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Auto merge of #67464 - Centril:rollup-j3mkl1m, r=Centril

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Rollup of 6 pull requests

Successful merges:

 - #67130 (Const prop should finish propagation into user defined variables)
 - #67163 (Split up ptr/mod.rs in libcore...)
 - #67314 (Don't suppress move errors for union fields)
 - #67392 (Fix unresolved type span inside async object)
 - #67404 (Separate region inference logic from error handling better)
 - #67428 (`is_binding_pat`: use explicit match & include or-pats in grammar)

Failed merges:

r? @ghost
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bors 2019-12-21 01:02:54 +00:00
commit 9ff30a7810
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src/libcore/ptr/const_ptr.rs Normal file
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@ -0,0 +1,755 @@
use crate::cmp::Ordering::{self, Less, Equal, Greater};
use crate::intrinsics;
use crate::mem;
use super::*;
// ignore-tidy-undocumented-unsafe
#[lang = "const_ptr"]
impl<T: ?Sized> *const T {
/// Returns `true` if the pointer is null.
///
/// Note that unsized types have many possible null pointers, as only the
/// raw data pointer is considered, not their length, vtable, etc.
/// Therefore, two pointers that are null may still not compare equal to
/// each other.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s: &str = "Follow the rabbit";
/// let ptr: *const u8 = s.as_ptr();
/// assert!(!ptr.is_null());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn is_null(self) -> bool {
// Compare via a cast to a thin pointer, so fat pointers are only
// considering their "data" part for null-ness.
(self as *const u8) == null()
}
/// Casts to a pointer of another type.
#[stable(feature = "ptr_cast", since = "1.38.0")]
#[rustc_const_stable(feature = "const_ptr_cast", since = "1.38.0")]
#[inline]
pub const fn cast<U>(self) -> *const U {
self as _
}
/// Returns `None` if the pointer is null, or else returns a reference to
/// the value wrapped in `Some`.
///
/// # Safety
///
/// While this method and its mutable counterpart are useful for
/// null-safety, it is important to note that this is still an unsafe
/// operation because the returned value could be pointing to invalid
/// memory.
///
/// When calling this method, you have to ensure that *either* the pointer is NULL *or*
/// all of the following is true:
/// - it is properly aligned
/// - it must point to an initialized instance of T; in particular, the pointer must be
/// "dereferencable" in the sense defined [here].
///
/// This applies even if the result of this method is unused!
/// (The part about being initialized is not yet fully decided, but until
/// it is, the only safe approach is to ensure that they are indeed initialized.)
///
/// Additionally, the lifetime `'a` returned is arbitrarily chosen and does
/// not necessarily reflect the actual lifetime of the data. *You* must enforce
/// Rust's aliasing rules. In particular, for the duration of this lifetime,
/// the memory the pointer points to must not get mutated (except inside `UnsafeCell`).
///
/// [here]: crate::ptr#safety
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let ptr: *const u8 = &10u8 as *const u8;
///
/// unsafe {
/// if let Some(val_back) = ptr.as_ref() {
/// println!("We got back the value: {}!", val_back);
/// }
/// }
/// ```
///
/// # Null-unchecked version
///
/// If you are sure the pointer can never be null and are looking for some kind of
/// `as_ref_unchecked` that returns the `&T` instead of `Option<&T>`, know that you can
/// dereference the pointer directly.
///
/// ```
/// let ptr: *const u8 = &10u8 as *const u8;
///
/// unsafe {
/// let val_back = &*ptr;
/// println!("We got back the value: {}!", val_back);
/// }
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[inline]
pub unsafe fn as_ref<'a>(self) -> Option<&'a T> {
if self.is_null() { None } else { Some(&*self) }
}
/// Calculates the offset from a pointer.
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// If any of the following conditions are violated, the result is Undefined
/// 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.
///
/// * The computed offset, **in bytes**, cannot overflow an `isize`.
///
/// * The offset being in bounds cannot rely on "wrapping around" the address
/// space. That is, the infinite-precision sum, **in bytes** must fit in a usize.
///
/// The compiler and standard library generally tries to ensure allocations
/// never reach a size where an offset is a concern. For instance, `Vec`
/// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
/// `vec.as_ptr().add(vec.len())` is always safe.
///
/// Most platforms fundamentally can't even construct such an allocation.
/// For instance, no known 64-bit platform can ever serve a request
/// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
/// However, some 32-bit and 16-bit platforms may successfully serve a request for
/// more than `isize::MAX` bytes with things like Physical Address
/// Extension. As such, memory acquired directly from allocators or memory
/// mapped files *may* be too large to handle with this function.
///
/// Consider using [`wrapping_offset`] instead if these constraints are
/// difficult to satisfy. The only advantage of this method is that it
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_offset`]: #method.wrapping_offset
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s: &str = "123";
/// let ptr: *const u8 = s.as_ptr();
///
/// unsafe {
/// println!("{}", *ptr.offset(1) as char);
/// println!("{}", *ptr.offset(2) as char);
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub unsafe fn offset(self, count: isize) -> *const T
where
T: Sized,
{
intrinsics::offset(self, count)
}
/// Calculates the offset from a pointer using wrapping arithmetic.
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// The resulting pointer does not need to be in bounds, but it is
/// potentially hazardous to dereference (which requires `unsafe`).
///
/// In particular, 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.
///
/// In other words, `x.wrapping_offset(y.wrapping_offset_from(x))` is
/// *not* the same as `y`, and dereferencing it is undefined behavior
/// unless `x` and `y` point into the same allocated object.
///
/// Compared to [`offset`], this method basically delays the requirement of staying
/// within the same allocated object: [`offset`] is immediate Undefined Behavior when
/// crossing object boundaries; `wrapping_offset` produces a pointer but still leads
/// to Undefined Behavior if that pointer is dereferenced. [`offset`] can be optimized
/// better and is thus preferrable in performance-sensitive code.
///
/// If you need to cross object boundaries, cast the pointer to an integer and
/// do the arithmetic there.
///
/// [`offset`]: #method.offset
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // Iterate using a raw pointer in increments of two elements
/// let data = [1u8, 2, 3, 4, 5];
/// let mut ptr: *const u8 = data.as_ptr();
/// let step = 2;
/// let end_rounded_up = ptr.wrapping_offset(6);
///
/// // This loop prints "1, 3, 5, "
/// while ptr != end_rounded_up {
/// unsafe {
/// print!("{}, ", *ptr);
/// }
/// ptr = ptr.wrapping_offset(step);
/// }
/// ```
#[stable(feature = "ptr_wrapping_offset", since = "1.16.0")]
#[inline]
pub fn wrapping_offset(self, count: isize) -> *const T
where
T: Sized,
{
unsafe { intrinsics::arith_offset(self, count) }
}
/// Calculates the distance between two pointers. The returned value is in
/// units of T: the distance in bytes is divided by `mem::size_of::<T>()`.
///
/// This function is the inverse of [`offset`].
///
/// [`offset`]: #method.offset
/// [`wrapping_offset_from`]: #method.wrapping_offset_from
///
/// # Safety
///
/// If any of the following conditions are violated, the result is Undefined
/// 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.
///
/// * The distance between the pointers, **in bytes**, cannot overflow an `isize`.
///
/// * The distance between the pointers, in bytes, must be an exact multiple
/// of the size of `T`.
///
/// * The distance being in bounds cannot rely on "wrapping around" the address space.
///
/// The compiler and standard library generally try to ensure allocations
/// never reach a size where an offset is a concern. For instance, `Vec`
/// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
/// `ptr_into_vec.offset_from(vec.as_ptr())` is always safe.
///
/// Most platforms fundamentally can't even construct such an allocation.
/// For instance, no known 64-bit platform can ever serve a request
/// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
/// However, some 32-bit and 16-bit platforms may successfully serve a request for
/// more than `isize::MAX` bytes with things like Physical Address
/// Extension. As such, memory acquired directly from allocators or memory
/// mapped files *may* be too large to handle with this function.
///
/// Consider using [`wrapping_offset_from`] instead if these constraints are
/// difficult to satisfy. The only advantage of this method is that it
/// enables more aggressive compiler optimizations.
///
/// # Panics
///
/// This function panics if `T` is a Zero-Sized Type ("ZST").
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(ptr_offset_from)]
///
/// let a = [0; 5];
/// let ptr1: *const i32 = &a[1];
/// let ptr2: *const i32 = &a[3];
/// unsafe {
/// assert_eq!(ptr2.offset_from(ptr1), 2);
/// assert_eq!(ptr1.offset_from(ptr2), -2);
/// assert_eq!(ptr1.offset(2), ptr2);
/// assert_eq!(ptr2.offset(-2), ptr1);
/// }
/// ```
#[unstable(feature = "ptr_offset_from", issue = "41079")]
#[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "41079")]
#[inline]
pub const unsafe fn offset_from(self, origin: *const T) -> isize
where
T: Sized,
{
let pointee_size = mem::size_of::<T>();
let ok = 0 < pointee_size && pointee_size <= isize::max_value() as usize;
// assert that the pointee size is valid in a const eval compatible way
// FIXME: do this with a real assert at some point
[()][(!ok) as usize];
intrinsics::ptr_offset_from(self, origin)
}
/// Calculates the distance between two pointers. The returned value is in
/// units of T: the distance in bytes is divided by `mem::size_of::<T>()`.
///
/// If the address different between the two pointers is not a multiple of
/// `mem::size_of::<T>()` then the result of the division is rounded towards
/// zero.
///
/// Though this method is safe for any two pointers, note that its result
/// will be mostly useless if the two pointers aren't into the same allocated
/// object, for example if they point to two different local variables.
///
/// # Panics
///
/// This function panics if `T` is a zero-sized type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(ptr_wrapping_offset_from)]
///
/// let a = [0; 5];
/// let ptr1: *const i32 = &a[1];
/// let ptr2: *const i32 = &a[3];
/// assert_eq!(ptr2.wrapping_offset_from(ptr1), 2);
/// assert_eq!(ptr1.wrapping_offset_from(ptr2), -2);
/// assert_eq!(ptr1.wrapping_offset(2), ptr2);
/// assert_eq!(ptr2.wrapping_offset(-2), ptr1);
///
/// let ptr1: *const i32 = 3 as _;
/// let ptr2: *const i32 = 13 as _;
/// assert_eq!(ptr2.wrapping_offset_from(ptr1), 2);
/// ```
#[unstable(feature = "ptr_wrapping_offset_from", issue = "41079")]
#[inline]
pub fn wrapping_offset_from(self, origin: *const T) -> isize
where
T: Sized,
{
let pointee_size = mem::size_of::<T>();
assert!(0 < pointee_size && pointee_size <= isize::max_value() as usize);
