threads / bug / 34284
Subject: [BUG] rebase should desambiguate abbreviated hashes before starting
I just ran into a funny edge-case when doing a long rebase: one of the rewritten commits got a sha1 starting with one of the abbreviated sha1's of a commit still to be applied.
As a result, the rebase stopped with a funny-looking "short SHA1 ... was ambiguous", which would not have occured if the shortened sha1's presented to the user were expanded to full sha1's before starting the rebase.
-- Yann Dirson - Bertin Technologies
Re: [BUG] rebase should desambiguate abbreviated hashes before starting
On 27 June 2013 18:55, Yann Dirson <dirson@bertin.fr> wrote:
> I just ran into a funny edge-case when doing a long rebase: one of > the rewritten commits got a sha1 starting with one of the abbreviated > sha1's of a commit still to be applied. > > As a result, the rebase stopped with a funny-looking "short SHA1 ... was > ambiguous", which would not have occured if the shortened sha1's presented > to the user were expanded to full sha1's before starting the rebase.
I do many large rebases, and I have experienced this about a dozen times in the last few years.
I'm not sure that rebase could predict the new hashes without actually creating the prior commits? So maybe the "short" SHA1 is "too short"?
When the rebase stops with this message, my workaround is:
The last (failed) entry is in .git/rebase-merge/done The next todo is the top entry in .git/rebase-merge/git-rebase-todo I enter the short SHA1 in gitk to find the long SHA1. I edit both the above files to move the failed entry back into the top of the todo file, with the long SHA1 And then git rebase --continue
Matthieu MoyRe: [BUG] rebase should desambiguate abbreviated hashes before starting
David <bouncingcats@gmail.com> writes:
> I'm not sure that rebase could predict the new hashes without actually creating > the prior commits? So maybe the "short" SHA1 is "too short"?
It's OK to show the short sha1 to the user, but "git rebase" could and should expand these to complete sha1 right after the editor is closed. I think that's what Yann means.
-- Matthieu Moy http://www-verimag.imag.fr/~moy/
Re: [BUG] rebase should desambiguate abbreviated hashes before starting
On 27 June 2013 21:04, Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> wrote:
> David <bouncingcats@gmail.com> writes: > >> I'm not sure that rebase could predict the new hashes without actually creating >> the prior commits? So maybe the "short" SHA1 is "too short"? > > It's OK to show the short sha1 to the user, but "git rebase" could and > should expand these to complete sha1 right after the editor is closed. I > think that's what Yann means.
Yes. I realised that just after clicking "send". Thanks :)
Junio C HamanoRe: [BUG] rebase should desambiguate abbreviated hashes before starting
Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> writes:
> David <bouncingcats@gmail.com> writes: > >> I'm not sure that rebase could predict the new hashes without actually creating >> the prior commits? So maybe the "short" SHA1 is "too short"? > > It's OK to show the short sha1 to the user, but "git rebase" could and > should expand these to complete sha1 right after the editor is closed. I > think that's what Yann means.
Yes, any "short" is by definition "too short". I agree that it is OK to show short one in "rebase -i" instruction sheet, as they are uniquely generated before the actual replaying of commits begins, and it is a sensible thing to do to convert them to the full form before starting to do the real work.
It could be something as simple like this (not tested).
git-rebase--interactive.sh | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+)
diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh index f953d8d..6766b44 100644 --- a/git-rebase--interactive.sh +++ b/git-rebase--interactive.sh @@ -678,6 +678,23 @@ skip_unnecessary_picks () { die "Could not skip unnecessary pick commands" } +# expand shortened commit object name to the full form +expand_todo_commit_names () { + while read -r command rest + do + case "$command" in + '#'*) + ;; + *) + sha1=$(git rev-parse --verify --quiet ${rest%% *}) + rest="$sha1 ${rest#* }" + ;; + esac + printf '%s\n' "$command${rest:+ }$rest" + done <"$todo" >"$todo.new" && + mv -f "$todo.new" "$todo" +} + # Rearrange the todo list that has both "pick sha1 msg" and # "pick sha1 fixup!/squash! msg" appears in it so that the latter # comes immediately after the former, and change "pick" to @@ -979,6 +996,8 @@ git_sequence_editor "$todo" || has_action "$todo" || die_abort "Nothing to do" +expand_todo_commit_names + test -d "$rewritten" || test -n "$force_rebase" || skip_unnecessary_picks output git checkout $onto || die_abort "could not detach HEAD"
Junio C HamanoRe: [BUG] rebase should desambiguate abbreviated hashes before starting
Junio C Hamano <gitster@pobox.com> writes:
> It could be something as simple like this (not tested).
>
> git-rebase--interactive.sh | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/git-rebase--interactive.sh b/git-rebase--interactive.sh
> index f953d8d..6766b44 100644
> --- a/git-rebase--interactive.sh
> +++ b/git-rebase--interactive.sh
> @@ -678,6 +678,23 @@ skip_unnecessary_picks () {
> die "Could not skip unnecessary pick commands"
> }
>
> +# expand shortened commit object name to the full form
> +expand_todo_commit_names () {
> + while read -r command rest
> + do
> + case "$command" in
> + '#'*)
> + ;;
> + *)
> + sha1=$(git rev-parse --verify --quiet ${rest%% *})
> + rest="$sha1 ${rest#* }"
> + ;;In case somebody wants to polish it to a real patch, this part should at least be:
case "$command" in
'#'* | exec)
# Be careful for oddball commands like 'exec'
# that do not have a short-SHA-1 at the beginning
# of $rest.
;;
*)
sha1=$(git rev-parse --verify --quiet ${rest%% *}) &&
rest="$sha1 ${rest#* }"
;;