Commented by: @AlexPeshkoff

> All five messages appear due to missing 'password' clause.

That's not always correct. In case 2 provided error text is absolutely correct - problem is not due to missing password clause but due to missing _any_clause. When parsing create or alter statement we do not know what part of it (create or alter) will be executed, and at least _some_ clause is needed in any case.

What about cases 1 and 4 - look here:
SQL> create table (x int);
Statement failed, SQLSTATE = 42000
Dynamic SQL Error
-SQL error code = -104
-Token unknown - line 1, column 14
-(
SQL>
Error happened due to missing table name, but error text is 'Token unknown'.
I.e. it makes no sense fixing this for some particular operator, we should change all parser behaviour to have more meaningful diags.

Messages in cases [3] and [5] may be enhanced.

Commented by: @AlexPeshkoff

Pavel not sure when was it fixed but currently in FB4 I get:

SQL> create or alter user u01 firstname 'john';
Statement failed, SQLSTATE = HY000
Password must be specified when creating user
SQL> create or alter user u01 revoke admin role;
Statement failed, SQLSTATE = HY000
Password must be specified when creating user
SQL>

I.e. places where changing diag made sense are already fixed.

Commented by: @pavel-zotov

> places where changing diag made sense are already fixed.

Yes, it is so.
Checked on:
4.0.0.2271 SS; 4.0.0.2265 SS; 4.0.0.2267 CS.
3.0.8.33392 SS; 3.0.8.33390 SC; 3.0.7.33388 CS.
-- all of them OK.