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Rollup merge of #32652 - VFLashM:refcell_ref_coercion, r=alexcrichton

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Added missing refcell ref/refmut coercions to unsized

Ref/RefMut should be coercible to unsized.
This commit adds a unit test and two missing CoerceUnsized implementations.
This commit is contained in:
Manish Goregaokar 2016-04-01 18:44:49 +05:30
commit cf0a01a161
2 changed files with 28 additions and 2 deletions
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10
src/libcore/cell.rs
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@ -147,8 +147,8 @@
use clone::Clone;
use cmp::{PartialEq, Eq};
use default::Default;
use marker::{Copy, Send, Sync, Sized};
use ops::{Deref, DerefMut, Drop, FnOnce};
use marker::{Copy, Send, Sync, Sized, Unsize};
use ops::{Deref, DerefMut, Drop, FnOnce, CoerceUnsized};
use option::Option;
use option::Option::{None, Some};
@ -634,6 +634,9 @@ impl<'b, T: ?Sized> Ref<'b, T> {
}
}
#[unstable(feature = "coerce_unsized", issue = "27732")]
impl<'b, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Ref<'b, U>> for Ref<'b, T> {}
impl<'b, T: ?Sized> RefMut<'b, T> {
/// Make a new `RefMut` for a component of the borrowed data, e.g. an enum
/// variant.
@ -766,6 +769,9 @@ impl<'b, T: ?Sized> DerefMut for RefMut<'b, T> {
}
}
#[unstable(feature = "coerce_unsized", issue = "27732")]
impl<'b, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<RefMut<'b, U>> for RefMut<'b, T> {}
/// The core primitive for interior mutability in Rust.
///
/// `UnsafeCell<T>` is a type that wraps some `T` and indicates unsafe interior operations on the

20
src/libcoretest/cell.rs
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@ -261,3 +261,23 @@ fn refcell_unsized() {
let comp: &mut [i32] = &mut [4, 2, 5];
assert_eq!(&*cell.borrow(), comp);
}
#[test]
fn refcell_ref_coercion() {
let cell: RefCell<[i32; 3]> = RefCell::new([1, 2, 3]);
{
let mut cellref: RefMut<[i32; 3]> = cell.borrow_mut();
cellref[0] = 4;
let mut coerced: RefMut<[i32]> = cellref;
coerced[2] = 5;
}
{
let comp: &mut [i32] = &mut [4, 2, 5];
let cellref: Ref<[i32; 3]> = cell.borrow();
assert_eq!(&*cellref, comp);
let coerced: Ref<[i32]> = cellref;
assert_eq!(&*coerced, comp);
}
}