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Update ch19-02-advanced-lifetimes.md

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Peter Glotfelty
2017-06-24 16:54:22 -07:00
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second-edition/src/ch19-02-advanced-lifetimes.md
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@@ -309,17 +309,16 @@ note: ...so that the reference type `&'a T` does not outlive the data it points
| ^^^^^^
```
Because we have a generic type parameter, we can't add a lifetime parameter in the
same way. Since `T` can be any type, `T` could itself be a reference or it could
Since `T` can be any type, `T` could itself be a reference or it could
be a type that holds one or more references, each of which have their own
lifetimes, and the compiler cannot determine that the contents of `T` outlive `'a`.
lifetimes, and the compiler can't be sure `T` will live for the entirety of `'a`.
Rust gave us helpful advice on how to specify the lifetime parameter in
Rust gave us helpful advice on how to specify the lifetime bound in
this case:
```text
consider adding an explicit lifetime bound `T: 'a` so that the reference type
`&'a T` does not outlive the data it points to.
`&'a T` does not outlive the data it points at.
```
The code in Listing 19-17 works because `T: 'a` syntax specifies that `T` can