`io::Sink` is useless since version 1.73 as `io::Empty` now has a superset of its features.

[vidhanio]

Should the entire Sink/sink() api be deprecated with the changes brought to io::Empty?

[Noratrieb]

It should maybe be "deprecated in future version" to stop people from newly using it (which is only mentioned in the docs).
I do not think there is any value for emitting warnings, which would be entirely useless churn.