Regression in ISQL diagnostic for SET command since v4

[aafemt]

Since v4 a wrong SET command produces less meaningful output.
Here is output for v3:

C:\Programs\Firebird\Firebird3>isql.exe
Use CONNECT or CREATE DATABASE to specify a database
SQL> set abc;
Valid options are:
AUTOddl                  BLOBdisplay              BAIL
BULK_INSERT              COUNT                    EXPLAIN
ECHO                     GENERATOR                HEADING
LIST                     MAXROWS                  NAMES
PLAN                     PLANONLY                 ROWCOUNT
ROLE                     STATs                    SQLDA_DISPLAY
SQL                      STATISTICS               TRANSaction
TERMinator               TIME                     TRUSTED
WIDTH                    WARNINGs                 WNG
Command error: set abc

And here is for v4:

C:\Programs\Firebird\Firebird4>isql.exe
Use CONNECT or CREATE DATABASE to specify a database
SQL> set abc;
Use CONNECT or CREATE DATABASE to specify a database

If connected, it is better:

SQL> set abc;
Statement failed, SQLSTATE = 42000
Dynamic SQL Error
-SQL error code = -104
-Token unknown - line 1, column 5
-abc

but not always:

SQL> set bail abc;
Command error: set bail abc

[mrotteveel]

That's because SET is also used for a lot of server-side syntax since Firebird 4.0 (SET ROLE, SET TRUSTED ROLE, SET BIND, SET DECFLOAT, SET SESSION IDLE TIMEOUT, SET STATEMENT TIMEOUT, SET TIME ZONE, SET OPTIMIZE, SET DEBUG OPTION and SET TRANSACTION).

In the past, it was only SET TRANSACTION, and back then ISQL just pretended it was an ISQL-side command instead of a server-side statement. In other words, ISQL is not aware (and, IMHO, should not be aware) which SET statements are supported server-side. And just displaying the list of ISQL-side SET commands if the server reports an error would also be problematic or confusing, even if you only do so for "Token unknown" errors.

[mrotteveel]

For the case of SET BAIL ABC: SET BAIL ... is an ISQL-side command and you made a syntax error after the part that ISQL uses to recognize it as an ISQL command, so it knows it's one of its own commands, and you just used the wrong syntax (option), so it doesn't forward it to the server.

[sim1984]

When there's no connection, it would be possible to display a list of available commands as before.

When the connection is established correctly, in the case of the command SET BAIL abc, it would be possible to not only display "Command error" but also display the correct syntax. This isn't a bug, but rather an improvement.

[mrotteveel]

When there's no connection, it would be possible to display a list of available commands as before.

Only if it is preceded by the original error, and if the explanation is modified to make clear it's only about ISQL commands, and to consult the Language Reference for server-side statements.

That might also work for other errors involving SET if it's shown after the server-side error.