bug#46422: [PATCH] Re: bug#46422: 'pr' screws up tabstops in multicolumn outpt?

[Erik Auerswald]

Hi,

On 13.02.21 15:17, Erik Auerswald wrote:
> On 11.02.21 20:20, Erik Auerswald wrote:
> > On Thu, Feb 11, 2021 at 06:09:28PM +0100, Leonard Janis Robert König 
> > wrote:
> > > On Thu, 2021-02-11 at 16:45 +0100, Erik Auerswald wrote:
> > > > On Thu, Feb 11, 2021 at 04:12:54PM +0100, Leonard Janis Robert
> > > > König wrote:
> > > > > On Thu, 2021-02-11 at 13:00 +0100, Erik Auerswald wrote:
> > > > > > On Wed, Feb 10, 2021 at 01:42:29PM +0100, Leonard Janis Robert
> > > > > > König wrote:
> > > > > > > I'm sorry if I this is not a bug but to be expected, but I thnk
> > > > > > > pr doesn't get the alignment of tabs in multicolumn output
> > > > > > > right.  [...]  This seems *kind* of related to multi-column
> > > > > > > merged output, as was discussed some years ago here:
> > > > > > > https://lists.gnu.org/archive/html/bug-coreutils/2007-03/msg00121.html 
> > > > > >
> > > > > > This thread contains the bug-introducing patch in message
> > > > > > https://lists.gnu.org/archive/html/bug-coreutils/2007-03/msg00160.html 
> > > > > >
> > > > > >
> > > > > > This is commit 553d347d3e08e00ee4f9df520b37c964c3f26e28.
> > > > >
> > > > > ah, thanks for digging, I read the message but must have missed
> > > > > the patch.
> > > > >
> > > > > > That commit removed the 'assume -e' part of the POSIX description
> > > > > > of the -COLUMN option from GNU pr.
> > > > > [...]
> > > > Your test case requires expanding tabs during input, which is
> > > > the reason that "expand | pr" could be used as a workaround (with
> > > > "expand | pr | unexpand", pr would not need to mess with tabs at all,
> > > > but I do think that GNU pr is currently buggy and should be fixed).
> > >
> > > Absolutely, expand would be a workaround (I happen to use `pr -e | pr`
> > > in my script, for other reasons).
> > > [...]
> > I have found a fix to the problem described by you.  I am quite sure that
> > this is not *correct*, but I did not find a way to make 
> > print_sep_string()
> > account for tabs that did not break quite a few existing tests, even if
> > the merged files problem from 2007 and this columnating bug were both
> > fixed.  Thus I just tighten the 2007 bug fix to apply in less cases.
> > This way all existing tests pass, and a new one pertaining to this bug
> > report passes, too.  I do think this is in the same spirit as the "fix"
> > from 2007 (commit 553d347d3e08e00ee4f9df520b37c964c3f26e28).
>
> I think the attached patch is a better fix than my previous one,
> because it applies the special treatment of TAB as separator more
> consistently.  It may still not be complete (the code seems quite
> convoluted to me) but I do think it improves the situation
> significantly, and does not make it worse.

It seems to me as if "untabify_input = true;" should be re-introduced
in one additional place to fix the regression from commit 553d347,
please see the attached patch version 3.

> I'd like to ask the GNU Coreutils maintainers to consider merging
> the attached patch.

The latest version, i.e., v3 for now.

Thanks,
Erik

coreutils-pr-fix_bug_46422.v3.patch
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