On Mon, Jan 22, 2018 at 07:54:18PM -0500, Eric Sunshine wrote:
> On Mon, Jan 22, 2018 at 6:51 PM, Elia Pinto <gitter.spiros@xxxxxxxxx> wrote:
> > This patch add explicit fallthrough compiler attribute
> > when needed on switch case statement eliminating
> > the compile warning [-Werror=implicit-fallthrough=].
> > It does this by means of a macro that takes into account
> > the versions of the compilers that include that attribute.
> > [...]
> > Signed-off-by: Elia Pinto <gitter.spiros@xxxxxxxxx>
> > ---
> > diff --git a/convert.c b/convert.c
> > @@ -1554,7 +1554,7 @@ static int ident_filter_fn(struct stream_filter *filter,
> > switch (ident->state) {
> > default:
> > strbuf_add(&ident->left, head, ident->state);
> > - /* fallthrough */
> > + GIT_FALLTHROUGH;
> > case IDENT_SKIPPING:
> > /* fallthrough */
>
> Why doesn't this /* fallthrough */ deserve the same treatment?
>
> > case IDENT_DRAINING:
I can't answer that philosophically, but I can tell you why the compiler
does not complain. :)
Usually case arms with no statements between them are exempt from
fallthrough warnings. So:
switch (foo)
case 1:
case 2:
case 3:
/* do one thing */
break;
case 4:
/* do another thing */
break;
}
does not need any annotations for cases 1 and 2 to fallthrough. Which
means that the original comment was not actually necessary for the
compiler, though the original author considered it a useful comment.
So there you get into philosophy. Should it be converted to a
compiler-visible annotation, or is it better left as a comment?
-Peff