let d = isize::wrapping_sub(self as _, origin as _);
d.wrapping_div(pointee_size as _)
}
/// Calculates the offset from a pointer (convenience for `.offset(count as isize)`).
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// If any of the following conditions are violated, the result is Undefined
/// 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.
///
/// * The computed offset, **in bytes**, cannot overflow an `isize`.
///
/// * The offset being in bounds cannot rely on "wrapping around" the address
/// space. That is, the infinite-precision sum must fit in a `usize`.
///
/// The compiler and standard library generally tries to ensure allocations
/// never reach a size where an offset is a concern. For instance, `Vec`
/// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
/// `vec.as_ptr().add(vec.len())` is always safe.
///
/// Most platforms fundamentally can't even construct such an allocation.
/// For instance, no known 64-bit platform can ever serve a request
/// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
/// However, some 32-bit and 16-bit platforms may successfully serve a request for
/// more than `isize::MAX` bytes with things like Physical Address
/// Extension. As such, memory acquired directly from allocators or memory
/// mapped files *may* be too large to handle with this function.
///
/// Consider using [`wrapping_add`] instead if these constraints are
/// difficult to satisfy. The only advantage of this method is that it
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_add`]: #method.wrapping_add
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s: &str = "123";
/// let ptr: *const u8 = s.as_ptr();
///
/// unsafe {
/// println!("{}", *ptr.add(1) as char);
/// println!("{}", *ptr.add(2) as char);
/// }
/// ```
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn add(self, count: usize) -> Self
where
T: Sized,
{
self.offset(count as isize)
}
/// Calculates the offset from a pointer (convenience for
/// `.offset((count as isize).wrapping_neg())`).
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// If any of the following conditions are violated, the result is Undefined
/// 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.
///
/// * The computed offset cannot exceed `isize::MAX` **bytes**.
///
/// * The offset being in bounds cannot rely on "wrapping around" the address
/// space. That is, the infinite-precision sum must fit in a usize.
///
/// The compiler and standard library generally tries to ensure allocations
/// never reach a size where an offset is a concern. For instance, `Vec`
/// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
/// `vec.as_ptr().add(vec.len()).sub(vec.len())` is always safe.
///
/// Most platforms fundamentally can't even construct such an allocation.
/// For instance, no known 64-bit platform can ever serve a request
/// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
/// However, some 32-bit and 16-bit platforms may successfully serve a request for
/// more than `isize::MAX` bytes with things like Physical Address
/// Extension. As such, memory acquired directly from allocators or memory
/// mapped files *may* be too large to handle with this function.
///
/// Consider using [`wrapping_sub`] instead if these constraints are
/// difficult to satisfy. The only advantage of this method is that it
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_sub`]: #method.wrapping_sub
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s: &str = "123";
///
/// unsafe {
/// let end: *const u8 = s.as_ptr().add(3);
/// println!("{}", *end.sub(1) as char);
/// println!("{}", *end.sub(2) as char);
/// }
/// ```
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn sub(self, count: usize) -> Self
where
T: Sized,
{
self.offset((count as isize).wrapping_neg())
}
/// Calculates the offset from a pointer using wrapping arithmetic.
/// (convenience for `.wrapping_offset(count as isize)`)
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// The resulting pointer does not need to be in bounds, but it is
/// potentially hazardous to dereference (which requires `unsafe`).
///
/// In particular, 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.
///
/// Compared to [`add`], this method basically delays the requirement of staying
/// within the same allocated object: [`add`] is immediate Undefined Behavior when
/// crossing object boundaries; `wrapping_add` produces a pointer but still leads
/// to Undefined Behavior if that pointer is dereferenced. [`add`] can be optimized
/// better and is thus preferrable in performance-sensitive code.
///
/// If you need to cross object boundaries, cast the pointer to an integer and
/// do the arithmetic there.
///
/// [`add`]: #method.add
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // Iterate using a raw pointer in increments of two elements
/// let data = [1u8, 2, 3, 4, 5];
/// let mut ptr: *const u8 = data.as_ptr();
/// let step = 2;
/// let end_rounded_up = ptr.wrapping_add(6);
///
/// // This loop prints "1, 3, 5, "
/// while ptr != end_rounded_up {
/// unsafe {
/// print!("{}, ", *ptr);
/// }
/// ptr = ptr.wrapping_add(step);
/// }
/// ```
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub fn wrapping_add(self, count: usize) -> Self
where
T: Sized,
{
self.wrapping_offset(count as isize)
}
/// Calculates the offset from a pointer using wrapping arithmetic.
/// (convenience for `.wrapping_offset((count as isize).wrapping_sub())`)
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// The resulting pointer does not need to be in bounds, but it is
/// potentially hazardous to dereference (which requires `unsafe`).
///
/// In particular, 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.
///
/// Compared to [`sub`], this method basically delays the requirement of staying
/// within the same allocated object: [`sub`] is immediate Undefined Behavior when
/// crossing object boundaries; `wrapping_sub` produces a pointer but still leads
/// to Undefined Behavior if that pointer is dereferenced. [`sub`] can be optimized
/// better and is thus preferrable in performance-sensitive code.
///
/// If you need to cross object boundaries, cast the pointer to an integer and
/// do the arithmetic there.
///
/// [`sub`]: #method.sub
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // Iterate using a raw pointer in increments of two elements (backwards)
/// let data = [1u8, 2, 3, 4, 5];
/// let mut ptr: *const u8 = data.as_ptr();
/// let start_rounded_down = ptr.wrapping_sub(2);
/// ptr = ptr.wrapping_add(4);
/// let step = 2;
/// // This loop prints "5, 3, 1, "
/// while ptr != start_rounded_down {
/// unsafe {
/// print!("{}, ", *ptr);
/// }
/// ptr = ptr.wrapping_sub(step);
/// }
/// ```
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub fn wrapping_sub(self, count: usize) -> Self
where
T: Sized,
{
self.wrapping_offset((count as isize).wrapping_neg())
}
/// Reads the value from `self` without moving it. This leaves the
/// memory in `self` unchanged.
///
/// See [`ptr::read`] for safety concerns and examples.
///
/// [`ptr::read`]: ./ptr/fn.read.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn read(self) -> T
where
T: Sized,
{
read(self)
}
/// Performs a volatile read of the value from `self` without moving it. This
/// leaves the memory in `self` unchanged.
///
/// Volatile operations are intended to act on I/O memory, and are guaranteed
/// to not be elided or reordered by the compiler across other volatile
/// operations.
///
/// See [`ptr::read_volatile`] for safety concerns and examples.
///
/// [`ptr::read_volatile`]: ./ptr/fn.read_volatile.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn read_volatile(self) -> T
where
T: Sized,
{
read_volatile(self)
}
/// Reads the value from `self` without moving it. This leaves the
/// memory in `self` unchanged.
///
/// Unlike `read`, the pointer may be unaligned.
///
/// See [`ptr::read_unaligned`] for safety concerns and examples.
///
/// [`ptr::read_unaligned`]: ./ptr/fn.read_unaligned.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn read_unaligned(self) -> T
where
T: Sized,
{
read_unaligned(self)
}
/// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
/// and destination may overlap.
///
/// NOTE: this has the *same* argument order as [`ptr::copy`].
///
/// See [`ptr::copy`] for safety concerns and examples.
///
/// [`ptr::copy`]: ./ptr/fn.copy.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn copy_to(self, dest: *mut T, count: usize)
where
T: Sized,
{
copy(self, dest, count)
}
/// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
/// and destination may *not* overlap.
///
/// NOTE: this has the *same* argument order as [`ptr::copy_nonoverlapping`].
///
/// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
///
/// [`ptr::copy_nonoverlapping`]: ./ptr/fn.copy_nonoverlapping.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)
where
T: Sized,
{
copy_nonoverlapping(self, dest, count)
}
/// Computes the offset that needs to be applied to the pointer in order to make it aligned to
/// `align`.
///
/// If it is not possible to align the pointer, the implementation returns
/// `usize::max_value()`. It is permissible for the implementation to *always*
/// return `usize::max_value()`. Only your algorithm's performance can depend
/// on getting a usable offset here, not its correctness.
///
/// The offset is expressed in number of `T` elements, and not bytes. The value returned can be
/// used with the `wrapping_add` method.
///
/// There are no guarantees whatsoever that offsetting the pointer will not overflow or go
/// beyond the allocation that the pointer points into. It is up to the caller to ensure that
/// the returned offset is correct in all terms other than alignment.
///
/// # Panics
///
/// The function panics if `align` is not a power-of-two.
///
/// # Examples
///
/// Accessing adjacent `u8` as `u16`
///
/// ```
/// # fn foo(n: usize) {
/// # use std::mem::align_of;
/// # unsafe {
/// let x = [5u8, 6u8, 7u8, 8u8, 9u8];
/// let ptr = &x[n] as *const u8;
/// let offset = ptr.align_offset(align_of::<u16>());
/// if offset < x.len() - n - 1 {
/// let u16_ptr = ptr.add(offset) as *const u16;
/// assert_ne!(*u16_ptr, 500);
/// } else {
/// // while the pointer can be aligned via `offset`, it would point
/// // outside the allocation
/// }
/// # } }
/// ```
#[stable(feature = "align_offset", since = "1.36.0")]
pub fn align_offset(self, align: usize) -> usize
where
T: Sized,
{
if !align.is_power_of_two() {
panic!("align_offset: align is not a power-of-two");
}
unsafe { align_offset(self, align) }
}
}
// Equality for pointers
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> PartialEq for *const T {
#[inline]
fn eq(&self, other: &*const T) -> bool { *self == *other }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Eq for *const T {}
// Comparison for pointers
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Ord for *const T {
#[inline]
fn cmp(&self, other: &*const T) -> Ordering {
if self < other {
Less
} else if self == other {
Equal
} else {
Greater
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> PartialOrd for *const T {
#[inline]
fn partial_cmp(&self, other: &*const T) -> Option<Ordering> {
Some(self.cmp(other))
}
#[inline]
fn lt(&self, other: &*const T) -> bool { *self < *other }
#[inline]
fn le(&self, other: &*const T) -> bool { *self <= *other }
#[inline]
fn gt(&self, other: &*const T) -> bool { *self > *other }
#[inline]
fn ge(&self, other: &*const T) -> bool { *self >= *other }
}

