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Constify mem::replace and ptr::replace

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This commit is contained in:
Albin Hedman 2021-03-13 20:38:43 +01:00
parent 64e2248794
commit 45988ee438
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2 changed files with 4 additions and 2 deletions
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3
library/core/src/mem/mod.rs
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@ -813,7 +813,8 @@ pub fn take<T: Default>(dest: &mut T) -> T {
#[inline] #[inline]
#[stable(feature = "rust1", since = "1.0.0")] #[stable(feature = "rust1", since = "1.0.0")]
#[must_use = "if you don't need the old value, you can just assign the new value directly"] #[must_use = "if you don't need the old value, you can just assign the new value directly"]
pub fn replace<T>(dest: &mut T, src: T) -> T { #[rustc_const_unstable(feature = "const_replace", issue = "83164")]
pub const fn replace<T>(dest: &mut T, src: T) -> T {
// SAFETY: We read from `dest` but directly write `src` into it afterwards, // SAFETY: We read from `dest` but directly write `src` into it afterwards,
// such that the old value is not duplicated. Nothing is dropped and // such that the old value is not duplicated. Nothing is dropped and
// nothing here can panic. // nothing here can panic.

3
library/core/src/ptr/mod.rs
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@ -584,7 +584,8 @@ const unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) {
/// ``` /// ```
#[inline] #[inline]
#[stable(feature = "rust1", since = "1.0.0")] #[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn replace<T>(dst: *mut T, mut src: T) -> T { #[rustc_const_unstable(feature = "const_replace", issue = "83164")]
pub const unsafe fn replace<T>(dst: *mut T, mut src: T) -> T {
// SAFETY: the caller must guarantee that `dst` is valid to be // SAFETY: the caller must guarantee that `dst` is valid to be
// cast to a mutable reference (valid for writes, aligned, initialized), // cast to a mutable reference (valid for writes, aligned, initialized),
// and cannot overlap `src` since `dst` must point to a distinct // and cannot overlap `src` since `dst` must point to a distinct