Parser cannot parse set operations combining SELECT * with SELECT <column list>

[lukaseder]

The following valid SQL query fails to parse:

select *
from t1
union all
select a
from t2

The error is:

Select list must contain 0 columns. Got: 1: [5:1] select *
from t1
union all
select a
[*]from t2

We must not check for column size correctness in set operations when we don't know the row size of one of the subqueries

[lukaseder]

The degree check is generally implemented wrong / too early.

We're currently checking for the correct degree of a SELECT subquery in a set operation already when the select list has been parsed. But at this point, we can't resolve asterisks yet, so we don't know the degree, which is one of the reasons why this special case here doesn't parse.

We can check things once we have parsed the entire set operation subquery, prior to assembling the subqueries in a combined query.

[lukaseder]

I'll keep the old degree check for now to double-check. Removing it breaks a few test assertions, e.g. when this isn't expected to parse: (a, b) = any (select 1)

[lukaseder]

Fixed in 3.15.0 and 3.14.4 (#10973)