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src/libcore/ptr/mod.rs
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@ -0,0 +1,925 @@
use crate::cmp::Ordering::{self, Less, Equal, Greater};
use crate::intrinsics;
use super::*;
// ignore-tidy-undocumented-unsafe
#[lang = "mut_ptr"]
impl<T: ?Sized> *mut T {
/// Returns `true` if the pointer is null.
///
/// Note that unsized types have many possible null pointers, as only the
/// raw data pointer is considered, not their length, vtable, etc.
/// Therefore, two pointers that are null may still not compare equal to
/// each other.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let mut s = [1, 2, 3];
/// let ptr: *mut u32 = s.as_mut_ptr();
/// assert!(!ptr.is_null());
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub fn is_null(self) -> bool {
// Compare via a cast to a thin pointer, so fat pointers are only
// considering their "data" part for null-ness.
(self as *mut u8) == null_mut()
}
/// Casts to a pointer of another type.
#[stable(feature = "ptr_cast", since = "1.38.0")]
#[rustc_const_stable(feature = "const_ptr_cast", since = "1.38.0")]
#[inline]
pub const fn cast<U>(self) -> *mut U {
self as _
}
/// Returns `None` if the pointer is null, or else returns a reference to
/// the value wrapped in `Some`.
///
/// # Safety
///
/// While this method and its mutable counterpart are useful for
/// null-safety, it is important to note that this is still an unsafe
/// operation because the returned value could be pointing to invalid
/// memory.
///
/// When calling this method, you have to ensure that if the pointer is
/// non-NULL, then it is properly aligned, dereferencable (for the whole
/// size of `T`) and points to an initialized instance of `T`. This applies
/// even if the result of this method is unused!
/// (The part about being initialized is not yet fully decided, but until
/// it is, the only safe approach is to ensure that they are indeed initialized.)
///
/// Additionally, the lifetime `'a` returned is arbitrarily chosen and does
/// not necessarily reflect the actual lifetime of the data. It is up to the
/// caller to ensure that for the duration of this lifetime, the memory this
/// pointer points to does not get written to outside of `UnsafeCell<U>`.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let ptr: *mut u8 = &mut 10u8 as *mut u8;
///
/// unsafe {
/// if let Some(val_back) = ptr.as_ref() {
/// println!("We got back the value: {}!", val_back);
/// }
/// }
/// ```
///
/// # Null-unchecked version
///
/// If you are sure the pointer can never be null and are looking for some kind of
/// `as_ref_unchecked` that returns the `&T` instead of `Option<&T>`, know that you can
/// dereference the pointer directly.
///
/// ```
/// let ptr: *mut u8 = &mut 10u8 as *mut u8;
///
/// unsafe {
/// let val_back = &*ptr;
/// println!("We got back the value: {}!", val_back);
/// }
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[inline]
pub unsafe fn as_ref<'a>(self) -> Option<&'a T> {
if self.is_null() { None } else { Some(&*self) }
}
/// Calculates the offset from a pointer.
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// If any of the following conditions are violated, the result is Undefined
/// 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.
///
/// * The computed offset, **in bytes**, cannot overflow an `isize`.
///
/// * The offset being in bounds cannot rely on "wrapping around" the address
/// space. That is, the infinite-precision sum, **in bytes** must fit in a usize.
///
/// The compiler and standard library generally tries to ensure allocations
/// never reach a size where an offset is a concern. For instance, `Vec`
/// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
/// `vec.as_ptr().add(vec.len())` is always safe.
///
/// Most platforms fundamentally can't even construct such an allocation.
/// For instance, no known 64-bit platform can ever serve a request
/// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
/// However, some 32-bit and 16-bit platforms may successfully serve a request for
/// more than `isize::MAX` bytes with things like Physical Address
/// Extension. As such, memory acquired directly from allocators or memory
/// mapped files *may* be too large to handle with this function.
///
/// Consider using [`wrapping_offset`] instead if these constraints are
/// difficult to satisfy. The only advantage of this method is that it
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_offset`]: #method.wrapping_offset
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let mut s = [1, 2, 3];
/// let ptr: *mut u32 = s.as_mut_ptr();
///
/// unsafe {
/// println!("{}", *ptr.offset(1));
/// println!("{}", *ptr.offset(2));
/// }
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
#[inline]
pub unsafe fn offset(self, count: isize) -> *mut T
where
T: Sized,
{
intrinsics::offset(self, count) as *mut T
}
/// Calculates the offset from a pointer using wrapping arithmetic.
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// The resulting pointer does not need to be in bounds, but it is
/// potentially hazardous to dereference (which requires `unsafe`).
///
/// In particular, 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.
///
/// In other words, `x.wrapping_offset(y.wrapping_offset_from(x))` is
/// *not* the same as `y`, and dereferencing it is undefined behavior
/// unless `x` and `y` point into the same allocated object.
///
/// Compared to [`offset`], this method basically delays the requirement of staying
/// within the same allocated object: [`offset`] is immediate Undefined Behavior when
/// crossing object boundaries; `wrapping_offset` produces a pointer but still leads
/// to Undefined Behavior if that pointer is dereferenced. [`offset`] can be optimized
/// better and is thus preferrable in performance-sensitive code.
///
/// If you need to cross object boundaries, cast the pointer to an integer and
/// do the arithmetic there.
///
/// [`offset`]: #method.offset
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // Iterate using a raw pointer in increments of two elements
/// let mut data = [1u8, 2, 3, 4, 5];
/// let mut ptr: *mut u8 = data.as_mut_ptr();
/// let step = 2;
/// let end_rounded_up = ptr.wrapping_offset(6);
///
/// while ptr != end_rounded_up {
/// unsafe {
/// *ptr = 0;
/// }
/// ptr = ptr.wrapping_offset(step);
/// }
/// assert_eq!(&data, &[0, 2, 0, 4, 0]);
/// ```
#[stable(feature = "ptr_wrapping_offset", since = "1.16.0")]
#[inline]
pub fn wrapping_offset(self, count: isize) -> *mut T
where
T: Sized,
{
unsafe { intrinsics::arith_offset(self, count) as *mut T }
}
/// Returns `None` if the pointer is null, or else returns a mutable
/// reference to the value wrapped in `Some`.
///
/// # Safety
///
/// As with [`as_ref`], this is unsafe because it cannot verify the validity
/// of the returned pointer, nor can it ensure that the lifetime `'a`
/// returned is indeed a valid lifetime for the contained data.
///
/// When calling this method, you have to ensure that *either* the pointer is NULL *or*
/// all of the following is true:
/// - it is properly aligned
/// - it must point to an initialized instance of T; in particular, the pointer must be
/// "dereferencable" in the sense defined [here].
///
/// This applies even if the result of this method is unused!
/// (The part about being initialized is not yet fully decided, but until
/// it is the only safe approach is to ensure that they are indeed initialized.)
///
/// Additionally, the lifetime `'a` returned is arbitrarily chosen and does
/// not necessarily reflect the actual lifetime of the data. *You* must enforce
/// Rust's aliasing rules. In particular, for the duration of this lifetime,
/// the memory this pointer points to must not get accessed (read or written)
/// through any other pointer.
///
/// [here]: crate::ptr#safety
/// [`as_ref`]: #method.as_ref
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let mut s = [1, 2, 3];
/// let ptr: *mut u32 = s.as_mut_ptr();
/// let first_value = unsafe { ptr.as_mut().unwrap() };
/// *first_value = 4;
/// println!("{:?}", s); // It'll print: "[4, 2, 3]".
/// ```
#[stable(feature = "ptr_as_ref", since = "1.9.0")]
#[inline]
pub unsafe fn as_mut<'a>(self) -> Option<&'a mut T> {
if self.is_null() { None } else { Some(&mut *self) }
}
/// Calculates the distance between two pointers. The returned value is in
/// units of T: the distance in bytes is divided by `mem::size_of::<T>()`.
///
/// This function is the inverse of [`offset`].
///
/// [`offset`]: #method.offset-1
/// [`wrapping_offset_from`]: #method.wrapping_offset_from-1
///
/// # Safety
///
/// If any of the following conditions are violated, the result is Undefined
/// 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.
///
/// * The distance between the pointers, **in bytes**, cannot overflow an `isize`.
///
/// * The distance between the pointers, in bytes, must be an exact multiple
/// of the size of `T`.
///
/// * The distance being in bounds cannot rely on "wrapping around" the address space.
///
/// The compiler and standard library generally try to ensure allocations
/// never reach a size where an offset is a concern. For instance, `Vec`
/// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
/// `ptr_into_vec.offset_from(vec.as_ptr())` is always safe.
///
/// Most platforms fundamentally can't even construct such an allocation.
/// For instance, no known 64-bit platform can ever serve a request
/// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
/// However, some 32-bit and 16-bit platforms may successfully serve a request for
/// more than `isize::MAX` bytes with things like Physical Address
/// Extension. As such, memory acquired directly from allocators or memory
/// mapped files *may* be too large to handle with this function.
///
/// Consider using [`wrapping_offset_from`] instead if these constraints are
/// difficult to satisfy. The only advantage of this method is that it
/// enables more aggressive compiler optimizations.
///
/// # Panics
///
/// This function panics if `T` is a Zero-Sized Type ("ZST").
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(ptr_offset_from)]
///
/// let mut a = [0; 5];
/// let ptr1: *mut i32 = &mut a[1];
/// let ptr2: *mut i32 = &mut a[3];
/// unsafe {
/// assert_eq!(ptr2.offset_from(ptr1), 2);
/// assert_eq!(ptr1.offset_from(ptr2), -2);
/// assert_eq!(ptr1.offset(2), ptr2);
/// assert_eq!(ptr2.offset(-2), ptr1);
/// }
/// ```
#[unstable(feature = "ptr_offset_from", issue = "41079")]
#[rustc_const_unstable(feature = "const_ptr_offset_from", issue = "41079")]
#[inline]
pub const unsafe fn offset_from(self, origin: *const T) -> isize
where
T: Sized,
{
(self as *const T).offset_from(origin)
}
/// Calculates the distance between two pointers. The returned value is in
/// units of T: the distance in bytes is divided by `mem::size_of::<T>()`.
///
/// If the address different between the two pointers is not a multiple of
/// `mem::size_of::<T>()` then the result of the division is rounded towards
/// zero.
///
/// Though this method is safe for any two pointers, note that its result
/// will be mostly useless if the two pointers aren't into the same allocated
/// object, for example if they point to two different local variables.
///
/// # Panics
///
/// This function panics if `T` is a zero-sized type.
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// #![feature(ptr_wrapping_offset_from)]
///
/// let mut a = [0; 5];
/// let ptr1: *mut i32 = &mut a[1];
/// let ptr2: *mut i32 = &mut a[3];
/// assert_eq!(ptr2.wrapping_offset_from(ptr1), 2);
/// assert_eq!(ptr1.wrapping_offset_from(ptr2), -2);
/// assert_eq!(ptr1.wrapping_offset(2), ptr2);
/// assert_eq!(ptr2.wrapping_offset(-2), ptr1);
///
/// let ptr1: *mut i32 = 3 as _;
/// let ptr2: *mut i32 = 13 as _;
/// assert_eq!(ptr2.wrapping_offset_from(ptr1), 2);
/// ```
#[unstable(feature = "ptr_wrapping_offset_from", issue = "41079")]
#[inline]
pub fn wrapping_offset_from(self, origin: *const T) -> isize
where
T: Sized,
{
(self as *const T).wrapping_offset_from(origin)
}
/// Calculates the offset from a pointer (convenience for `.offset(count as isize)`).
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// If any of the following conditions are violated, the result is Undefined
/// 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.
///
/// * The computed offset, **in bytes**, cannot overflow an `isize`.
///
/// * The offset being in bounds cannot rely on "wrapping around" the address
/// space. That is, the infinite-precision sum must fit in a `usize`.
///
/// The compiler and standard library generally tries to ensure allocations
/// never reach a size where an offset is a concern. For instance, `Vec`
/// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
/// `vec.as_ptr().add(vec.len())` is always safe.
///
/// Most platforms fundamentally can't even construct such an allocation.
/// For instance, no known 64-bit platform can ever serve a request
/// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
/// However, some 32-bit and 16-bit platforms may successfully serve a request for
/// more than `isize::MAX` bytes with things like Physical Address
/// Extension. As such, memory acquired directly from allocators or memory
/// mapped files *may* be too large to handle with this function.
///
/// Consider using [`wrapping_add`] instead if these constraints are
/// difficult to satisfy. The only advantage of this method is that it
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_add`]: #method.wrapping_add
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s: &str = "123";
/// let ptr: *const u8 = s.as_ptr();
