Re: [PATCH v2] rebase: write script before initializing state

[Phillip Wood <phillip.wood123@gmail.com>]

On 11/07/2025 22:25, Junio C Hamano wrote:
> Øystein Walle <oystwa@gmail.com> writes:
> 
>> If rebase.instructionFormat is invalid the repository is left in a
>> strange state when the interactive rebase fails. `git status` outputs
>> both the same as it would have in the normal case *and* something
>> related to the interactive rebase:
>>
>>      $ git -c rebase.instructionFormat=blah rebase -i
>>      fatal: invalid --pretty format: blah
>>      $ git status
>>      On branch master
>>      Your branch is ahead of 'upstream/master' by 1 commit.
>>        (use "git push" to publish your local commits)
>>
>>      git-rebase-todo is missing.
>>      No commands done.
>>      No commands remaining.
>>      You are currently editing a commit while rebasing branch 'master' on '8db3019401'.
>>        (use "git commit --amend" to amend the current commit)
>>        (use "git rebase --continue" once you are satisfied with your changes)
>>
>> get_commit_format() calls die() on failure so we cannot handle the error
>> gracefully. By attempting to write the rebase script before initializing
>> the state this bad state can be avoided.
>>
>> Signed-off-by: Øystein Walle <oystwa@gmail.com>
>> ---
>> So sorry for the delay. I saw that the signoff was missing, then saw
>> Phillip's review, decided to think about it and then life happened in
>> the mean time...
> 
> No need to be sorry.  Life happens, indeed.
> 
>> This patch is identical to the first one except it has the missing
>> signoff and a few typos in the commit message corrected. Phillip's
>> suggestions are noted and appreciated but unfortunately I am unable to
>> work on the at the moment. And I do think my patch is at least an
>> improvement albeit perhaps less thorough than it could have been.
> 
> Well, as long as we are making a step in the right direction, such a
> partial improvement gives us a better foundation for somebody else
> to further build on.

I don't think this is a better (or worse) foundation for future 
improvement as solving this when the user passes '--autostash' needs a 
different approach. When that option is given we create the state 
directory earlier so moving when we call init_basic_state() has no effect.

>  It does not look like that this patch would
> make it harder to later give us a more thorough solution.

I agree with this. I don't think this change makes fixing the 
'--autostash' case harder, but fixing that case makes this change 
redundant.
> Thanks for working on the topic.

Yes, thank you Øystein

Phillip

>>   builtin/rebase.c             | 42 ++++++++++++++++++------------------
>>   t/t3415-rebase-autosquash.sh | 10 +++++++++
>>   2 files changed, 31 insertions(+), 21 deletions(-)
>>
>> diff --git a/builtin/rebase.c b/builtin/rebase.c
>> index 2e8c4ee678..8139816417 100644
>> --- a/builtin/rebase.c
>> +++ b/builtin/rebase.c
>> @@ -293,15 +293,6 @@ static int do_interactive_rebase(struct rebase_options *opts, unsigned flags)
>>   				&revisions, &shortrevisions))
>>   		goto cleanup;
>>   
>> -	if (init_basic_state(&replay,
>> -			     opts->head_name ? opts->head_name : "detached HEAD",
>> -			     opts->onto, &opts->orig_head->object.oid))
>> -		goto cleanup;
>> -
>> -	if (!opts->upstream && opts->squash_onto)
>> -		write_file(path_squash_onto(), "%s\n",
>> -			   oid_to_hex(opts->squash_onto));
>> -
>>   	strvec_pushl(&make_script_args, "", revisions, NULL);
>>   	if (opts->restrict_revision)
>>   		strvec_pushf(&make_script_args, "^%s",
>> @@ -310,21 +301,30 @@ static int do_interactive_rebase(struct rebase_options *opts, unsigned flags)
>>   	ret = sequencer_make_script(the_repository, &todo_list.buf,
>>   				    make_script_args.nr, make_script_args.v,
>>   				    flags);
>> -
>> -	if (ret)
>> +	if (ret) {
>>   		error(_("could not generate todo list"));
>> -	else {
>> -		discard_index(the_repository->index);
>> -		if (todo_list_parse_insn_buffer(the_repository, &replay,
>> -						todo_list.buf.buf, &todo_list))
>> -			BUG("unusable todo list");
>> -
>> -		ret = complete_action(the_repository, &replay, flags,
>> -			shortrevisions, opts->onto_name, opts->onto,
>> -			&opts->orig_head->object.oid, &opts->exec,
>> -			opts->autosquash, opts->update_refs, &todo_list);
>> +		goto cleanup;
>>   	}
>>   
>> +	if (init_basic_state(&replay,
>> +			     opts->head_name ? opts->head_name : "detached HEAD",
>> +			     opts->onto, &opts->orig_head->object.oid))
>> +		goto cleanup;
>> +
>> +	if (!opts->upstream && opts->squash_onto)
>> +		write_file(path_squash_onto(), "%s\n",
>> +			   oid_to_hex(opts->squash_onto));
>> +
>> +	discard_index(the_repository->index);
>> +	if (todo_list_parse_insn_buffer(the_repository, &replay,
>> +					todo_list.buf.buf, &todo_list))
>> +		BUG("unusable todo list");
>> +
>> +	ret = complete_action(the_repository, &replay, flags,
>> +		shortrevisions, opts->onto_name, opts->onto,
>> +		&opts->orig_head->object.oid, &opts->exec,
>> +		opts->autosquash, opts->update_refs, &todo_list);
>> +
>>   cleanup:
>>   	replay_opts_release(&replay);
>>   	free(revisions);
>> diff --git a/t/t3415-rebase-autosquash.sh b/t/t3415-rebase-autosquash.sh
>> index 26b42a526a..5d093e3a7a 100755
>> --- a/t/t3415-rebase-autosquash.sh
>> +++ b/t/t3415-rebase-autosquash.sh
>> @@ -394,6 +394,16 @@ test_expect_success 'autosquash with empty custom instructionFormat' '
>>   	)
>>   '
>>   
>> +test_expect_success 'autosquash with invalid custom instructionFormat' '
>> +	git reset --hard base &&
>> +	test_commit invalid-instructionFormat-test &&
>> +	(
>> +		test_must_fail git -c rebase.instructionFormat=blah \
>> +			rebase --autosquash  --force-rebase -i HEAD^ &&
>> +		test_path_is_missing .git/rebase-merge
>> +	)
>> +'
>> +
>>   set_backup_editor () {
>>   	write_script backup-editor.sh <<-\EOF
>>   	cp "$1" .git/backup-"$(basename "$1")"