From: Sergey Organov <sorganov@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH] diff: fix behaviour of the "-s" option
Date: Fri, 05 May 2023 11:32:51 +0300 [thread overview]
Message-ID: <87sfcbyy8c.fsf@osv.gnss.ru> (raw)
In-Reply-To: <xmqqfs8bith1.fsf_-_@gitster.g> (Junio C. Hamano's message of "Thu, 04 May 2023 16:10:02 -0700")
Junio C Hamano <gitster@pobox.com> writes:
> Junio C Hamano <gitster@pobox.com> writes:
>
>> I haven't run any tests (not just your new one, but existing ones)
>> but ...
>
> And of course, not writing tests fails to even realize that the bug
> has two components, "-s" failing to clear the bits previously set,
> and other options not clearing the bit set by "-s".
>
> This version may still be rough, but at least the full test suite
> has been run with it, so I have a bit more confidence than the
> earlier one (which may not mean much).
>
> ------- >8 ------------- >8 ------------- >8 -------------
> Sergey Organov noticed and reported "--patch --no-patch --raw"
> behaves differently from "--raw". It turns out there are a few
> interesting bugs in the implementation and documentation.
>
> * First, the documentation for "--no-patch" was unclear that it
> could be read to mean "--no-patch" countermands an earlier
> "--patch" but not other things. The intention of "--no-patch"
> ever since it was introduced at d09cd15d (diff: allow --no-patch
> as synonym for -s, 2013-07-16) was to serve as a synonym for
> "-s", so "--raw --patch --no-patch" should have produced no
> output, but it can be (mis)read to allow showing only "--raw"
> output.
>
> * Then the interaction between "-s" and other format options were
> poorly implemented. Modern versions of Git uses one bit each to
> represent formatting options like "--patch", "--stat" in a single
> output_format word, but for historical reasons, "-s" also is
> represented as another bit in the same word. This allows two
> interesting bugs to happen, and we have both.
>
> (1) After setting a format bit, then setting NO_OUTPUT with "-s",
> the code to process another "--<format>" option drops the
> NO_OUTPUT bit to allow output to be shown again. However,
> the code to handle "-s" only set NO_OUTPUT without unsetting
> format bits set earlier, so the earlier format bit got
> revealed upon seeing the second "--<format>" option. THis is
> the problem Sergey observed.
>
> (2) After setting NO_OUTPUT with "-s", code to process
> "--<format>" option can forget to unset NO_OUTPUT, leaving
> the command still silent.
>
> It is tempting to change the meaning of "--no-patch" to mean
> "disable only the patch format output" and reimplement "-s" as "not
> showing anything", but it would be an end-user visible change in
> behaviour. Let's fix the interactions of these bits to first make
> "-s" work as intended.
>
> The fix is conceptually very simple.
>
> * Whenever we set DIFF_FORMAT_FOO becasuse we saw the "--foo"
> option (e.g. DIFF_FORMAT_RAW is set when the "--raw" option is
> given), we make sure we drop DIFF_FORMAT_NO_OUTPUT. We forgot to
> do so in some of the options and caused (2) above.
>
> * When processing "-s" option, we should not just set
> DIFF_FORMAT_NO_OUTPUT bit, but clear other DIFF_FORMAT_* bits.
> We didn't do so and retained format bits set by options
> previously seen, causing (1) above.
Sounds good to me. Doesn't this makes DIFF_FORMAT_NO_OUTPUT obsolete as
well, I wonder, as absence of any output bits effectively means "no
output"?
Thanks,
-- Sergey Organov
next prev parent reply other threads:[~2023-05-05 8:33 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-03 13:41 [PATCH] t4013: add expected failure for "log --patch --no-patch" Sergey Organov
2023-05-03 16:57 ` Junio C Hamano
2023-05-03 17:31 ` Sergey Organov
2023-05-03 18:07 ` Junio C Hamano
2023-05-03 18:32 ` Felipe Contreras
2023-05-03 19:49 ` Sergey Organov
2023-05-04 15:50 ` Junio C Hamano
2023-05-04 18:24 ` Sergey Organov
2023-05-04 20:53 ` Junio C Hamano
2023-05-04 21:37 ` Re* " Junio C Hamano
2023-05-04 23:10 ` [PATCH] diff: fix behaviour of the "-s" option Junio C Hamano
2023-05-05 5:28 ` Junio C Hamano
2023-05-05 16:51 ` Junio C Hamano
2023-05-09 1:16 ` Felipe Contreras
2023-05-05 8:32 ` Sergey Organov [this message]
2023-05-05 16:31 ` Junio C Hamano
2023-05-05 17:07 ` Sergey Organov
2023-05-05 16:59 ` [PATCH v2] diff: fix interaction between the "-s" option and other options Junio C Hamano
2023-05-05 17:41 ` Eric Sunshine
2023-05-05 19:01 ` Junio C Hamano
2023-05-05 21:19 ` [PATCH 0/2] dirstat: leakfix Junio C Hamano
2023-05-05 21:19 ` [PATCH 1/2] diff: refactor common tail part of dirstat computation Junio C Hamano
2023-05-05 21:19 ` [PATCH 2/2] diff: plug leaks in dirstat Junio C Hamano
2023-05-09 0:38 ` [PATCH v2] diff: fix interaction between the "-s" option and other options Felipe Contreras
2023-05-09 1:22 ` Junio C Hamano
2023-05-09 3:50 ` Felipe Contreras
2023-05-10 4:26 ` Junio C Hamano
2023-05-10 23:16 ` Felipe Contreras
2023-05-10 23:41 ` Felipe Contreras
2023-05-11 1:25 ` Jeff King
2023-05-13 3:07 ` Felipe Contreras
2023-05-11 1:50 ` Junio C Hamano
2023-05-13 5:32 ` Felipe Contreras
2023-05-09 1:34 ` [PATCH] t4013: add expected failure for "log --patch --no-patch" Felipe Contreras
2023-05-10 13:54 ` Sergey Organov
2023-05-10 21:54 ` Felipe Contreras
2023-05-09 1:03 ` Felipe Contreras
2023-05-04 18:07 ` Junio C Hamano
2023-05-04 18:26 ` Sergey Organov
2023-05-09 1:07 ` Felipe Contreras
2023-05-10 13:40 ` Sergey Organov
2023-05-10 21:39 ` Felipe Contreras
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87sfcbyy8c.fsf@osv.gnss.ru \
--to=sorganov@gmail.com \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).