///
/// unsafe {
/// println!("{}", *ptr.add(1) as char);
/// println!("{}", *ptr.add(2) as char);
/// }
/// ```
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn add(self, count: usize) -> Self
where
T: Sized,
{
self.offset(count as isize)
}
/// Calculates the offset from a pointer (convenience for
/// `.offset((count as isize).wrapping_neg())`).
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// If any of the following conditions are violated, the result is Undefined
/// 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.
///
/// * The computed offset cannot exceed `isize::MAX` **bytes**.
///
/// * The offset being in bounds cannot rely on "wrapping around" the address
/// space. That is, the infinite-precision sum must fit in a usize.
///
/// The compiler and standard library generally tries to ensure allocations
/// never reach a size where an offset is a concern. For instance, `Vec`
/// and `Box` ensure they never allocate more than `isize::MAX` bytes, so
/// `vec.as_ptr().add(vec.len()).sub(vec.len())` is always safe.
///
/// Most platforms fundamentally can't even construct such an allocation.
/// For instance, no known 64-bit platform can ever serve a request
/// for 2<sup>63</sup> bytes due to page-table limitations or splitting the address space.
/// However, some 32-bit and 16-bit platforms may successfully serve a request for
/// more than `isize::MAX` bytes with things like Physical Address
/// Extension. As such, memory acquired directly from allocators or memory
/// mapped files *may* be too large to handle with this function.
///
/// Consider using [`wrapping_sub`] instead if these constraints are
/// difficult to satisfy. The only advantage of this method is that it
/// enables more aggressive compiler optimizations.
///
/// [`wrapping_sub`]: #method.wrapping_sub
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// let s: &str = "123";
///
/// unsafe {
/// let end: *const u8 = s.as_ptr().add(3);
/// println!("{}", *end.sub(1) as char);
/// println!("{}", *end.sub(2) as char);
/// }
/// ```
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn sub(self, count: usize) -> Self
where
T: Sized,
{
self.offset((count as isize).wrapping_neg())
}
/// Calculates the offset from a pointer using wrapping arithmetic.
/// (convenience for `.wrapping_offset(count as isize)`)
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// The resulting pointer does not need to be in bounds, but it is
/// potentially hazardous to dereference (which requires `unsafe`).
///
/// In particular, 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.
///
/// Compared to [`add`], this method basically delays the requirement of staying
/// within the same allocated object: [`add`] is immediate Undefined Behavior when
/// crossing object boundaries; `wrapping_add` produces a pointer but still leads
/// to Undefined Behavior if that pointer is dereferenced. [`add`] can be optimized
/// better and is thus preferrable in performance-sensitive code.
///
/// If you need to cross object boundaries, cast the pointer to an integer and
/// do the arithmetic there.
///
/// [`add`]: #method.add
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // Iterate using a raw pointer in increments of two elements
/// let data = [1u8, 2, 3, 4, 5];
/// let mut ptr: *const u8 = data.as_ptr();
/// let step = 2;
/// let end_rounded_up = ptr.wrapping_add(6);
///
/// // This loop prints "1, 3, 5, "
/// while ptr != end_rounded_up {
/// unsafe {
/// print!("{}, ", *ptr);
/// }
/// ptr = ptr.wrapping_add(step);
/// }
/// ```
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub fn wrapping_add(self, count: usize) -> Self
where
T: Sized,
{
self.wrapping_offset(count as isize)
}
/// Calculates the offset from a pointer using wrapping arithmetic.
/// (convenience for `.wrapping_offset((count as isize).wrapping_sub())`)
///
/// `count` is in units of T; e.g., a `count` of 3 represents a pointer
/// offset of `3 * size_of::<T>()` bytes.
///
/// # Safety
///
/// The resulting pointer does not need to be in bounds, but it is
/// potentially hazardous to dereference (which requires `unsafe`).
///
/// In particular, 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.
///
/// Compared to [`sub`], this method basically delays the requirement of staying
/// within the same allocated object: [`sub`] is immediate Undefined Behavior when
/// crossing object boundaries; `wrapping_sub` produces a pointer but still leads
/// to Undefined Behavior if that pointer is dereferenced. [`sub`] can be optimized
/// better and is thus preferrable in performance-sensitive code.
///
/// If you need to cross object boundaries, cast the pointer to an integer and
/// do the arithmetic there.
///
/// [`sub`]: #method.sub
///
/// # Examples
///
/// Basic usage:
///
/// ```
/// // Iterate using a raw pointer in increments of two elements (backwards)
/// let data = [1u8, 2, 3, 4, 5];
/// let mut ptr: *const u8 = data.as_ptr();
/// let start_rounded_down = ptr.wrapping_sub(2);
/// ptr = ptr.wrapping_add(4);
/// let step = 2;
/// // This loop prints "5, 3, 1, "
/// while ptr != start_rounded_down {
/// unsafe {
/// print!("{}, ", *ptr);
/// }
/// ptr = ptr.wrapping_sub(step);
/// }
/// ```
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub fn wrapping_sub(self, count: usize) -> Self
where
T: Sized,
{
self.wrapping_offset((count as isize).wrapping_neg())
}
/// Reads the value from `self` without moving it. This leaves the
/// memory in `self` unchanged.
///
/// See [`ptr::read`] for safety concerns and examples.
///
/// [`ptr::read`]: ./ptr/fn.read.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn read(self) -> T
where
T: Sized,
{
read(self)
}
/// Performs a volatile read of the value from `self` without moving it. This
/// leaves the memory in `self` unchanged.
///
/// Volatile operations are intended to act on I/O memory, and are guaranteed
/// to not be elided or reordered by the compiler across other volatile
/// operations.
///
/// See [`ptr::read_volatile`] for safety concerns and examples.
///
/// [`ptr::read_volatile`]: ./ptr/fn.read_volatile.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn read_volatile(self) -> T
where
T: Sized,
{
read_volatile(self)
}
/// Reads the value from `self` without moving it. This leaves the
/// memory in `self` unchanged.
///
/// Unlike `read`, the pointer may be unaligned.
///
/// See [`ptr::read_unaligned`] for safety concerns and examples.
///
/// [`ptr::read_unaligned`]: ./ptr/fn.read_unaligned.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn read_unaligned(self) -> T
where
T: Sized,
{
read_unaligned(self)
}
/// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
/// and destination may overlap.
///
/// NOTE: this has the *same* argument order as [`ptr::copy`].
///
/// See [`ptr::copy`] for safety concerns and examples.
///
/// [`ptr::copy`]: ./ptr/fn.copy.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn copy_to(self, dest: *mut T, count: usize)
where
T: Sized,
{
copy(self, dest, count)
}
/// Copies `count * size_of<T>` bytes from `self` to `dest`. The source
/// and destination may *not* overlap.
///
/// NOTE: this has the *same* argument order as [`ptr::copy_nonoverlapping`].
///
/// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
///
/// [`ptr::copy_nonoverlapping`]: ./ptr/fn.copy_nonoverlapping.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn copy_to_nonoverlapping(self, dest: *mut T, count: usize)
where
T: Sized,
{
copy_nonoverlapping(self, dest, count)
}
/// Copies `count * size_of<T>` bytes from `src` to `self`. The source
/// and destination may overlap.
///
/// NOTE: this has the *opposite* argument order of [`ptr::copy`].
///
/// See [`ptr::copy`] for safety concerns and examples.
///
/// [`ptr::copy`]: ./ptr/fn.copy.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn copy_from(self, src: *const T, count: usize)
where
T: Sized,
{
copy(src, self, count)
}
/// Copies `count * size_of<T>` bytes from `src` to `self`. The source
/// and destination may *not* overlap.
///
/// NOTE: this has the *opposite* argument order of [`ptr::copy_nonoverlapping`].
///
/// See [`ptr::copy_nonoverlapping`] for safety concerns and examples.
///
/// [`ptr::copy_nonoverlapping`]: ./ptr/fn.copy_nonoverlapping.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn copy_from_nonoverlapping(self, src: *const T, count: usize)
where
T: Sized,
{
copy_nonoverlapping(src, self, count)
}
/// Executes the destructor (if any) of the pointed-to value.
///
/// See [`ptr::drop_in_place`] for safety concerns and examples.
///
/// [`ptr::drop_in_place`]: ./ptr/fn.drop_in_place.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn drop_in_place(self) {
drop_in_place(self)
}
/// Overwrites a memory location with the given value without reading or
/// dropping the old value.
///
/// See [`ptr::write`] for safety concerns and examples.
///
/// [`ptr::write`]: ./ptr/fn.write.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn write(self, val: T)
where
T: Sized,
{
write(self, val)
}
/// Invokes memset on the specified pointer, setting `count * size_of::<T>()`
/// bytes of memory starting at `self` to `val`.
///
/// See [`ptr::write_bytes`] for safety concerns and examples.
///
/// [`ptr::write_bytes`]: ./ptr/fn.write_bytes.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn write_bytes(self, val: u8, count: usize)
where
T: Sized,
{
write_bytes(self, val, count)
}
/// Performs a volatile write of a memory location with the given value without
/// reading or dropping the old value.
///
/// Volatile operations are intended to act on I/O memory, and are guaranteed
/// to not be elided or reordered by the compiler across other volatile
/// operations.
///
/// See [`ptr::write_volatile`] for safety concerns and examples.
///
/// [`ptr::write_volatile`]: ./ptr/fn.write_volatile.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn write_volatile(self, val: T)
where
T: Sized,
{
write_volatile(self, val)
}
/// Overwrites a memory location with the given value without reading or
/// dropping the old value.
///
/// Unlike `write`, the pointer may be unaligned.
///
/// See [`ptr::write_unaligned`] for safety concerns and examples.
///
/// [`ptr::write_unaligned`]: ./ptr/fn.write_unaligned.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn write_unaligned(self, val: T)
where
T: Sized,
{
write_unaligned(self, val)
}
/// Replaces the value at `self` with `src`, returning the old
/// value, without dropping either.
///
/// See [`ptr::replace`] for safety concerns and examples.
///
/// [`ptr::replace`]: ./ptr/fn.replace.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn replace(self, src: T) -> T
where
T: Sized,
{
replace(self, src)
}
/// Swaps the values at two mutable locations of the same type, without
/// deinitializing either. They may overlap, unlike `mem::swap` which is
/// otherwise equivalent.
///
/// See [`ptr::swap`] for safety concerns and examples.
///
/// [`ptr::swap`]: ./ptr/fn.swap.html
#[stable(feature = "pointer_methods", since = "1.26.0")]
#[inline]
pub unsafe fn swap(self, with: *mut T)
where
T: Sized,
{
swap(self, with)
}
/// Computes the offset that needs to be applied to the pointer in order to make it aligned to
/// `align`.
///
/// If it is not possible to align the pointer, the implementation returns
/// `usize::max_value()`. It is permissible for the implementation to *always*
/// return `usize::max_value()`. Only your algorithm's performance can depend
/// on getting a usable offset here, not its correctness.
///
/// The offset is expressed in number of `T` elements, and not bytes. The value returned can be
/// used with the `wrapping_add` method.
///
/// There are no guarantees whatsoever that offsetting the pointer will not overflow or go
/// beyond the allocation that the pointer points into. It is up to the caller to ensure that
/// the returned offset is correct in all terms other than alignment.
///
/// # Panics
///
/// The function panics if `align` is not a power-of-two.
///
/// # Examples
///
/// Accessing adjacent `u8` as `u16`
///
/// ```
/// # fn foo(n: usize) {
/// # use std::mem::align_of;
/// # unsafe {
/// let x = [5u8, 6u8, 7u8, 8u8, 9u8];
/// let ptr = &x[n] as *const u8;
/// let offset = ptr.align_offset(align_of::<u16>());
/// if offset < x.len() - n - 1 {
/// let u16_ptr = ptr.add(offset) as *const u16;
/// assert_ne!(*u16_ptr, 500);
/// } else {
/// // while the pointer can be aligned via `offset`, it would point
/// // outside the allocation
/// }
/// # } }
/// ```
#[stable(feature = "align_offset", since = "1.36.0")]
pub fn align_offset(self, align: usize) -> usize
where
T: Sized,
{
if !align.is_power_of_two() {
panic!("align_offset: align is not a power-of-two");
}
unsafe { align_offset(self, align) }
}
}
// Equality for pointers
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> PartialEq for *mut T {
#[inline]
fn eq(&self, other: &*mut T) -> bool { *self == *other }
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Eq for *mut T {}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> Ord for *mut T {
#[inline]
fn cmp(&self, other: &*mut T) -> Ordering {
if self < other {
Less
} else if self == other {
Equal
} else {
Greater
}
}
}
#[stable(feature = "rust1", since = "1.0.0")]
impl<T: ?Sized> PartialOrd for *mut T {
#[inline]
fn partial_cmp(&self, other: &*mut T) -> Option<Ordering> {
Some(self.cmp(other))
}
#[inline]
fn lt(&self, other: &*mut T) -> bool { *self < *other }
#[inline]
fn le(&self, other: &*mut T) -> bool { *self <= *other }
#[inline]
fn gt(&self, other: &*mut T) -> bool { *self > *other }
#[inline]
fn ge(&self, other: &*mut T) -> bool { *self >= *other }
}

