Re: [PATCH v2] checkout/switch: disallow checking out same branch in multiple worktrees

[Carlo Arenas <carenas@gmail.com>]

On Tue, Jan 17, 2023 at 10:52 PM Junio C Hamano <gitster@pobox.com> wrote:
>
> Carlo Marcelo Arenas Belón  <carenas@gmail.com> writes:
>
> > As reflected on the tests, this will change the behaviour of those
> > commands when they are invoked in a worktree that has that requested
> > branch checked out, as that matches the logic used by branch, is safer
> > (assuming both commands are user facing) and can be overriden with an
> > existing flag.
>
> ... meaning you can "--force", or something else?  Allowing an
> existing option to be used as the safety valve does make sense,
> especially if the option is something users are already familiar
> with (like "--force") and naturally expected to work.

the following is the way to override:

$ git checkout --ignore-other-worktrees -B foo

> There might need an documentation update.  Back when "checkout -b"
> and "branch" was written, there wasn't "multiple worktrees connected
> to a single repository" hence there was no need to provide safety
> against checking out the same branch in two different places.  "git
> branch" might have learned to give that safety while "git checkout
> -b", which _ought_ to be equivalent to "git branch" followed by "git
> checkout", might have forgot to do so.

Not sure if it was originally forgotten, but it is definitely working now;
this change only fixes the uppercase (-B) version.

> After this change, it may
> still be correct to say that "checkout -b" is equivalent to "branch"
> followed by "checkout", but if the documentation to "branch" talks
> about this safety, it probably deserves to be mentioned in the
> documentation to "checkout -b", as well, if only to give an appropriate
> place to talk about how to override it "with an existing flag".

Interestingly, when the flag was added in 1d0fa898ea (checkout: add
--ignore-other-wortrees, 2015-01-03), it was only added to `checkout`.

`git branch` has no flag and will die even when `-f` is used

Carlo