Re: [PATCH 1/2] ll_binary_merge(): handle XDL_MERGE_FAVOR_UNION

[Junio C Hamano <gitster@pobox.com>]

Jeff King <peff@peff.net> writes:

> Prior to commit a944af1d86 (merge: teach -Xours/-Xtheirs to binary
> ll-merge driver, 2012-09-08), we always reported a conflict from
> ll_binary_merge() by returning "1" (in the xdl_merge and ll_merge code,
> this value is the number of conflict hunks). After that commit, we
> report zero conflicts if the "variant" flag is set, under the assumption
> that it is one of XDL_MERGE_FAVOR_OURS or XDL_MERGE_FAVOR_THEIRS.
>
> But this gets confused by XDL_MERGE_FAVOR_UNION. We do not know how to
> do a binary union merge, but erroneously report no conflicts anyway (and
> just blindly use the "ours" content as the result).
>
> Let's tighten our check to just the cases that a944af1d86 meant to
> cover. This fixes the union case (which existed already back when that
> commit was made), as well as future-proofing us against any other
> variants that get added later.

Makes sense.

> Note that you can't trigger this from "git merge-file --union", as that
> bails on binary files before even calling into the ll-merge machinery.
> The test here uses the "union" merge attribute, which does erroneously
> report a successful merge.

Nice discovery.

Thanks.