10
src/librustc/hir/mod.rs
View file

@ -1857,6 +1857,16 @@ impl fmt::Display for YieldSource {
} }
} }
impl From<GeneratorKind> for YieldSource {
fn from(kind: GeneratorKind) -> Self {
match kind {
// Guess based on the kind of the current generator.
GeneratorKind::Gen => Self::Yield,
GeneratorKind::Async(_) => Self::Await,
}
}
}
// N.B., if you change this, you'll probably want to change the corresponding // N.B., if you change this, you'll probably want to change the corresponding
// type structure in middle/ty.rs as well. // type structure in middle/ty.rs as well.
#[derive(RustcEncodable, RustcDecodable, Debug, HashStable)] #[derive(RustcEncodable, RustcDecodable, Debug, HashStable)]

10
src/librustc/middle/region.rs
View file

@ -1173,6 +1173,7 @@ fn resolve_local<'tcx>(
/// | VariantName(..., P&, ...) /// | VariantName(..., P&, ...)
/// | [ ..., P&, ... ] /// | [ ..., P&, ... ]
/// | ( ..., P&, ... ) /// | ( ..., P&, ... )
/// | ... "|" P& "|" ...
/// | box P& /// | box P&
fn is_binding_pat(pat: &hir::Pat) -> bool { fn is_binding_pat(pat: &hir::Pat) -> bool {
// Note that the code below looks for *explicit* refs only, that is, it won't // Note that the code below looks for *explicit* refs only, that is, it won't
@ -1212,6 +1213,7 @@ fn resolve_local<'tcx>(
pats3.iter().any(|p| is_binding_pat(&p)) pats3.iter().any(|p| is_binding_pat(&p))
} }
PatKind::Or(ref subpats) |
PatKind::TupleStruct(_, ref subpats, _) | PatKind::TupleStruct(_, ref subpats, _) |
PatKind::Tuple(ref subpats, _) => { PatKind::Tuple(ref subpats, _) => {
subpats.iter().any(|p| is_binding_pat(&p)) subpats.iter().any(|p| is_binding_pat(&p))
@ -1221,7 +1223,13 @@ fn resolve_local<'tcx>(
is_binding_pat(&subpat) is_binding_pat(&subpat)
} }
_ => false, PatKind::Ref(_, _) |
PatKind::Binding(hir::BindingAnnotation::Unannotated, ..) |
PatKind::Binding(hir::BindingAnnotation::Mutable, ..) |
PatKind::Wild |
PatKind::Path(_) |
PatKind::Lit(_) |
PatKind::Range(_, _, _) => false,
} }
} }

37
src/librustc_mir/borrow_check/diagnostics/region_errors.rs
View file

@ -1,10 +1,13 @@
//! Error reporting machinery for lifetime errors. //! Error reporting machinery for lifetime errors.
use rustc::hir::def_id::DefId; use rustc::hir::def_id::DefId;
use rustc::infer::error_reporting::nice_region_error::NiceRegionError; use rustc::infer::{
use rustc::infer::InferCtxt; error_reporting::nice_region_error::NiceRegionError,
use rustc::infer::NLLRegionVariableOrigin; InferCtxt, NLLRegionVariableOrigin,
use rustc::mir::{ConstraintCategory, Local, Location, Body}; };
use rustc::mir::{
ConstraintCategory, Local, Location, Body,
};
use rustc::ty::{self, RegionVid}; use rustc::ty::{self, RegionVid};
use rustc_index::vec::IndexVec; use rustc_index::vec::IndexVec;
use rustc_errors::DiagnosticBuilder; use rustc_errors::DiagnosticBuilder;
@ -93,6 +96,32 @@ pub struct ErrorConstraintInfo {
} }
impl<'tcx> RegionInferenceContext<'tcx> { impl<'tcx> RegionInferenceContext<'tcx> {
/// Converts a region inference variable into a `ty::Region` that
/// we can use for error reporting. If `r` is universally bound,
/// then we use the name that we have on record for it. If `r` is
/// existentially bound, then we check its inferred value and try
/// to find a good name from that. Returns `None` if we can't find
/// one (e.g., this is just some random part of the CFG).
pub fn to_error_region(&self, r: RegionVid) -> Option<ty::Region<'tcx>> {
self.to_error_region_vid(r).and_then(|r| self.definitions[r].external_name)
}
/// Returns the [RegionVid] corresponding to the region returned by
/// `to_error_region`.
pub fn to_error_region_vid(&self, r: RegionVid) -> Option<RegionVid> {
if self.universal_regions.is_universal_region(r) {
Some(r)
} else {
let r_scc = self.constraint_sccs.scc(r);
let upper_bound = self.universal_upper_bound(r);
if self.scc_values.contains(r_scc, upper_bound) {
self.to_error_region_vid(upper_bound)
} else {
None
}
}
}
/// Tries to find the best constraint to blame for the fact that /// Tries to find the best constraint to blame for the fact that
/// `R: from_region`, where `R` is some region that meets /// `R: from_region`, where `R` is some region that meets
/// `target_test`. This works by following the constraint graph, /// `target_test`. This works by following the constraint graph,

