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Use intrinsic pointer methods

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This commit is contained in:
Alan Egerton 2021-11-27 16:59:18 +00:00
parent 9f714ef035
commit afa6f92c46
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GPG Key ID: 07CAC3CCA7E0643F
1 changed files with 5 additions and 7 deletions
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12
compiler/rustc_data_structures/src/functor.rs
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@ -1,6 +1,5 @@
use rustc_index::vec::{Idx, IndexVec};
use std::mem;
use std::ptr;
pub trait IdFunctor: Sized {
type Inner;
@ -29,12 +28,12 @@ impl<T> IdFunctor for Box<T> {
let raw = Box::into_raw(self);
Ok(unsafe {
// SAFETY: The raw pointer points to a valid value of type `T`.
let value = ptr::read(raw);
let value = raw.read();
// SAFETY: Converts `Box<T>` to `Box<MaybeUninit<T>>` which is the
// inverse of `Box::assume_init()` and should be safe.
let mut raw: Box<mem::MaybeUninit<T>> = Box::from_raw(raw.cast());
// SAFETY: Write the mapped value back into the `Box`.
ptr::write(raw.as_mut_ptr(), f(value)?);
raw.write(f(value)?);
// SAFETY: We just initialized `raw`.
raw.assume_init()
})
@ -57,14 +56,13 @@ impl<T> IdFunctor for Vec<T> {
let start = self.as_mut_ptr();
for i in 0..len {
let p = start.add(i);
match f(ptr::read(p)) {
Ok(value) => ptr::write(p, value),
match f(p.read()) {
Ok(val) => p.write(val),
Err(err) => {
// drop all other elements in self
// (current element was "moved" into the call to f)
for j in (0..i).chain(i + 1..len) {
let p = start.add(j);
ptr::drop_in_place(p);
start.add(j).drop_in_place();
}
// returning will drop self, releasing the allocation