Re: git bisect bad @

From: Ramkumar Ramachandra <r@artagnon.com>
Date: Jan 9, 2022, 20:48 UTC
Message-ID: <fead25d6-6f5f-487a-ad4c-0657fe9785fd@www.fastmail.com>
In-Reply-To: <xmqqilus3ctf.fsf@gitster.g>

Hi,

Junio C Hamano wrote:

Show 9 quoted lines

> So, perhaps there is something you are not quite telling us,
> e.g. your problem happens during a replay an old bisect session
> after HEAD has moved---if we had a bug that records symbolic object
> names in the replay log, it may produce a nonsense result in such a
> case (but I doubt that is the case---I am reasonably sure that the
> log also records concrete object names)?
> 
> Perhaps you can try again with a better minimum reproducible
> example?

Indeed, I was a bit naive to assume that bisect didn't rev-parse. I'm happy to report that I've found the minimum reproducible example.

  # on coq.git, for those curious
  $ git bisect start
  $ git bisect bad @
  $ git bisect good V8.14.1
  $ git bisect run bisect.sh # oops!
  Lancement de  'bisect.sh'
  'bisect.sh': bisect.sh: command not found
  La base de fusion ea3595845f5013359b2ba4402f948e454350a74c est mauvaise.
  Cela signifie que le bogue été corrigé entre
  ea3595845f5013359b2ba4402f948e454350a74c et [2e100906d5d0c276335665ffefedb906d21165ca].
  error: la bissection a échoué : 'git bisect--helper --bisect-state (null)' a retourné le code erreur -3
  $ git bisect run ./bisect.sh # let's try again!
  # churn ... build ... test
  Cela signifie que le bogue été corrigé entre ea3595845f5013359b2ba4402f948e454350a74c et 
  [2e100906d5d0c276335665ffefedb906d21165ca ea3595845f5013359b2ba4402f948e454350a74c].
  error: la bissection a échoué : 'git bisect--helper --bisect-state (null)' a retourné le code erreur -3

In all three of my runs, there was never a straightforward non-erroring sequence of git-bisect invocations (although my terminal history is lost). Perhaps git-bisect can be hardened a bit, instead of needlessly punishing the user with a long build + test that doesn't lead anywhere?

Warm regards, Ram