147
src/librustc_mir/borrow_check/region_infer/mod.rs
View file

@ -928,32 +928,6 @@ impl<'tcx> RegionInferenceContext<'tcx> {
} }
} }
/// Converts a region inference variable into a `ty::Region` that
/// we can use for error reporting. If `r` is universally bound,
/// then we use the name that we have on record for it. If `r` is
/// existentially bound, then we check its inferred value and try
/// to find a good name from that. Returns `None` if we can't find
/// one (e.g., this is just some random part of the CFG).
pub fn to_error_region(&self, r: RegionVid) -> Option<ty::Region<'tcx>> {
self.to_error_region_vid(r).and_then(|r| self.definitions[r].external_name)
}
/// Returns the [RegionVid] corresponding to the region returned by
/// `to_error_region`.
pub fn to_error_region_vid(&self, r: RegionVid) -> Option<RegionVid> {
if self.universal_regions.is_universal_region(r) {
Some(r)
} else {
let r_scc = self.constraint_sccs.scc(r);
let upper_bound = self.universal_upper_bound(r);
if self.scc_values.contains(r_scc, upper_bound) {
self.to_error_region_vid(upper_bound)
} else {
None
}
}
}
/// Invoked when we have some type-test (e.g., `T: 'X`) that we cannot /// Invoked when we have some type-test (e.g., `T: 'X`) that we cannot
/// prove to be satisfied. If this is a closure, we will attempt to /// prove to be satisfied. If this is a closure, we will attempt to
/// "promote" this type-test into our `ClosureRegionRequirements` and /// "promote" this type-test into our `ClosureRegionRequirements` and
@ -1164,7 +1138,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
/// include the CFG anyhow. /// include the CFG anyhow.
/// - For each `end('x)` element in `'r`, compute the mutual LUB, yielding /// - For each `end('x)` element in `'r`, compute the mutual LUB, yielding
/// a result `'y`. /// a result `'y`.
fn universal_upper_bound(&self, r: RegionVid) -> RegionVid { pub (in crate::borrow_check) fn universal_upper_bound(&self, r: RegionVid) -> RegionVid {
debug!("universal_upper_bound(r={:?}={})", r, self.region_value_str(r)); debug!("universal_upper_bound(r={:?}={})", r, self.region_value_str(r));
// Find the smallest universal region that contains all other // Find the smallest universal region that contains all other
@ -1458,19 +1432,34 @@ impl<'tcx> RegionInferenceContext<'tcx> {
debug!("check_polonius_subset_errors: subset_error longer_fr={:?},\ debug!("check_polonius_subset_errors: subset_error longer_fr={:?},\
shorter_fr={:?}", longer_fr, shorter_fr); shorter_fr={:?}", longer_fr, shorter_fr);
self.report_or_propagate_universal_region_error( let propagated = self.try_propagate_universal_region_error(
*longer_fr, *longer_fr,
*shorter_fr, *shorter_fr,
infcx,
body, body,
local_names,
upvars,
mir_def_id,
&mut propagated_outlives_requirements, &mut propagated_outlives_requirements,
&mut outlives_suggestion,
errors_buffer,
region_naming,
); );
if !propagated {
// If we are not in a context where we can't propagate errors, or we
// could not shrink `fr` to something smaller, then just report an
// error.
//
// Note: in this case, we use the unapproximated regions to report the
// error. This gives better error messages in some cases.
let db = self.report_error(
body,
local_names,
upvars,
infcx,
mir_def_id,
*longer_fr,
NLLRegionVariableOrigin::FreeRegion,
*shorter_fr,
&mut outlives_suggestion,
region_naming,
);
db.buffer(errors_buffer);
}
} }
// Handle the placeholder errors as usual, until the chalk-rustc-polonius triumvirate has // Handle the placeholder errors as usual, until the chalk-rustc-polonius triumvirate has
@ -1594,48 +1583,59 @@ impl<'tcx> RegionInferenceContext<'tcx> {
return None; return None;
} }
self.report_or_propagate_universal_region_error( let propagated = self.try_propagate_universal_region_error(
longer_fr, longer_fr,
shorter_fr, shorter_fr,
infcx,
body, body,
local_names,
upvars,
mir_def_id,
propagated_outlives_requirements, propagated_outlives_requirements,
outlives_suggestion, );
errors_buffer,
region_naming, if propagated {
) None
} else {
// If we are not in a context where we can't propagate errors, or we
// could not shrink `fr` to something smaller, then just report an
// error.
//
// Note: in this case, we use the unapproximated regions to report the
// error. This gives better error messages in some cases.
let db = self.report_error(
body,
local_names,
upvars,
infcx,
mir_def_id,
longer_fr,
NLLRegionVariableOrigin::FreeRegion,
shorter_fr,
outlives_suggestion,
region_naming,
);
db.buffer(errors_buffer);
Some(ErrorReported)
}
} }
fn report_or_propagate_universal_region_error( /// Attempt to propagate a region error (e.g. `'a: 'b`) that is not met to a closure's
/// creator. If we cannot, then the caller should report an error to the user.
///
/// Returns `true` if the error was propagated, and `false` otherwise.
fn try_propagate_universal_region_error(
&self, &self,
longer_fr: RegionVid, longer_fr: RegionVid,
shorter_fr: RegionVid, shorter_fr: RegionVid,
infcx: &InferCtxt<'_, 'tcx>,
body: &Body<'tcx>, body: &Body<'tcx>,
local_names: &IndexVec<Local, Option<Symbol>>,
upvars: &[Upvar],
mir_def_id: DefId,
propagated_outlives_requirements: &mut Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>, propagated_outlives_requirements: &mut Option<&mut Vec<ClosureOutlivesRequirement<'tcx>>>,
outlives_suggestion: &mut OutlivesSuggestionBuilder<'_>, ) -> bool {
errors_buffer: &mut Vec<Diagnostic>,
region_naming: &mut RegionErrorNamingCtx,
) -> Option<ErrorReported> {
debug!(
"report_or_propagate_universal_region_error: fr={:?} does not outlive shorter_fr={:?}",
longer_fr, shorter_fr,
);
if let Some(propagated_outlives_requirements) = propagated_outlives_requirements { if let Some(propagated_outlives_requirements) = propagated_outlives_requirements {
// Shrink `longer_fr` until we find a non-local region (if we do). // Shrink `longer_fr` until we find a non-local region (if we do).
// We'll call it `fr-` -- it's ever so slightly smaller than // We'll call it `fr-` -- it's ever so slightly smaller than
// `longer_fr`. // `longer_fr`.
if let Some(fr_minus) = if let Some(fr_minus) =
self.universal_region_relations.non_local_lower_bound(longer_fr) { self.universal_region_relations.non_local_lower_bound(longer_fr) {
debug!("report_or_propagate_universal_region_error: fr_minus={:?}", fr_minus); debug!("try_propagate_universal_region_error: fr_minus={:?}", fr_minus);
let blame_span_category = let blame_span_category =
self.find_outlives_blame_span(body, longer_fr, self.find_outlives_blame_span(body, longer_fr,
@ -1648,7 +1648,7 @@ impl<'tcx> RegionInferenceContext<'tcx> {
.universal_region_relations .universal_region_relations
.non_local_upper_bounds(&shorter_fr); .non_local_upper_bounds(&shorter_fr);
debug!( debug!(
"report_or_propagate_universal_region_error: shorter_fr_plus={:?}", "try_propagate_universal_region_error: shorter_fr_plus={:?}",
shorter_fr_plus shorter_fr_plus
); );
for &&fr in &shorter_fr_plus { for &&fr in &shorter_fr_plus {
@ -1660,32 +1660,11 @@ impl<'tcx> RegionInferenceContext<'tcx> {
category: blame_span_category.0, category: blame_span_category.0,
}); });
} }
return None; return true;
} }
} }
// If we are not in a context where we can't propagate errors, or we false
// could not shrink `fr` to something smaller, then just report an
// error.
//
// Note: in this case, we use the unapproximated regions to report the
// error. This gives better error messages in some cases.
let db = self.report_error(
body,
local_names,
upvars,
infcx,
mir_def_id,
longer_fr,
NLLRegionVariableOrigin::FreeRegion,
shorter_fr,
outlives_suggestion,
region_naming,
);
db.buffer(errors_buffer);
Some(ErrorReported)
} }
fn check_bound_universal_region( fn check_bound_universal_region(

31
src/librustc_mir/dataflow/move_paths/builder.rs
View file

@ -103,6 +103,13 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
} }
}; };
// The move path index of the first union that we find. Once this is
// some we stop creating child move paths, since moves from unions
// move the whole thing.
// We continue looking for other move errors though so that moving
// from `*(u.f: &_)` isn't allowed.
let mut union_path = None;
for (i, elem) in place.projection.iter().enumerate() { for (i, elem) in place.projection.iter().enumerate() {
let proj_base = &place.projection[..i]; let proj_base = &place.projection[..i];
let body = self.builder.body; let body = self.builder.body;
@ -127,9 +134,8 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
InteriorOfTypeWithDestructor { container_ty: place_ty }, InteriorOfTypeWithDestructor { container_ty: place_ty },
)); ));
} }
// move out of union - always move the entire union
ty::Adt(adt, _) if adt.is_union() => { ty::Adt(adt, _) if adt.is_union() => {
return Err(MoveError::UnionMove { path: base }); union_path.get_or_insert(base);
} }
ty::Slice(_) => { ty::Slice(_) => {
return Err(MoveError::cannot_move_out_of( return Err(MoveError::cannot_move_out_of(
@ -155,15 +161,22 @@ impl<'b, 'a, 'tcx> Gatherer<'b, 'a, 'tcx> {
_ => {} _ => {}
}; };
base = self.add_move_path(base, elem, |tcx| { if union_path.is_none() {
Place { base = self.add_move_path(base, elem, |tcx| {
base: place.base.clone(), Place {
projection: tcx.intern_place_elems(&place.projection[..i+1]), base: place.base.clone(),
} projection: tcx.intern_place_elems(&place.projection[..i+1]),
}); }
});
}
} }
Ok(base) if let Some(base) = union_path {
// Move out of union - always move the entire union.
Err(MoveError::UnionMove { path: base })
} else {
Ok(base)
}
} }
fn add_move_path( fn add_move_path(

