Consider adding a where bound (that's already present)

[CAD97]

playground, r/rust thread (includes larger examples)

use std::marker::PhantomData;

pub trait FromPest<'a>: Sized {
    type Rule;
    const RULE: Self::Rule;
}

impl<'a, T> FromPest<'a> for PhantomData<T>
where
    T: FromPest<'a>,
{
    type Rule = T::Rule;
    const RULE: T::Rule = T::RULE;
}

error[E0277]: the trait bound `T: FromPest<'a>` is not satisfied
  --> src/lib.rs:13:5
   |
13 |     const RULE: T::Rule = T::RULE;
   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `FromPest<'a>` is not implemented for `T`
   |
   = help: consider adding a `where T: FromPest<'a>` bound

---

I'm unsure as to whether this is a compiler bug or something I've missed, but at the very least, this error is less than helpful at exposing the actual issue.

[kennytm]

Duplicate of #46969.

[CAD97]

Well that shows how much I looked, I guess.