Re: bugreport: git apply -3 confusing "lacks the necessary blob"

From: Jan Kratochvil <jan@jankratochvil.net>
Date: Aug 27, 2021, 15:15 UTC
Message-ID: <YSkBg3lBAZ2pxCP2@host1.jankratochvil.net>
In-Reply-To: <xmqqtujkui9v.fsf@gitster.g>

On Fri, 20 Aug 2021 19:40:12 +0200, Junio C Hamano wrote:

> But I think Jan is talking about the case where users get a patch
> that lacks the "index" information out of other people's "diff"
> implementation and try to "apply -3" without realizing that it is
> not Git's "diff" output.

For example from Phabricator:
	https://reviews.llvm.org/file/data/3ceoc32b3yv43vk3nw4q/PHID-FILE-lfeeh2qu4vrngdcwwudo/D107456.diff

> Perhaps something like the attached patch would be a good start.

Do you plan to check it in?

Thanks, Jan Kratochvil

Show 13 quoted lines

> diff --git i/apply.c w/apply.c
> index 44bc31d6eb..9972ada57e 100644
> --- i/apply.c
> +++ w/apply.c
> @@ -3566,6 +3566,8 @@ static int try_threeway(struct apply_state *state,
>  	/* Preimage the patch was prepared for */
>  	if (patch->is_new)
>  		write_object_file("", 0, blob_type, &pre_oid);
> +	else if (!*patch->old_oid_prefix && !*patch->new_oid_prefix)
> +		return error(_("cannot 'apply -3' a patch without the index line"));
>  	else if (get_oid(patch->old_oid_prefix, &pre_oid) ||
>  		 read_blob_object(&buf, &pre_oid, patch->old_mode))
>  		return error(_("repository lacks the necessary blob to perform 3-way merge."));