4 files changed, 102 insertions, 2 deletions

diff --git a/commit-reach.c b/commit-reach.c
index d806291d5d..940fbf2e17 100644
--- a/commit-reach.c
+++ b/commit-reach.c
@@ -595,3 +595,50 @@ int can_all_from_reach_with_flag(struct object_array *from,
 	}
 	return 1;
 }
+
+int can_all_from_reach(struct commit_list *from, struct commit_list *to,
+		       int cutoff_by_min_date)
+{
+	struct object_array from_objs = OBJECT_ARRAY_INIT;
+	time_t min_commit_date = cutoff_by_min_date ? from->item->date : 0;
+	struct commit_list *from_iter = from, *to_iter = to;
+	int result;
+
+	while (from_iter) {
+		add_object_array(&from_iter->item->object, NULL, &from_objs);
+
+		if (!parse_commit(from_iter->item)) {
+			if (from_iter->item->date < min_commit_date)
+				min_commit_date = from_iter->item->date;
+		}
+
+		from_iter = from_iter->next;
+	}
+
+	while (to_iter) {
+		if (!parse_commit(to_iter->item)) {
+			if (to_iter->item->date < min_commit_date)
+				min_commit_date = to_iter->item->date;
+		}
+
+		to_iter->item->object.flags |= PARENT2;
+
+		to_iter = to_iter->next;
+	}
+
+	result = can_all_from_reach_with_flag(&from_objs, PARENT2, PARENT1,
+					      min_commit_date);
+
+	while (from) {
+		clear_commit_marks(from->item, PARENT1);
+		from = from->next;
+	}
+
+	while (to) {
+		clear_commit_marks(to->item, PARENT2);
+		to = to->next;
+	}
+
+	object_array_clear(&from_objs);
+	return result;
+}
diff --git a/commit-reach.h b/commit-reach.h
index b28bc22fcd..aa202c9703 100644
--- a/commit-reach.h
+++ b/commit-reach.h
@@ -72,5 +72,7 @@ int can_all_from_reach_with_flag(struct object_array *from,
 				 unsigned int with_flag,
 				 unsigned int assign_flag,
 				 time_t min_commit_date);
+int can_all_from_reach(struct commit_list *from, struct commit_list *to,
+		       int commit_date_cutoff);
 
 #endif
diff --git a/t/helper/test-reach.c b/t/helper/test-reach.c
index e32e193b70..c79729cac0 100644
--- a/t/helper/test-reach.c
+++ b/t/helper/test-reach.c
@@ -29,7 +29,7 @@ int cmd__reach(int ac, const char **av)
 {
 	struct object_id oid_A, oid_B;
 	struct commit *A, *B;
-	struct commit_list *X;
+	struct commit_list *X, *Y;
 	struct commit **X_array;
 	int X_nr, X_alloc;
 	struct strbuf buf = STRBUF_INIT;
@@ -41,7 +41,7 @@ int cmd__reach(int ac, const char **av)
 		exit(1);
 
 	A = B = NULL;
-	X = NULL;
+	X = Y = NULL;
 	X_nr = 0;
 	X_alloc = 16;
 	ALLOC_ARRAY(X_array, X_alloc);
@@ -86,6 +86,10 @@ int cmd__reach(int ac, const char **av)
 				X_array[X_nr++] = c;
 				break;
 
+			case 'Y':
+				commit_list_insert(c, &Y);
+				break;
+
 			default:
 				die("unexpected start of line: %c", buf.buf[0]);
 		}
@@ -106,6 +110,8 @@ int cmd__reach(int ac, const char **av)
 		struct commit_list *list = reduce_heads(X);
 		printf("%s(X):\n", av[1]);
 		print_sorted_commit_ids(list);
+	} else if (!strcmp(av[1], "can_all_from_reach")) {
+		printf("%s(X,Y):%d\n", av[1], can_all_from_reach(X, Y, 1));
 	}
 
 	exit(0);
diff --git a/t/t6600-test-reach.sh b/t/t6600-test-reach.sh
index 17c6467988..e41eb397a7 100755
--- a/t/t6600-test-reach.sh
+++ b/t/t6600-test-reach.sh
@@ -160,4 +160,49 @@ test_expect_success 'reduce_heads' '
 	test_three_modes reduce_heads
 '
 
+test_expect_success 'can_all_from_reach:hit' '
+	cat >input <<-\EOF &&
+	X:commit-2-10
+	X:commit-3-9
+	X:commit-4-8
+	X:commit-5-7
+	X:commit-6-6
+	X:commit-7-5
+	X:commit-8-4
+	X:commit-9-3
+	Y:commit-1-9
+	Y:commit-2-8
+	Y:commit-3-7
+	Y:commit-4-6
+	Y:commit-5-5
+	Y:commit-6-4
+	Y:commit-7-3
+	Y:commit-8-1
+	EOF
+	echo "can_all_from_reach(X,Y):1" >expect &&
+	test_three_modes can_all_from_reach
+'
+
+test_expect_success 'can_all_from_reach:miss' '
+	cat >input <<-\EOF &&
+	X:commit-2-10
+	X:commit-3-9
+	X:commit-4-8
+	X:commit-5-7
+	X:commit-6-6
+	X:commit-7-5
+	X:commit-8-4
+	X:commit-9-3
+	Y:commit-1-9
+	Y:commit-2-8
+	Y:commit-3-7
+	Y:commit-4-6
+	Y:commit-5-5
+	Y:commit-6-4
+	Y:commit-8-5
+	EOF
+	echo "can_all_from_reach(X,Y):0" >expect &&
+	test_three_modes can_all_from_reach
+'
+
 test_done