52
src/librustc_mir/transform/const_prop.rs
View file

@ -262,7 +262,7 @@ struct ConstPropagator<'mir, 'tcx> {
ecx: InterpCx<'mir, 'tcx, ConstPropMachine>, ecx: InterpCx<'mir, 'tcx, ConstPropMachine>,
tcx: TyCtxt<'tcx>, tcx: TyCtxt<'tcx>,
source: MirSource<'tcx>, source: MirSource<'tcx>,
can_const_prop: IndexVec<Local, bool>, can_const_prop: IndexVec<Local, ConstPropMode>,
param_env: ParamEnv<'tcx>, param_env: ParamEnv<'tcx>,
// FIXME(eddyb) avoid cloning these two fields more than once, // FIXME(eddyb) avoid cloning these two fields more than once,
// by accessing them through `ecx` instead. // by accessing them through `ecx` instead.
@ -708,17 +708,28 @@ impl<'mir, 'tcx> ConstPropagator<'mir, 'tcx> {
} }
} }
/// The mode that `ConstProp` is allowed to run in for a given `Local`.
#[derive(Clone, Copy, Debug, PartialEq)]
enum ConstPropMode {
/// The `Local` can be propagated into and reads of this `Local` can also be propagated.
FullConstProp,
/// The `Local` can be propagated into but reads cannot be propagated.
OnlyPropagateInto,
/// No propagation is allowed at all.
NoPropagation,
}
struct CanConstProp { struct CanConstProp {
can_const_prop: IndexVec<Local, bool>, can_const_prop: IndexVec<Local, ConstPropMode>,
// false at the beginning, once set, there are not allowed to be any more assignments // false at the beginning, once set, there are not allowed to be any more assignments
found_assignment: IndexVec<Local, bool>, found_assignment: IndexVec<Local, bool>,
} }
impl CanConstProp { impl CanConstProp {
/// returns true if `local` can be propagated /// returns true if `local` can be propagated
fn check(body: ReadOnlyBodyAndCache<'_, '_>) -> IndexVec<Local, bool> { fn check(body: ReadOnlyBodyAndCache<'_, '_>) -> IndexVec<Local, ConstPropMode> {
let mut cpv = CanConstProp { let mut cpv = CanConstProp {
can_const_prop: IndexVec::from_elem(true, &body.local_decls), can_const_prop: IndexVec::from_elem(ConstPropMode::FullConstProp, &body.local_decls),
found_assignment: IndexVec::from_elem(false, &body.local_decls), found_assignment: IndexVec::from_elem(false, &body.local_decls),
}; };
for (local, val) in cpv.can_const_prop.iter_enumerated_mut() { for (local, val) in cpv.can_const_prop.iter_enumerated_mut() {
@ -728,10 +739,10 @@ impl CanConstProp {
// FIXME(oli-obk): lint variables until they are used in a condition // FIXME(oli-obk): lint variables until they are used in a condition
// FIXME(oli-obk): lint if return value is constant // FIXME(oli-obk): lint if return value is constant
let local_kind = body.local_kind(local); let local_kind = body.local_kind(local);
*val = local_kind == LocalKind::Temp || local_kind == LocalKind::ReturnPointer;
if !*val { if local_kind == LocalKind::Arg || local_kind == LocalKind::Var {
trace!("local {:?} can't be propagated because it's not a temporary", local); *val = ConstPropMode::OnlyPropagateInto;
trace!("local {:?} can't be const propagated because it's not a temporary", local);
} }
} }
cpv.visit_body(body); cpv.visit_body(body);
@ -753,7 +764,7 @@ impl<'tcx> Visitor<'tcx> for CanConstProp {
// only occur in independent execution paths // only occur in independent execution paths
MutatingUse(MutatingUseContext::Store) => if self.found_assignment[local] { MutatingUse(MutatingUseContext::Store) => if self.found_assignment[local] {
trace!("local {:?} can't be propagated because of multiple assignments", local); trace!("local {:?} can't be propagated because of multiple assignments", local);
self.can_const_prop[local] = false; self.can_const_prop[local] = ConstPropMode::NoPropagation;
} else { } else {
self.found_assignment[local] = true self.found_assignment[local] = true
}, },
@ -766,7 +777,7 @@ impl<'tcx> Visitor<'tcx> for CanConstProp {
NonUse(_) => {}, NonUse(_) => {},
_ => { _ => {
trace!("local {:?} can't be propagaged because it's used: {:?}", local, context); trace!("local {:?} can't be propagaged because it's used: {:?}", local, context);
self.can_const_prop[local] = false; self.can_const_prop[local] = ConstPropMode::NoPropagation;
}, },
} }
} }
@ -800,10 +811,10 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
if let Ok(place_layout) = self.tcx.layout_of(self.param_env.and(place_ty)) { if let Ok(place_layout) = self.tcx.layout_of(self.param_env.and(place_ty)) {
if let Some(local) = place.as_local() { if let Some(local) = place.as_local() {
let source = statement.source_info; let source = statement.source_info;
let can_const_prop = self.can_const_prop[local];
if let Some(()) = self.const_prop(rval, place_layout, source, place) { if let Some(()) = self.const_prop(rval, place_layout, source, place) {
if self.can_const_prop[local] { if can_const_prop == ConstPropMode::FullConstProp ||
trace!("propagated into {:?}", local); can_const_prop == ConstPropMode::OnlyPropagateInto {
if let Some(value) = self.get_const(local) { if let Some(value) = self.get_const(local) {
if self.should_const_prop(value) { if self.should_const_prop(value) {
trace!("replacing {:?} with {:?}", rval, value); trace!("replacing {:?} with {:?}", rval, value);
@ -812,13 +823,18 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
value, value,
statement.source_info, statement.source_info,
); );
if can_const_prop == ConstPropMode::FullConstProp {
trace!("propagated into {:?}", local);
}
} }
} }
} else { }
trace!("can't propagate into {:?}", local); }
if local != RETURN_PLACE { if self.can_const_prop[local] != ConstPropMode::FullConstProp {
self.remove_const(local); trace!("can't propagate into {:?}", local);
} if local != RETURN_PLACE {
self.remove_const(local);
} }
} }
} }
@ -826,7 +842,7 @@ impl<'mir, 'tcx> MutVisitor<'tcx> for ConstPropagator<'mir, 'tcx> {
} else { } else {
match statement.kind { match statement.kind {
StatementKind::StorageLive(local) | StatementKind::StorageLive(local) |
StatementKind::StorageDead(local) if self.can_const_prop[local] => { StatementKind::StorageDead(local) => {
let frame = self.ecx.frame_mut(); let frame = self.ecx.frame_mut();
frame.locals[local].value = frame.locals[local].value =
if let StatementKind::StorageLive(_) = statement.kind { if let StatementKind::StorageLive(_) = statement.kind {

21
src/librustc_typeck/check/generator_interior.rs
View file

@ -19,6 +19,7 @@ struct InteriorVisitor<'a, 'tcx> {
region_scope_tree: &'tcx region::ScopeTree, region_scope_tree: &'tcx region::ScopeTree,
expr_count: usize, expr_count: usize,
kind: hir::GeneratorKind, kind: hir::GeneratorKind,
prev_unresolved_span: Option<Span>,
} }
impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> { impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
@ -32,7 +33,6 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
debug!("generator_interior: attempting to record type {:?} {:?} {:?} {:?}", debug!("generator_interior: attempting to record type {:?} {:?} {:?} {:?}",
ty, scope, expr, source_span); ty, scope, expr, source_span);
let live_across_yield = scope.map(|s| { let live_across_yield = scope.map(|s| {
self.region_scope_tree.yield_in_scope(s).and_then(|yield_data| { self.region_scope_tree.yield_in_scope(s).and_then(|yield_data| {
// If we are recording an expression that is the last yield // If we are recording an expression that is the last yield
@ -54,15 +54,11 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
}).unwrap_or_else(|| Some(YieldData { }).unwrap_or_else(|| Some(YieldData {
span: DUMMY_SP, span: DUMMY_SP,
expr_and_pat_count: 0, expr_and_pat_count: 0,
source: match self.kind { // Guess based on the kind of the current generator. source: self.kind.into(),
hir::GeneratorKind::Gen => hir::YieldSource::Yield,
hir::GeneratorKind::Async(_) => hir::YieldSource::Await,
},
})); }));
if let Some(yield_data) = live_across_yield { if let Some(yield_data) = live_across_yield {
let ty = self.fcx.resolve_vars_if_possible(&ty); let ty = self.fcx.resolve_vars_if_possible(&ty);
debug!("type in expr = {:?}, scope = {:?}, type = {:?}, count = {}, yield_span = {:?}", debug!("type in expr = {:?}, scope = {:?}, type = {:?}, count = {}, yield_span = {:?}",
expr, scope, ty, self.expr_count, yield_data.span); expr, scope, ty, self.expr_count, yield_data.span);
@ -74,9 +70,12 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
yield_data.source); yield_data.source);
// If unresolved type isn't a ty_var then unresolved_type_span is None // If unresolved type isn't a ty_var then unresolved_type_span is None
let span = self.prev_unresolved_span.unwrap_or_else(
|| unresolved_type_span.unwrap_or(source_span)
);
self.fcx.need_type_info_err_in_generator( self.fcx.need_type_info_err_in_generator(
self.kind, self.kind,
unresolved_type_span.unwrap_or(source_span), span,
unresolved_type, unresolved_type,
) )
.span_note(yield_data.span, &*note) .span_note(yield_data.span, &*note)
@ -94,6 +93,13 @@ impl<'a, 'tcx> InteriorVisitor<'a, 'tcx> {
} else { } else {
debug!("no type in expr = {:?}, count = {:?}, span = {:?}", debug!("no type in expr = {:?}, count = {:?}, span = {:?}",
expr, self.expr_count, expr.map(|e| e.span)); expr, self.expr_count, expr.map(|e| e.span));
let ty = self.fcx.resolve_vars_if_possible(&ty);
if let Some((unresolved_type, unresolved_type_span))
= self.fcx.unresolved_type_vars(&ty) {
debug!("remained unresolved_type = {:?}, unresolved_type_span: {:?}",
unresolved_type, unresolved_type_span);
self.prev_unresolved_span = unresolved_type_span;
}
} }
} }
} }
@ -112,6 +118,7 @@ pub fn resolve_interior<'a, 'tcx>(
region_scope_tree: fcx.tcx.region_scope_tree(def_id), region_scope_tree: fcx.tcx.region_scope_tree(def_id),
expr_count: 0, expr_count: 0,
kind, kind,
prev_unresolved_span: None,
}; };
intravisit::walk_body(&mut visitor, body); intravisit::walk_body(&mut visitor, body);

2
src/test/mir-opt/const_prop/aggregate.rs
View file

@ -19,7 +19,7 @@ fn main() {
// ... // ...
// _3 = (const 0i32, const 1i32, const 2i32); // _3 = (const 0i32, const 1i32, const 2i32);
// _2 = const 1i32; // _2 = const 1i32;
// _1 = Add(move _2, const 0i32); // _1 = const 1i32;
// ... // ...
// } // }
// END rustc.main.ConstProp.after.mir // END rustc.main.ConstProp.after.mir

2
src/test/mir-opt/const_prop/array_index.rs
View file

@ -26,7 +26,7 @@ fn main() {
// assert(const true, "index out of bounds: the len is move _4 but the index is _3") -> bb1; // assert(const true, "index out of bounds: the len is move _4 but the index is _3") -> bb1;
// } // }
// bb1: { // bb1: {
// _1 = _2[_3]; // _1 = const 2u32;
// ... // ...
// return; // return;
// } // }

