Re: [PATCH] mergetool: Provide an empty file when no base exists

From: Junio C Hamano <gitster@pobox.com>
Date: Jan 20, 2012, 07:00 UTC
Message-ID: <7vhazqhn8u.fsf@alter.siamese.dyndns.org>
In-Reply-To: <1327042010-79552-1-git-send-email-davvid@gmail.com>

David Aguilar <davvid@gmail.com> writes:

Show 25 quoted lines

> Some mergetools cannot cope when $BASE is missing.
> This can happen when two branches add the same file.
> Provide an empty file to make these tools happy.
>
> Reported-by: Jason Wenger <jcwenger@gmail.com>
> Signed-off-by: David Aguilar <davvid@gmail.com>
> ---
>  git-mergetool.sh     |    6 +++++-
>  t/t7610-mergetool.sh |   27 ++++++++++++++++++++++++++-
>  2 files changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/git-mergetool.sh b/git-mergetool.sh
> index 085e213..8521b81 100755
> --- a/git-mergetool.sh
> +++ b/git-mergetool.sh
> @@ -224,7 +224,11 @@ merge_file () {
>      mv -- "$MERGED" "$BACKUP"
>      cp -- "$BACKUP" "$MERGED"
>  
> -    base_present   && checkout_staged_file 1 "$MERGED" "$BASE"
> +    if base_present; then
> +	checkout_staged_file 1 "$MERGED" "$BASE"
> +    else
> +	touch "$BASE"
> +    fi

Using "touch" for things like this is a disease.

You not just want to make sure it exists, but also you want to make sure it is empty, so it would make your intention more explicit and clear if you wrote this as

	>"$BASE"

instead.

I also wonder if it may help mergetools if we come up with a fake base image using the common material between the two files, in a way similar to how git-merge-one-file.sh does it (look for "Added $4 in both, but differently"), but obviously it would belong to a separate patch.

Thanks.