Re: [PATCH v4 2/6] commit: add amend suboption to --fixup to create amend! commit

[Charvi Mendiratta <charvi077@gmail.com>]

On Thu, 11 Mar 2021 at 11:55, Eric Sunshine <sunshine@sunshineco.com> wrote:
>
[...]
> Two style nits:
>
> * opening curly brace of function goes on its own line
>
> * we don't normally have a blank line at the top of the function body
> preceding the declarations
>
> So:
>
>     static int prepare_amend_commit(...)
>     {
>         const  char *buffer, *subject, *fmt;
>

Okay, I will fix it.

> > +       buffer = get_commit_buffer(commit, NULL);
> > +       find_commit_subject(buffer, &subject);
> > +       /*
> > +        * If we amend the 'amend!' commit then we don't want to
> > +        * duplicate the subject line.
> > +        */
> > +       fmt = starts_with(subject, "amend!") ? "%b" : "%B";
> > +       format_commit_message(commit, fmt, sb, ctx);
> > +       unuse_commit_buffer(commit, buffer);
> > +       return 0;
> > +}
>
> What is the significance of this function's return value? At least in
> this patch, the single caller of this function ignores the return
> value, which suggests that the function need not return any value.
> Will a later patch add other possible return values to indicate an
> error or something?
>

No, it will not return another value later. I will remove it from here.

> > @@ -745,15 +764,32 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
> > +               char *fmt = xstrfmt("%s! %%s\n\n", fixup_prefix);
> > +               commit = lookup_commit_reference_by_name(fixup_commit);
> >                 if (!commit)
> > +                       die(_("could not lookup commit %s"), fixup_commit);
> >                 ctx.output_encoding = get_commit_output_encoding();
> > +               format_commit_message(commit, fmt, &sb, &ctx);
> > +               free(fmt);
>
> Nit: it would reduce the cognitive load slightly if `fmt` is prepared
> just before it is used rather than being prepared at the top of the
> block:
>
>     fmt = xstrfmt("%s! %%s\n\n", fixup_prefix);
>     format_commit_message(commit, fmt, &sb, &ctx);
>     free(fmt);
>
> Subjective and not at all worth a re-roll.
>

Agree, will fix it.

> > @@ -1227,6 +1269,34 @@ static int parse_and_validate_options(int argc, const char *argv[],
> > +       if (fixup_message) {
> > +               /*
> > +                * To check if fixup_message that contains ':' is a commit
> > +                * reference for example: --fixup="HEAD^{/^area: string}" or
> > +                * a suboption of `--fixup`.
> > +                *
> > +                * As `amend` suboption contains only alpha character.
> > +                * So check if first non alpha character in fixup_message
> > +                * is ':'.
> > +                */
>
> I have a tough time figuring out what this comment is trying to say,
> and I don't think I would have understood it if Junio had not already
> explained earlier in this thread why this code is as complex as it is
> (rather than using, say, skip_prefix()). Perhaps the entire comment
> can be replaced with this:
>

I admit, this comment seems confusing...

>     Extract <option> (i.e. `amend`) from `--fixup=<option>:<commit>`,
>     if present. To avoid being fooled by a legitimate ":" in <commit>
>     (i.e. `--fixup="HEAD^{/^area: string}"`), <option> must be
>     composed of only alphabetic characters.
>
> Not necessarily worth a re-roll.
>

.. and I think we can reword it as suggested by Junio in patch[v4
3/6], as it seems more clear.

> > +               size_t len = get_alpha_len(fixup_message);
> > +               if (len && fixup_message[len] == ':') {
> > +                       fixup_message[len++] = '\0';
> > +                       fixup_commit = fixup_message + len;
>
> An alternate -- just about as compact and perhaps more idiomatic --
> way to write all this without introducing the new get_alpha_len()
> function:
>
>     char *p = fixup_mesage;
>     while (isalpha(*p))
>         p++;
>     if (p > fixup_message && *p == ':') {
>         *p = '\0';
>         fixup_commit = p + 1;
>
> Subjective and not at all worth a re-roll.
>

Earlier we had discussed[1] keeping a separate helper function, so
that it may re-use it later. But I agree above is easier to get and
compact so I think maybe it will be ok, for this patch series to
replace it with the above and remove the function.

[1] https://lore.kernel.org/git/xmqqpn0xdse8.fsf@gitster.g/