error[E0599]: the function or associated item `make_g` exists for fn pointer `for<'a> fn(&'a ())`, but its trait bounds were not satisfied --> $DIR/issue-57362-2.rs:22:25 | LL | let x = ::make_g(); | ^^^^^^ function or associated item cannot be called on `for<'a> fn(&'a ())` due to unsatisfied trait bounds | = note: the following trait bounds were not satisfied: `for<'a> fn(&'a ()): X` = help: items from traits can only be used if the trait is implemented and in scope note: `X` defines an item `make_g`, perhaps you need to implement it --> $DIR/issue-57362-2.rs:8:1 | LL | trait X { | ^^^^^^^ error: aborting due to previous error For more information about this error, try `rustc --explain E0599`.