Re: [PATCH v2] grep: correctly identify utf-8 characters with \{b,w} in -P

From: Carlo Arenas <carenas@gmail.com>
Date: Jan 10, 2023, 04:49 UTC
Message-ID: <CAPUEsphgxU4R6PTEd1N7VwQ+Da1CRRvyNkeas0k2gn0WkDA+2A@mail.gmail.com>
In-Reply-To: <230109.86v8lf297g.gmgdl@evledraar.gmail.com>

On Mon, Jan 9, 2023 at 4:17 AM Ævar Arnfjörð Bjarmason <avarab@gmail.com> wrote:

Show 5 quoted lines

>Rather than trying to opt-out with "/a" or "/aa" I think this should be opt-in.
>
> As the example at the start shows you can already do this with "(*UCP)"
> in the pattern, so perhaps we should just link to the pcre2pattern(3)
> manual from git-grep(1)?

Considering that PCRE is used internally even for cases that don't specify -P how would that opt-in work?

For example, in a repository with code that uses utf identifiers, the following will fail:

  $ git grep -w -E motion
  u.c:  int émotion = 0;
  $ git grep -w -E '(*UCP)motion'
  fatal: command line, '(*UCP)motion': Invalid preceding regular expression
  $ git -P grep -P -w '(*UCP)motion'
  u.c:  int émotion = 0;

Carlo

CC removed gnu and the obsoleted PCRE developer list (if really needed would be better to use the documented pcre2-dev@googlegroups.com, instead)