Help to fix some lifetime issues

[sharp hedge]

pub trait Decode: Sized {
    fn decode(bytes: &[u8]) -> Result<Self>;
}

impl Decode for &str {
    fn decode(bytes: &[u8]) -> Result<&str> {
        str::from_utf8(bytes).map_err(Error::Utf8)
    }
}

Compiler errors:

error: `impl` item signature doesn't match `trait` item signature
error: found `fn(&'1 [u8]) -> std::result::Result<&'1 str, Error>`
note: expected signature `fn(&'1 [u8]) -> std::result::Result<&'2 str, Error>`
   found signature `fn(&'1 [u8]) -> std::result::Result<&'1 str, Error>`
error: expected `fn(&'1 [u8]) -> std::result::Result<&'2 str, Error>`
help: the lifetime requirements from the `impl` do not correspond to the requirements in the `trait`
help: consider borrowing this type parameter in the trait

[lime rock]

The issue here is that the Decode trait assumes that Self has nothing to do with bytes, i.e. that it doesn't borrow any data

To fix this, you'd need to update the trait and impl:

pub trait Decode<'a>: Sized {
    fn decode(bytes: &'a [u8]) -> Result<Self>;
}

impl<'a> Decode<'a> for &'a str {
    fn decode(bytes: &'a [u8]) -> Result<Self> {
        str::from_utf8(bytes).map_err(Error::Utf8)
    }
}

Now, Decode indicates that the value can be bounded by the lifetime of the bytes, which the &str is.

Note that it doesn't have to be bounded by the lifetime, so this is also valid:

impl<'a> Decode<'a> for Vec<u8> {
    fn decode(bytes: &'a [u8]) -> Result<Self> {
        Ok(Vec::from(bytes))
    }
}

The Vec has no lifetimes, but that's okay