rust - 我不明白错误 E0508

Question

当我尝试编译这段代码时，出现 E0508​​ 错误:

cannot move out of type [Enum; 2], a non-copy fixed-size array

enum Enum {
    Val1 = 0,
    Val2 = 1,
}

fn main() {
    let a = [Enum::Val1, Enum::Val2];
    let x: i32 = a[0] as i32 + a[1] as i32;
    println!("{}", x);
}

我只想访问枚举类型数组中的单个值。

Answer 1

较小的复制品:

enum Enum {
    Val1 = 0,
    Val2 = 1,
}

fn main() {
    let a = [Enum::Val1];
    a[0] as i32;
}

最简单的解决方法是使您的枚举复制:

#[derive(Copy, Clone)]
enum Enum {
    Val1 = 0,
    Val2 = 1,
}

where is the copy needed?

这是一个很好的问题，我不完全确定为什么在强制转换为整数时需要移动值。不过，这与数组无关:

#[derive(Debug)]
enum Enum {
    Val1 = 0,
    Val2 = 1,
}

fn main() {
    let a = Enum::Val1;
    let b = a as i32;
    println!("{:?}", a); // Error: a was moved in the line above
}