GNU bug report logs - #16865
grep -wP and backreferences

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Package: grep;

Reported by: Stephane Chazelas <stephane.chazelas <at> gmail.com>

Date: Mon, 24 Feb 2014 16:31:02 UTC

Severity: normal

Done: Jim Meyering <jim <at> meyering.net>

Bug is archived. No further changes may be made.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Stephane Chazelas <stephane.chazelas <at> gmail.com>
To: bug-grep <at> gnu.org
Subject: grep -wP and backreferences
Date: Mon, 24 Feb 2014 10:01:54 +0000

Hello,

Backreferences don't work with -w or -x in combination with -P:

$ echo aa | grep -Pw '(.)\1'
$

Or they work in an unexpected way:

$ echo aa | grep -Pw '(.)\2'
aa

The fix is simple:


--- src/pcresearch.c~	2014-02-24 09:59:56.864374362 +0000
+++ src/pcresearch.c	2014-02-24 07:33:04.666398105 +0000
@@ -75,9 +75,9 @@ Pcompile (char const *pattern, size_t si
 
   *n = '\0';
   if (match_lines)
-    strcpy (n, "^(");
+    strcpy (n, "^(?:");
   if (match_words)
-    strcpy (n, "\\b(");
+    strcpy (n, "\\b(?:");
   n += strlen (n);
 
   /* The PCRE interface doesn't allow NUL bytes in the pattern, so
This bug report was last modified 11 years and 90 days ago.

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