149
src/test/mir-opt/const_prop/optimizes_into_variable.rs Normal file
View file

@ -0,0 +1,149 @@
// compile-flags: -C overflow-checks=on
struct Point {
x: u32,
y: u32,
}
fn main() {
let x = 2 + 2;
let y = [0, 1, 2, 3, 4, 5][3];
let z = (Point { x: 12, y: 42}).y;
}
// END RUST SOURCE
// START rustc.main.ConstProp.before.mir
// let mut _0: ();
// let _1: i32;
// let mut _2: (i32, bool);
// let mut _4: [i32; 6];
// let _5: usize;
// let mut _6: usize;
// let mut _7: bool;
// let mut _9: Point;
// scope 1 {
// debug x => _1;
// let _3: i32;
// scope 2 {
// debug y => _3;
// let _8: u32;
// scope 3 {
// debug z => _8;
// }
// }
// }
// bb0: {
// StorageLive(_1);
// _2 = CheckedAdd(const 2i32, const 2i32);
// assert(!move (_2.1: bool), "attempt to add with overflow") -> bb1;
// }
// bb1: {
// _1 = move (_2.0: i32);
// StorageLive(_3);
// StorageLive(_4);
// _4 = [const 0i32, const 1i32, const 2i32, const 3i32, const 4i32, const 5i32];
// StorageLive(_5);
// _5 = const 3usize;
// _6 = const 6usize;
// _7 = Lt(_5, _6);
// assert(move _7, "index out of bounds: the len is move _6 but the index is _5") -> bb2;
// }
// bb2: {
// _3 = _4[_5];
// StorageDead(_5);
// StorageDead(_4);
// StorageLive(_8);
// StorageLive(_9);
// _9 = Point { x: const 12u32, y: const 42u32 };
// _8 = (_9.1: u32);
// StorageDead(_9);
// _0 = ();
// StorageDead(_8);
// StorageDead(_3);
// StorageDead(_1);
// return;
// }
// END rustc.main.ConstProp.before.mir
// START rustc.main.ConstProp.after.mir
// let mut _0: ();
// let _1: i32;
// let mut _2: (i32, bool);
// let mut _4: [i32; 6];
// let _5: usize;
// let mut _6: usize;
// let mut _7: bool;
// let mut _9: Point;
// scope 1 {
// debug x => _1;
// let _3: i32;
// scope 2 {
// debug y => _3;
// let _8: u32;
// scope 3 {
// debug z => _8;
// }
// }
// }
// bb0: {
// StorageLive(_1);
// _2 = (const 4i32, const false);
// assert(!const false, "attempt to add with overflow") -> bb1;
// }
// bb1: {
// _1 = const 4i32;
// StorageLive(_3);
// StorageLive(_4);
// _4 = [const 0i32, const 1i32, const 2i32, const 3i32, const 4i32, const 5i32];
// StorageLive(_5);
// _5 = const 3usize;
// _6 = const 6usize;
// _7 = const true;
// assert(const true, "index out of bounds: the len is move _6 but the index is _5") -> bb2;
// }
// bb2: {
// _3 = const 3i32;
// StorageDead(_5);
// StorageDead(_4);
// StorageLive(_8);
// StorageLive(_9);
// _9 = Point { x: const 12u32, y: const 42u32 };
// _8 = const 42u32;
// StorageDead(_9);
// _0 = ();
// StorageDead(_8);
// StorageDead(_3);
// StorageDead(_1);
// return;
// }
// END rustc.main.ConstProp.after.mir
// START rustc.main.SimplifyLocals.after.mir
// let mut _0: ();
// let _1: i32;
// let mut _3: [i32; 6];
// scope 1 {
// debug x => _1;
// let _2: i32;
// scope 2 {
// debug y => _2;
// let _4: u32;
// scope 3 {
// debug z => _4;
// }
// }
// }
// bb0: {
// StorageLive(_1);
// _1 = const 4i32;
// StorageLive(_2);
// StorageLive(_3);
// _3 = [const 0i32, const 1i32, const 2i32, const 3i32, const 4i32, const 5i32];
// _2 = const 3i32;
// StorageDead(_3);
// StorageLive(_4);
// _4 = const 42u32;
// StorageDead(_4);
// StorageDead(_2);
// StorageDead(_1);
// return;
// }
// END rustc.main.SimplifyLocals.after.mir

2
src/test/mir-opt/const_prop/read_immutable_static.rs
View file

@ -25,7 +25,7 @@ fn main() {
// _2 = const 2u8; // _2 = const 2u8;
// ... // ...
// _4 = const 2u8; // _4 = const 2u8;
// _1 = Add(move _2, move _4); // _1 = const 4u8;
// ... // ...
// } // }
// END rustc.main.ConstProp.after.mir // END rustc.main.ConstProp.after.mir

2
src/test/mir-opt/const_prop/repeat.rs
View file

@ -30,7 +30,7 @@ fn main() {
// } // }
// bb1: { // bb1: {
// _2 = const 42u32; // _2 = const 42u32;
// _1 = Add(move _2, const 0u32); // _1 = const 42u32;
// ... // ...
// return; // return;
// } // }

30
src/test/ui/borrowck/move-from-union-field-issue-66500.rs Normal file
View file

@ -0,0 +1,30 @@
// Moving from a reference/raw pointer should be an error, even when they're
// the field of a union.
#![feature(untagged_unions)]
union Pointers {
a: &'static String,
b: &'static mut String,
c: *const String,
d: *mut String,
}
unsafe fn move_ref(u: Pointers) -> String {
*u.a
//~^ ERROR cannot move out of `*u.a`
}
unsafe fn move_ref_mut(u: Pointers) -> String {
*u.b
//~^ ERROR cannot move out of `*u.b`
}
unsafe fn move_ptr(u: Pointers) -> String {
*u.c
//~^ ERROR cannot move out of `*u.c`
}
unsafe fn move_ptr_mut(u: Pointers) -> String {
*u.d
//~^ ERROR cannot move out of `*u.d`
}
fn main() {}

27
src/test/ui/borrowck/move-from-union-field-issue-66500.stderr Normal file
View file

@ -0,0 +1,27 @@
error[E0507]: cannot move out of `*u.a` which is behind a shared reference
--> $DIR/move-from-union-field-issue-66500.rs:14:5
|
LL | *u.a
| ^^^^ move occurs because `*u.a` has type `std::string::String`, which does not implement the `Copy` trait
error[E0507]: cannot move out of `*u.b` which is behind a mutable reference
--> $DIR/move-from-union-field-issue-66500.rs:18:5
|
LL | *u.b
| ^^^^ move occurs because `*u.b` has type `std::string::String`, which does not implement the `Copy` trait
error[E0507]: cannot move out of `*u.c` which is behind a raw pointer
--> $DIR/move-from-union-field-issue-66500.rs:22:5
|
LL | *u.c
| ^^^^ move occurs because `*u.c` has type `std::string::String`, which does not implement the `Copy` trait
error[E0507]: cannot move out of `*u.d` which is behind a raw pointer
--> $DIR/move-from-union-field-issue-66500.rs:26:5
|
LL | *u.d
| ^^^^ move occurs because `*u.d` has type `std::string::String`, which does not implement the `Copy` trait
error: aborting due to 4 previous errors
For more information about this error, try `rustc --explain E0507`.

20
src/test/ui/consts/offset_from_ub.stderr
View file

@ -1,11 +1,11 @@
error: any use of this value will cause an error error: any use of this value will cause an error
--> $SRC_DIR/libcore/ptr/mod.rs:LL:COL --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
| |
LL | intrinsics::ptr_offset_from(self, origin) LL | intrinsics::ptr_offset_from(self, origin)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| | | |
| ptr_offset_from cannot compute offset of pointers into different allocations. | ptr_offset_from cannot compute offset of pointers into different allocations.
| inside call to `std::ptr::<impl *const Struct>::offset_from` at $DIR/offset_from_ub.rs:19:27 | inside call to `std::ptr::const_ptr::<impl *const Struct>::offset_from` at $DIR/offset_from_ub.rs:19:27
| |
::: $DIR/offset_from_ub.rs:13:1 ::: $DIR/offset_from_ub.rs:13:1
| |
@ -21,13 +21,13 @@ LL | | };
= note: `#[deny(const_err)]` on by default = note: `#[deny(const_err)]` on by default
error: any use of this value will cause an error error: any use of this value will cause an error
--> $SRC_DIR/libcore/ptr/mod.rs:LL:COL --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
| |
LL | intrinsics::ptr_offset_from(self, origin) LL | intrinsics::ptr_offset_from(self, origin)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| | | |
| a memory access tried to interpret some bytes as a pointer | a memory access tried to interpret some bytes as a pointer
| inside call to `std::ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:25:14 | inside call to `std::ptr::const_ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:25:14
| |
::: $DIR/offset_from_ub.rs:23:1 ::: $DIR/offset_from_ub.rs:23:1
| |
@ -38,13 +38,13 @@ LL | | };
| |__- | |__-
error: any use of this value will cause an error error: any use of this value will cause an error
--> $SRC_DIR/libcore/ptr/mod.rs:LL:COL --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
| |
LL | intrinsics::ptr_offset_from(self, origin) LL | intrinsics::ptr_offset_from(self, origin)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| | | |
| exact_div: 1 cannot be divided by 2 without remainder | exact_div: 1 cannot be divided by 2 without remainder
| inside call to `std::ptr::<impl *const u16>::offset_from` at $DIR/offset_from_ub.rs:33:14 | inside call to `std::ptr::const_ptr::<impl *const u16>::offset_from` at $DIR/offset_from_ub.rs:33:14
| |
::: $DIR/offset_from_ub.rs:28:1 ::: $DIR/offset_from_ub.rs:28:1
| |
@ -58,13 +58,13 @@ LL | | };
| |__- | |__-
error: any use of this value will cause an error error: any use of this value will cause an error
--> $SRC_DIR/libcore/ptr/mod.rs:LL:COL --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
| |
LL | intrinsics::ptr_offset_from(self, origin) LL | intrinsics::ptr_offset_from(self, origin)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| | | |
| invalid use of NULL pointer | invalid use of NULL pointer
| inside call to `std::ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:39:14 | inside call to `std::ptr::const_ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:39:14
| |
::: $DIR/offset_from_ub.rs:36:1 ::: $DIR/offset_from_ub.rs:36:1
| |
@ -76,13 +76,13 @@ LL | | };
| |__- | |__-
error: any use of this value will cause an error error: any use of this value will cause an error
--> $SRC_DIR/libcore/ptr/mod.rs:LL:COL --> $SRC_DIR/libcore/ptr/const_ptr.rs:LL:COL
| |
LL | intrinsics::ptr_offset_from(self, origin) LL | intrinsics::ptr_offset_from(self, origin)
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
| | | |
| a memory access tried to interpret some bytes as a pointer | a memory access tried to interpret some bytes as a pointer
| inside call to `std::ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:46:14 | inside call to `std::ptr::const_ptr::<impl *const u8>::offset_from` at $DIR/offset_from_ub.rs:46:14
| |
::: $DIR/offset_from_ub.rs:42:1 ::: $DIR/offset_from_ub.rs:42:1
| |