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[beta] backport: Remove unsound TrustedRandomAccess implementations #86222

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[beta] backport: Remove unsound TrustedRandomAccess implementations #86222

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29 changes: 1 addition & 28 deletions library/alloc/src/collections/vec_deque/into_iter.rs
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
use core::fmt;
use core::iter::{FusedIterator, TrustedLen, TrustedRandomAccess};
use core::iter::{FusedIterator, TrustedLen};

use super::VecDeque;

Expand Down Expand Up @@ -36,22 +36,6 @@ impl<T> Iterator for IntoIter<T> {
let len = self.inner.len();
(len, Some(len))
}

#[inline]
unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
where
Self: TrustedRandomAccess,
{
// Safety: The TrustedRandomAccess contract requires that callers only pass an index
// that is in bounds.
// Additionally Self: TrustedRandomAccess is only implemented for T: Copy which means even
// multiple repeated reads of the same index would be safe and the
// values are !Drop, thus won't suffer from double drops.
unsafe {
let idx = self.inner.wrap_add(self.inner.tail, idx);
self.inner.buffer_read(idx)
}
}
}

#[stable(feature = "rust1", since = "1.0.0")]
Expand All @@ -74,14 +58,3 @@ impl<T> FusedIterator for IntoIter<T> {}

#[unstable(feature = "trusted_len", issue = "37572")]
unsafe impl<T> TrustedLen for IntoIter<T> {}

#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
// T: Copy as approximation for !Drop since get_unchecked does not update the pointers
// and thus we can't implement drop-handling
unsafe impl<T> TrustedRandomAccess for IntoIter<T>
where
T: Copy,
{
const MAY_HAVE_SIDE_EFFECT: bool = false;
}
25 changes: 1 addition & 24 deletions library/core/src/array/iter.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@

use crate::{
fmt,
iter::{self, ExactSizeIterator, FusedIterator, TrustedLen, TrustedRandomAccess},
iter::{self, ExactSizeIterator, FusedIterator, TrustedLen},
mem::{self, MaybeUninit},
ops::Range,
ptr,
Expand Down Expand Up @@ -130,18 +130,6 @@ impl<T, const N: usize> Iterator for IntoIter<T, N> {
fn last(mut self) -> Option<Self::Item> {
self.next_back()
}

#[inline]
unsafe fn __iterator_get_unchecked(&mut self, idx: usize) -> Self::Item
where
Self: TrustedRandomAccess,
{
// SAFETY: Callers are only allowed to pass an index that is in bounds
// Additionally Self: TrustedRandomAccess is only implemented for T: Copy which means even
// multiple repeated reads of the same index would be safe and the
// values aree !Drop, thus won't suffer from double drops.
unsafe { self.data.get_unchecked(self.alive.start + idx).assume_init_read() }
}
}

#[stable(feature = "array_value_iter_impls", since = "1.40.0")]
Expand Down Expand Up @@ -196,17 +184,6 @@ impl<T, const N: usize> FusedIterator for IntoIter<T, N> {}
#[stable(feature = "array_value_iter_impls", since = "1.40.0")]
unsafe impl<T, const N: usize> TrustedLen for IntoIter<T, N> {}

#[doc(hidden)]
#[unstable(feature = "trusted_random_access", issue = "none")]
// T: Copy as approximation for !Drop since get_unchecked does not update the pointers
// and thus we can't implement drop-handling
unsafe impl<T, const N: usize> TrustedRandomAccess for IntoIter<T, N>
where
T: Copy,
{
const MAY_HAVE_SIDE_EFFECT: bool = false;
}

#[stable(feature = "array_value_iter_impls", since = "1.40.0")]
impl<T: Clone, const N: usize> Clone for IntoIter<T, N> {
fn clone(&self) -> Self {
Expand Down