MDEV-28060 Online DDL fails while checking for instant alter condition

- InnoDB fails to skip newly created column while checking for
change column when table is in redundant row format. This issue
is caused the MDEV-18035 (ccb1acbd)

mysql-test/suite/innodb/r/instant_alter_bugs.result

@@ -448,4 +448,13 @@ ALTER TABLE t ADD d INT;
 affected rows: 0
 info: Records: 0  Duplicates: 0  Warnings: 0
 DROP TABLE t;
+#
+# MDEV-28060 Online DDL fails while checking for instant
+#		alter condition
+#
+CREATE TABLE t1(f1 CHAR(10) NOT NULL)ROW_FORMAT=REDUNDANT,ENGINE=InnoDB;
+ALTER TABLE t1 ADD COLUMN(f2 INT NOT NULL, f3 INT NOT NULL,
+f4 INT NOT NULL, f5 INT NOT NULL),
+CHANGE COLUMN f1 f1 CHAR(10) DEFAULT NULL;
+DROP TABLE t1;
 SET GLOBAL innodb_purge_rseg_truncate_frequency=@save_frequency;

mysql-test/suite/innodb/t/instant_alter_bugs.test

@@ -466,4 +466,13 @@ ALTER TABLE t ADD d INT;
 --disable_info
 DROP TABLE t;
 
+--echo #
+--echo # MDEV-28060 Online DDL fails while checking for instant
+--echo #		alter condition
+--echo #
+CREATE TABLE t1(f1 CHAR(10) NOT NULL)ROW_FORMAT=REDUNDANT,ENGINE=InnoDB;
+ALTER TABLE t1 ADD COLUMN(f2 INT NOT NULL, f3 INT NOT NULL,
+			  f4 INT NOT NULL, f5 INT NOT NULL),
+	       CHANGE COLUMN f1 f1 CHAR(10) DEFAULT NULL;
+DROP TABLE t1;
 SET GLOBAL innodb_purge_rseg_truncate_frequency=@save_frequency;

storage/innobase/handler/handler0alter.cc

@@ -1795,8 +1795,13 @@ instant_alter_column_possible(
 		Field** af = altered_table->field;
 		Field** const end = altered_table->field
 			+ altered_table->s->fields;
+		List_iterator_fast<Create_field> cf_it(
+			ha_alter_info->alter_info->create_list);
 		for (unsigned c = 0; af < end; af++) {
-			if (!(*af)->stored_in_db()) {
+			const Create_field* cf = cf_it++;
+			if (!cf->field || !(*af)->stored_in_db()) {
+				/* Ignore virtual or newly created
+				column */
 				continue;
 			}