Wrong Error Message "Add is not a Trait"

[CryZe]

I made a mistake while implementing Add for a type. Instead of using + for specifying multiple constraints, I accidentally used , and for some reason the compiler can't handle this very well. Instead of complaining about the , it says that Add is not a Trait

Playground Link

struct Okok<T: Clone>(T);

use std::ops::Add;

impl<T: Clone, Add> Add for Okok<T> {
    type Output = usize;

    fn add(self, rhs: Self) -> Self::Output {
        unimplemented!();
    }
}
...

error[E0404]: `Add` is not a trait
 --> <anon>:5:21
  |
5 | impl<T: Clone, Add> Add for Okok<T> {
  |                     ^^^ not a trait

error: cannot continue compilation due to previous error

This happens on both Nightly, Beta and Stable.

[petrochenkov]

Compiler can't complain about ,, everything is syntactically correct - the first Add is interpreted as a fresh type parameter.

The error message should say something like "error: expected trait, found type parameter Add" + "note: ^^^ type parameter Add is defined here"

[CryZe]

Oh yeah, that would make sense.