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]

1 files changed, 1 insertions, 1 deletions

diff --git a/src/libcore/any.rs b/src/libcore/any.rs
index 0b621863e2c..4a35dde08eb 100644
--- a/src/libcore/any.rs
+++ b/src/libcore/any.rs
@@ -183,7 +183,7 @@ mod tests {
         let mut b = box 7u;
 
         let a_r = &mut a as &mut Any;
-        let tmp: &mut uint = b;
+        let tmp: &mut uint = &mut *b;
         let b_r = tmp as &mut Any;
 
         match a_r.as_mut::<uint>() {