The issue is about handling errors when the user specifies something strange instead of a type, e.g. CREATE TABLE try1 (a int PRIMARY KEY, b list<zzz>):
* the error message only talks about collections, while zzz could also be an UDT;
* the same error message is given even when zzz is not a valid collection or UDT name.
The first point has already been fixed, now Scylla says 'Non-frozen user types or collections are not allowed inside collections: list<zzz>'. This commit fixes the second.
Whether the type is a valid UDT or not is checked in cql3_type::raw_ut::prepare_internal, but 'non-frozen' check triggers first in cql3_type::raw_collection::prepare_internal, before we recursively get to the argument types of the collection. The patch reverses the order here, first thing we recurse and ensure that the collection argument types are valid, and only then we apply the collection checks. A side effect of this is that the error messages of the checks in raw_collection will include the keyspace name, because it will now be assigned in raw_ut::prepare_internal before them.
The patch affects the validation order, so in case of list<zzz<xxx>> the message could be different, but it doesn't seem to be possible according to the Cql grammar.
Examples:
create type ut2 (a int, b list<ut1>); --> error('Unknown type ks.ut1')
create type ut1 (a int);
create type ut2 (a int, b list<ut1>); --> error('Non-frozen user types or collections are not allowed inside collections: list<ks.ut1>')
create type ut2 (a int, b list<frozen<ut1>>); --> OK
Fixes: scylladb#3541
Closes#10726