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Re: [bug #37737] Contained subexpressions don't follow POSIX
From: |
Eric Blake |
Subject: |
Re: [bug #37737] Contained subexpressions don't follow POSIX |
Date: |
Wed, 14 Nov 2012 15:35:25 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:16.0) Gecko/20121029 Thunderbird/16.0.2 |
On 11/14/2012 03:29 PM, Роман Донченко wrote:
> Eric Blake <address@hidden> писал в своём письме Thu, 15 Nov 2012
> 02:11:57 +0400:
>
>> For reference, on Cygwin (where m4 uses gnulib's regex engine, rather
>> than glibc's) I get correct behavior:
>>
>> $ printf %s 'regexp(abab, \(a\(b\)*\)*\2, \&-\1-\2)' | m4
>> -1
>
> That's interesting, because I don't:
>
> $ uname -sr
> CYGWIN_NT-6.1-WOW64 1.7.17(0.262/5/3)
>
> $ m4 --version
> m4 (GNU M4) 1.4.16
> Packaged by Cygwin (1.4.16-1)
> (etc, etc)
>
> $ printf %s 'regexp(abab, \(a\(b\)*\)*\2, \&-\1-\2)' | m4
> abab-a-b
>
> In fact, Cygwin was where I did the test in the OP (although I've
> previously observed the bug on Linux, too).
Arg, chalk that up to a typo on my part: when I was retyping the command
line between the systems, I omitted a comma. The correct result would
be the empty string, not -1; and I confirm that cygwin has the same
behavior as Linux (probably due to gnulib copying from glibc).
--
Eric Blake address@hidden +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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