sync: implement `watch::Receiver::mark_unseen()`#5962

Merged

Darksonn merged 6 commits intotokio-rs:masterfrom victor-timofei:receiver-mark-unseen

Sep 11, 2023

+75-2

Commits on Aug 29, 2023

Commits on Aug 30, 2023

Commits on Sep 1, 2023

use usize and start initial version at 2
victor-timofei
committed

Commits on Sep 3, 2023

update comment and extend tests
victor-timofei
committed