[Oberon] Unreferenced/unused code in Project Oberon 2013

[Luca Boasso]

I noticed the + operator used with array of chars:  *ORS.Mark("!" + x.name
<http://x.name> + " is not used")*
Have you extended the compiler or is this pseudo code?

On Tue, Sep 28, 2021 at 12:14 AM Chris Burrows <cfbsoftware at gmail.com>
wrote:

> > > -----Original Message-----
> > > From: Oberon [mailto:oberon-bounces at lists.inf.ethz.ch] On Behalf Of
> > > Michael Schierl
> > > Sent: Sunday, 28 April 2019 6:13 AM
> > > To: ETH Oberon and related systems
> > > Subject: [Oberon] Unreferenced/unused code in Project Oberon 2013
> > >
> > > I used some scripts to identify unreferenced code (after stumbling
> > > upon some unused variables in TextFrames)
> >
>
> I previously objected to removing unreferenced code in a reply to this
> message but the mention of unused variables did grab my attention. The
> latest (v8) versions of my ARM Cortex-M Oberon-07 compilers now warn
> of unused imports, consts, types and variables. Most of the time these
> are harmless but every now and then they can usefully indicate a
> potential source of problems that has been overlooked.
>
> I am working on a similar change to the Astrobe for RISC5 compiler.
> Other compilers based on the Project Oberon RISC5 compiler can be
> modified to do the same. The changes might be something like this:
>
> 1. Introduce a new field into ORB.ObjDesc:
>
>     used: BOOLEAN
>
> 2. Initialise 'new.used' to FALSE in ORB.NewObj after 'new' is created.
>
> 3. Set 'new.used', if the object is found, in ORB.ThisObj:
>     ....
>     UNTIL (x # NIL) OR (s = NIL);
>     IF x # NIL THEN x.used := TRUE END;
>
> 4. Set 'obj.used' for pointers in ORP.Declarations
>    ...
>    IF obj.name = ptbase.name THEN ptbase.type.base := obj.type;
> obj.used := TRUE END ;
>
> 5. Introduce a new procedure in ORP to report the unused objects:
>
>   PROCEDURE CheckUnused();
>     VAR x: ORB.Object;
>   BEGIN x := ORB.topScope.next;
>     WHILE (x # NIL) DO
>       IF ~x.used & ~x.expo & ((x.class # ORB.Mod) OR x.rdo) THEN
>         ORS.Mark("!" + x.name + " is not used")
>       END;
>       x := x.next
>     END
>   END CheckUnused;
>
> 6. Allow for warnings (message beginning with '!') as well as error
> messages in ORS.Mark:
>
>   IF msg[0] # "!" THEN INC(errcnt); errpos := p + 4 END
>
> 7. Call CheckUnused in ORP.Module, after the statement sequence has
> been processed, to warn about unused globals:
>       ...
>       IF sym = ORS.begin THEN ORS.Get(sym); StatSequence END ;
>       CheckUnused();
>
> 8. Call CheckUnused in ORP.ProcedureDecl after the RETURN has been
> processed to warn about unused locals:
>       ...
>       ORG.Return(type.base.form, x, locblksize, int);
>       CheckUnused();
>
> Unused locals warnings will appear when each procedure has been
> compiled. Unused global warnings will appear after the whole module
> has been compiled.
>
> Regards,
> Chris Burrows
> CFB Software
> https://www.astrobe.com/RISC5
> --
> Oberon at lists.inf.ethz.ch mailing list for ETH Oberon and related systems
> https://lists.inf.ethz.ch/mailman/listinfo/oberon
>
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