error[E0308]: mismatched types
  --> $DIR/issue-99073.rs:6:13
   |
LL | fn fix<F: Fn(G), G: Fn()>(f: F) -> impl Fn() {
   |                                    --------- the expected opaque type
LL |     move || f(fix(&f))
   |             ^^^^^^^^^^ types differ
   |
   = note: expected opaque type `impl Fn()`
           found type parameter `G`

error: aborting due to previous error

For more information about this error, try `rustc --explain E0308`.