[fpc-devel] "Case statement does not handle all possible cases" Warning

Ondrej Pokorny lazarus at kluug.net
Sun May 19 17:42:19 CEST 2019

On 19.05.2019 09:34, Sven Barth via fpc-devel wrote:
> J. Gareth Moreton <gareth at moreton-family.com 
> <mailto:gareth at moreton-family.com>> schrieb am So., 19. Mai 2019, 05:17:
>     I just feel that in this case, it should be a note, not a warning,
>     unless you're compiling under a dialect of Pascal (e.g. Extended)
>     that
>     is stricter in its interpretation of the whitesheet and demands an
>     error
>     be returned.
> No, I don't think so. The compiler might generate quite some hints and 
> notes some of which might be false positives (take the "uninitialized 
> variable" in context of "var" parameters) and thus this note/hint 
> would be lost among the noise.

What makes you think an incomplete case statement might not be a false 

> Also you need to keep in mind that enums are not necessarily static 
> over the lifetime of the software. E.g. (using the compiler as an 
> example) a new def type could be added. If you now haven't added empty 
> else-clauses to the case-statements you'll now get a nice warning for 
> every such case statement so that you can be reasonably sure you 
> caught all.

A note would do just the same.

That all said, I very much like this new enum warning. A note would just 
do the same job (and I don't care if it's a warning or a note).

> At my work (where we use MSVC) we enabled the compiler's warning for 
> this reason.

In FPC we needed such a construct at every case block

     {$IF (Ord(High(TMyEnum)) <> 2)} {$MESSAGE Warning 'Case does not 
respond to all possible values'} {$IFEND}

to get a warning when a new enum value is added. We don't need it 
anymore, good.


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