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Rollup merge of #75250 - RalfJung:uninit-const-ptr, r=oli-obk 

make MaybeUninit::as_(mut_)ptr const

I think it was just an oversight that they are not const yet.

I also changed their implementation as the old one created references to uninitialized memory.^^
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Yuki Okushi 2020-08-08 11:36:05 +09:00 committed by GitHub
parent 255434d83c ec5d78d350
commit b032a15fa8
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1 changed files with 8 additions and 4 deletions
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12
library/core/src/mem/maybe_uninit.rs
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@ -405,9 +405,11 @@ impl<T> MaybeUninit<T> {
/// (Notice that the rules around references to uninitialized data are not finalized yet, but
/// until they are, it is advisable to avoid them.)
#[stable(feature = "maybe_uninit", since = "1.36.0")]
#[rustc_const_unstable(feature = "const_maybe_uninit_as_ptr", issue = "75251")]
#[inline(always)]
pub fn as_ptr(&self) -> *const T {
unsafe { &*self.value as *const T }
pub const fn as_ptr(&self) -> *const T {
// `MaybeUninit` and `ManuallyDrop` are both `repr(transparent)` so we can cast the pointer.
self as *const _ as *const T
}
/// Gets a mutable pointer to the contained value. Reading from this pointer or turning it
@ -442,9 +444,11 @@ impl<T> MaybeUninit<T> {
/// (Notice that the rules around references to uninitialized data are not finalized yet, but
/// until they are, it is advisable to avoid them.)
#[stable(feature = "maybe_uninit", since = "1.36.0")]
#[rustc_const_unstable(feature = "const_maybe_uninit_as_ptr", issue = "75251")]
#[inline(always)]
pub fn as_mut_ptr(&mut self) -> *mut T {
unsafe { &mut *self.value as *mut T }
pub const fn as_mut_ptr(&mut self) -> *mut T {
// `MaybeUninit` and `ManuallyDrop` are both `repr(transparent)` so we can cast the pointer.
self as *mut _ as *mut T
}
/// Extracts the value from the `MaybeUninit<T>` container. This is a great way