Bogus associated type HKT syntax somehow compiles with no errors

[theemathas]

Code:

pub trait A : Copy {}

struct Foo;

pub trait D {
    fn f<T>(self)
        where T<Bogus = Foo>: A;
}

fn main() {}

playpen

This isn't supposed to compile at all.

Probably a variant of #23544

[bombless]

use std::marker::PhantomFn;

trait Trait<T>: PhantomFn<Self, T> {}

impl<T> Trait<T> for () where Trait<T>: Eq {}

fn main() {}

This seems similar (illegal bounds at where clause)

[theemathas]

This is incorrectly labelled. This should be I-wrong, not I-ICE

[huonw]

@bombless I'm not sure that is illegal, since Trait<T> is a valid type (its is a DST): that impl is just conditional on whether the Trait<T> type implements Eq, e.g.

use std::marker::PhantomFn;

trait Trait<T>: PhantomFn<Self, T> {}

impl<T> Trait<T> for () where Trait<T>: Eq {}


fn foo<T, U: Trait<T>>() {}


impl PartialEq for Trait<u16> {
    fn eq(&self, _: &Trait<u16>) -> bool { false }
}
impl Eq for Trait<u16> {}


fn main() {
    foo::<u16, ()>();

    // foo::<u8, ()>();
    // error: the trait `core::cmp::Eq` is not implemented for the type `Trait<u8>`
}

[Stebalien]

Triage: can't reproduce.

tmp.rs:7:17: 7:28 error: associated type bindings are not allowed here [E0229]
tmp.rs:7         where T<Bogus = Foo>: A;
                         ^~~~~~~~~~~
error: aborting due to previous error