How can I implement Rust's Copy trait?

Question

I am trying to initialise an array of structs in Rust:

enum Direction {     North,     East,     South,     West, }  struct RoadPoint {     direction: Direction,     index: i32, }  // Initialise the array, but failed. let data = [RoadPoint { direction: Direction::East, index: 1 }; 4];  

When I try to compile, the compiler complains that the Copy trait is not implemented:

error[E0277]: the trait bound `main::RoadPoint: std::marker::Copy` is not satisfied   --> src/main.rs:15:16    | 15 |     let data = [RoadPoint { direction: Direction::East, index: 1 }; 4];     |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ the trait `std::marker::Copy` is not implemented for `main::RoadPoint`    |    = note: the `Copy` trait is required because the repeated element will be copied 

How can the Copy trait be implemented?

Answer 1

You don't have to implement Copy yourself; the compiler can derive it for you:

#[derive(Copy, Clone)] enum Direction {     North,     East,     South,     West, }  #[derive(Copy, Clone)] struct RoadPoint {     direction: Direction,     index: i32, } 

Note that every type that implements Copy must also implement Clone. Clone can also be derived.