error[E0596]: cannot borrow data in an index of `HashMap<&str, String>` as mutable --> $DIR/index-mut-help.rs:10:5 | LL | map["peter"].clear(); | ^^^^^^^^^^^^ cannot borrow as mutable | = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<&str, String>` = help: to modify a `HashMap<&str, String>`, use `.get_mut()`, `.insert()` or the entry API error[E0594]: cannot assign to data in an index of `HashMap<&str, String>` --> $DIR/index-mut-help.rs:11:5 | LL | map["peter"] = "0".to_string(); | ^^^^^^^^^^^^ cannot assign | = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<&str, String>` help: to modify a `HashMap<&str, String>`, use `.get_mut()`, `.insert()` or the entry API | LL | map.insert("peter", "0".to_string()); | ~~~~~~~~ ~ + LL | map.get_mut("peter").map(|val| { *val = "0".to_string(); }); | ~~~~~~~~~ ~~~~~~~~~~~~~~~~~~ ++++ LL | let val = map.entry("peter").or_insert("0".to_string()); | +++++++++ ~~~~~~~ ~~~~~~~~~~~~ + error[E0596]: cannot borrow data in an index of `HashMap<&str, String>` as mutable --> $DIR/index-mut-help.rs:12:13 | LL | let _ = &mut map["peter"]; | ^^^^^^^^^^^^^^^^^ cannot borrow as mutable | = help: trait `IndexMut` is required to modify indexed content, but it is not implemented for `HashMap<&str, String>` = help: to modify a `HashMap<&str, String>`, use `.get_mut()`, `.insert()` or the entry API error: aborting due to 3 previous errors Some errors have detailed explanations: E0594, E0596. For more information about an error, try `rustc --explain E0594`.