Subject: Re: [PATCH] branch: let '--edit-description' default to rebased branch during rebase

From: SZEDER Gábor <[email-masked]>
Date: Fri, 24 Jan 2020 23:41:13 +0100

On Sun, Jan 12, 2020 at 08:59:04PM -0500, Eric Sunshine wrote:
> On Sun, Jan 12, 2020 at 7:14 AM SZEDER Gábor <[email-masked]> wrote:
> > On Sat, Jan 11, 2020 at 08:27:11PM -0500, Eric Sunshine wrote:
> > > Taking a deeper look at the code, I'm wondering it would make more
> > > sense to call wt_status_get_state(), which handles 'rebase' and
> > > 'bisect'. Is there a reason that you limited this check to only
> > > 'rebase'?
> >
> > What branch name does wt_status_get_state() return while bisecting?
> > The branch where I started from?  Because that's what 'git status'
> > shows:
> > But am I really on that branch?  Does it really makes sense to edit
> > the description of 'mybranch' by default while bisecting through an
> > old revision range?  I do not think so.
> 
> It's not clear what downside you are pointing out; i.e. why would it
> be a bad thing to be able to set the branch description even while
> bisecting -- especially since `git status` affirms that it knows the
> branch?

No, during a bisect operation 'git status' knows the branch where I
_was_ when I started bisecting, and where a 'git bisect reset' will
eventually bring me back when I'm finished, and that has no relation
whatsoever to the revision range that I'm bisecting.

Consider this case:

  $ git checkout --orphan unrelated-history
  Switched to a new branch 'unrelated-history'
  $ git commit -m "test"
  [unrelated-history (root-commit) 639b9d1047] test
  <...>
  $ git bisect start v2.25.0 v2.24.0
  Bisecting: 361 revisions left to test after this (roughly 9 steps)
  [7034cd094bda4edbcdff7fad1a28fcaaf9b9a040] Sync with Git 2.24.1
  $ git status 
  HEAD detached at 7034cd094b
  You are currently bisecting, started from branch 'unrelated-history'.
    (use "git bisect reset" to get back to the original branch)
  
  nothing to commit, working tree clean

I can't possible be on branch 'unrelated-history' during that
bisection.

OTOH, while during a rebase we are technically on a detached HEAD as
well, that rebase operation is all about constructing the new history
of the rebased branch, and once finished that branch will be updated
to point to the tip of the new history, thus it will include all the
commits created while on the detached HEAD.  Therefore, it makes sense
conceptually to treat it as if we were on the rebased branch.  That's
why it makes sense to display the name of the rebased branch in the
Bash prompt, and that's why I think it makes sense to default to edit
the description of the rebased branch without explicitly naming it.

With bisect that just doesn't make sense.