Subject: Re: [PATCH 3/7] revision: use die_for_incompatible_opt3() for --graph/--reverse/--walk-reflogs

From: Patrick Steinhardt <[email-masked]>
Date: Wed, 6 Dec 2023 14:08:04 +0100

On Wed, Dec 06, 2023 at 12:51:57PM +0100, René Scharfe wrote:
> The revision options --reverse is incompatibel with --walk-reflogs and
> --graph is incompatible with both --reverse and --walk-reflogs.  So they
> are all incompatible with each other.
> 
> Use the function for checking three mutually incompatible options,
> die_for_incompatible_opt3(), to perform this check in one place and
> without repetition.  This is shorter and clearer.
> 
> Signed-off-by: René Scharfe <[email-masked]>
> ---
>  revision.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/revision.c b/revision.c
> index b2861474b1..1b7e1af6c6 100644
> --- a/revision.c
> +++ b/revision.c
> @@ -3036,8 +3036,6 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
>  		revs->grep_filter.ignore_locale = 1;
>  	compile_grep_patterns(&revs->grep_filter);
> 
> -	if (revs->reverse && revs->reflog_info)
> -		die(_("options '%s' and '%s' cannot be used together"), "--reverse", "--walk-reflogs");
>  	if (revs->reflog_info && revs->limited)
>  		die("cannot combine --walk-reflogs with history-limiting options");
>  	if (revs->rewrite_parents && revs->children.name)
> @@ -3048,11 +3046,10 @@ int setup_revisions(int argc, const char **argv, struct rev_info *revs, struct s
>  	/*
>  	 * Limitations on the graph functionality
>  	 */
> -	if (revs->reverse && revs->graph)
> -		die(_("options '%s' and '%s' cannot be used together"), "--reverse", "--graph");
> +	die_for_incompatible_opt3(!!revs->graph, "--graph",
> +				  !!revs->reverse, "--reverse",
> +				  !!revs->reflog_info, "--walk-reflogs");

I've been wondering why we use `!!` here, as `die_for_incompatible_*()`
doesn't care for the actual value but only checks that it is non-zero.
Is it because of the type mismatch, where these flags here use unsigned
ints whereas `die_for_incompatible_*()` expect ints?

Patrick