error[E0277]: expected a `std::ops::FnMut<(char,)>` closure, found `std::string::String` --> $DIR/issue-62843.rs:4:32 | LL | println!("{:?}", line.find(pattern)); | ^^^^^^^ | | | expected an implementor of trait `std::str::pattern::Pattern<'_>` | help: consider borrowing here: `&pattern` | = note: the trait bound `std::string::String: std::str::pattern::Pattern<'_>` is not satisfied = note: required because of the requirements on the impl of `std::str::pattern::Pattern<'_>` for `std::string::String` error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.