XMLTYPE value stored in a user variable loses the type (and hence all checks), becomes longtext

MariaDB [test]> set @x=CAST('<a/>' AS XMLTYPE);

Query OK, 0 rows affected (0,001 sec)

MariaDB [test]> select @x+1;

+------+

| @x+1 |

+------+

|    1 |

+------+

1 row in set (0,001 sec)

MariaDB [test]> create table tb as select @x;

Query OK, 1 row affected (0,060 sec)

Records: 1  Duplicates: 0  Warnings: 0

MariaDB [test]> show create table tb;

+-------+------------------------------------------------------------------------------------------------------------------------+

| Table | Create Table                                                                                                           |

+-------+------------------------------------------------------------------------------------------------------------------------+

| tb    | CREATE TABLE `tb` (

  `@x` longtext DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci |

+-------+------------------------------------------------------------------------------------------------------------------------+

1 row in set (0,001 sec)

MariaDB [test]> set @x= PointFromText('POINT(10 10)');

Query OK, 0 rows affected (0,010 sec)

MariaDB [test]> select @x;

+---------------------------+

| @x                        |

+---------------------------+

|              $@      $@ |

+---------------------------+

1 row in set (0,001 sec)

MariaDB [test]> select @x+1;

ERROR 4078 (HY000): Illegal parameter data types geometry and int for operation '+'

MariaDB [test]> create table  tb2 as select @x;

Query OK, 1 row affected (0,058 sec)

Records: 1  Duplicates: 0  Warnings: 0

MariaDB [test]> show create table tb2;

+-------+-------------------------------------------------------------------------------------------------------------------------+

| Table | Create Table                                                                                                            |

+-------+-------------------------------------------------------------------------------------------------------------------------+

| tb2   | CREATE TABLE `tb2` (

  `@x` geometry DEFAULT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_uca1400_ai_ci |

+-------+-------------------------------------------------------------------------------------------------------------------------+

1 row in set (0,001 sec)