Using type parameters in trait bounds doesn't count for error[E0392]: "parameter A1 is never used".

[roSievers]

I have a struct with a bunch of type parameters. Some of them are used for members and some of them are used to nail down the other type parameters.

pub struct MapStatistic<A1, A2, B, Stat, Pre>
    where Stat: Statistic<A2, B>,
          Pre: Fn(A1) -> A2
{
    preprocessor: Pre,
    statistic: Stat,
}

This uses all five type parameters but still triggers error[E0392] complaining about unused type parameters. I can fix it by adding phantom: PhantomData<(A1, A2, B)>, but I believe that shouldn't be necessary.

This issue looks related: #35146
And now that I read it again after posting this comment it might even be the same thing. The lack of where is something I didn't see before.

[Mark-Simulacrum]

Duplicate of #35146, closing.