Triggers can't see DEFAULT values

I spoke about this in the list moths ago, but I forgot to file a bug.

Try the following code:

DROP TABLE IF EXISTS t;

CREATE TABLE t (a INT DEFAULT 999) ENGINE = InnoDB;

DELIMITER ||

CREATE TRIGGER t_bi

	BEFORE INSERT

	ON t

	FOR EACH ROW

BEGIN

	SET NEW.a = DEFAULT;

END;

||

DELIMITER ;

INSERT INTO t VALUES (0);

SELECT * FROM t;

I get no errors, but t.a is NULL (which would be ok if a.t had no default value).

Since I'm not sure about the syntax, I tried DEFAULT(a) and DEFAULT(t.a), but in both cases I got an error. I have no idea if the errors are expected or not, but as far as I understand the syntax in the example should work.