Subject: Re: bug#21670: surprising bug in grep -e with anchors

From: Shlomi Fish <[email-masked]>
Date: Mon, 12 Oct 2015 11:14:21 +0300

Hi all,

On Sun, 11 Oct 2015 21:34:05 -0700
Paul Eggert <[email-masked]> wrote:

> greg boyd wrote:
> > test case (single line)
> > abchelloabc
> >
> > grep does not find the line with grep -e '^hello'  nor with grep -e 'hello$'
> > however, the line is output with
> > grep -e '^hello' -e 'hello$'  
> 
> Oooo, that's a good one.  Give your student extra credit!  As it happens, the 
> bug was recently fixed by this patch by Norihiro Tanaka:
> 
> http://git.savannah.gnu.org/cgit/grep.git/commit/?id=256a4b494fe1c48083ba73b4f62607234e4fefd5
> 
> and the fix should appear in the next grep release.  However, since the patch 
> was supposed to affect only performance, it appears that the bug fix was due
> to luck, and I'm taking the liberty of adding your student's test case by 
> installing the attached further patch, to help prevent this bug from coming
> back in a future version.

thanks to greg, to greg's student, and to Paul for their contributions!

Regards,

	Shlomi Fish

-- 
-----------------------------------------------------------------
Shlomi Fish       http://www.shlomifish.org/
Perl Humour - http://perl-begin.org/humour/

The first phrase that needs to be taught when teaching a new language is how to
say “Do you speak English?”. The first thing that needs to be taught when
teaching a new computer tool is how to exit it.

Please reply to list if it's a mailing list post - http://shlom.in/reply .