Rereborrowing loses lifetime information.

[stevenblenkinsop]

This code fails to compile:
fn rereborrow(v: &r/int) -> &r/int { &_&_v }

fn main() {}

With error:
test.rs:1:38: 1:42 error: illegal borrow: borrowed value does not live long enough
test.rs:1 fn rereborrow(v: &r/int) -> &r/int { &_&v }
^~~~
test.rs:1:35: 1:44 note: borrowed pointer must be valid for the lifetime &r as defined on the block at 1:35...
test.rs:1 fn rereborrow(v: &r/int) -> &r/int { &&v }
^~~~~~~~~
test.rs:1:35: 1:44 note: ...but borrowed value is only valid for the block at 1:35
test.rs:1 fn rereborrow(v: &r/int) -> &r/int { &&_v }
^~~~~~~~~
error: aborting due to previous error

shell returned 101

[catamorphism]

I'm not sure if this is by design or not -- we'll have to wait for @nikomatsakis to answer that.

[nikomatsakis]

I believe this is a duplicate of #3148 which also suggests a workaround.