Re: [PATCH] parse-options: fix SunCC compiler warning

From: Junio C Hamano <gitster@pobox.com>
Date: Dec 10, 2018, 06:36 UTC
Message-ID: <xmqqy38xkhvd.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20181209102724.8707-1-pclouds@gmail.com>

Nguyễn Thái Ngọc Duy  <pclouds@gmail.com> writes:

Show 8 quoted lines

> The compiler reports this because show_gitcomp() never actually
> returns a value:
>
>     "parse-options.c", line 520: warning: Function has no return
>     statement : show_gitcomp
>
> The function calls exit() and will never return. Update and mark it
> NORETURN.

Yuck. This should do for now, but I am not impressed by the choice to hook show_gitcomp() call into parse_options_step(), which forces such an abnormal exit deeper in the callchain [*1*]. For readers (not compilers), it would help to have a comment at the caller that says that show_gitcomp() never returns and exits.

	side note #1.  Perhaps parse_options_start() would have been
	a better place, instead of parse_options_step() that is
	repeatedly called in a loop and itself has a loop.  ANd
	worse yet, the check is done inside the loop even though the
	call is to be made only when the --git-completion-helper
	option is given as the sole request.

Thanks.

Show 30 quoted lines

> Reported-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  parse-options.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/parse-options.c b/parse-options.c
> index 3b874a83a0..6577e52f63 100644
> --- a/parse-options.c
> +++ b/parse-options.c
> @@ -474,8 +474,8 @@ static void show_negated_gitcomp(const struct option *opts, int nr_noopts)
>  	}
>  }
>  
> -static int show_gitcomp(struct parse_opt_ctx_t *ctx,
> -			const struct option *opts)
> +static void NORETURN show_gitcomp(struct parse_opt_ctx_t *ctx,
> +				  const struct option *opts)
>  {
>  	const struct option *original_opts = opts;
>  	int nr_noopts = 0;
> @@ -550,7 +550,7 @@ int parse_options_step(struct parse_opt_ctx_t *ctx,
>  
>  		/* lone --git-completion-helper is asked by git-completion.bash */
>  		if (ctx->total == 1 && !strcmp(arg + 1, "-git-completion-helper"))
> -			return show_gitcomp(ctx, options);
> +			show_gitcomp(ctx, options);
>  
>  		if (arg[1] != '-') {
>  			ctx->opt = arg + 1;