> >
> > // fltk3::alert("%s",existing_file_label); // error
> > fltk3::alert((char*)"%s",existing_file_label); // ok
> >
> > Though I have concerns about casting a "fixed" string like
> that just to
> > "trick" the compiler into doing the "obvious" conversion.
>
> From what I understand of the "mechanics" of const vs. non-const, it
> shouldn't have any effect on the mechanics of the executable. "const"
> just forces the variable / etc. into read-only memory which
> has no write
> access (hence writing to const strings causes a segmentation fault).
Yup - my worry is that if we use "%s" like that, the compiler will
create a const char array, we then cast away the const-ness, and
(conceivably) could then write to that string - segfault, bad.
So I'm not keen on casting away the inherent const-ness of the fixed
string...
Though in practice I don't think alert() and so forth do ever actually
write to the passed string, so in practice we are surely OK to do that?
> > I suppose the best bet *might* be to add a third option
> that expands to
> > (const char *, const char*) that would then take precedence
> over either
> > of the ambiguous cases here and so avoid the problem...?
> TBH it looks like existing_file_label shouldn't be declared const
> anyway, and on top of that I'm not sure why the first parameter in
> "alert" isn't const - it seems to me that this parameter
> should always
> be const? This no doubt makes sense to Matt though!
The "first" option that the compiler offers is the one expanding
"alert(va_list, const char *);" where the va_list is expanded here as a
"char*", so it's (possibly) not really in our remit to be able to set
how the va_list is interpreted?
> If existing_file_label were to be changed to char*, this
> should then be
> matched to the second version of alert()....
Though we need a general solution too, since it is not just alert() that
has problems, also message(), choice() etc... All the places where we've
added va_list I suspect (though have not checked in detail...) so I'm
not sure how best we proceed.
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