Re: warn/croak on "string" "string" auto-joins

[Gabor Greif <gabor at mac dot com>]

Am Mittwoch den, 18. August 2004, um 02:21, schrieb Adam Monsen:

> Hi Gabor,
>
> Thanks for your input!
>
> On Wed, 18 Aug 2004 01:25:10 +0200, Gabor Greif <gabor@mac.com> wrote:
> > Adam Monsen <haircut at gmail dot com> wrote:
> > > String auto-joins can be dangerous. Is there a way to tell the
> > > compiler to warn/croak when an auto-join occurs?
> > >
> > > For instance, find the bug in this code:
> > >
> > > char *months[] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul",
> > > "Aug" "Sep", "Oct", "Nov", "Dec"};
> > >
> > > If not, I'd like to suggest a way to ask the compiler to strictly
> > > check for this.
> >
> > The compiler cannot shield you from all programmer errors.
>
> Agreed.
>
> > This would have helped early and is good practice:
> >
> > char *months[12] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul",
> > "Aug" "Sep", "Oct", "Nov", "Dec"};
> >
> > --> high probability warning
>
> I'm not sure I understand, what does "high probability warning" mean?
> I get no errors/warnings from the following:
>
> #include <stdio.h>
> int main( void )
> {
>   char *months[15] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul",
> "Aug" "Sep", "Oct", "Nov", "Dec"};
>   printf("7: %s\n", months[8]);
>   return 0;
> }
>
> compiled with 'gcc -Wall -pedantic -ansi', using GCC 3.3.3.

Hmm, I could have sworn that a mismatch in array dimensions
does emit a warning (too many initializers do error out "como").
Looks like this is not the case. Sorry for bothering you :-(

> > Cheers,
> >
> >     Gabor
> >
> > PS: I often assemble longer (format) strings from smaller ones
> > by means of macros, so if this ever to become a warning I'd
> > prefer to exclude macro-expanded occurrences.
>
> But you currently have no use for the warning, correct? Or, do you
> feel it is useful? I'm confused.

No use for the warning, as I have never made this particular error,
but it does indeed look hard to debug. So if it occurs in the source
like in your example I would not mind to be warned by the compiler.
However in case the concatenation comes from macro expansion,
warning on it would be bad.

  Gabor


> --
> Adam Monsen <adamm@wazamatta.com>
> http://adammonsen.com/