MDEV-31416 ASAN errors in dict_v_col_t::detach upon adding key to virtual column

- InnoDB throws ASAN error while adding the index on virtual column
of system versioned table. InnoDB wrongly assumes that virtual
column collation type changes, creates new column with different
character set. This leads to failure while detaching the column
from indexes.

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

@@ -134,3 +134,12 @@ t	CREATE TABLE `t` (
   FULLTEXT KEY `a` (`a`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8mb3 COLLATE=utf8mb3_unicode_520_ci
 DROP TABLE t;
+#
+# MDEV-31416 ASAN errors in dict_v_col_t::detach upon
+#         adding key to virtual column
+#
+CREATE TABLE t (a INT) ENGINE=InnoDB WITH SYSTEM VERSIONING;
+SET SYSTEM_VERSIONING_ALTER_HISTORY= KEEP;
+ALTER TABLE t ADD COLUMN v VARCHAR(128) GENERATED ALWAYS AS (CRC32('MariaDB'));
+ALTER TABLE t ADD INDEX (v);
+DROP TABLE t;

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

@@ -144,4 +144,13 @@ ALTER TABLE t MODIFY COLUMN a VARCHAR(512);
 SHOW CREATE TABLE t;
 DROP TABLE t;
 
+--echo #
+--echo # MDEV-31416 ASAN errors in dict_v_col_t::detach upon
+--echo #         adding key to virtual column
+--echo #
+CREATE TABLE t (a INT) ENGINE=InnoDB WITH SYSTEM VERSIONING;
+SET SYSTEM_VERSIONING_ALTER_HISTORY= KEEP;
+ALTER TABLE t ADD COLUMN v VARCHAR(128) GENERATED ALWAYS AS (CRC32('MariaDB'));
+ALTER TABLE t ADD INDEX (v);
+DROP TABLE t;
 --source include/wait_until_count_sessions.inc

storage/innobase/handler/handler0alter.cc

@@ -1387,7 +1387,8 @@ struct ha_innobase_inplace_ctx : public inplace_alter_handler_ctx
     for (unsigned i= 0; i < index->n_fields; i++)
     {
       const char *field_name= index->fields[i].name();
-      if (!field_name || !dtype_is_string_type(index->fields[i].col->mtype))
+      if (!field_name || !dtype_is_string_type(index->fields[i].col->mtype) ||
+	  index->fields[i].col->is_virtual())
         continue;
       for (uint j= 0; j < altered_table.s->fields; j++)
       {