GNU bug report logs - #16848
diff reports a diff on identical lines

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Vincent Lefevre <vincent <at> vinc17.net>
To: bug-diffutils <at> gnu.org
Subject: diff reports a diff on identical lines
Date: Sun, 23 Feb 2014 03:52:48 +0100

[Message part 1 (text/plain, inline)]

On some pair of files, "diff" reports a diff on identical lines.
See the attached archive. At line 1272 of "diff -u out1 out2":

@@ -137681,90 +138934,186 @@
 26659
 468
 462
-26946
+26946
+470
+814
+815
[...]

This chunk shouldn't contain:

-26946
+26946

There's the same problem without the "-u" option.

-- 
Vincent Lefèvre <vincent <at> vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)

[bug.tar.xz (application/octet-stream, attachment)]

Message #8 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Vincent Lefevre <vincent <at> vinc17.net>
To: bug-diffutils <at> gnu.org
Subject: Re: diff reports a diff on identical lines
Date: Sun, 23 Feb 2014 03:55:44 +0100

On 2014-02-23 03:52:48 +0100, Vincent Lefevre wrote:
> On some pair of files, "diff" reports a diff on identical lines.
> See the attached archive. At line 1272 of "diff -u out1 out2":
[...]

I forgot: this happens with diff 3.3 under Debian/unstable.

-- 
Vincent Lefèvre <vincent <at> vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)

Message #11 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Eric Deplagne <Eric <at> Deplagne.name>
To: bug-diffutils <at> gnu.org
Subject: Re: [bug-diffutils] bug#16848: diff reports a diff on identical lines
Date: Sun, 23 Feb 2014 07:24:31 +0100

[Message part 1 (text/plain, inline)]

On Sun, 23 Feb 2014 03:52:48 +0100, Vincent Lefevre wrote:
> On some pair of files, "diff" reports a diff on identical lines.
> See the attached archive. At line 1272 of "diff -u out1 out2":
> 
> @@ -137681,90 +138934,186 @@
>  26659
>  468
>  462
> -26946
> +26946
> +470
> +814
> +815
> [...]
> 
> This chunk shouldn't contain:
> 
> -26946
> +26946
> 
> There's the same problem without the "-u" option.

  Some whitespace diff ?

-- 
  Eric Deplagne

[signature.asc (application/pgp-signature, inline)]

Message #16 received at 16848-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Vincent Lefevre <vincent <at> vinc17.net>, 16848-done <at> debbugs.gnu.org
Cc: Gnulib bugs <bug-gnulib <at> gnu.org>
Subject: Re: [bug-diffutils] bug#16848: diff reports a diff on identical lines
Date: Sun, 23 Feb 2014 22:59:40 -0800

[Message part 1 (text/plain, inline)]

Thanks for the bug report.

I applied the attached three patches; the first is to gnulib and changes 
gnulib's diffseq module to handle that case better, the second is to 
diffutils and brings diffutils up to the latest gnulib, and the third is 
also to diffutils and makes diffutils compatible with the new gnulib in 
order to use the fix.  I'll CC: this to bug-gnulib.  The fix works for 
me so I'm marking this bug as fixed, but if it still doesn't work for 
you I can reopen it.

[diffseq.patch (text/plain, attachment)]

[0001-build-update-gnulib-submodule-to-latest.patch (text/plain, attachment)]

[0002-diff-remove-TOO_EXPENSIVE-heuristic.patch (text/plain, attachment)]

Message #19 received at 16848-done <at> debbugs.gnu.org (full text, mbox):

From: Jim Meyering <jim <at> meyering.net>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 16848-done <at> debbugs.gnu.org, Gnulib bugs <bug-gnulib <at> gnu.org>,
 Vincent Lefevre <vincent <at> vinc17.net>
Subject: Re: [bug-diffutils] bug#16848: diff reports a diff on identical lines
Date: Mon, 24 Feb 2014 11:31:38 -0800

On Sun, Feb 23, 2014 at 10:59 PM, Paul Eggert <eggert <at> cs.ucla.edu> wrote:
> Thanks for the bug report.
>
> I applied the attached three patches; the first is to gnulib and changes
> gnulib's diffseq module to handle that case better, the second is to
> diffutils and brings diffutils up to the latest gnulib, and the third is
> also to diffutils and makes diffutils compatible with the new gnulib in
> order to use the fix.  I'll CC: this to bug-gnulib.  The fix works for me so
> I'm marking this bug as fixed, but if it still doesn't work for you I can
> reopen it.

Great!  Thanks a lot, Paul.
If you find the time, would you please also add a test case like the
one Vincent posted?

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