From 7ae0fd9ed86e0b9f8359a7fbbc5d45001acb6ff6 Mon Sep 17 00:00:00 2001
From: Junio C Hamano <gitster@pobox.com>
Date: Tue, 18 Oct 2016 16:25:53 -0700
Subject: merge-base: WIP finish integrating major-only

---
 builtin/merge-base.c | 15 ++++++++++++---
 commit.c             | 11 ++++++-----
 2 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/builtin/merge-base.c b/builtin/merge-base.c
index c0d1822eb3..16f3f3d15a 100644
--- a/builtin/merge-base.c
+++ b/builtin/merge-base.c
@@ -6,11 +6,14 @@
 #include "revision.h"
 #include "parse-options.h"
 
-static int show_merge_base(struct commit **rev, int rev_nr, int show_all)
+static int show_merge_base(struct commit **rev, int rev_nr, int show_all,
+			   int show_major)
 {
 	struct commit_list *result;
 
-	result = get_merge_bases_many_dirty(rev[0], rev_nr - 1, rev + 1);
+	result = (show_major
+		  ? get_major_merge_bases(rev[0], rev[1])
+		  : get_merge_bases_many_dirty(rev[0], rev_nr - 1, rev + 1));
 
 	if (!result)
 		return 1;
@@ -208,10 +211,13 @@ int cmd_merge_base(int argc, const char **argv, const char *prefix)
 	struct commit **rev;
 	int rev_nr = 0;
 	int show_all = 0;
+	int show_major = 0;
 	int cmdmode = 0;
 
 	struct option options[] = {
 		OPT_BOOL('a', "all", &show_all, N_("output all common ancestors")),
+		OPT_BOOL(0, "major-base-only", &show_major,
+			 N_("show only merge bases on first-parent chain")),
 		OPT_CMDMODE(0, "octopus", &cmdmode,
 			    N_("find ancestors for a single n-way merge"), 'o'),
 		OPT_CMDMODE(0, "independent", &cmdmode,
@@ -255,5 +261,8 @@ int cmd_merge_base(int argc, const char **argv, const char *prefix)
 	ALLOC_ARRAY(rev, argc);
 	while (argc-- > 0)
 		rev[rev_nr++] = get_commit_reference(*argv++);
-	return show_merge_base(rev, rev_nr, show_all);
+
+	if (show_major && rev_nr != 2)
+		die("--major-base-only can be used only with two commits");
+	return show_merge_base(rev, rev_nr, show_all, show_major);
 }
diff --git a/commit.c b/commit.c
index bf2432fae8..5792c1c4ca 100644
--- a/commit.c
+++ b/commit.c
@@ -957,6 +957,7 @@ static struct commit_list *get_merge_bases_many_0(struct commit *one,
 	struct commit **rslt;
 	struct commit_list *result;
 	int cnt, i;
+	char *major;
 
 	result = merge_bases_many(one, n, twos);
 
@@ -981,16 +982,14 @@ static struct commit_list *get_merge_bases_many_0(struct commit *one,
 	/* There are more than one */
 	cnt = commit_list_count(result);
 	rslt = xcalloc(cnt, sizeof(*rslt));
+	major = xcalloc(cnt, sizeof(*major));
 	for (list = result, i = 0; list; list = list->next)
 		rslt[i++] = list->item;
 	free_commit_list(result);
 
 	if (major_only) {
-		/* debug */
 		for (i = 0; i < cnt; i++)
-			fprintf(stderr, "%c %s\n",
-				(rslt[i]->object.flags & FPCHAIN) ? '+' : '-',
-				oid_to_hex(&rslt[i]->object.oid));
+			major[i] = !!(rslt[i]->object.flags & FPCHAIN);
 	}
 
 	clear_commit_marks(one, all_flags);
@@ -999,11 +998,13 @@ static struct commit_list *get_merge_bases_many_0(struct commit *one,
 	mark_redundant(rslt, cnt);
 	result = NULL;
 	for (i = 0; i < cnt; i++)
-		if (!(rslt[i]->object.flags & STALE))
+		if (!(rslt[i]->object.flags & STALE) &&
+		    (!major_only || major[i]))
 			commit_list_insert_by_date(rslt[i], &result);
 		else
 			rslt[i]->object.flags &= ~STALE;
 	free(rslt);
+	free(major);
 	return result;
 }
 
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