Poorly worded lifetime error message

[mdinger]

struct Mine<'a> {
    s: &'a str,
}

impl <'a>Iterator<&'a str> for Mine<'a> {
    fn next(&'a mut self) -> Option<&'a str> {
        Some("hi")
    }
}

impl <'a>Mine<'a> {
    fn new(s: &str) -> Mine {
        Mine { s: "hi" }
    }
}

fn main() {}

Error:

<anon>:6:5: 8:6 error: method `next` has an incompatible type for trait: expected concrete lifetime, found bound lifetime parameter  [E0053]
<anon>:6     fn next(&'a mut self) -> Option<&'a str> {
<anon>:7         Some("hi")
<anon>:8     }
<anon>:6:46: 8:6 note: expected concrete lifetime is the lifetime 'a as defined on the block at 6:45
<anon>:6     fn next(&'a mut self) -> Option<&'a str> {
<anon>:7         Some("hi")
<anon>:8     }
error: aborting due to previous error
playpen: application terminated with error code 101

---

This should be 2 sentences or something. It's hardly a sentence.

<anon>:6:46: 8:6 note: expected concrete lifetime is the lifetime 'a as defined on the block at 6:45
//                                               ^ Period? Semicolon? Something else?

[subhashb]

I think the sentence was actually meant as concrete lifetime that's expected, is the lifetime 'a as defined on the block at....

Can simply be reworded as expected concrete lifetime is 'a as defined on the block at...
What say?

[mdinger]

The 2nd has the same problem: Expected concrete lifetime. Is 'a as defined on the block at 6:45? It still needs a break.

Here is some discussion of this type of error however the error is still unclear. Which is a bound and which is concrete? What do the terms actually mean?

The error is also kinda odd because:

 fn next(&'a mut self) -> Option<&'a str>
//                                      ^ It point to this as the problem
//        ^ But this is the actual problem

[steveklabnik]

This error now looks like this:

hello.rs:7:5: 9:6 error: method `next` has an incompatible type for trait: expected bound lifetime parameter , found concrete lifetime [E0053]
hello.rs:7     fn next(&'a mut self) -> Option<&'a str> {
hello.rs:8         Some("hi")
hello.rs:9     }
error: aborting due to previous error

So off of these issues are gone.