Re: [PATCH 0/6][Outreachy] commit: Implementation of "amend!" commit

Charvi Mendiratta [off-list ref] writes:

This patch series teaches `git commit --fixup` to create "amend!" commit
as an alternative that works with `git rebase --autosquash`. It allows to
fixup both the content and the commit message of the specified commit.
Here we add two suboptions to the `--fixup`, first `amend` suboption that
creates an "amend!" commit. It takes the staged changes and also allows to
edit the commit message of the commit we are fixing.
Example usuage:
git commit --fixup=amend:<commit>

Secondly, `reword` suboption that creates an empty "amend!" commit i.e it
ignores the staged changes and only allows to reword/edit the commit message
of the commit we are fixing.
Example usuage:
git commit --fixup=reword:<commit>

We used to have only --fixup that was meant to squeeze in minor
corrections to the contents recorded, and it kept the log message
of the original commit intact.

Now we have two other ways, --fixup=reword that is meant to correct
only the log message while keeping the contents intact from the
original, and --fixup=amend that is meant to allow users to do both.
They are nice additions to our toolbox.

While trying to use the --fixup=amend myself to "touch up" somebody
else's work today, another thing that we did not discuss so far came
to my mind (sorry, if this was discussed and resolved in your
previous discussions with other reviewers).  What should we do to
the authorship?

For the original --fixup, it is reasonably obvious that the original
authorship should be kept, as the intended use case is to make a
small tweak that does not change the intention of the commit in any
way (and that is why the log message from the original is kept), and
with --fixup=reword, it would probably be the same (the contents
were written by the original author alone, and the person fixing-up
is not changing only the log message).  So these two have a
reasonably good default model for the authorship information for the
final outcome: the original authorship should be kept (of course,
the user can easily take over the authorship later with "git commit
--amend --reset-author" perhaps run as part of "rebase -i", if the
contribution is significant enough to deserve the transfer of the
authorship).

But I am not sure what the default behaviour for the authorship when
--fixup=amend:<commit> is used to update somebody else's commit.  I
think it is OK to leave it to whatever the code happens to do right
now (simply because I have no strong reason to vote for either way
between keeping the original and letting the amending user take it
over), but I think it should be documented what happens in each
case.

Thanks.

On Wed, 24 Feb 2021 at 01:25, Junio C Hamano [off-list ref] wrote:

[...]

We used to have only --fixup that was meant to squeeze in minor
corrections to the contents recorded, and it kept the log message
of the original commit intact.

Now we have two other ways, --fixup=reword that is meant to correct
only the log message while keeping the contents intact from the
original, and --fixup=amend that is meant to allow users to do both.
They are nice additions to our toolbox.

While trying to use the --fixup=amend myself to "touch up" somebody
else's work today, another thing that we did not discuss so far came
to my mind (sorry, if this was discussed and resolved in your
previous discussions with other reviewers).  What should we do to
the authorship?

Yes, for the authorship similar to `--fixup`, when used with suboptions
`amend` or `reword`, it keeps the original authorship.

For the original --fixup, it is reasonably obvious that the original
authorship should be kept, as the intended use case is to make a
small tweak that does not change the intention of the commit in any
way (and that is why the log message from the original is kept), and
with --fixup=reword, it would probably be the same (the contents
were written by the original author alone, and the person fixing-up
is not changing only the log message).  So these two have a
reasonably good default model for the authorship information for the
final outcome: the original authorship should be kept (of course,
the user can easily take over the authorship later with "git commit
--amend --reset-author" perhaps run as part of "rebase -i", if the
contribution is significant enough to deserve the transfer of the
authorship).

But I am not sure what the default behaviour for the authorship when
--fixup=amend:<commit> is used to update somebody else's commit.  I
think it is OK to leave it to whatever the code happens to do right
now (simply because I have no strong reason to vote for either way
between keeping the original and letting the amending user take it
over), but I think it should be documented what happens in each
case.

Okay, I agree. We have included in the tests where we check both the
resulting commit message and the author details  but yes I will document
it as well.

Thanks and Regards,
Charvi