error[E0381]: used binding `x` isn't initialized --> $DIR/borrowck-use-uninitialized-in-cast-trait.rs:9:13 | LL | let x: &i32; | - binding declared here but left uninitialized LL | let y = x as *const dyn Foo; | ^ `*x` used here but it isn't initialized | help: consider assigning a value | LL | let x: &i32 = todo!(); | +++++++++ error: aborting due to previous error For more information about this error, try `rustc --explain E0381`.