[fpc-devel] [Patch/RFC] Warnings for (in/over)complete case statements

[Mattias Gaertner]

On Wed, 2 Jan 2019 12:05:17 +0100 (CET)
Michael Van Canneyt <michael at freepascal.org> wrote:

> On Wed, 2 Jan 2019, Sven Barth via fpc-devel wrote:
> 
> > Am Mi., 2. Jan. 2019, 11:08 hat Bart <bartjunk64 at gmail.com>
> > geschrieben: 
> >> On Wed, Jan 2, 2019 at 9:44 AM Martok <listbox at martoks-place.de>
> >> wrote: 
> >>> - If a case statement on an ordinal does not contain labels for
> >>> all  
> >> values of  
> >>> the ordinal, and no else statement is given, raise a new warning  
> >> (W6059). This  
> >>> is actually defined as an error in ISO7185 and a
> >>> dynamic-violation in  
> >> IEC10206.
> >>
> >> So now I will have to add a useless else statement for every case
> >> statement that uses e.g. integers, or rewrite them to
> >> if..then..else or if value in [...]?
> >> And how will I mage this when my code runs on different
> >> architecture where the full range of the ordinal may differ?
> >>
> >> Please no (to this part of the proposal).
> >>  
> >
> > Warnings can always be disabled by {$warn NR off} or - I believe - a
> > command line switch.
> > One could also decide to have it be a default off warning for the
> > non ISO modes (FPC, Delphi, MacPas) like some of the string
> > conversion warnings.  
> 
> I would strongly advise to have it off by default for all but the ISO
> modes.
> 
> You have perfectly valid code today (see the example of indexed
> properties) which would start generating exceptions, and you should
> not be forced to add a {$ } directive or an "else" clause to a case
> statement for this.

I do hope you meant warnings, not exceptions.

 
> I agree this warning is very useful for enumerated types, but really
> not for integers. There are too many cases where it would be a false
> positive.

I have a lot of code with enums, where these warnings will force me to
do a lot of changes.

Mattias