Simple query with IF expression causes an assertion abort

[Igor Babaev]

The following simple query causes an assertion abort in MariaDB 5.1/5.2:

SELECT if(1, (SELECT min('hello')), NULL);

(see also bug#12620084 for mysql code line)

[Oleksandr "Sanja" Byelkin (sanja-byelkin)]

Problem is that cached_field_type of Item_func_if appeared to be MYSQL_TYPE_NULL...

[Oleksandr "Sanja" Byelkin (sanja-byelkin)]

Above caused by subselect reporting that it is constant and null_value is set in the tests:

  bool null1=args[1]->const_item() && args[1]->null_value;
  bool null2=args[2]->const_item() && args[2]->null_value;

IMHO above tests are not correct: they should chec basic_constant_item or call is_null_value() method to really evaluate the item.