On Mon, Nov 07, 2011 at 02:12:28PM +0100, Andreas Schwab wrote:
> Ævar Arnfjörð Bjarmason <avarab@xxxxxxxxx> writes:
>
> > I.e. we'll always have GREP_HEADER_AUTHOR = 0 and
> > GREP_HEADER_COMMITTER = 1, we'll never have GREP_HEADER_AUTHOR = and
> > GREP_HEADER_COMMITTER = <some int>.
>
> That is irrelevant. You can always assign -1 to an object of enumerated
> type and the implicit conversion to the underlying type is fully
> defined, no matter what type the compiler choses.
Yes, but now you are getting into implementation-defined behavior, which
is also something to avoid. IOW, I don't think it's wrong for a static
analyzer to complain about:
if (enum_with_only_positive_values < 0)
just because you could say:
enum_with_only_positive_values = -1;
and it would work on _some_ platforms. That same static analyzer should
be complaining about the second line, which is where the real potential
bug is. If you want "-1" as an enumerated value, then add it to your
enum definition and the compiler will do the right thing.
It is perfectly fine to do:
enum foo { a = -1, b, c };
...
if (foo < 0)
...
and the static analyzer should not complain about the conditional there.
-Peff
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