How to end borrow in this code?

help
2

By changing your trait definition to:

// Hack: introduce an implicit `where Self : 'b` bound
trait BufferedInput<'b, B, _whereSelfOutlivesb = &'b Self> {
    fn read(&'_ mut self, buf: B) -> &'b [u8];
}

then something like:

        for<'local>
            &'static [u8] : BufferedInput<'local, <S as Storage<'local>>::Buffer>
        ,

will yield a constraint that only uses small enough 'local lifetimes,

and from there:

impl<'i, 'j : 'i> BufferedInput<'i, ()> for &'j [u8] {
    /// Directly borrow data from `self`, do not copy,
    /// return data that borrow from `self`
    fn read(&'_ mut self, _buf: ()) -> &'i [u8] {
        self
    }
}

yields a correctly higher-order bound for &[u8].

By the way, don't worry if the solution does not seem obvious to come by "alone", it's a kind of messy area of the language which will get better / clearer once we have generic_associated_types :slightly_smiling_face:

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