error[E0381]: used binding `v` isn't initialized --> $DIR/borrowck-init-plus-equal.rs:3:9 | LL | let mut v: isize; | ----- binding declared here but left uninitialized LL | v = v + 1; | ^ `v` used here but it isn't initialized | help: consider assigning a value | LL | let mut v: isize = 0; | +++ error: aborting due to previous error For more information about this error, try `rustc --explain E0381`.