Merge branch 'js/checkout-detach-count' into maint

When checking out another commit from an already detached state, we used
to report all commits that are not reachable from any of the refs as
lossage, but some of them might be reachable from the new HEAD, and there
is no need to warn about them.

By Johannes Sixt
* js/checkout-detach-count:
  checkout (detached): truncate list of orphaned commits at the new HEAD
  t2020-checkout-detach: check for the number of orphaned commits

1 files changed, 7 insertions, 6 deletions

diff --git a/builtin/checkout.c b/builtin/checkout.c
index 6b9061f26f..160f678b8c 100644
--- a/builtin/checkout.c
+++ b/builtin/checkout.c
@@ -671,10 +671,10 @@ static void suggest_reattach(struct commit *commit, struct rev_info *revs)
  * HEAD.  If it is not reachable from any ref, this is the last chance
  * for the user to do so without resorting to reflog.
  */
-static void orphaned_commit_warning(struct commit *commit)
+static void orphaned_commit_warning(struct commit *old, struct commit *new)
 {
 	struct rev_info revs;
-	struct object *object = &commit->object;
+	struct object *object = &old->object;
 	struct object_array refs;
 
 	init_revisions(&revs, NULL);
@@ -684,16 +684,17 @@ static void orphaned_commit_warning(struct commit *commit)
 	add_pending_object(&revs, object, sha1_to_hex(object->sha1));
 
 	for_each_ref(add_pending_uninteresting_ref, &revs);
+	add_pending_sha1(&revs, "HEAD", new->object.sha1, UNINTERESTING);
 
 	refs = revs.pending;
 	revs.leak_pending = 1;
 
 	if (prepare_revision_walk(&revs))
 		die(_("internal error in revision walk"));
-	if (!(commit->object.flags & UNINTERESTING))
-		suggest_reattach(commit, &revs);
+	if (!(old->object.flags & UNINTERESTING))
+		suggest_reattach(old, &revs);
 	else
-		describe_detached_head(_("Previous HEAD position was"), commit);
+		describe_detached_head(_("Previous HEAD position was"), old);
 
 	clear_commit_marks_for_object_array(&refs, ALL_REV_FLAGS);
 	free(refs.objects);
@@ -730,7 +731,7 @@ static int switch_branches(struct checkout_opts *opts, struct branch_info *new)
 	}
 
 	if (!opts->quiet && !old.path && old.commit && new->commit != old.commit)
-		orphaned_commit_warning(old.commit);
+		orphaned_commit_warning(old.commit, new->commit);
 
 	update_refs_for_switch(opts, &old, new);