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Date:	Sat, 17 Jan 2004 21:04:50 -0800
From:	Yitzchak Scott-Thoennes <sthoenna AT efn DOT org>
To:	cygwin AT cygwin DOT com
Subject:	Re: cygwin/regex is non-POSIX
Message-ID:	<20040118050449.GA3672@efn.org>
References:	<uhdyxm0ji DOT fsf AT gnu DOT org>
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On Thu, Jan 15, 2004 at 03:14:57PM -0500, Sam Steingold <sds AT gnu DOT org> wrote:
> the cygwin regex is not POSIX.
> backrefs are not available by default (apparently you need REG_BACKR for
> that), "(a|)*" cannot be compiled because of "empty (sub)expression",
> &c &c.
> any plans to fix this? (e.g., by replacing it with gnu regex?)
> thanks.

SUSv3 says:
  A vertical-line appearing first or last in an ERE, or immediately
  following a vertical-line or a left-parenthesis, or immediately
  preceding a right-parenthesis, produces undefined results.

Also, it says backrefs part of basic regular expressions but not
exteneded ones.  From your mention of | I assume you are using
REG_EXTENDED.  If REG_EXTENDED|REG_BACKR allows backrefs, it doesn't
appear to be documented.

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