Confusing `E0284` "type annotations needed" when trait method bound trait bound conflict in associated type.

[zachs18]

Given the following code (playground link):

pub trait Extension: IntoIterator<Item = u32> + Sized {
    fn test(self) -> Vec<u64>
    where
        Self: IntoIterator<Item = u64>,
    {
        self.into_iter().collect()
    }
}

(i.e. the bound on fn test conflicts with the bound of its trait by way of associated types)

The current output is:

error[E0284]: type annotations needed: cannot satisfy `<Self as IntoIterator>::Item == u32`
  |
note: required by a bound in `Extension`
 --> src/lib.rs:1:35
  |
1 | pub trait Extension: IntoIterator<Item = u32> + Sized {
  |                                   ^^^^^^^^^^ required by this bound in `Extension`

For more information about this error, try `rustc --explain E0284`.
error: could not compile `playground` due to previous error

Ideally the output should look like: something mentioning the conflicting bounds. (Or under #![feature(trivial_bounds)], maybe it could just be a trivially false bound?).

error[E0000]: conflicting bounds: cannot satisfy both `<Self as IntoIterator>::Item == u32` and `<Self as IntoIterator>::Item == u64`
  |
note: bounds in `Extension` and `fn test`
 --> src/lib.rs:1:35
  |
1 | pub trait Extension: IntoIterator<Item = u32> + Sized {
  |                                   ^^^^^^^^^^ required by this bound in `Extension`
4 |         Self: IntoIterator<Item = u64>,
  |                            ^^^^^^^^^^ required by this bound in `fn test`

error: could not compile `playground` due to previous error

Same result on stable, beta, and nightly.

Related: #103292, (can't find the issue at the moment, but impl<T: Trait<Assoc = u32>> SecondTrait for T conflicting with impl<T: Trait<Assoc = u64>> SecondTrait for T when it shouldn't is related).

@rustbot modify labels +A-traits +D-confusing +A-associated-items