编译期的报错信息是 cannot move out of *allergen which is behind a shared reference move occurs because *allergen has type Allergen, which does not implement the Copy trait

代码如下

use self::Allergen::*;


#[derive(Debug, PartialEq, Eq)]
pub enum Allergen {
    Eggs = 1 << 0,
    Peanuts = 1 << 1,
    Shellfish = 1 << 2,
    Strawberries = 1 << 3,
    Tomatoes = 1 << 4,
    Chocolate = 1 << 5,
    Pollen = 1 << 6,
    Cats = 1 << 7,
}

const ALLERGENS: [Allergen; 8] =
    [Eggs, Peanuts, Shellfish, Strawberries, Tomatoes, Chocolate, Pollen, Cats];

pub struct Allergies {
    allergens: u32,
}

impl Allergies {
    pub fn new(n: u32) -> Self {
        Allergies { allergens: n }
    }

    pub fn is_allergic_to(&self, allergen: &Allergen) -> bool {
        let allergen = *allergen as u32;
        self.allergens & allergen == allergen
    }

    pub fn allergies(&self) -> Vec<Allergen> {
        unimplemented!("Return the list of allergens contained within the score with which the Allergies struct was made.");
    }
}

我觉得很神奇的是给pub enum Allergen加了 derive copy clone就能干掉报错

为什么呢？