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

Matthieu Moy wrote:

[ I apologize for not being more reactive the last few years. I still 
love Git and this ml, but I'm struggling to find time to contribute. ]

On 5/11/23 19:37, Junio C Hamano wrote:

quoted

The behaviour came in the v1.8.4 days with a series that was merged
by e2ecd252 (Merge branch 'mm/diff-no-patch-synonym-to-s',
2013-07-22), which

  * made "--no-patch" a synonym for "-s";

  * fixed "-s --patch", in which the effect of "-s" got stuck and did
    not allow the patch output to be re-enabled again with "--patch";

  * updated documentation to explain "--no-patch" as a synonym for
    "-s".

While it is very clear that the intent of the author was to make it
a synonym for "-s" and not a "feature-wise enable/disable" option,
that is what we've run with for the past 10 years.

That's too old for me to remember exactly my state of mind, but if you 
want to do a bit of archeology, the origin is there:

https://public-inbox.org/git/51E3DC47.70107@googlemail.com/

Yes, I had already sent a link to that thread [1].

Essentially, Stefan Beller was using 'git show --format="%ad"' and 
expecting it to show only the author date, and for merge commits it also 
showed the patch (--cc). I suggested -s and noticed that the option 
wasn't easily discoverable, hence the patch series to better document it 
and add --no-patch as a synonym.

That was my understanding. So the goal was to make the silencing of `git show`
output more accessible.

Probably I did not get all the subtleties of the different kinds of 
outputs. I guess I considered the output of diff to be the one specified 
by --format plus the patch (not considering --raw, --stat & friends), 
hence "get only the output specified by --format" and "disable the 
patch" were synonym to me. Looking more closely, it's rather clear to me 
they are not, and that

   git show --raw --patch --no-patch

should be equivalent to

   git show --raw

Indeed, but at the time such funcionality was not easy to achieve, on the other
hand making `--no-patch` be synonymous with `-s` was easy, so that's the path
that was followed. But that was not the goal, that was a means to an end.

Adding `--silent` as a synonym to `-s` would have also served a similar goal.

I sent a patch to add such `--silent` alias [2], and I also sent a patch to
decouple `--no-patch` from `-s` [3].

All these three keep working as it was originally intended by your patch:

 * git show -s
 * git show --silent
 * git show --no-patch

The only difference is that now these are different:

 * git show --patch --raw --no-patch
 * git show --patch --raw --silent

Which wasn't considered back then.

Cheers.

[1] https://lore.kernel.org/git/645d3122bd1d2_26011a2947a@chronos.notmuch/ (local)
[2] https://lore.kernel.org/git/20230512080339.2186324-7-felipe.contreras@gmail.com/ (local)
[3] https://lore.kernel.org/git/20230512080339.2186324-6-felipe.contreras@gmail.com/ (local)

-- 
Felipe Contreras