GNU bug report logs - #46422
'pr' screws up tabstops in multicolumn outpt?

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From: Erik Auerswald <auerswal <at> unix-ag.uni-kl.de>
To: Leonard Janis Robert König <ljrk <at> ljrk.org>
Cc: 46422 <at> debbugs.gnu.org
Subject: bug#46422: [PATCH] Re: bug#46422: 'pr' screws up tabstops in multicolumn outpt?
Date: Sun, 14 Feb 2021 20:22:28 +0100

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

Hi,

On 13.02.21 21:28, Leonard Janis Robert König wrote:
> On Sat, 2021-02-13 at 21:15 +0100, Erik Auerswald wrote:
>> On 13.02.21 19:29, Leonard Janis Robert König wrote:
>>> [...]
>>> That being said, I don't see this exact distinction reflected in
>>> the
>>> code, so perhaps I just misunderstood.
>>
>> Disabling "Tabification" only when "-s" was active is missing.  That
>> resulted in the 2007 bug.  Making the needed special treatment always
>> used fixed the 2007 bug, but broke your use case.
>>
>> That some special treatment is needed and intended can be gleaned
>> from the following comment (with line numbers from pr.c in the
>> current master branch @ 2de30c7350a77b091afa1eb284acdf082c0f6aa5):
>>
>> 1031  /* It's rather pointless to define a TAB separator with column
>> 1032     alignment */

The code after that comment does not disable alignment, but changes
the separator from a TAB to a space.

>> My patch adds the special treatment, since it works both for the 2007
>> bug and this bug (bug#46422).

The attached version 4 of my patch does that in a way that more
clearly shows the intent.  I think this is a better fix for the
2007 bug than commit 553d347d3e08e00ee4f9df520b37c964c3f26e28.
Expanding TABs on input is enabled unless when a single TAB is
used as column separator.  This conforms better to POSIX and
does not introduce the regression that causes the current bug
(bug#46422).

I have added more test cases, because manual testing showed that
the options "-s" and "-s$'\t'" were treated differently by pr.

Using "-s" to activate the default TAB separator should result
in the same output as using "-s$'\t'" to specify one TAB character
as separator, i.e., the default, explicitly.

>>> [...] with the patch my rather obscure (and complex)
>>> use case of printing thousands of lines of code works properly now!
>>
>> Thanks for testing!
> 
> Thanks all to you

May I ask you to test the new patch (v4) as well?

Thanks,
Erik

[coreutils-pr-fix_bug_46422.v4.patch (text/x-patch, attachment)]

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