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 `FnMut<(char,)>` closure, found `std::string::String`
   |
   = help: the trait `std::ops::FnMut<(char,)>` is not implemented for `std::string::String`
   = note: borrowing the `std::string::String` might fix the problem
   = 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`.