/// Behavior:
///
/// * Both the starting and resulting pointer must be either in bounds or one
- /// byte past the end of the same allocated object. Note that in Rust,
- /// every (stack-allocated) variable is considered a separate allocated object.
+ /// byte past the end of the same [allocated object].
///
/// * The computed offset, **in bytes**, cannot overflow an `isize`.
///
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_offset`]: #method.wrapping_offset
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
///
/// This operation itself is always safe, but using the resulting pointer is not.
///
- /// The resulting pointer remains attached to the same allocated object that `self` points to.
- /// It may *not* be used to access a different allocated object. Note that in Rust, every
- /// (stack-allocated) variable is considered a separate allocated object.
+ /// The resulting pointer remains attached to the same [allocated object] that `self` points to.
+ /// It may *not* be used to access a different allocated object.
///
/// In other words, `let z = x.wrapping_offset((y as isize) - (x as isize))` does *not* make `z`
/// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
/// do the arithmetic there.
///
/// [`offset`]: #method.offset
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
/// Behavior:
///
/// * Both the starting and other pointer must be either in bounds or one
- /// byte past the end of the same allocated object. Note that in Rust,
- /// every (stack-allocated) variable is considered a separate allocated object.
+ /// byte past the end of the same [allocated object].
///
/// * Both pointers must be *derived from* a pointer to the same object.
/// (See below for an example.)
/// such large allocations either.)
///
/// [`add`]: #method.add
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Panics
///
/// Behavior:
///
/// * Both the starting and resulting pointer must be either in bounds or one
- /// byte past the end of the same allocated object. Note that in Rust,
- /// every (stack-allocated) variable is considered a separate allocated object.
+ /// byte past the end of the same [allocated object].
///
/// * The computed offset, **in bytes**, cannot overflow an `isize`.
///
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_add`]: #method.wrapping_add
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
/// Behavior:
///
/// * Both the starting and resulting pointer must be either in bounds or one
- /// byte past the end of the same allocated object. Note that in Rust,
- /// every (stack-allocated) variable is considered a separate allocated object.
+ /// byte past the end of the same [allocated object].
///
/// * The computed offset cannot exceed `isize::MAX` **bytes**.
///
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_sub`]: #method.wrapping_sub
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
///
/// This operation itself is always safe, but using the resulting pointer is not.
///
- /// The resulting pointer remains attached to the same allocated object that `self` points to.
- /// It may *not* be used to access a different allocated object. Note that in Rust, every
- /// (stack-allocated) variable is considered a separate allocated object.
+ /// The resulting pointer remains attached to the same [allocated object] that `self` points to.
+ /// It may *not* be used to access a different allocated object.
///
/// In other words, `let z = x.wrapping_add((y as usize) - (x as usize))` does *not* make `z`
/// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
/// do the arithmetic there.
///
/// [`add`]: #method.add
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
///
/// This operation itself is always safe, but using the resulting pointer is not.
///
- /// The resulting pointer remains attached to the same allocated object that `self` points to.
- /// It may *not* be used to access a different allocated object. Note that in Rust, every
- /// (stack-allocated) variable is considered a separate allocated object.
+ /// The resulting pointer remains attached to the same [allocated object] that `self` points to.
+ /// It may *not* be used to access a different allocated object.
///
/// In other words, `let z = x.wrapping_sub((x as usize) - (y as usize))` does *not* make `z`
/// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
/// do the arithmetic there.
///
/// [`sub`]: #method.sub
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
/// * The pointer must be [valid] for reads for `ptr.len() * mem::size_of::<T>()` many bytes,
/// and it must be properly aligned. This means in particular:
///
- /// * The entire memory range of this slice must be contained within a single allocated object!
+ /// * The entire memory range of this slice must be contained within a single [allocated object]!
/// Slices can never span across multiple allocated objects.
///
/// * The pointer must be aligned even for zero-length slices. One
/// See also [`slice::from_raw_parts`][].
///
/// [valid]: crate::ptr#safety
+ /// [allocated object]: crate::ptr#allocated-object
#[inline]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
pub unsafe fn as_uninit_slice<'a>(self) -> Option<&'a [MaybeUninit<T>]> {
//! has size 0, i.e., even if memory is not actually touched. Consider using
//! [`NonNull::dangling`] in such cases.
//!
+//! ## Allocated object
+//!
+//! For several operations, such as [`offset`] or field projections (`expr.field`), the notion of an
+//! "allocated object" becomes relevant. An allocated object is a contiguous region of memory.
+//! Common examples of allocated objects include stack-allocated variables (each variable is a
+//! separate allocated object), heap allocations (each allocation created by the global allocator is
+//! a separate allocated object), and `static` variables.
+//!
//! [aliasing]: ../../nomicon/aliasing.html
//! [book]: ../../book/ch19-01-unsafe-rust.html#dereferencing-a-raw-pointer
//! [ub]: ../../reference/behavior-considered-undefined.html
/// Behavior:
///
/// * Both the starting and resulting pointer must be either in bounds or one
- /// byte past the end of the same allocated object. Note that in Rust,
- /// every (stack-allocated) variable is considered a separate allocated object.
