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

From: Matthieu Moy <matthieu.moy@univ-lyon1.fr>
Date: May 12, 2023, 08:15 UTC
Message-ID: <4f713a29-1a34-2f71-ee54-c01020be903a@univ-lyon1.fr>
In-Reply-To: <5bb24e0208dd4a8ca5f6697d578f3ae0@SAMBXP02.univ-lyon1.fr>

[ 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:

Show 15 quoted lines

> 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/

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.

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

Cheers,

-- 
Matthieu Moy
https://matthieu-moy.fr/