Subject: Re: [PATCH v2 3/6] commit: add a reword suboption to --fixup

From: Junio C Hamano <[email-masked]>
Date: Thu, 25 Feb 2021 12:32:59 -0800

Charvi Mendiratta <[email-masked]> writes:

> `git commit --fixup=reword:<commit>` creates an empty "amend!" commit
> that will reword <commit> without changing its contents when it is
> rebased with --autosquash.
>
> Apart from ignoring staged changes it works similarly to
> `--fixup=amend:<commit>`.
>
> Mentored-by: Christian Couder <[email-masked]>
> Mentored-by: Phillip Wood <[email-masked]>
> Helped-by: Junio C Hamano <[email-masked]>
> Signed-off-by: Charvi Mendiratta <[email-masked]>
> ---
>  builtin/commit.c | 46 +++++++++++++++++++++++++++++++++++++---------
>  1 file changed, 37 insertions(+), 9 deletions(-)
>
> diff --git a/builtin/commit.c b/builtin/commit.c
> index 56ae15a762..82e77aa61d 100644
> --- a/builtin/commit.c
> +++ b/builtin/commit.c
> @@ -1177,6 +1177,27 @@ static void finalize_deferred_config(struct wt_status *s)
>  		s->ahead_behind_flags = AHEAD_BEHIND_FULL;
>  }
>  
> +static void check_fixup_reword_options(int argc) {
> +	if (whence != FROM_COMMIT) {
> +		if (whence == FROM_MERGE)
> +			die(_("You are in the middle of a merge -- cannot reword."));
> +		else if (is_from_cherry_pick(whence))
> +			die(_("You are in the middle of a cherry-pick -- cannot reword."));
> +	}
> +	if (argc)
> +		die(_("cannot combine reword option of --fixup with paths"));

It would be easier if the user is told "foo" in the message when

    $ git commit --fixup=reword:HEAD~ -- foo

(from your tests) is attempted, no?

> +	if (patch_interactive)
> +		die(_("cannot combine reword option of --fixup with --patch"));
> +	if (interactive)
> +		die(_("cannot combine reword option of --fixup with --interactive"));
> +	if (all)
> +		die(_("cannot combine reword option of --fixup with --all"));
> +	if (also)
> +		die(_("cannot combine reword option of --fixup with --include"));
> +	if (only)
> +		die(_("cannot combine reword option of --fixup with --only"));
> +}
> +
>  /* returns the length of intial segment of alpha characters only */
>  static size_t get_alpha_len(char *fixup_message) {
>  	const char alphas[] = "abcdefghijklmnopqrstuvwxyz";
> @@ -1261,18 +1282,25 @@ static int parse_and_validate_options(int argc, const char *argv[],
>  
>  	if (fixup_message) {
>  		/*
> -		 * As `amend` suboption contains only alpha
> -		 * character. So check if first non alpha
> -		 * character in fixup_message is ':'.
> +		 * As `amend`/`reword` suboptions contains only alpha
> +		 * characters. So check if first non alpha character
> +		 * in fixup_message is ':'.
>  		 */
>  		size_t len = get_alpha_len(fixup_message);
>  		if (len && fixup_message[len] == ':') {
>  			fixup_message[len] = '\0';
>  			fixup_commit = fixup_message + ++len;
> -			if (starts_with("amend", fixup_message))
> +			if (starts_with("amend", fixup_message) ||
> +				starts_with("reword", fixup_message)) {
>  				fixup_prefix = "amend";
> -			else
> +				if (*fixup_message == 'r') {

> +					check_fixup_reword_options(argc);
> +					allow_empty = 1;
> +					only = 1;

OK.  We make sure that there is no pathspec and then by giving
only==1, we ignore any difference that already may exist between
HEAD and the index.  IOW

	edit somefile
	git add somefile
	git commit --fixup=reword:<commit>

will still record the same tree as HEAD, without affected by the
addition of somefile to the index that is done before.

Good.

> +				}
> +			} else {
>  				die(_("unknown option: --fixup=%s:%s"), fixup_message, fixup_commit);
> +			}
>  		} else {
>  			fixup_commit = fixup_message;
>  			fixup_prefix = "fixup";
> @@ -1558,11 +1586,11 @@ int cmd_commit(int argc, const char **argv, const char *prefix)
>  		OPT_STRING('c', "reedit-message", &edit_message, N_("commit"), N_("reuse and edit message from specified commit")),
>  		OPT_STRING('C', "reuse-message", &use_message, N_("commit"), N_("reuse message from specified commit")),
>  		/*
> -		 * TRANSLATORS: please do not translate [amend:]
> -		 * Here "amend" is an option to the --fixup command
> -		 * line flag, that creates amend! commit.
> +		 * TRANSLATORS: please do not translate [(amend|reword):]
> +		 * Here "amend" and "reword" are options to the --fixup
> +		 * command line flag, that creates amend! commit.

I am not sure this comment is all that helpful to the translaters.
If they are not allowed to translate <amend|reword> part, telling
them what that part means does not help them very much.

	Leave "[(amend|reword):]" as-is, and only translate <commit>.

would be more direct without distracting them with useless piece of
information, no?

>  		 */
> -		OPT_STRING(0, "fixup", &fixup_message, N_("[amend:]commit"), N_("use autosquash formatted message to fixup or amend specified commit")),
> +		OPT_STRING(0, "fixup", &fixup_message, N_("[(amend|reword):]commit"), N_("use autosquash formatted message to fixup or amend/reword specified commit")),
>  		OPT_STRING(0, "squash", &squash_message, N_("commit"), N_("use autosquash formatted message to squash specified commit")),
>  		OPT_BOOL(0, "reset-author", &renew_authorship, N_("the commit is authored by me now (used with -C/-c/--amend)")),
>  		OPT_BOOL('s', "signoff", &signoff, N_("add a Signed-off-by trailer")),