO t1 VALUES ('abcdefghi'),('ABCDEFGHI');
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT LOWER(t) t2 FROM t1) sub;
+c2
+abcdefghi-abcdefghi
+abcdefghi-abcdefghi
+SELECT CONCAT(t2,'-',t2) c2 FROM (SELECT UPPER(t) t2 FROM t1) sub;
+c2
+ABCDEFGHI-ABCDEFGHI
+ABCDEFGHI-ABCDEFGHI
+DROP TABLE t1;
+SET optimizer_switch=@save_optimizer_switch;
 # End of 10.0 tests
 #
 # End of tests

mysql-test/t/ctype_binary.test

@@ -24,6 +24,9 @@ SET NAMES binary;
 --echo #
 SELECT _binary 0x7E, _binary X'7E', _binary B'01111110';
 
+SET NAMES utf8, character_set_connection=binary;
+--source include/ctype_mdev13118.inc
+
 --echo #
 --echo # End of 10.0 tests
 --echo #

mysql-test/t/ctype_eucjpms.test

@@ -536,6 +536,8 @@ DROP TABLE t1;
 --error ER_INVALID_CHARACTER_STRING
 SELECT _eucjpms 0x8EA0;
 
+SET NAMES eucjpms;
+--source include/ctype_mdev13118.inc
 
 --echo #
 --echo # End of 10.0 tests

mysql-test/t/ctype_euckr.test

@@ -197,3 +197,14 @@ set collation_connection=euckr_bin;
 --echo # End of 5.6 tests
 --echo #
 
+
+--echo #
+--echo # Start of 10.0 tests
+--echo #
+
+SET NAMES utf8, character_set_connection=euckr;
+--source include/ctype_mdev13118.inc
+
+--echo #
+--echo # End of 10.0 tests
+--echo #

mysql-test/t/ctype_gbk.test

@@ -199,6 +199,9 @@ let $ctype_unescape_combinations=selected;
 SET NAMES gbk;
 --source include/ctype_E05C.inc
 
+SET NAMES utf8, character_set_connection=gbk;
+--source include/ctype_mdev13118.inc
+
 --echo #
 --echo # MDEV-9886 Illegal mix of collations with a view comparing a field to a binary constant
 --echo #

mysql-test/t/ctype_latin1.test

@@ -260,6 +260,9 @@ SELECT * FROM v1;
 DROP VIEW v1;
 DROP TABLE t1;
 
+SET NAMES latin1;
+--source include/ctype_mdev13118.inc
+
 
 --echo #
 --echo # End of 10.0 tests

mysql-test/t/ctype_ucs.test

@@ -984,6 +984,10 @@ DROP TABLE t1;
 SET optimizer_switch=@save_optimizer_switch;
 
 
+SET NAMES utf8, character_set_connection=ucs2;
+--source include/ctype_mdev13118.inc
+
+
 --echo #
 --echo # End of 10.0 tests
 --echo #

mysql-test/t/ctype_ujis.test

@@ -1366,6 +1366,10 @@ DROP TABLE t1;
 SELECT _ujis 0x8EA0;
 
 
+SET NAMES ujis;
+--source include/ctype_mdev13118.inc
+
+
 --echo #
 --echo # End of 10.0 tests
 --echo #

mysql-test/t/ctype_utf16.test

@@ -866,6 +866,11 @@ SET @arg00=_binary 0x00FF;
 EXECUTE stmt USING @arg00;
 DEALLOCATE PREPARE stmt;
 
+
+SET NAMES utf8, character_set_connection=utf16;
+--source include/ctype_mdev13118.inc
+
+
 --echo #
 --echo # End of 10.0 tests
 --echo #

mysql-test/t/ctype_utf16le.test

@@ -744,3 +744,16 @@ SET NAMES utf8, collation_connection=utf16le_bin;
 --echo #
 --echo # End of 5.6 tests
 --echo #
+
+
+--echo #
+--echo # Start of 10.0 tests
+--echo #
+
+
+SET NAMES utf8, character_set_connection=utf16le;
+--source include/ctype_mdev13118.inc
+
+--echo #
+--echo # Start of 10.0 tests
+--echo #

mysql-test/t/ctype_utf32.test

@@ -979,6 +979,14 @@ SET @arg00=_binary 0x00FF;
 EXECUTE stmt USING @arg00;
 DEALLOCATE PREPARE stmt;
 
+
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET NAMEs utf8, character_set_connection=utf32;
+--source include/ctype_mdev13118.inc
+
+
 --echo #
 --echo # End of 10.0 tests
 --echo #

mysql-test/t/ctype_utf8.test

@@ -1880,6 +1880,13 @@ SELECT * FROM v1;
 DROP VIEW v1;
 
 
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET NAMES utf8;
+--source include/ctype_mdev13118.inc
+
+
 --echo #
 --echo # End of 10.0 tests
 --echo #

mysql-test/t/ctype_utf8mb4.test

@@ -1913,6 +1913,14 @@ DROP TABLE t1;
 
 SET NAMES default;
 
+
+#
+# MDEV-13118 Wrong results with LOWER and UPPER and subquery
+#
+SET NAMES utf8mb4;
+--source include/ctype_mdev13118.inc
+
+
 --echo # End of 10.0 tests
 
