Re: [PATCH] pull: abort if --ff-only is given and fast-forwarding is impossible

[Alex Henrie <alexhenrie24@gmail.com>]

On Sun, Jul 11, 2021 at 11:08 AM Felipe Contreras
<felipe.contreras@gmail.com> wrote:
>
> Alex Henrie wrote:
> > The warning about pulling without specifying how to reconcile divergent
> > branches says that after setting pull.rebase to true, --ff-only can
> > still be passed on the command line to require a fast-forward. Make that
> > actually work.
>
> I don't know where that is being said, but it's wrong: --ff-only is
> meant for merge only.
>
> > --- a/builtin/pull.c
> > +++ b/builtin/pull.c
> > @@ -1046,9 +1046,14 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
> >
> >       can_ff = get_can_ff(&orig_head, &merge_heads.oid[0]);
> >
> > -     if (rebase_unspecified && !opt_ff && !can_ff) {
> > -             if (opt_verbosity >= 0)
> > -                     show_advice_pull_non_ff();
> > +     if (!can_ff) {
> > +             if (opt_ff) {
> > +                     if (!strcmp(opt_ff, "--ff-only"))
> > +                             die_ff_impossible();
>
> As I've mentioned multiple times already, this is wrong.
>
> The advice clearly says:
>
>   You can also pass --rebase, --no-rebase, or --ff-only on the command
>   line to override the configured default per invocation.
>
> With your patch now this is even less true:
>
>   git -c pull.ff=only pull --rebase

I think it's an improvement over the current situation. --no-rebase
does not override pull.ff=only, so it makes sense that --rebase does
not override pull.ff=only either. Besides, it's generally better to
abort instead of rewriting history if it's not perfectly clear that
the user meant to rewrite the history.

-Alex