Re: [PATCH v3 2/2] apply: reload .gitattributes after patching it

From: Junio C Hamano <gitster@pobox.com>
To: "brian m. carlson" <sandals@crustytoothpaste.net>
Cc: git@vger.kernel.org, "SZEDER Gábor" <szeder.dev@gmail.com>,
	"Taylor Blau" <me@ttaylorr.com>, "Jeff King" <peff@peff.net>
Subject: Re: [PATCH v3 2/2] apply: reload .gitattributes after patching it
Date: Tue, 13 Aug 2019 11:08:46 -0700	[thread overview]
Message-ID: <xmqq7e7h7xap.fsf@gitster-ct.c.googlers.com> (raw)
In-Reply-To: <20190813024307.705016-3-sandals@crustytoothpaste.net> (brian m. carlson's message of "Tue, 13 Aug 2019 02:43:07 +0000")

"brian m. carlson" <sandals@crustytoothpaste.net> writes:

> When applying multiple patches with git am, or when rebasing using the
> am backend, it's possible that one of our patches has updated a
> gitattributes file. Currently, we cache this information, so if a
> file in a subsequent patch has attributes applied, the file will be
> written out with the attributes in place as of the time we started the
> rebase or am operation, not with the attributes applied by the previous
> patch. This problem does not occur when using the -m or -i flags to
> rebase.

Back when "am" was a script that repeatedly calls "apply --index &&
commit-tree", caching the original contents of the attributes file
and using it throughout the series would have been impossible to
begin with, so this must be a regression when we rewrote it in C and
moved to do everything in a single process without clearly the state
between the steps, I guess.

"rebase -m" and "rebase -i" are not repeated run_command() calls
that invoke "git cherry-pick" or "git merge" these days, either, so
I am somewhat curious how they avoid fallilng into the same trap.

Thanks for the fix.  Will queue.