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From:   Junio C Hamano <gitster@pobox.com>
To:     Phillip Wood <phillip.wood123@gmail.com>
Cc:     Jacob Abel <jacobabel@nullpo.dev>, phillip.wood@dunelm.org.uk,
        git@vger.kernel.org
Subject: Re: [PATCH] t2400: Fix test failures when using grep 2.5
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Date:   Sun, 16 Jul 2023 19:38:55 -0700
In-Reply-To: <3f3a3f5b-70fd-ec3f-acbb-d585b5eb6cbc@gmail.com> (Phillip Wood's
        message of "Sun, 16 Jul 2023 16:34:52 +0100")
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Phillip Wood <phillip.wood123@gmail.com> writes:

> One thing I forgot to mention was that I think it would be better to
> explain in the commit message that "\s" etc. are not part of POSIX
> EREs and that is why they do not work.

Yes, that is a very good point.  We have been burned by regular
expression implementations that use or do not use "enhanced" bit in
the recent past, IIRC.

> I think it might be better to just diagnose if HEAD is a dangling
> symbolic-ref or contains an invalid oid and leave it at that. See the
> documentation in refs.h for refs_resolve_ref_unsafe() for how to check
> if HEAD is a dangling symbolic ref - if rego_get_oid(repo, "HEAD")
> fails and it is not a dangling symbolic ref then it contains an
> invalid oid.

Sounds doable and sensible.  If we can easily test it without
peeking into the filesystem, that would be very good.

Thanks.