error[E0107]: trait takes 0 generic arguments but 1 generic argument was supplied
  --> $DIR/unboxed-closure-sugar-wrong-trait.rs:5:8
   |
LL | fn f<F:Trait(isize) -> isize>(x: F) {}
   |        ^^^^^------- help: remove these parenthetical generics
   |        |
   |        expected 0 generic arguments
   |
note: trait defined here, with 0 generic parameters
  --> $DIR/unboxed-closure-sugar-wrong-trait.rs:3:7
   |
LL | trait Trait {}
   |       ^^^^^

error[E0220]: associated type `Output` not found for `Trait`
  --> $DIR/unboxed-closure-sugar-wrong-trait.rs:5:24
   |
LL | fn f<F:Trait(isize) -> isize>(x: F) {}
   |                        ^^^^^ associated type `Output` not found

error: aborting due to 2 previous errors

Some errors have detailed explanations: E0107, E0220.
For more information about an error, try `rustc --explain E0107`.