When preparing a `field_selection`, we need to prepare the UDT value,
and then verify that it has this field.
`field_selection_test_assignment` prepares the UDT value using the same
receiver as the whole `field_selection`. This is wrong, this receiver
has the type of the field, and not the UDT.
It's impossible to create a receiver for the UDT. Many different UDTs
can produce an `int` value when the field `a` is selected.
Therefore the receiver should be `nullptr`.
No unit test is added, as this bug doesn't currently cause any issues.
Preparing a column value doesn't do any type checks, so nothing fails.
Still it's good to fix it, just to be correct.
Signed-off-by: Jan Ciolek <jan.ciolek@scylladb.com>
Closesscylladb/scylladb#14788
e5f0468761