From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 29 Sep 2026 21:19:26 GMT
Subject: Re: [PATCH 7/5] merge-ll: report an error when reading external merge results fails
Message-ID: <xmqqv77neowx.fsf@gitster.g>
In-Reply-To: <20260929204421.GB1734030@coredump.intra.peff.net>

Jeff King <peff@peff.net> writes:

> +test_expect_success SANITY 'rerere preserves conflicts when driver output is unreadable' '
> +	test_create_repo unreadable-output &&
> +	(

> +		cd unreadable-output &&
> +		git config rerere.enabled true &&
> +		git config rerere.autoupdate true &&
> +		write_script merge-driver <<-\EOF &&
> +		git merge-file "$@"
> +		status=$?
> +		if test -f fail-read
> +		then
> +			chmod 0 "$1" || exit 1
> +		fi

Can we lose SANITY by "rm $1" instead of "chmod 0"?

> +		exit "$status"
> +		EOF
> +		git config merge.unreadable.driver "./merge-driver %A %O %B" &&
> +		echo "file merge=unreadable" >.gitattributes &&
> +		test_commit base file base &&
> +		git checkout -b one &&
> +		test_commit --no-tag one file one &&
> +		git checkout -b two base &&
> +		test_commit --no-tag two file two &&
> +
> +		# Teach rerere a resolution while the driver works normally.
> +		test_must_fail git merge one &&
> +		echo resolved >file &&
> +		git rerere &&
> +		git merge --abort &&
> +
> +		# Recreate the conflict without replaying the resolution yet.
> +		test_must_fail git -c rerere.enabled=false merge one &&
> +
> +		# We will expect the same conflicted content after rerere fails
> +		# below.
> +		cp file expect &&
> +		git ls-files -u >expect-index &&
> +		test_file_not_empty expect-index &&
> +
> +		# Now we try rerere again, but the merge driver will cause the
> +		# read to fail.
> +		>fail-read &&
> +		git rerere 2>err &&
> +		test_grep "Could not open" err &&
> +
> +		# And we expect the conflicted state.
> +		test_cmp expect file &&
> +		git ls-files -u >actual-index &&
> +		test_cmp expect-index actual-index
> +	)
> +'
> +
>  test_done