Re: [PATCH v3 10/21] checkout: split part of it to new command 'switch'

[Elijah Newren <newren@gmail.com>]

On Mon, Mar 11, 2019 at 1:51 PM Phillip Wood <phillip.wood123@gmail.com> wrote:
> On 11/03/2019 17:24, Elijah Newren wrote:
> > On Mon, Mar 11, 2019 at 4:47 AM Duy Nguyen <pclouds@gmail.com> wrote:
> >> On Mon, Mar 11, 2019 at 6:16 PM Phillip Wood <phillip.wood123@gmail.com> wrote:
> >>> On 08/03/2019 09:57, Nguyễn Thái Ngọc Duy wrote:
> >>>> "git checkout" doing too many things is a source of confusion for many
> >>>> users (and it even bites old timers sometimes). To remedy that, the
> >>>> command will be split into two new ones: switch and
> >>>> something-to-checkout-paths.
> >>>
> >>> I think this is a good idea, thanks for working on it. I wonder if it
> >>> would be a good idea to have the new command refuse to checkout a new
> >>> branch if there is a cherry-pick/revert/merge/rebase in progress (with
> >>> an option to override the check) as switching branches in the middle of
> >>> one of those is likely to be confusing to users (if I do it it is
> >>> normally because I've forgotten that I've not run 'git whatever
> >>> --continue').
> >>
> >> Interesting. I think this would be a good default if we have an escape
> >> hatch (which could even come later). I often wander off to some other
> >> branch and go back. But then half the time I end up forgetting I'm in
> >> a middle of something and just "git rebase --quit" :P
> >>
> >> Of course with git-stash (*) and git-worktree, I guess there's little
> >> reason to just switch away from a something-in-progress worktree. I'll
> >> try to implement this in the next round, unless someone objects.
> >
> > No objection here; I like this idea.
> >

Keeping this hunk since it's now relevant to the comment below...

> >>>> +-f::
> >>>> +--force::
> >>>> +     Proceed even if the index or the working tree differs from
> >>>> +     HEAD. Both the index and working tree are restored to match
> >>>> +     the switching target. This is used to throw away local
> >>>> +     changes.
> >>>
> >>> I'd always thought that --force meant "throw away my local changes if
> >>> they conflict with the new branch" not "throw them away regardless"
> >>> (which is better as it is deterministic). Maybe we can come up with a
> >>> clearer name here --discard-changes? At the moment --force does not
> >>> throw away conflicts properly (see the script below in my comments about
> >>> --merge).
> >>
> >> Yeah if you want to redefine --force, now is a very good time.
> >> Personally I'd rather have separate options than the "one catch all"
> >> --force (or worse, multiple of --force). I'll leave this for the
> >> community to decide.
> >>
> >> Adding Elijah too. He also had some concern about "git restore
> >> --force". Maybe he's interested in this as well.
> >
> > I like Phillip's suggestion of --discard-changes.  I also like how he
> > came up with a simple testcase showing one bug each with checkout's
> > current -m and -f handling; we should fix those.
>
> With regard to discarding conflicts, do we want it to clear up any state
> associated with the conflicts (like reset)? They rarely happen in
> isolation, there's a MERGE_HEAD or CHERRY_PICK_HEAD etc. I'm not sure
> what it should do in the middle of a rebase or when cherry-picking a
> range of commits. I think it would be surprising if it was the
> equivalent of rebase/cherry-pick --quit but just clearing the conflicts
> in those contexts may not be very useful in practice.

You already suggested above (outside the context of --discard-changes)
that we should just error out if there is some special mid-operation
state (be it from a merge, cherry-pick, rebase, or bisect).  The user
can then manually resolve the operation first, or, perhaps use a
special override to force the switch command to proceed despite the
presence of mid-operation state.

Personally, I'm leaning towards --discard-changes operating within
that same context; I think that mid-operation special state should
require a more explicit and operation-specific step to remove (e.g.
rebase --quit).