小编Phi*_*aig的帖子

以下代码示例是我遇到的问题的缩小版本.

trait Offset: Default {}

trait Reader {
    type Offset: Offset;
}

impl Offset for usize {}

impl<'a> Reader for &'a [u8] {
    type Offset = usize;
}

// OK
// struct Header<R: Reader>(R, usize);

// Bad
struct Header<R: Reader>(R, R::Offset);

impl <R: Reader<Offset=usize>> Header<R> {
    fn new(r: R) -> Self {
        Header(r, 0)
    }
}

fn test<R: Reader>(_: Header<R>, _: Header<R>) {}

fn main() {
    let buf1 = [0u8];
    let slice1 = &buf1[..];
    let header1 = Header::new(slice1);

    let buf2 …