Jeff King <peff@xxxxxxxx> writes:
> This patch defines the patch-id of a merge commit as
> essentially "null"; it has no patch-id. As a result,
> merges cannot match patch-ids via "--cherry-pick", and
> "format-patch --base" will not list merges in its list of
> prerequisite patch ids.
At first I wondered if such a change would make all merges look the
same, but the patch-ids.c comparison is not for ordering/sorting but
only for equality, so as long as the comparison function knows that
a comparison of anything with "null" yields "They are different", we
are OK.
> diff --git a/patch-ids.c b/patch-ids.c
> index 77e4663..8d06099 100644
> --- a/patch-ids.c
> +++ b/patch-ids.c
> @@ -7,18 +7,40 @@
> int commit_patch_id(struct commit *commit, struct diff_options *options,
> unsigned char *sha1, int diff_header_only)
> {
> - if (commit->parents)
> + if (commit->parents) {
> + if (commit->parents->next)
> + return PATCH_ID_NONE;
> diff_tree_sha1(commit->parents->item->object.oid.hash,
> commit->object.oid.hash, "", options);
> - else
> + } else
> diff_root_tree_sha1(commit->object.oid.hash, "", options);
> diffcore_std(options);
> - return diff_flush_patch_id(options, sha1, diff_header_only);
> + if (diff_flush_patch_id(options, sha1, diff_header_only))
> + return PATCH_ID_ERROR;
> + return PATCH_ID_OK;
> +}
Looks sensible. Thanks.