Deserialize for dynamically sized struct generates invalid code

[dtolnay]

extern crate serde;

#[macro_use]
extern crate serde_derive;

#[derive(Deserialize)]
struct S {
    last: [u8],
}

error[E0277]: the trait bound `[u8]: std::marker::Sized` is not satisfied in `S`
 --> src/main.rs:6:10
  |
6 | #[derive(Deserialize)]
  |          ^^^^^^^^^^^ within `S`, the trait `std::marker::Sized` is not implemented for `[u8]`
  |
  = note: `[u8]` does not have a constant size known at compile-time
  = note: required because it appears within the type `S`
  = note: required by `serde::Deserialize`

[dtolnay]

There is no way to implement a working Deserialize for this type because Deserialize requires Self: Sized, but it would be nice to at least detect the case of dynamically sized slice as the last field and fail with a message rather than generating broken code.