+ /// byte past the end of the same [allocated object].
///
/// * The computed offset, **in bytes**, cannot overflow an `isize`.
///
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_offset`]: #method.wrapping_offset
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
///
/// This operation itself is always safe, but using the resulting pointer is not.
///
- /// The resulting pointer remains attached to the same allocated object that `self` points to.
- /// It may *not* be used to access a different allocated object. Note that in Rust, every
- /// (stack-allocated) variable is considered a separate allocated object.
+ /// The resulting pointer remains attached to the same [allocated object] that `self` points to.
+ /// It may *not* be used to access a different allocated object.
///
/// In other words, `let z = x.wrapping_offset((y as isize) - (x as isize))` does *not* make `z`
/// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
/// do the arithmetic there.
///
/// [`offset`]: #method.offset
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
/// Behavior:
///
/// * Both the starting and other pointer must be either in bounds or one
- /// byte past the end of the same allocated object. Note that in Rust,
- /// every (stack-allocated) variable is considered a separate allocated object.
+ /// byte past the end of the same [allocated object].
///
/// * Both pointers must be *derived from* a pointer to the same object.
/// (See below for an example.)
/// such large allocations either.)
///
/// [`add`]: #method.add
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Panics
///
/// Behavior:
///
/// * Both the starting and resulting pointer must be either in bounds or one
- /// byte past the end of the same allocated object. Note that in Rust,
- /// every (stack-allocated) variable is considered a separate allocated object.
+ /// byte past the end of the same [allocated object].
///
/// * The computed offset, **in bytes**, cannot overflow an `isize`.
///
/// Behavior:
///
/// * Both the starting and resulting pointer must be either in bounds or one
- /// byte past the end of the same allocated object. Note that in Rust,
- /// every (stack-allocated) variable is considered a separate allocated object.
+ /// byte past the end of the same [allocated object].
///
/// * The computed offset cannot exceed `isize::MAX` **bytes**.
///
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_sub`]: #method.wrapping_sub
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
///
/// This operation itself is always safe, but using the resulting pointer is not.
///
- /// The resulting pointer remains attached to the same allocated object that `self` points to.
- /// It may *not* be used to access a different allocated object. Note that in Rust, every
- /// (stack-allocated) variable is considered a separate allocated object.
+ /// The resulting pointer remains attached to the same [allocated object] that `self` points to.
+ /// It may *not* be used to access a different allocated object.
///
/// In other words, `let z = x.wrapping_add((y as usize) - (x as usize))` does *not* make `z`
/// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
/// do the arithmetic there.
///
/// [`add`]: #method.add
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
///
/// This operation itself is always safe, but using the resulting pointer is not.
///
- /// The resulting pointer remains attached to the same allocated object that `self` points to.
- /// It may *not* be used to access a different allocated object. Note that in Rust, every
- /// (stack-allocated) variable is considered a separate allocated object.
+ /// The resulting pointer remains attached to the same [allocated object] that `self` points to.
+ /// It may *not* be used to access a different allocated object.
///
/// In other words, `let z = x.wrapping_sub((x as usize) - (y as usize))` does *not* make `z`
/// the same as `y` even if we assume `T` has size `1` and there is no overflow: `z` is still
/// do the arithmetic there.
///
/// [`sub`]: #method.sub
+ /// [allocated object]: crate::ptr#allocated-object
///
/// # Examples
///
/// * The pointer must be [valid] for reads for `ptr.len() * mem::size_of::<T>()` many bytes,
/// and it must be properly aligned. This means in particular:
///
- /// * The entire memory range of this slice must be contained within a single allocated object!
+ /// * The entire memory range of this slice must be contained within a single [allocated object]!
/// Slices can never span across multiple allocated objects.
///
/// * The pointer must be aligned even for zero-length slices. One
/// See also [`slice::from_raw_parts`][].
///
/// [valid]: crate::ptr#safety
+ /// [allocated object]: crate::ptr#allocated-object
#[inline]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
pub unsafe fn as_uninit_slice<'a>(self) -> Option<&'a [MaybeUninit<T>]> {
/// * The pointer must be [valid] for reads and writes for `ptr.len() * mem::size_of::<T>()`
/// many bytes, and it must be properly aligned. This means in particular:
///
- /// * The entire memory range of this slice must be contained within a single allocated object!
+ /// * The entire memory range of this slice must be contained within a single [allocated object]!
/// Slices can never span across multiple allocated objects.
///
/// * The pointer must be aligned even for zero-length slices. One
/// See also [`slice::from_raw_parts_mut`][].
///
/// [valid]: crate::ptr#safety
+ /// [allocated object]: crate::ptr#allocated-object
#[inline]
#[unstable(feature = "ptr_as_uninit", issue = "75402")]
pub unsafe fn as_uninit_slice_mut<'a>(self) -> Option<&'a mut [MaybeUninit<T>]> {