error[E0277]: expected a `std::ops::FnOnce<()>` closure, found `{integer}` --> $DIR/closure-expected.rs:3:15 | LL | let y = x.or_else(4); | ^^^^^^^ expected an `FnOnce<()>` closure, found `{integer}` | = help: the trait `std::ops::FnOnce<()>` is not implemented for `{integer}` = note: wrap the `{integer}` in a closure with no arguments: `|| { /* code */ } error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.