error[E0596]: cannot borrow `*v` as mutable, as it is behind a `&` reference --> $DIR/issue-82032.rs:10:13 | LL | for v in self.0.values() { | --------------- | | | | | help: use mutable method: `values_mut()` | this iterator yields `&` references LL | v.flush(); | ^ `v` is a `&` reference, so the data it refers to cannot be borrowed as mutable error: aborting due to previous error For more information about this error, try `rustc --explain E0596`.