diff-merges: let new options enable diff without -p

New options don't have any visible effect unless -p is either given or
implied, as unlike -c/-cc we don't imply -p with --diff-merges. To fix
this, this patch adds new functionality by letting new options enable
output of diffs for merge commits only.

Add 'merges_need_diff' field and set it whenever diff output for merges is
enabled by any of the new options.

Extend diff output logic accordingly, to output diffs for merges when
'merges_need_diff' is set even when no -p has been provided.

Signed-off-by: Sergey Organov <sorganov@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/revision.h b/revision.h
index bfbae52..494d861 100644
--- a/revision.h
+++ b/revision.h
@@ -194,6 +194,7 @@ struct rev_info {
 			always_show_header:1,
 			/* Diff-merge flags */
 			explicit_diff_merges: 1,
+			merges_need_diff: 1,
 			separate_merges: 1,
 			combine_merges:1,
 			combined_all_paths:1,