Re: worktree add already exists

[Duy Nguyen <pclouds@gmail.com>]

On Sun, Jun 2, 2019 at 2:11 PM Eric Sunshine <sunshine@sunshineco.com> wrote:
>
> On Mon, May 27, 2019 at 11:32 AM Ingo Wolf <ingo.wolf@gmx.de> wrote:
> > $ ls -a barework
> > ./  ../  test.txt
> > $ git -C bare worktree add --no-checkout ../barework
> > Preparing worktree (new branch 'barework')
> > fatal: '../barework' already exists
> > $ git -C bare branch
> >    barework
> > * master
> > Why this doesn't just work and if not why is barework branch made then,
> > why at all ?
>
> It is by design that "git worktree add" (in general) fails if the
> target directory already exists and is non-empty. This is consistent
> with how "git clone" behaves. As for why your particular use-case
> isn't directly supported, it's likely that nobody has yet asked for
> it, and nobody thought about this particular case when --no-checkout
> was added (which came some time after basic "git worktree add" itself
> was implemented).
>
> It is an accident of implementation that the new branch gets created
> before "git worktree add" errors out due to the existing non-empty
> directory (and, likely, nobody complained about it, so it went
> unnoticed). This particular issue probably can be easily fixed now
> that the logic for checking if the target directory can be a valid
> worktree has been factored out of the code which actually creates the
> new directory[1].
>
> [1]: 45059e6468 (worktree: prepare for more checks of whether path can
> become worktree, 2018-08-28)
>
> > I would like to attach an existing dir to git (make it a workdir) and
> > then update the index with git reset and checkin the differences.
>
> I haven't thought through the possible ramifications, but the actual
> implementation might be as simple as changing this code in
> builtin/worktree.c:validate_worktree_add():
>
>     if (file_exists(path) && !is_empty_dir(path))
>         die(_("'%s' already exists"), path);
>
> to:
>
>     if (opts->checkout && file_exists(path) && !is_empty_dir(path))
>         die(_("'%s' already exists"), path);
>
> or something.

Coming from "git clone" background I would still expect --no-checkout
to abort on non-empty directory (i.e. we always start at a good known
state). Maybe another option can be used in combination with
--no-checkout for this. And do we want the same option in "git clone"?
-- 
Duy