Re: Format string wrapper and -Wformat-nonliteral

[Tobias Mueller <4tmuelle+gcc at informatik dot uni-hamburg dot de>]

Hey,

Tobias Mueller wrote:
> Kevin P. Fleming wrote:
> > Tobias Mueller wrote:
> >
> > > I think I want to make gcc
> > >  * know that the wrapper is not responsible for the format string and
> > >    thus the call to strftime is allowed
> > >  * pass the responsibility up to the callers and thus check whether they
> > >    call the wrapper with "good" strings.
> > >
> > >
> > > And I don't know how to do that. Do you have any advices?
> >
> > <snip>
> >
> > > size_t my_strftime(char *s, size_t max, const char *fmt,
> > >                    const struct tm *tm)
> >
> > Add "__attribute__((format (strftime, 3, 0)))" to your function 
> > declaration.
>
> Well, I tried that:
>
> size_t my_strftime(char *s, size_t max, const char *fmt,
>                    const struct tm *tm)
>                    __attribute__((format (strftime, 3, 0)))
> {...}
>
> and it fails:
> > muelli@bigbox /tmp $ gcc -Wformat  -Wformat-nonliteral 
> > -Werror=format-nonliteral  -Wfatal-errors -o mystrftime{,.c}
> > mystrftime.c:9: error: expected â,â or â;â before â{â token
> > compilation terminated due to -Wfatal-errors.
> > muelli@bigbox /tmp $ 

Now I tried

__attribute__(( format (strftime, 3, 0) ))
size_t my_strftime(char *s, size_t max, const char *fmt,
                   const struct tm *tm)
{...}

and at least it doesn't throw a syntax error. But it still fails to compile:
> muelli@bigbox /tmp $ gcc -Wformat  -Wformat-nonliteral -Werror=format-nonliteral -o mystrftime{,.c} 
> mystrftime.c: In function âmy_strftimeâ:
> mystrftime.c:14: error: format not a string literal, format string not checked
> muelli@bigbox /tmp $ 


What would be the next step in solving this issue? Maybe filing a bug 
would be appropriate?

Cheers,
  Tobi