Re: New orphan worktree?

From: Eric Sunshine <sunshine@sunshineco.com>
Date: Feb 23, 2021, 00:55 UTC
Message-ID: <CAPig+cQxYtw5z_bRQbS6MLgHQM2OTs5oRfpvKSOwZo8GcuwpTg@mail.gmail.com>
In-Reply-To: <87czwr8wou.fsf@evledraar.gmail.com>

On Mon, Feb 22, 2021 at 7:17 PM Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:

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> On Tue, Feb 23 2021, Eric Sunshine wrote:
> > I'm not sure I follow. In git-switch, --orphan does not imply -c even
> > though --orphan also creates a new branch (thus seems to work similar
> > to -c); it is nevertheless mutually-exclusive with -c and -C. The same
> > goes for --orphan in git-branch.
>
> I think we're on the same page with regards to what I meant. I.e. I
> don't see how it makes sense to conflate the type of branch we want
> (orphan or not orphan) with whether we want to clobber that branch or
> not (switch -c or -C, or worktree -b or -B)

I see where you're coming from in viewing --orphan as a modifier of branch creation rather than as a branch-creation option itself. However, as far as UI is concerned, that ship sailed a long time ago, I suppose.

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> > As far as combining --orphan and -C (or -c), I'm not sure how we would
> > arrange that using the existing parse_options() mechanism. It seems
> > too magical and has potential for weird corner cases.
>
> Isn't it just having --orphan be an OPTION_STRING with
> PARSE_OPT_LASTARG_DEFAULT. I.e. to support:
>
>     git switch -b branch --orphan
>     git switch -B branch --orphan
>     git switch --orphan branch
>
> And:
>
>     git worktree add -b branch --orphan
>     git worktree add -B branch --orphan
>
> I didn't test it, just skimmed the code.

I haven't dived into this stuff in a long time, but I'm having trouble convincing myself that it would work out as intended. If I'm reading PARSE_OPT_LASTARG_DEFAULT correctly, `git switch -b <branch> --orphan` would not be the same as `git switch --orphan -b <branch>`, and I don't think it would work at all for git-worktree-add which has additional <path> and <commitish> arguments (i.e. `git worktree add -b <branch> --orphan <path> [<commitish>]`).

Anyhow, as I responded elsewhere to Junio, my present leaning is toward -b, -B, --orphan all being mutually-exclusive branch-creation options, each taking a <branch> argument -- just like they are in git-checkout and git-switch (-c/-C, in this case) -- and allowing --force to overwrite an existing branch (in which case, -B can be viewed as shorthand for `--force -b`).

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> > Since git-worktree doesn't yet support --orphan, we certainly have
> > more leeway and could go with your proposal of having --orphan be
> > boolean and always requiring it to be used in conjunction with -b/-B.
> > However, I'm quite hesitant to take that approach since it breaks with
> > existing precedent in git-branch and git-switch, in which case
> > --orphan takes its own argument (<branch>) and is mutually-exclusive
> > with -b/-B/-c/-C.
>
> In git-branch? Isn't it only git [checkout|switch] that takes --orphan?

Um, yes, I meant git-checkout everywhere I wrote git-branch. Sorry for the confusion.

> I think not having a -B or -C equivalent at all would be preferrable to
> having a --force special-case just to work around the lack of it for
> --orphan.

I'm having trouble wrapping my brain around this statement.