error[E0277]: the type `[{integer}]` cannot be indexed by `i32` --> $DIR/index-help.rs:3:7 | LL | x[0i32]; | ^^^^ slice indices are of type `usize` or ranges of `usize` | = help: the trait `SliceIndex<[{integer}]>` is not implemented for `i32` = help: the trait `SliceIndex<[T]>` is implemented for `usize` = note: required for `Vec<{integer}>` to implement `Index<i32>` error: aborting due to previous error For more information about this error, try `rustc --explain E0277`.