小编she*_*ath的帖子

// main.rs
#[derive(Clone, Copy)]
struct A(f64, f64);
impl<T> Mul<T> for A
where
    f64: From<T>,
    T: Copy, // f64: Mul<T>,
{
    type Output = A;
    fn mul(mut self, rhs: T) -> Self::Output {
        self.0 = self.0 * f64::from(rhs);
        self.1 = self.1 * f64::from(rhs);
        self
    }
}

impl Mul<A> for i32 {
    type Output = A;
    fn mul(self, mut rhs: A) -> Self::Output {
        rhs.0 = rhs.0 * f64::from(self);
        rhs.1 = rhs.1 * f64::from(self);
        rhs
    }
}

fn main() {
    let mut …