[kawogi]

In your specific example `std::convert::Infallible` can be used: https://doc.rust-lang.org/std/convert/enum.Infallible.html

[ratmice]

Sure, in the Result case, less in the option case. I didn't mention it because Infallible is documented and named specifically as an Error "The error type for errors that can never happen". The use of uninhabited types as an unreachable code optimization is useful beyond errors though.