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Re: Dealing with character ranges in grep


From: Johannes Meixner
Subject: Re: Dealing with character ranges in grep
Date: Fri, 17 Jun 2011 11:55:09 +0200 (CEST)
User-agent: Alpine 2.00 (LNX 1167 2008-08-23)


Hello Jim,

On Jun 16 10:44 Jim Meyering wrote (excerpt):
Thus, if we go this route, we are effectively saying
that people who want self-consistent regex-handling
in our tools must build with --with-included-regex or end
up causing subtle problems.
...
It goes like this (at least for gawk, grep and sed):

  change how dfa.c interprets ranges like [a-z]
  change how gnulib's reg* code handles ranges

Always use the included regex code (the one from gnulib),
so that its interpretation is consistent with that of dfa.c.

Grep's current upstream default is to build --with-included-regex,
which makes grep use glibc's regex code.

Isn't there a typo?

Shouldn't it read
 "Grep's current upstream default is to build --without-included-regex,
  which makes grep use glibc's regex code."

At leats for grep-2.7 "configure --help" shows me:
-----------------------------------------------------------------------
  --without-included-regex
        don't compile regex; this is the default on systems
        with recent-enough versions of the GNU C Library
        (use with caution on other systems).
-----------------------------------------------------------------------

Or do I misunderstand something here?

To make this proposed change go through, that configure-time option would
have to be eliminated, so that we always build with the gnulib-provided
regex code.  Of course, if glibc ever changes, we can detect that and
automatically prefer it when possible.

For the record, at least Fedora's grep and sed both build
--without-included-regex, so would be affected.

Same for openSUSE and all the "Suse Linux Enterprise" products.


Kind Regards
Johannes Meixner
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