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

[David Gibson <david@gibson.dropbear.id.au>]

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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.

> ---
>  tap.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/tap.c b/tap.c
> index d630f6d..6db5d88 100644
> --- a/tap.c
> +++ b/tap.c
> @@ -118,6 +118,8 @@ unsigned long tap_l2_max_len(const struct ctx *c)
>  	}
>  	/* NOLINTEND(bugprone-branch-clone) */
>  	ASSERT(0);
> +
> +	return 0; /* Unreachable, for cppcheck's sake */
>  }
>  
>  /**

-- 
David Gibson (he or they)	| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you, not the other way
				| around.
http://www.ozlabs.org/~dgibson

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