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From: Junio C Hamano <gitster@pobox.com>
To: Jeff King <peff@peff.net>
Cc: "Taylor Blau" <me@ttaylorr.com>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	git@vger.kernel.org, "Carlo Arenas" <carenas@gmail.com>,
	"brian m. carlson" <sandals@crustytoothpaste.net>
Subject: Re: New-ish warning in refs.c with GCC (at least 11.2) under -O3
Date: Thu, 18 Nov 2021 15:23:55 -0800	[thread overview]
Message-ID: <xmqqwnl5ujxw.fsf@gitster.g> (raw)
In-Reply-To: <YZQhLh2BU5Hquhpo@coredump.intra.peff.net> (Jeff King's message of "Tue, 16 Nov 2021 16:22:54 -0500")

Jeff King <peff@peff.net> writes:

> +	/*
> +	 * Should be a noop per the ALLOWED_FLAGS check above, but this
> +	 * is necessary to work around a problem with some versions of
> +	 * "gcc -O3 -Wnonnull", which otherwise thinks that you can have the
> +	 * flag set with a NULL new_oid.
> +	 */
> +	flags &= ~REF_HAVE_OLD | REF_HAVE_NEW;

Are you missing parentheses around ~(OLD|NEW)?

>  	flags |= (new_oid ? REF_HAVE_NEW : 0) | (old_oid ? REF_HAVE_OLD : 0);
>  
>  	ref_transaction_add_update(transaction, refname, flags,
>
> I do find it interesting that gcc really _is_ convinced that those flags
> can be set coming in, since clearing them makes the problem go away.
> ...
> Reading over the code, it all looks OK. And that size is...weirdly huge.

The original bug is really annoying and this looks even worse.
Hopefully it won't come down from experimental to more stable tracks
before they are corrected.


  reply	other threads:[~2021-11-18 23:24 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-11-15 17:41 New-ish warning in refs.c with GCC (at least 11.2) under -O3 Ævar Arnfjörð Bjarmason
2021-11-15 22:39 ` Jeff King
2021-11-16 20:29   ` Taylor Blau
2021-11-16 21:22     ` Jeff King
2021-11-18 23:23       ` Junio C Hamano [this message]
2021-11-19 21:28         ` [PATCH] refs: work around gcc-11 warning with REF_HAVE_NEW Jeff King

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