bjoernager/rust
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Revert "Auto merge of #53508 - japaric:maybe-uninit, r=RalfJung"

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This reverts commit c6e3d7fa31, reversing
changes made to 4591a245c7.
This commit is contained in:
Ralf Jung 2018-09-25 15:07:27 +02:00
parent 6622172734
commit e37d6d37e7
20 changed files with 85 additions and 350 deletions
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32
src/libcore/ptr.rs
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@ -79,7 +79,7 @@ use ops::CoerceUnsized;
use fmt;
use hash;
use marker::{PhantomData, Unsize};
use mem::{self, MaybeUninit};
use mem;
use nonzero::NonZero;
use cmp::Ordering::{self, Less, Equal, Greater};
@ -294,12 +294,16 @@ pub const fn null_mut<T>() -> *mut T { 0 as *mut T }
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn swap<T>(x: *mut T, y: *mut T) {
// Give ourselves some scratch space to work with
let mut tmp = MaybeUninit::<T>::uninitialized();
let mut tmp: T = mem::uninitialized();
// Perform the swap
copy_nonoverlapping(x, tmp.as_mut_ptr(), 1);
copy_nonoverlapping(x, &mut tmp, 1);
copy(y, x, 1); // `x` and `y` may overlap
copy_nonoverlapping(tmp.get_ref(), y, 1);
copy_nonoverlapping(&tmp, y, 1);
// y and t now point to the same thing, but we need to completely forget `tmp`
// because it's no longer relevant.
mem::forget(tmp);
}
/// Swaps `count * size_of::<T>()` bytes between the two regions of memory
@ -386,8 +390,8 @@ unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) {
while i + block_size <= len {
// Create some uninitialized memory as scratch space
// Declaring `t` here avoids aligning the stack when this loop is unused
let mut t = mem::MaybeUninit::<Block>::uninitialized();
let t = t.as_mut_ptr() as *mut u8;
let mut t: Block = mem::uninitialized();
let t = &mut t as *mut _ as *mut u8;
let x = x.add(i);
let y = y.add(i);
@ -401,10 +405,10 @@ unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) {
if i < len {
// Swap any remaining bytes
let mut t = mem::MaybeUninit::<UnalignedBlock>::uninitialized();
let mut t: UnalignedBlock = mem::uninitialized();
let rem = len - i;
let t = t.as_mut_ptr() as *mut u8;
let t = &mut t as *mut _ as *mut u8;
let x = x.add(i);
let y = y.add(i);
@ -569,9 +573,9 @@ pub unsafe fn replace<T>(dst: *mut T, mut src: T) -> T {
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn read<T>(src: *const T) -> T {
let mut tmp = MaybeUninit::<T>::uninitialized();
copy_nonoverlapping(src, tmp.as_mut_ptr(), 1);
tmp.into_inner()
let mut tmp: T = mem::uninitialized();
copy_nonoverlapping(src, &mut tmp, 1);
tmp
}
/// Reads the value from `src` without moving it. This leaves the
@ -636,11 +640,11 @@ pub unsafe fn read<T>(src: *const T) -> T {
#[inline]
#[stable(feature = "ptr_unaligned", since = "1.17.0")]
pub unsafe fn read_unaligned<T>(src: *const T) -> T {
let mut tmp = MaybeUninit::<T>::uninitialized();
let mut tmp: T = mem::uninitialized();
copy_nonoverlapping(src as *const u8,
tmp.as_mut_ptr() as *mut u8,
&mut tmp as *mut T as *mut u8,
mem::size_of::<T>());
tmp.into_inner()
tmp
}
/// Overwrites a memory location with the given value without reading or