rust-lang/rust — pull request #15171 by pcwalton (2014-06-25 06:14:59+00:00)
Title: librustc: Remove cross borrowing from mutable `Box`es to `&mut`.

This will break code like:

fn f(x: &mut int) {}

let mut a = box 1i;
f(a);

Change it to:

fn f(x: &mut int) {}

let mut a = box 1i;
f(&mut *a);

RFC 33; issue #10504.

[breaking-change]

r? @brson