Re: [PATCH v2] [GSOC][RFC] format-patch: pass --left-only to range-diff

>
> On Tue, Mar 9, 2021 at 3:35 AM ZheNing Hu via GitGitGadget
> <gitgitgadget@gmail.com> wrote:
> > In https://lore.kernel.org/git/YBx5rmVsg1LJhSKN@nand.local/,
> > Taylor Blau proposing `git format-patch --cover-letter
> > --range-diff` may mistakenly place upstream commit in the
> > range-diff output. Teach `format-patch` pass `--left-only`
> > to range-diff,can avoid this kind of mistake.
> >
> > Signed-off-by: ZheNing Hu <adlternative@gmail.com>
> > ---
> > diff --git a/builtin/log.c b/builtin/log.c
> > @@ -2085,9 +2089,12 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
> >         if (creation_factor < 0)
> >                 creation_factor = RANGE_DIFF_CREATION_FACTOR_DEFAULT;
> > -       else if (!rdiff_prev)
> > -               die(_("--creation-factor requires --range-diff"));
> > -
> > +       else if (!rdiff_prev) {
> > +               if (creation_factor >= 0)
> > +                       die(_("--creation-factor requires --range-diff"));
> > +               if (left_only)
> > +                       die(_("--left-only requires --range-diff"));
> > +       }
>
> This logic starts getting difficult to reason about. It would be
> easier to understand if written like this:
>
>     if (!rdiff_prev) {
>         if (creation_factor >= 0)
>             die(_("--creation-factor requires --range-diff"));
>         if (left_only)
>             die(_("--left-only requires --range-diff"));
>     }
>
>     if (creation_factor < 0)
>         creation_factor = RANGE_DIFF_..._DEFAULT;
>
> or this (which reduces the indentation a bit):
>
>     if (creation_factor >= 0 && !rdiff_prev)
>         die(_("--creation-factor requires --range-diff"));
>     if (left_only && !rdiff_prev)
>         die(_("--left-only requires --range-diff"));
>
>     if (creation_factor < 0)
>         creation_factor = RANGE_DIFF_..._DEFAULT;
>

> Subjective; not necessarily worth a re-roll.
>
> > @@ -2134,7 +2141,8 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
> >                 make_cover_letter(&rev, !!output_directory,
> > -                                 origin, nr, list, branch_name, quiet);
> > +                                 origin, nr, list, branch_name, quiet,
> > +                                       left_only);
>
> Nit: This indentation looks odd. One would expect `origin` and
> `left_only` to have the same indentation.
>
> > diff --git a/t/t3206-range-diff.sh b/t/t3206-range-diff.sh
> > @@ -748,4 +748,32 @@ test_expect_success '--left-only/--right-only' '
> > +test_expect_success 'format-patch --range-diff --left-only' '
> > +       rm -fr repo &&
> > +       git init repo &&
> > +       ...
> > +       ! grep  "> 1: .* feature$"  0000-cover-letter.patch
> > +'
> > +
> > +
> >  test_done
>
> Nit: One blank line before test_done() is typical, not two.