Rollup merge of #76655 - CDirkx:const-pin, r=ecstatic-morse
Make some methods of `Pin` unstable const Make the following methods unstable const under the `const_pin` feature: - `new` - `new_unchecked` - `into_inner` - `into_inner_unchecked` - `get_ref` - `into_ref` - `get_mut` - `get_unchecked_mut` Of these, `into_inner` and `into_inner_unchecked` require the unstable `const_precise_live_drops`. Also adds tests for these methods in a const context. Tracking issue: #76654 r? @ecstatic-morse
This commit is contained in:
commit
537ede465f
|
@ -78,6 +78,7 @@
|
|||
#![feature(const_int_pow)]
|
||||
#![feature(constctlz)]
|
||||
#![feature(const_panic)]
|
||||
#![feature(const_pin)]
|
||||
#![feature(const_fn_union)]
|
||||
#![feature(const_generics)]
|
||||
#![feature(const_option)]
|
||||
|
|
|
@ -471,9 +471,10 @@ impl<P: Deref<Target: Unpin>> Pin<P> {
|
|||
///
|
||||
/// Unlike `Pin::new_unchecked`, this method is safe because the pointer
|
||||
/// `P` dereferences to an [`Unpin`] type, which cancels the pinning guarantees.
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
#[inline(always)]
|
||||
pub fn new(pointer: P) -> Pin<P> {
|
||||
#[rustc_const_unstable(feature = "const_pin", issue = "76654")]
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
pub const fn new(pointer: P) -> Pin<P> {
|
||||
// SAFETY: the value pointed to is `Unpin`, and so has no requirements
|
||||
// around pinning.
|
||||
unsafe { Pin::new_unchecked(pointer) }
|
||||
|
@ -483,9 +484,10 @@ impl<P: Deref<Target: Unpin>> Pin<P> {
|
|||
///
|
||||
/// This requires that the data inside this `Pin` is [`Unpin`] so that we
|
||||
/// can ignore the pinning invariants when unwrapping it.
|
||||
#[stable(feature = "pin_into_inner", since = "1.39.0")]
|
||||
#[inline(always)]
|
||||
pub fn into_inner(pin: Pin<P>) -> P {
|
||||
#[rustc_const_unstable(feature = "const_pin", issue = "76654")]
|
||||
#[stable(feature = "pin_into_inner", since = "1.39.0")]
|
||||
pub const fn into_inner(pin: Pin<P>) -> P {
|
||||
pin.pointer
|
||||
}
|
||||
}
|
||||
|
@ -556,9 +558,10 @@ impl<P: Deref> Pin<P> {
|
|||
///
|
||||
/// [`mem::swap`]: crate::mem::swap
|
||||
#[lang = "new_unchecked"]
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
#[inline(always)]
|
||||
pub unsafe fn new_unchecked(pointer: P) -> Pin<P> {
|
||||
#[rustc_const_unstable(feature = "const_pin", issue = "76654")]
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
pub const unsafe fn new_unchecked(pointer: P) -> Pin<P> {
|
||||
Pin { pointer }
|
||||
}
|
||||
|
||||
|
@ -589,9 +592,10 @@ impl<P: Deref> Pin<P> {
|
|||
///
|
||||
/// If the underlying data is [`Unpin`], [`Pin::into_inner`] should be used
|
||||
/// instead.
|
||||
#[stable(feature = "pin_into_inner", since = "1.39.0")]
|
||||
#[inline(always)]
|
||||
pub unsafe fn into_inner_unchecked(pin: Pin<P>) -> P {
|
||||
#[rustc_const_unstable(feature = "const_pin", issue = "76654")]
|
||||
#[stable(feature = "pin_into_inner", since = "1.39.0")]
|
||||
pub const unsafe fn into_inner_unchecked(pin: Pin<P>) -> P {
|
||||
pin.pointer
|
||||
}
|
||||
}
|
||||
|
@ -693,18 +697,20 @@ impl<'a, T: ?Sized> Pin<&'a T> {
|
|||
/// with the same lifetime as the original `Pin`.
|
||||
///
|
||||
/// ["pinning projections"]: self#projections-and-structural-pinning
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
#[inline(always)]
|
||||
pub fn get_ref(self) -> &'a T {
|
||||
#[rustc_const_unstable(feature = "const_pin", issue = "76654")]
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
pub const fn get_ref(self) -> &'a T {
|
||||
self.pointer
|
||||
}
|
||||
}
|
||||
|
||||
impl<'a, T: ?Sized> Pin<&'a mut T> {
|
||||
/// Converts this `Pin<&mut T>` into a `Pin<&T>` with the same lifetime.
