Subject: Re: [PATCH 2/3] diff-merges: cleanup set_diff_merges()

From: Junio C Hamano <[email-masked]>
Date: Thu, 15 Sep 2022 13:41:17 -0700

Sergey Organov <[email-masked]> writes:

> Get rid of special-casing of 'suppress' in set_diff_merges(). Instead
> set 'merges_need_diff' flag correctly in every option handling
> function.
>
> Signed-off-by: Sergey Organov <[email-masked]>
> ---
>  diff-merges.c | 30 +++++++++++++++++++-----------
>  1 file changed, 19 insertions(+), 11 deletions(-)

Looks OK to me.

Everybody else says set_X() but set_none() has nothing to do ther
than calling suppress(), so the change does not really make a
functional difference (as you said in the cover letter).

Is the idea that the original value in .merges_need_diff member does
not matter because in every case it is set to either 0 or 1?  Most
cases call common_setup() to set it to 1 like this here...

> +static void common_setup(struct rev_info *revs)
> +{
> +	suppress(revs);
> +	revs->merges_need_diff = 1;
> +}

... but this does not touch (in other words, it does not explicitly
clear) it, ...

> +static void set_none(struct rev_info *revs)
> +{
> +	suppress(revs);
> +}

 ... so we still rely on somebody to set the .merges_need_diff
to 0 initially, right?

> -
> -	/* NOTE: the merges_need_diff flag is cleared by func() call */
> -	if (func != suppress)
> -		revs->merges_need_diff = 1;
>  }

It is very good to see this one go.

>  /*
> @@ -115,6 +122,7 @@ int diff_merges_parse_opts(struct rev_info *revs, const char **argv)
>  
>  	if (!suppress_m_parsing && !strcmp(arg, "-m")) {
>  		set_to_default(revs);
> +		revs->merges_need_diff = 0;

I am wondering how this becomes necessary?  Is it because
set_to_default() would flip the member to 1 unconditionally, or
something?  If it weren't for this hunk, the lossage of the previous
hunk is a very good clean-up, but if we need to do this, I cannot
shake the feeling that we mostly shifted the dirt around, without
really cleaning it?  I dunno.

> @@ -125,7 +133,7 @@ int diff_merges_parse_opts(struct rev_info *revs, const char **argv)
>  		set_remerge_diff(revs);
>  		revs->merges_imply_patch = 1;
>  	} else if (!strcmp(arg, "--no-diff-merges")) {
> -		suppress(revs);
> +		set_none(revs);

We do not need to explicitly set .merges_need_diff to 0 here,
presumably because it is initialized to 0 and nobody touched it,
right?

>  	} else if (!strcmp(arg, "--combined-all-paths")) {
>  		revs->combined_all_paths = 1;
>  	} else if ((argcount = parse_long_opt("diff-merges", argv, &optarg))) {
> @@ -139,7 +147,7 @@ int diff_merges_parse_opts(struct rev_info *revs, const char **argv)
>  
>  void diff_merges_suppress(struct rev_info *revs)
>  {
> -	suppress(revs);
> +	set_none(revs);
>  }
>  
>  void diff_merges_default_to_first_parent(struct rev_info *revs)