Given the following code (Rust Playground):
use std::fmt::Debug;
use std::marker::PhantomData;
trait Herp: Debug {}
#[derive(Debug)]
struct Derp<S: ?Sized> {
phantom: PhantomData<S>
}
impl<S: ?Sized> Herp for Derp<S> {}
The following error occurs:
error[E0277]: the trait bound `S: std::fmt::Debug` is not satisfied
--> src/...
|
37 | impl<S: ?Sized> Herp for Derp<S> {}
| ^^^^
|
= help: consider adding a `where S: std::fmt::Debug` bound
= note: required because of the requirements on the impl of `std::fmt::Debug` for `Derp<S>`
= note: required by `Herp
I find this behaviour inappropriate because Debug is derived properly for Derp and PhantomData<T> should implement Debug regardless of type T (docs). I also couldn't find anything else on my search that could apparently induce this error.
Why can't I implement a trait that requires Debug for a type containing a phantom?
