On Fri, Jun 19, 2020 at 01:31:42PM -0700, Junio C Hamano wrote:
> Sergey Organov <sorganov@xxxxxxxxx> writes:
>
> >> But then if you do
> >>
> >> $ git reflog expire --expire=now refs/heads/newbranch
> >> $ git commit --allow=empty -m two
> >> $ git show -s newbranch@{1}
> >> ...
> >> And it is unintuitive. It is understandable to the users that all
> >> the ref history before "reflog expire" is lost---it was what the end
> >> user asked Git to do. But after creating one commit on the state
> >> (or do anything else that moves the ref) and finding it regrettable,
> >> "git reset --hard @{1}" should be a viable way to recover from the
> >> mistake made _after_ the reflog entries were expired.
>
> And the expiration does not have to be --expire=now; what happens
> more often is when I expire entries older than (say) a week, the
> reflog for a topic branch that hasn't seen any activity may become
> empty. Then I "git am" the new round on the same base, compare and
> then update, perhaps like so:
>
> ... git reflog expire has emptied the log for so/topic ...
> $ git checkout so/topic
> $ git log master.. ;# remind myself what the previous round had
> $ git checkout master... ;# detach HEAD at the previous base
> $ git am -s ./+so-v2-topic ;# apply
> $ git range-diff @{-1}... ;# compare
> $ git checkout -B so/topic
>
> Now, I'm used to see this work after the above:
>
> $ git range-diff @{1}... ;# compare again just to be sure
>
> but because there is only one entry in the reflog, which was created
> when the last "checkout -B" updated the so/topic branch, "there is
> only one entry" error kicks in.
>
> > Makes sense. The first solution that comes to mind is immediately record
> > current state after "reflog expire", so that there will be 2 entries for
> > the case in question.
>
> Perhaps.
>
> Or we could change the lookup side to use the value of the ref
> itself when asked for @{0}, and use the "old" side of the only entry
> when asked for @{1}. That way, we do not need to play games with an
> artificial entry at all, which may be a better solution.
Or more generally, use the old side from @{n} when asked for @{n+1} when
there are only n entries in the reflog.
Mike
