Function orphaned_commit_warning

builtin/checkout.c:1127–1155

* We are about to leave commit that was at the tip of a detached * HEAD. If it is not reachable from any ref, this is the last chance * for the user to do so without resorting to reflog. */

 * for the user to do so without resorting to reflog.
 */
static void orphaned_commit_warning(struct commit *old_commit, struct commit *new_commit)
{
	struct rev_info revs;
	struct object *object = &old_commit->object;

	repo_init_revisions(the_repository, &revs, NULL);
	setup_revisions(0, NULL, &revs, NULL);

	object->flags &= ~UNINTERESTING;
	add_pending_object(&revs, object, oid_to_hex(&object->oid));

	refs_for_each_ref(get_main_ref_store(the_repository),
			  add_pending_uninteresting_ref, &revs);
	if (new_commit)
		add_pending_oid(&revs, "HEAD",
				&new_commit->object.oid,
				UNINTERESTING);

	if (prepare_revision_walk(&revs))
		die(_("internal error in revision walk"));
	if (!(old_commit->object.flags & UNINTERESTING))
		suggest_reattach(old_commit, &revs);
	else
		describe_detached_head(_("Previous HEAD position was"), old_commit);

	/* Clean up objects used, as they will be reused. */
	repo_clear_commit_marks(the_repository, ALL_REV_FLAGS);
	release_revisions(&revs);
}

static int switch_branches(const struct checkout_opts *opts,
			   struct branch_info *new_branch_info)