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Liballoc DoubleEndedIterator limit unsafe to pointer arithmethic

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This commit is contained in:
Ivan Tham 2020-07-05 12:27:23 +08:00
parent cc0d634550
commit 50315238aa
1 changed files with 11 additions and 15 deletions
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26
library/alloc/src/vec.rs
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@ -2703,7 +2703,7 @@ impl<T> Iterator for IntoIter<T> {
// purposefully don't use 'ptr.offset' because for
// vectors with 0-size elements this would return the
// same pointer.
self.ptr = unsafe { arith_offset(self.ptr as *const T, 1) as *mut T };
self.ptr = unsafe { arith_offset(self.ptr as *const i8, 1) as *mut T };
// Make up a value of this ZST.
Some(unsafe { mem::zeroed() })
@ -2735,22 +2735,18 @@ impl<T> Iterator for IntoIter<T> {
impl<T> DoubleEndedIterator for IntoIter<T> {
#[inline]
fn next_back(&mut self) -> Option<T> {
unsafe {
if self.end == self.ptr {
None
} else {
if mem::size_of::<T>() == 0 {
// See above for why 'ptr.offset' isn't used
self.end = arith_offset(self.end as *const i8, -1) as *mut T;
if self.end == self.ptr {
None
} else if mem::size_of::<T>() == 0 {
// See above for why 'ptr.offset' isn't used
self.end = unsafe { arith_offset(self.end as *const i8, -1) as *mut T };
// Make up a value of this ZST.
Some(mem::zeroed())
} else {
self.end = self.end.offset(-1);
// Make up a value of this ZST.
Some(unsafe { mem::zeroed() })
} else {
self.end = unsafe { self.end.offset(-1) };
Some(ptr::read(self.end))
}
}
Some(unsafe { ptr::read(self.end) })
}
}
}