Jean, All,
On 2013-07-12 11:07 +0200, Jean Delvare spake thusly:
[--SNIP--]
> > > > > +static int sym_rel_comp( const void *sym1, const void *sym2 )
> > > > > +{
> > > > > + struct sym_match *s1 = *(struct sym_match **)sym1;
> > > > > + struct sym_match *s2 = *(struct sym_match **)sym2;
> > > >
> > > > You shouldn't need these casts.
> > >
> > > Probably not, indeed, but I like to write (and read) what I expect to
> > > happen, and pointer arithmetics is always something I dread to foobar.
> >
> > In fact, we need the cast, otherwise gcc whines about const/non-const.
>
> And quite rightly so, as you are taking const pointers (i.e. the caller
> told you you are _not_ allowed to change the contents) and making them
> non-const pointers (i.e. you give yourself the right to still change the
> contents.) It happens that your function doesn't actually change the
> contents, so no harm done, but this is still conceptually wrong.
> Preserving the const nature of pointers down the call chain lets the
> compiler warn you if a function changes data it was not supposed to.
>
> So what you want to do is:
>
> static int sym_rel_comp(const void *sym1, const void *sym2)
> {
> const struct sym_match *s1 = sym1;
> const struct sym_match *s2 = sym2;
>
> This is both concise and correct, and it makes gcc happy.
Yes, that's what I thought to, and what I was about to do. Thanks for
confirming this! :-)
Regards,
Yann E. MORIN.
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