Impl Serialize/Deserialize for !

[tikue]

Serialize is straightforward. As for Deserialize, I guess it would just panic? This is useful for me when serializing and deserializing types like Result<T, !>.

[dtolnay]

If we do Deserialize for ! it should error, not panic.

Is Result<T, !> the only instance where you need this? Would it make more sense to specialize De/Serialize for Result<T, !> instead of implementing them for !? Result<T, !> is equivalent to T so we might as well serialize it the same way.

[tikue]

The Result<T, !> was actually a simplified example. My actual use case involves an error type where one variant is generic: the actual type being deserialized is Result<T, Error<!>>. Basically, if a user implements a service that can never return an application error, the application error is !, and the framework error is Error<!>.

[tikue]

That being said, it could definitely make sense to specialize the Result<T, !> case as well!