From: Jeff King <peff@peff.net>
Date: Thu, 19 Mar 2020 15:53:07 GMT
Subject: Re: [PATCH 1/6] t4061: use POSIX compliance regex(7)
Message-ID: <20200319155307.GB3513282@coredump.intra.peff.net>
In-Reply-To: <c45d6383173d8d3e73cdcdd6e993d3259d519a68.1584625896.git.congdanhqx@gmail.com>

On Thu, Mar 19, 2020 at 09:00:02PM +0700, Đoàn Trần Công Danh wrote:

> BRE interprets `+` literally, and
> `\+` is undefined for POSIX BRE, from:
> https://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_03_02
> 
> > The interpretation of an ordinary character preceded
> > by an unescaped <backslash> ( '\\' ) is undefined, except for:
> > - The characters ')', '(', '{', and '}'
> > - The digits 1 to 9 inclusive
> > - A character inside a bracket expression
> 
> This test is failing with busybox sed, the default sed of Alpine Linux
> 
> Fix it by using literal `+` instead.

This makes sense, I think. It could hurt a sed which is expected ERE and
needs the "+" escaped, but I think such a sed would be wrong (and I
imagine would break things elsewhere).

-Peff