Make has_commit() non-static

Move has_commit() from branch to a common location, in preparation for
using it in "git-tag". Rename it to is_descendant_of() to make it more
unique and descriptive.

Signed-off-by: Jake Goulding <goulding@vivisimo.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-branch.c

@@ -193,21 +193,6 @@ struct ref_list {
 	int kinds;
 };
 
-static int has_commit(struct commit *commit, struct commit_list *with_commit)
-{
-	if (!with_commit)
-		return 1;
-	while (with_commit) {
-		struct commit *other;
-
-		other = with_commit->item;
-		with_commit = with_commit->next;
-		if (in_merge_bases(other, &commit, 1))
-			return 1;
-	}
-	return 0;
-}
-
 static int append_ref(const char *refname, const unsigned char *sha1, int flags, void *cb_data)
 {
 	struct ref_list *ref_list = (struct ref_list*)(cb_data);
@@ -231,7 +216,7 @@ static int append_ref(const char *refname, const unsigned char *sha1, int flags,
 		return error("branch '%s' does not point at a commit", refname);
 
 	/* Filter with with_commit if specified */
-	if (!has_commit(commit, ref_list->with_commit))
+	if (!is_descendant_of(commit, ref_list->with_commit))
 		return 0;
 
 	/* Don't add types the caller doesn't want */
@@ -401,7 +386,8 @@ static void print_ref_list(int kinds, int detached, int verbose, int abbrev, str
 	qsort(ref_list.list, ref_list.index, sizeof(struct ref_item), ref_cmp);
 
 	detached = (detached && (kinds & REF_LOCAL_BRANCH));
-	if (detached && head_commit && has_commit(head_commit, with_commit)) {
+	if (detached && head_commit &&
+	    is_descendant_of(head_commit, with_commit)) {
 		struct ref_item item;
 		item.name = xstrdup("(no branch)");
 		item.kind = REF_LOCAL_BRANCH;

commit.c

@@ -705,6 +705,21 @@ struct commit_list *get_merge_bases(struct commit *one, struct commit *two,
 	return get_merge_bases_many(one, 1, &two, cleanup);
 }
 
+int is_descendant_of(struct commit *commit, struct commit_list *with_commit)
+{
+	if (!with_commit)
+		return 1;
+	while (with_commit) {
+		struct commit *other;
+
+		other = with_commit->item;
+		with_commit = with_commit->next;
+		if (in_merge_bases(other, &commit, 1))
+			return 1;
+	}
+	return 0;
+}
+
 int in_merge_bases(struct commit *commit, struct commit **reference, int num)
 {
 	struct commit_list *bases, *b;

commit.h

@@ -133,6 +133,7 @@ extern int is_repository_shallow(void);
 extern struct commit_list *get_shallow_commits(struct object_array *heads,
 		int depth, int shallow_flag, int not_shallow_flag);
 
+int is_descendant_of(struct commit *, struct commit_list *);
 int in_merge_bases(struct commit *, struct commit **, int);
 
 extern int interactive_add(int argc, const char **argv, const char *prefix);