 --echo #

sql/item_strfunc.cc

@@ -1566,32 +1566,27 @@ String *Item_str_conv::val_str(String *str)
 {
   DBUG_ASSERT(fixed == 1);
   String *res;
-  if (!(res=args[0]->val_str(str)))
-  {
-    null_value=1; /* purecov: inspected */
-    return 0; /* purecov: inspected */
-  }
-  null_value=0;
+  uint alloced_length, len;
+
+  if ((null_value= (!(res= args[0]->val_str(&tmp_value)) ||
+                    str->alloc((alloced_length= res->length() * multiply)))))
+    return 0;
+
   if (multiply == 1)
   {
-    uint len;
-    res= copy_if_not_alloced(&tmp_value, res, res->length());
-    len= converter(collation.collation, (char*) res->ptr(), res->length(),
-                                        (char*) res->ptr(), res->length());
-    DBUG_ASSERT(len <= res->length());
-    res->length(len);
+    str->copy(*res); // Should not fail (it was alloced above)
+    len= converter(collation.collation, (char*) str->ptr(), str->length(),
+                                        (char*) str->ptr(), alloced_length);
   }
   else
   {
-    uint len= res->length() * multiply;
-    tmp_value.alloc(len);
-    tmp_value.set_charset(collation.collation);
     len= converter(collation.collation, (char*) res->ptr(), res->length(),
-                                        (char*) tmp_value.ptr(), len);
-    tmp_value.length(len);
-    res= &tmp_value;
+                                        (char*) str->ptr(), alloced_length);
+    str->set_charset(collation.collation);
   }
-  return res;
+  DBUG_ASSERT(len <= alloced_length);
+  str->length(len);
+  return str;
 }
 
 
@@ -1783,7 +1778,7 @@ String *Item_func_substr_index::val_str(String *str)
   DBUG_ASSERT(fixed == 1);
   char buff[MAX_FIELD_WIDTH];
   String tmp(buff,sizeof(buff),system_charset_info);
-  String *res= args[0]->val_str(str);
+  String *res= args[0]->val_str(&tmp_value);
   String *delimiter= args[1]->val_str(&tmp);
   int32 count= (int32) args[2]->val_int();
   uint offset;
@@ -1832,20 +1827,31 @@ String *Item_func_substr_index::val_str(String *str)
       if (pass == 0) /* count<0 */
       {
         c+=n+1;
-        if (c<=0) return res; /* not found, return original string */
+        if (c<=0)
+        {
+          str->copy(res->ptr(), res->length(), collation.collation);
+          return str; // not found, return the original string
+        }
         ptr=res->ptr();
       }
       else
       {
-        if (c) return res; /* Not found, return original string */
+        if (c)
+        {
+          str->copy(res->ptr(), res->length(), collation.collation);
+          return str; // not found, return the original string
+        }
         if (count>0) /* return left part */
         {
-	  tmp_value.set(*res,0,(ulong) (ptr-res->ptr()));
+          str->copy(res->ptr(), (uint32) (ptr-res->ptr()), collation.collation);
+          return str;
         }
         else /* return right part */
         {
-	  ptr+= delimiter_length;
-	  tmp_value.set(*res,(ulong) (ptr-res->ptr()), (ulong) (strend-ptr));
+          ptr+= delimiter_length;
+          str->copy(res->ptr() + (ptr-res->ptr()), (uint32) (strend - ptr),
+                    collation.collation);
+          return str;
         }
       }
     }
@@ -1857,13 +1863,16 @@ String *Item_func_substr_index::val_str(String *str)
     {					// start counting from the beginning
       for (offset=0; ; offset+= delimiter_length)
       {
-	if ((int) (offset= res->strstr(*delimiter, offset)) < 0)
-	  return res;			// Didn't find, return org string
-	if (!--count)
-	{
-	  tmp_value.set(*res,0,offset);
-	  break;
-	}
+        if ((int) (offset= res->strstr(*delimiter, offset)) < 0)
+        {
+          str->copy(res->ptr(), res->length(), collation.collation);
+          return str; // not found, return the original string
+        }
+        if (!--count)
+        {
+          str->copy(res->ptr(), offset, collation.collation);
+          return str;
+        }
       }
     }
     else
@@ -1878,30 +1887,32 @@ String *Item_func_substr_index::val_str(String *str)
           address space less than where the found substring is located
           in res
         */
-	if ((int) (offset= res->strrstr(*delimiter, offset)) < 0)
-	  return res;			// Didn't find, return org string
+        if ((int) (offset= res->strrstr(*delimiter, offset)) < 0)
+        {
+          str->copy(res->ptr(), res->length(), collation.collation);
+          return str; // not found, return the original string
+        }
         /*
           At this point, we've searched for the substring
           the number of times as supplied by the index value
         */
-	if (!++count)
-	{
-	  offset+= delimiter_length;
-	  tmp_value.set(*res,offset,res->length()- offset);
-	  break;
-	}
+        if (!++count)
+        {
+          offset+= delimiter_length;
+          str->copy(res->ptr() + offset, res->length() - offset,
+                    collation.collation);
+          return str;
+        }
       }
       if (count)
-        return res;                     // Didn't find, return org string
+      {
+        str->copy(res->ptr(), res->length(), collation.collation);
+        return str; // not found, return the original string
+      }
     }
   }
-  /*
-    We always mark tmp_value as const so that if val_str() is called again
-    on this object, we don't disrupt the contents of tmp_value when it was
-    derived from another String.
-  */
-  tmp_value.mark_as_const();
-  return (&tmp_value);
+  DBUG_ASSERT(0);
+  return NULL;
 }
 
 /*