Outlives error for where-clause with HRTB and no trait bounds

[compiler-errors]

The following code [playground]:

pub struct Bar
where
    for<'a> &'a mut Self:;

fn main() {}

Should compile, but it does not. Instead it fails with:

error[E0477]: the type `&'a mut Bar` does not fulfill the required lifetime
 --> src/main.rs:3:13
  |
3 |     for<'a> &'a mut Self:;
  |             ^^^^^^^^^^^^
  |
note: type must outlive the empty lifetime as required by this binding
 --> src/main.rs:3:13
  |
3 |     for<'a> &'a mut Self:;
  |             ^^^^^^^^^^^^

I think this is because we instantiate the predicate for<'a> &'a mut Self: ReEmpty(U0) here, which doesn't hold because of the HRTB.

[compiler-errors]

This is fixed with @jackh726's ReEmpty PR. Marking as needs test.

[jackh726]

wait huh

really? Which PR? The one open?

[jackh726]

Oh, I guess the TypeOutlives -> WellFormed.

Neat.