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Rollup merge of rust-lang#78728 - a1phyr:const_cell_into_inner, r=dto…
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…lnay

Constantify `UnsafeCell::into_inner` and related

Tracking issue: rust-lang#78729

This PR constantifies:
- `UnsafeCell::into_inner`
- `Cell::into_inner`
- `RefCell::into_inner`
- `Atomic*::into_inner`

r? ``@dtolnay``
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m-ou-se authored Nov 7, 2020
2 parents a9157ad + 795bbfe commit 3f35770
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Showing 5 changed files with 26 additions and 8 deletions.
11 changes: 6 additions & 5 deletions library/core/src/cell.rs
Original file line number Diff line number Diff line change
Expand Up @@ -406,7 +406,8 @@ impl<T> Cell<T> {
/// assert_eq!(five, 5);
/// ```
#[stable(feature = "move_cell", since = "1.17.0")]
pub fn into_inner(self) -> T {
#[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
pub const fn into_inner(self) -> T {
self.value.into_inner()
}
}
Expand Down Expand Up @@ -668,12 +669,11 @@ impl<T> RefCell<T> {
/// let five = c.into_inner();
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
#[inline]
pub fn into_inner(self) -> T {
pub const fn into_inner(self) -> T {
// Since this function takes `self` (the `RefCell`) by value, the
// compiler statically verifies that it is not currently borrowed.
// Therefore the following assertion is just a `debug_assert!`.
debug_assert!(self.borrow.get() == UNUSED);
self.value.into_inner()
}

Expand Down Expand Up @@ -1682,7 +1682,8 @@ impl<T> UnsafeCell<T> {
/// ```
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub fn into_inner(self) -> T {
#[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
pub const fn into_inner(self) -> T {
self.value
}
}
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1 change: 1 addition & 0 deletions library/core/src/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -70,6 +70,7 @@
#![feature(cfg_target_has_atomic)]
#![feature(const_alloc_layout)]
#![feature(const_discriminant)]
#![feature(const_cell_into_inner)]
#![feature(const_checked_int_methods)]
#![feature(const_euclidean_int_methods)]
#![feature(const_float_classify)]
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9 changes: 6 additions & 3 deletions library/core/src/sync/atomic.rs
Original file line number Diff line number Diff line change
Expand Up @@ -355,7 +355,8 @@ impl AtomicBool {
/// ```
#[inline]
#[stable(feature = "atomic_access", since = "1.15.0")]
pub fn into_inner(self) -> bool {
#[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
pub const fn into_inner(self) -> bool {
self.v.into_inner() != 0
}

Expand Down Expand Up @@ -931,7 +932,8 @@ impl<T> AtomicPtr<T> {
/// ```
#[inline]
#[stable(feature = "atomic_access", since = "1.15.0")]
pub fn into_inner(self) -> *mut T {
#[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
pub const fn into_inner(self) -> *mut T {
self.p.into_inner()
}

Expand Down Expand Up @@ -1452,7 +1454,8 @@ assert_eq!(some_var.into_inner(), 5);
```"),
#[inline]
#[$stable_access]
pub fn into_inner(self) -> $int_type {
#[rustc_const_unstable(feature = "const_cell_into_inner", issue = "78729")]
pub const fn into_inner(self) -> $int_type {
self.v.into_inner()
}
}
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12 changes: 12 additions & 0 deletions library/core/tests/cell.rs
Original file line number Diff line number Diff line change
Expand Up @@ -422,3 +422,15 @@ fn refcell_format() {
let msg = format!("{name} {}", &*what.borrow(), name = &*name.borrow());
assert_eq!(msg, "rust rocks".to_string());
}

#[allow(dead_code)]
fn const_cells() {
const UNSAFE_CELL: UnsafeCell<i32> = UnsafeCell::new(3);
const _: i32 = UNSAFE_CELL.into_inner();

const REF_CELL: RefCell<i32> = RefCell::new(3);
const _: i32 = REF_CELL.into_inner();

const CELL: Cell<i32> = Cell::new(3);
const _: i32 = CELL.into_inner();
}
1 change: 1 addition & 0 deletions library/core/tests/lib.rs
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
#![feature(box_syntax)]
#![feature(cell_update)]
#![feature(const_assume)]
#![feature(const_cell_into_inner)]
#![feature(core_intrinsics)]
#![feature(core_private_bignum)]
#![feature(core_private_diy_float)]
Expand Down

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