Re: [PATCH v3 17/21] switch: no implicit dwim, use --guess to dwim

[Junio C Hamano <gitster@pobox.com>]

Eric Sunshine <sunshine@sunshineco.com> writes:

> With git-checkout, it's very easy to accidentally get into a detached
> HEAD state, so it makes some sense to protect newcomers, by default,
> from that accident in git-switch. However, auto-creation of a new
> local branch is not, for a couple reasons, nearly so weighty a matter.
> First, in many cases it may be less likely to happen since it requires
> presence of a corresponding remote tracking branch. Second, it's
> intuitively easy to recover from it: when git-switch reports that it
> created a new branch, though perhaps surprising, the user would
> naturally know to look for a command to "delete a branch".
>
> And, unlike a detached HEAD, which newcomers may mistakenly believe
> lead to irretrievable loss of work, an unexpected branch creation
> carries no such penalty, perceived or real.

I suspect that it actually cuts both ways.  An auto-vivified local
branch 'foo' that happens to have the same name as 'origin/foo' is
still a different line of history UNLESS the user makes sure the
divergence is reconciled with "push" and "pull" (possibly configured
to "pull --rebase", but that is a secondary detail that depends on
the workflow).  Even when 'switch' reports that it created a new
branch, a newcomer would probably not realize that it is "new", and
different from the branch that the remote has.

>> So if it is deemed to be too confusing to dwim in this
>> case, could we add a hint suggesting the command? Something like:
>> "No suitable branch <foo> found, however there is a remote tracking
>> branch <origin/foo> that you can siwtch and create with `git switch
>> --guess foo`" (or maybe the one without guess)?
>
> That could be helpful if git-switch continues to make --no-guess the
> default, but making --guess the default (as it is in git-checkout)
> would likely be even better (for the reasons enumerated above).

I do not have a huge issue with making "--guess" the default, but
then the user may be entitled to help with an advice message when
the command, especially with the implicit "--guess", auto-vivifies a
new local branch based on a remote-tracking branch to stress that
this is a new branch and different from the history the remote side
has.