Re: Can we clarify the purpose of `git diff -s`?

From: Junio C Hamano <gitster@pobox.com>
Date: May 12, 2023, 19:21 UTC
Message-ID: <xmqqv8gxpd8r.fsf@gitster.g>
In-Reply-To: <87h6shif6q.fsf@osv.gnss.ru>

Sergey Organov <sorganov@gmail.com> writes:

Show 7 quoted lines

> --patch. Thus, making --no-patch a synonym for -s was a mistake in the
> first place that leaked through review process at that time, and
>
>    git show --format="%ad" --no-patch
>
> will still work the same way even if we fix --no-patch to disable
> --patch only.

Not so fast. I have a show.outputFormat configuration variable to teach builtin/log.c::show_setup_revisions_tweak() to tweak the hardcoded default from DIFF_FORMAT_PATCH to others (primarily because I often find myself doing "git show -p --stat"). Changing "--no-patch" to toggle only "--patch" away will close the door for future improvement like that, and "will still work" is an illusion.

The user needs to be told that "--no-patch" no longer means "-s" and somebody needs to apologize to them that we are deliberately breaking their reliance they held for 10 years, based on what we documented and prepare a smooth transition for them. Until the time when nobody uses "--no-patch" as a synonym for "-s" any longer, such a future improvement would be blocked. And that is another reason why I want to be much more careful about "should --no-patch be changed to mean something other than -s" than "should -s be fixed not to be sticky for some but not all options". The latter is not a documented "feature" and it clearly was a bug that "-s --raw" did not honor "--raw". The former was a documented "feature", even though it may have been a suboptimal one.