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make slice::{split_at,split_at_unchecked} const functions

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This commit is contained in:
Trevor Spiteri 2022-08-02 22:22:16 +02:00
parent 06f4950cbd
commit 97c963d081
2 changed files with 10 additions and 4 deletions
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1
library/core/src/lib.rs
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@ -137,6 +137,7 @@
#![feature(const_size_of_val)] #![feature(const_size_of_val)]
#![feature(const_slice_from_raw_parts_mut)] #![feature(const_slice_from_raw_parts_mut)]
#![feature(const_slice_ptr_len)] #![feature(const_slice_ptr_len)]
#![feature(const_slice_split_at_not_mut)]
#![feature(const_str_from_utf8_unchecked_mut)] #![feature(const_str_from_utf8_unchecked_mut)]
#![feature(const_swap)] #![feature(const_swap)]
#![feature(const_trait_impl)] #![feature(const_trait_impl)]

13
library/core/src/slice/mod.rs
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@ -1538,13 +1538,14 @@ impl<T> [T] {
/// } /// }
/// ``` /// ```
#[stable(feature = "rust1", since = "1.0.0")] #[stable(feature = "rust1", since = "1.0.0")]
#[rustc_const_unstable(feature = "const_slice_split_at_not_mut", issue = "none")]
#[inline] #[inline]
#[track_caller] #[track_caller]
#[must_use] #[must_use]
pub fn split_at(&self, mid: usize) -> (&[T], &[T]) { pub const fn split_at(&self, mid: usize) -> (&[T], &[T]) {
assert!(mid <= self.len()); assert!(mid <= self.len());
// SAFETY: `[ptr; mid]` and `[mid; len]` are inside `self`, which // SAFETY: `[ptr; mid]` and `[mid; len]` are inside `self`, which
// fulfills the requirements of `from_raw_parts_mut`. // fulfills the requirements of `split_at_unchecked`.
unsafe { self.split_at_unchecked(mid) } unsafe { self.split_at_unchecked(mid) }
} }
@ -1623,11 +1624,15 @@ impl<T> [T] {
/// } /// }
/// ``` /// ```
#[unstable(feature = "slice_split_at_unchecked", reason = "new API", issue = "76014")] #[unstable(feature = "slice_split_at_unchecked", reason = "new API", issue = "76014")]
#[rustc_const_unstable(feature = "const_slice_split_at_not_mut", issue = "none")]
#[inline] #[inline]
#[must_use] #[must_use]
pub unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T]) { pub const unsafe fn split_at_unchecked(&self, mid: usize) -> (&[T], &[T]) {
let len = self.len();
let ptr = self.as_ptr();
// SAFETY: Caller has to check that `0 <= mid <= self.len()` // SAFETY: Caller has to check that `0 <= mid <= self.len()`
unsafe { (self.get_unchecked(..mid), self.get_unchecked(mid..)) } unsafe { (from_raw_parts(ptr, mid), from_raw_parts(ptr.add(mid), len - mid)) }
} }
/// Divides one mutable slice into two at an index, without doing bounds checking. /// Divides one mutable slice into two at an index, without doing bounds checking.