On Thu, Aug 31, 2017 at 12:13:19PM -0700, William Ahern wrote:
> On Thu, Aug 31, 2017 at 02:08:07PM +0200, Otto Moerbeek wrote:
> > Hi,
> >
> > /usr/src/usr.sbin/sasyncd/carp.c:157:12: warning: comparison of
> > unsigned enum expression < 0 is always false [-Wtautological-compare]
> > if (state < 0 || state > FAIL)
> > ~~~~~ ^ ~
> > /usr/src/usr.sbin/sasyncd/carp.c:166:20: warning: comparison of
> > unsigned enum expression < 0 is always false [-Wtautological-compare]
> > if (current_state < 0 || current_state > FAIL) {
> > ~~~~~~~~~~~~~ ^ ~
if (!(state >= INIT && state <= FAIL))
state = FAIL;
and
if (!(current_sate >= INIT && current_state <= FAIL) {
log_err ...
...
return;
}
More better?
--patrick
> >
> > this warning is a tiny bit interesting. A compiler is free to choose
> > the type of the enum, as long as it can represent all given values.
> > So another compiler might choose not to make it unsigned. So I came up
> > with this fix that is not depending on the signedness of the type. But
> > most of the time avoiding enum is better, I suppose.
>
> It's free to choose the integer type of the enum, but enumeration members
> (i.e. the constant identifiers) have int type.
>
> The identifiers in an enumerator list are declared as constants that have
> type int and may appear wherever such are permitted.
>
> C11 (N1570) 6.7.2.2p3.
>
> Furthermore, the defining expression of the constant must be representable
> as an int. 6.7.2.2p2.
>
> I've always vascillated about which operand to cast, and to which type, when
> silencing compilers' annoying warnings. But now that I've read the section
> more closely I think I'll just cast the operand with enum type to int, all
> things being equal.
>
