Subject: Re: [PATCH 2/5] parse-options.c: use new bug() API for optbug()

From: Josh Steadmon <[email-masked]>
Date: Fri, 27 May 2022 10:03:52 -0700

On 2022.05.21 19:14, Ævar Arnfjörð Bjarmason wrote:
> When we run into bugs in parse-options.c usage it's good to be able to
> note all the issues we ran into before dying. This use-case is why we
> have the optbug() function introduced in 1e5ce570ca3 (parse-options:
> clearer reporting of API misuse, 2010-12-02)
> 
> Let's change this code to use the new bug() API introduced in the
> preceding commit, which cuts down on the verbosity of
> parse_options_check().
> 
> There are existing uses of BUG() in adjacent code that should have
> been using optbug() that aren't being changed here. That'll be done in
> a subsequent commit. This only changes the optbug() callers.
> 
> Signed-off-by: Ævar Arnfjörð Bjarmason <[email-masked]>
> ---
>  parse-options.c | 36 +++++++++++++++++-------------------
>  1 file changed, 17 insertions(+), 19 deletions(-)
> 
> diff --git a/parse-options.c b/parse-options.c
> index 6e57744fd22..7fff588a45f 100644
> --- a/parse-options.c
> +++ b/parse-options.c
> @@ -14,15 +14,15 @@ enum opt_parsed {
>  	OPT_UNSET = 1<<1,
>  };
>  
> -static int optbug(const struct option *opt, const char *reason)
> +static void optbug(const struct option *opt, const char *reason)
>  {
> -	if (opt->long_name) {
> -		if (opt->short_name)
> -			return error("BUG: switch '%c' (--%s) %s",
> -				     opt->short_name, opt->long_name, reason);
> -		return error("BUG: option '%s' %s", opt->long_name, reason);
> -	}
> -	return error("BUG: switch '%c' %s", opt->short_name, reason);
> +	if (opt->long_name && opt->short_name)
> +		bug("switch '%c' (--%s) %s", opt->short_name,
> +		    opt->long_name, reason);
> +	else if (opt->long_name)
> +		bug("option '%s' %s", opt->long_name, reason);
> +	else
> +		bug("switch '%c' %s", opt->short_name, reason);
>  }
>  
>  static const char *optname(const struct option *opt, enum opt_parsed flags)
> @@ -441,28 +441,27 @@ static void check_typos(const char *arg, const struct option *options)
>  
>  static void parse_options_check(const struct option *opts)
>  {
> -	int err = 0;
>  	char short_opts[128];
>  
>  	memset(short_opts, '\0', sizeof(short_opts));
>  	for (; opts->type != OPTION_END; opts++) {
>  		if ((opts->flags & PARSE_OPT_LASTARG_DEFAULT) &&
>  		    (opts->flags & PARSE_OPT_OPTARG))
> -			err |= optbug(opts, "uses incompatible flags "
> -					"LASTARG_DEFAULT and OPTARG");
> +			optbug(opts, "uses incompatible flags "
> +			       "LASTARG_DEFAULT and OPTARG");
>  		if (opts->short_name) {
>  			if (0x7F <= opts->short_name)
> -				err |= optbug(opts, "invalid short name");
> +				optbug(opts, "invalid short name");
>  			else if (short_opts[opts->short_name]++)
> -				err |= optbug(opts, "short name already used");
> +				optbug(opts, "short name already used");
>  		}
>  		if (opts->flags & PARSE_OPT_NODASH &&
>  		    ((opts->flags & PARSE_OPT_OPTARG) ||
>  		     !(opts->flags & PARSE_OPT_NOARG) ||
>  		     !(opts->flags & PARSE_OPT_NONEG) ||
>  		     opts->long_name))
> -			err |= optbug(opts, "uses feature "
> -					"not supported for dashless options");
> +			optbug(opts, "uses feature "
> +			       "not supported for dashless options");
>  		switch (opts->type) {
>  		case OPTION_COUNTUP:
>  		case OPTION_BIT:
> @@ -471,7 +470,7 @@ static void parse_options_check(const struct option *opts)
>  		case OPTION_NUMBER:
>  			if ((opts->flags & PARSE_OPT_OPTARG) ||
>  			    !(opts->flags & PARSE_OPT_NOARG))
> -				err |= optbug(opts, "should not accept an argument");
> +				optbug(opts, "should not accept an argument");
>  			break;
>  		case OPTION_CALLBACK:
>  			if (!opts->callback && !opts->ll_callback)
> @@ -494,10 +493,9 @@ static void parse_options_check(const struct option *opts)
>  		}
>  		if (opts->argh &&
>  		    strcspn(opts->argh, " _") != strlen(opts->argh))
> -			err |= optbug(opts, "multi-word argh should use dash to separate words");
> +			optbug(opts, "multi-word argh should use dash to separate words");
>  	}
> -	if (err)
> -		exit(128);
> +	BUG_if_bug();

It might be worth noting in the commit message that this changes the
exit value in this case. On the other hand, it seems unlikely that
people are depending on this to detect programmer error that shouldn't
show up in the first place. I guess I don't feel too strongly about
this, it's probably fine to not mention it.

>  }
>  
>  static void parse_options_start_1(struct parse_opt_ctx_t *ctx,
> -- 
> 2.36.1.960.g7a4e2fc85c9
>