Add CAST(expr AS pluggable_type)

       | IDENT_sys

         {

           const Type_handler *h;

           if (!(h= Type_handler::handler_by_name_or_error($1)))

             MYSQL_YYABORT;

           $$.set(h);

           Lex->charset= NULL;

         }

Item *

Type_handler_geometry::create_typecast_item(THD *thd, Item *item,

                                           const Type_cast_attributes &attr)

                                           const

{

  DBUG_EXECUTE_IF("emulate_geometry_create_typecast_item",

    return new (thd->mem_root) Item_func_geometry_from_text(thd, item);

  );

  return NULL;

}