On 22/01/14 12:41, Scott Lawrence wrote:
This code compiles successfully: http://ix.io/a34 . I believe this
behavior is correct. Just so it's clear what this code does: f() takes
a `&mut int` and adds it to an array - the idea is that all of the
`&mut int` can be changed at some later time. Naturally, there's some
fancy lifetime juggling involved in this (which I may have gotten wrong).
Uncommenting the commented parts (the method f() in the impl A, in
particular) yields the error message shown at the bottom, which
appears to say that the lifetime created in the second parameter of
f() does not necessarily outlive itself.
Is there some especially complicated aspect of lifetimes as they
interact with &self, or is this indeed a bug?
I think it's the compiler tricking you: the 'a in `fn f<'a>(&mut self,
...)` is shadowing the `impl<'a> A<'a>` i.e. they are different
lifetimes that happen to have the same identifier. Changing it to `fn
f(&mut self, &'a mut int)` should work.
There's a bug open about warning on shadowed generics, because, as this
demonstrates, you end up with hard-to-diagnose error messages:
https://github.com/mozilla/rust/issues/11658
Huon
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