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

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Message #47 received at 46422 <at> debbugs.gnu.org (full text, mbox):

From: Leonard Janis Robert König <ljrk <at> ljrk.org>
To: Erik Auerswald <auerswal <at> unix-ag.uni-kl.de>
Cc: 46422 <at> debbugs.gnu.org
Subject: Re: bug#46422: [PATCH] Re: bug#46422: 'pr' screws up tabstops in
 multicolumn outpt?
Date: Sun, 14 Feb 2021 20:34:00 +0100

On Sun, 2021-02-14 at 20:22 +0100, Erik Auerswald wrote:
> 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?

Sure!  I got identical output compared to the previous version (I don't
use `-s`) so it doesn't seem to break anything, but fixes the bug as
intended.

Thanks again!

~leo

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