Re: [PATCH] tap: Avoid bogus missingReturn cppcheck warning in tap_l2_max_len()

[Stefano Brivio <sbrivio@redhat.com>]

On Fri, 16 May 2025 17:25:21 +1000
David Gibson <david@gibson.dropbear.id.au> wrote:

> On Thu, May 15, 2025 at 06:05:01PM +0200, Stefano Brivio wrote:
> > Cppcheck 2.14.2 on Alpine Linux (musl) says that:
> > 
> > tap.c:111:19: error: Found an exit path from function with non-void return type that has missing return statement [missingReturn]
> >  switch (c->mode) {
> >                   ^
> > 
> > This exit path is not reachable because we ASSERT(0) after the switch,
> > but for some reason cppcheck doesn't see this with musl headers. Hide
> > the warning with a redundant return statement.
> > 
> > Signed-off-by: Stefano Brivio <sbrivio@redhat.com>  
> 
> Hm.  Alternatively you could change this to call abort_with_msg()
> directly.  That's marked as ((noreturn)) so with any luck cppcheck
> will then be able to figure out what's going on.  Although, I'm
> slightly surprised it can't do so already: I thought I put the
> ((noreturn)) in there to avoid warnings exactly like this.

So, I checked, and abort_with_msg(""); works. ASSERT() ultimately
expands to abort_with_msg(), but for some reason cppcheck together with
Clang can't "follow" that, I suppose it's something related to the
pre-processor.

But in any case, abort_with_msg("") doesn't look as descriptive and
as obviously redundant as a return statement with a comment, so I don't
quite see the benefit changing it (also considering that I need to test
other versions, which takes time).

-- 
Stefano