error[E0594]: cannot assign to `*foo`, which is behind a `&` reference --> $DIR/issue-92015.rs:6:5 | LL | *foo = 1; | ^^^^^^^^ `foo` is a `&` reference, so the data it refers to cannot be written | help: consider specifying this binding's type | LL | let foo: &mut i32 = Some(&0).unwrap(); | ++++++++++ error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0594`.