error[E0596]: cannot borrow data in a `&` reference as mutable --> $DIR/index-mut-help.rs:11:5 | LL | map["peter"].clear(); | ^^^^^^^^^^^^ cannot borrow as mutable | = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `std::collections::HashMap<&str, std::string::String>` error[E0594]: cannot assign to data in a `&` reference --> $DIR/index-mut-help.rs:12:5 | LL | map["peter"] = "0".to_string(); | ^^^^^^^^^^^^ cannot assign error[E0596]: cannot borrow data in a `&` reference as mutable --> $DIR/index-mut-help.rs:13:13 | LL | let _ = &mut map["peter"]; | ^^^^^^^^^^^^^^^^^ cannot borrow as mutable | = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `std::collections::HashMap<&str, std::string::String>` error: aborting due to 3 previous errors For more information about this error, try `rustc --explain E0596`.