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Rollup merge of #53784 - tbu-:pr_doc_slice_isize_max, r=RalfJung

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Document that slices cannot be larger than `isize::MAX` bytes

Fixes #53676.
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kennytm 2018-10-01 16:12:54 +08:00 committed by GitHub
commit 818a05d6e3
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1 changed files with 14 additions and 3 deletions
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15
src/libcore/slice/mod.rs
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@ -34,6 +34,7 @@
use cmp;
use fmt;
use intrinsics::assume;
use isize;
use iter::*;
use ops::{FnMut, Try, self};
use option::Option;
@ -4080,6 +4081,9 @@ fn may_have_side_effect() -> bool { false }
/// them from other data. You can obtain a pointer that is usable as `data`
/// for zero-length slices using [`NonNull::dangling()`].
///
/// The total size of the slice must be no larger than `isize::MAX` **bytes**
/// in memory. See the safety documentation of [`pointer::offset`].
///
/// # Caveat
///
/// The lifetime for the returned slice is inferred from its usage. To
@ -4101,10 +4105,13 @@ fn may_have_side_effect() -> bool { false }
/// ```
///
/// [`NonNull::dangling()`]: ../../std/ptr/struct.NonNull.html#method.dangling
/// [`pointer::offset`]: ../../std/primitive.pointer.html#method.offset
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
debug_assert!(data as usize % mem::align_of::<T>() == 0, "attempt to create unaligned slice");
debug_assert!(mem::size_of::<T>().saturating_mul(len) <= isize::MAX as usize,
"attempt to create slice covering half the address space");
Repr { raw: FatPtr { data, len } }.rust
}
@ -4114,14 +4121,18 @@ pub unsafe fn from_raw_parts<'a, T>(data: *const T, len: usize) -> &'a [T] {
/// This function is unsafe for the same reasons as [`from_raw_parts`], as well
/// as not being able to provide a non-aliasing guarantee of the returned
/// mutable slice. `data` must be non-null and aligned even for zero-length
/// slices as with [`from_raw_parts`]. See the documentation of
/// [`from_raw_parts`] for more details.
/// slices as with [`from_raw_parts`]. The total size of the slice must be no
/// larger than `isize::MAX` **bytes** in memory.
///
/// See the documentation of [`from_raw_parts`] for more details.
///
/// [`from_raw_parts`]: ../../std/slice/fn.from_raw_parts.html
#[inline]
#[stable(feature = "rust1", since = "1.0.0")]
pub unsafe fn from_raw_parts_mut<'a, T>(data: *mut T, len: usize) -> &'a mut [T] {
debug_assert!(data as usize % mem::align_of::<T>() == 0, "attempt to create unaligned slice");
debug_assert!(mem::size_of::<T>().saturating_mul(len) <= isize::MAX as usize,
"attempt to create slice covering half the address space");
Repr { raw: FatPtr { data, len } }.rust_mut
}