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
#[inline(always)]
|
||||
pub fn into_ref(self) -> Pin<&'a T> {
|
||||
#[rustc_const_unstable(feature = "const_pin", issue = "76654")]
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
pub const fn into_ref(self) -> Pin<&'a T> {
|
||||
Pin { pointer: self.pointer }
|
||||
}
|
||||
|
||||
|
@ -717,9 +723,10 @@ impl<'a, T: ?Sized> Pin<&'a mut T> {
|
|||
/// that lives for as long as the borrow of the `Pin`, not the lifetime of
|
||||
/// the `Pin` itself. This method allows turning the `Pin` into a reference
|
||||
/// with the same lifetime as the original `Pin`.
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
#[inline(always)]
|
||||
pub fn get_mut(self) -> &'a mut T
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
#[rustc_const_unstable(feature = "const_pin", issue = "76654")]
|
||||
pub const fn get_mut(self) -> &'a mut T
|
||||
where
|
||||
T: Unpin,
|
||||
{
|
||||
|
@ -736,9 +743,10 @@ impl<'a, T: ?Sized> Pin<&'a mut T> {
|
|||
///
|
||||
/// If the underlying data is `Unpin`, `Pin::get_mut` should be used
|
||||
/// instead.
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
#[inline(always)]
|
||||
pub unsafe fn get_unchecked_mut(self) -> &'a mut T {
|
||||
#[stable(feature = "pin", since = "1.33.0")]
|
||||
#[rustc_const_unstable(feature = "const_pin", issue = "76654")]
|
||||
pub const unsafe fn get_unchecked_mut(self) -> &'a mut T {
|
||||
self.pointer
|
||||
}
|
||||
|
||||
|
|
|
@ -43,6 +43,8 @@
|
|||
#![feature(iter_order_by)]
|
||||
#![feature(cmp_min_max_by)]
|
||||
#![feature(iter_map_while)]
|
||||
#![feature(const_mut_refs)]
|
||||
#![feature(const_pin)]
|
||||
#![feature(const_slice_from_raw_parts)]
|
||||
#![feature(const_raw_ptr_deref)]
|
||||
#![feature(never_type)]
|
||||
|
@ -79,6 +81,7 @@ mod num;
|
|||
mod ops;
|
||||
mod option;
|
||||
mod pattern;
|
||||
mod pin;
|
||||
mod ptr;
|
||||
mod result;
|
||||
mod slice;
|
||||
|
|
|
@ -0,0 +1,31 @@
|
|||
use core::pin::Pin;
|
||||
|
||||
#[test]
|
||||
fn pin_const() {
|
||||
// test that the methods of `Pin` are usable in a const context
|
||||
|
||||
const POINTER: &'static usize = &2;
|
||||
|
||||
const PINNED: Pin<&'static usize> = Pin::new(POINTER);
|
||||
const PINNED_UNCHECKED: Pin<&'static usize> = unsafe { Pin::new_unchecked(POINTER) };
|
||||
assert_eq!(PINNED_UNCHECKED, PINNED);
|
||||
|
||||
const INNER: &'static usize = Pin::into_inner(PINNED);
|
||||
assert_eq!(INNER, POINTER);
|
||||
|
||||
const INNER_UNCHECKED: &'static usize = unsafe { Pin::into_inner_unchecked(PINNED) };
|
||||
assert_eq!(INNER_UNCHECKED, POINTER);
|
||||
|
||||
const REF: &'static usize = PINNED.get_ref();
|
||||
assert_eq!(REF, POINTER);
|
||||
|
||||
// Note: `pin_mut_const` tests that the methods of `Pin<&mut T>` are usable in a const context.
|
||||
// A const fn is used because `&mut` is not (yet) usable in constants.
|
||||
const fn pin_mut_const() {
|
||||
let _ = Pin::new(&mut 2).into_ref();
|
||||
let _ = Pin::new(&mut 2).get_mut();
|
||||
let _ = unsafe { Pin::new(&mut 2).get_unchecked_mut() };
|
||||
}
|
||||
|
||||
pin_mut_const();
|
||||
}
|
Loading…
Reference in New Issue