error[E0277]: the trait bound `for<'a> &'a _: Trait` is not satisfied --> $DIR/issue-89333.rs:6:5 | LL | test(&|| 0); | ^^^^^^^^^^^ the trait `for<'a> Trait` is not implemented for `&'a _` | help: this trait has no implementations, consider adding one --> $DIR/issue-89333.rs:9:1 | LL | trait Trait {} | ^^^^^^^^^^^ note: required by a bound in `test` --> $DIR/issue-89333.rs:11:55 | LL | fn test(arg: &impl Fn() -> T) where for<'a> &'a T: Trait {} | ^^^^^ required by this bound in `test` error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0277`.