error[E0594]: cannot assign to `**t1`, which is behind a `&` reference --> $DIR/borrowck-borrow-mut-base-ptr-in-aliasable-loc.rs:9:5 | LL | let t1 = t0; | -- consider changing this binding's type to be: `&mut &mut isize` LL | let p: &isize = &**t0; LL | **t1 = 22; | ^^^^^^^^^ `t1` is a `&` reference, so the data it refers to cannot be written error[E0502]: cannot borrow `**t0` as immutable because it is also borrowed as mutable --> $DIR/borrowck-borrow-mut-base-ptr-in-aliasable-loc.rs:14:21 | LL | let t1 = &mut *t0; | -------- mutable borrow occurs here LL | let p: &isize = &**t0; | ^^^^^ immutable borrow occurs here LL | **t1 = 22; | --------- mutable borrow later used here error[E0596]: cannot borrow `**t0` as mutable, as it is behind a `&` reference --> $DIR/borrowck-borrow-mut-base-ptr-in-aliasable-loc.rs:19:26 | LL | let x: &mut isize = &mut **t0; | ^^^^^^^^^ `t0` is a `&` reference, so the data it refers to cannot be borrowed as mutable | help: consider changing this to be a mutable reference | LL | fn foo4(t0: &mut &mut isize) { | ~~~~~~~~~~~~~~~ error: aborting due to 3 previous errors Some errors have detailed explanations: E0502, E0594, E0596. For more information about an error, try `rustc --explain E0502`.