error[E0502]: cannot borrow `v` as mutable because it is also borrowed as immutable --> $DIR/borrowck-loan-blocks-mut-uniq.rs:10:12 | LL | borrow(&*v, | ------ --- immutable borrow occurs here | | | immutable borrow later used by call LL | |w| { | ^^^ mutable borrow occurs here LL | v = Box::new(4); | - second borrow occurs due to use of `v` in closure error: aborting due to 1 previous error For more information about this error, try `rustc --explain E0502`.