On 6/3/22 20:18, Bruno Haible wrote:
This warning punishes a traditional habit, namely to backslash-escape
a leading ASCII '-' character, so as to avoid it from being interpreted
as an option.
That's the first I've heard of that habit. Even 7th Edition Unix
supported 'grep -e PAT FILE', but I guess some nonstandard grep
implementations removed -e. These days, although I would think 'grep --
PAT FILE' would work everywhere, there may be scripts that still use
that old habit.
If we want to support "grep '\-PAT' FILE", we can do so in grep rather
than in dfa.c; it might not be wise to treat \- as - everywhere, as that
would preclude future extensions such as A\-B meaning r.e. subtraction.
We could add something like the attached to GNU grep, if you and Jim
think it's a good idea (I hope Jim doesn't get tired of these "just one
more thing" changes before a release...).From fe5ed6852a51d6b6ea9c407f10019ecd427d4eb0 Mon Sep 17 00:00:00 2001
From: Paul Eggert <[email protected]>
Date: Sat, 4 Jun 2022 15:41:38 -0700
Subject: [PATCH] =?UTF-8?q?grep:=20don=E2=80=99t=20diagnose=20"grep=20'\-c?=
=?UTF-8?q?'"?=
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* src/dfasearch.c (GEAcompile): Skip past leading backslash of a
pattern that begins with "\-". Inspired by a remark by Bruno Haible:
https://lists.gnu.org/r/bug-gnulib/2022-06/msg00022.html
---
src/dfasearch.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/src/dfasearch.c b/src/dfasearch.c
index 8d832f0..730d0e4 100644
--- a/src/dfasearch.c
+++ b/src/dfasearch.c
@@ -203,6 +203,13 @@ GEAcompile (char *pattern, idx_t size, reg_syntax_t syntax_bits,
dfasyntax (dc->dfa, &localeinfo, syntax_bits, dfaopts);
bool bs_safe = !localeinfo.multibyte | localeinfo.using_utf8;
+ /* If a pattern starts with "\-" omit the backslash, to suppress a
+ stray-backslash warning if a script uses the non-POSIX
+ "grep '\-x'" to avoid treating "-x" as an option. */
+ bool skip_bs = pattern[0] == '\\' && pattern[1] == '-';
+ pattern += skip_bs;
+ size -= skip_bs;
+
/* For GNU regex, pass the patterns separately to detect errors like
"[\nallo\n]\n", where the patterns are "[", "allo" and "]", and
this should be a syntax error. The same for backref, where the
--
2.36.1
