1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 // FIXME: talk about offset, copy_memory, copy_nonoverlapping_memory
13 //! Raw, unsafe pointers, `*const T`, and `*mut T`.
15 //! *[See also the pointer primitive types](../../std/primitive.pointer.html).*
17 #![stable(feature = "rust1", since = "1.0.0")]
20 use ops::{CoerceUnsized, Deref};
23 use marker::{PhantomData, Unsize};
27 use cmp::Ordering::{self, Less, Equal, Greater};
29 // FIXME #19649: intrinsic docs don't render, so these have no docs :(
31 #[stable(feature = "rust1", since = "1.0.0")]
32 pub use intrinsics::copy_nonoverlapping;
34 #[stable(feature = "rust1", since = "1.0.0")]
35 pub use intrinsics::copy;
37 #[stable(feature = "rust1", since = "1.0.0")]
38 pub use intrinsics::write_bytes;
41 #[stable(feature = "drop_in_place", since = "1.8.0")]
42 pub use intrinsics::drop_in_place;
45 /// Executes the destructor (if any) of the pointed-to value.
47 /// This has two use cases:
49 /// * It is *required* to use `drop_in_place` to drop unsized types like
50 /// trait objects, because they can't be read out onto the stack and
53 /// * It is friendlier to the optimizer to do this over `ptr::read` when
54 /// dropping manually allocated memory (e.g. when writing Box/Rc/Vec),
55 /// as the compiler doesn't need to prove that it's sound to elide the
58 /// # Undefined Behavior
60 /// This has all the same safety problems as `ptr::read` with respect to
61 /// invalid pointers, types, and double drops.
62 #[stable(feature = "drop_in_place", since = "1.8.0")]
63 #[lang="drop_in_place"]
65 #[allow(unconditional_recursion)]
66 pub unsafe fn drop_in_place<T: ?Sized>(to_drop: *mut T) {
67 // Code here does not matter - this is replaced by the
68 // real drop glue by the compiler.
69 drop_in_place(to_drop);
72 /// Creates a null raw pointer.
79 /// let p: *const i32 = ptr::null();
80 /// assert!(p.is_null());
83 #[stable(feature = "rust1", since = "1.0.0")]
84 pub const fn null<T>() -> *const T { 0 as *const T }
86 /// Creates a null mutable raw pointer.
93 /// let p: *mut i32 = ptr::null_mut();
94 /// assert!(p.is_null());
97 #[stable(feature = "rust1", since = "1.0.0")]
98 pub const fn null_mut<T>() -> *mut T { 0 as *mut T }
100 /// Swaps the values at two mutable locations of the same type, without
101 /// deinitializing either. They may overlap, unlike `mem::swap` which is
102 /// otherwise equivalent.
106 /// This function copies the memory through the raw pointers passed to it
109 /// Ensure that these pointers are valid before calling `swap`.
111 #[stable(feature = "rust1", since = "1.0.0")]
112 pub unsafe fn swap<T>(x: *mut T, y: *mut T) {
113 // Give ourselves some scratch space to work with
114 let mut tmp: T = mem::uninitialized();
117 copy_nonoverlapping(x, &mut tmp, 1);
118 copy(y, x, 1); // `x` and `y` may overlap
119 copy_nonoverlapping(&tmp, y, 1);
121 // y and t now point to the same thing, but we need to completely forget `tmp`
122 // because it's no longer relevant.
126 /// Replaces the value at `dest` with `src`, returning the old
127 /// value, without dropping either.
131 /// This is only unsafe because it accepts a raw pointer.
132 /// Otherwise, this operation is identical to `mem::replace`.
134 #[stable(feature = "rust1", since = "1.0.0")]
135 pub unsafe fn replace<T>(dest: *mut T, mut src: T) -> T {
136 mem::swap(&mut *dest, &mut src); // cannot overlap
140 /// Reads the value from `src` without moving it. This leaves the
141 /// memory in `src` unchanged.
145 /// Beyond accepting a raw pointer, this is unsafe because it semantically
146 /// moves the value out of `src` without preventing further usage of `src`.
147 /// If `T` is not `Copy`, then care must be taken to ensure that the value at
148 /// `src` is not used before the data is overwritten again (e.g. with `write`,
149 /// `zero_memory`, or `copy_memory`). Note that `*src = foo` counts as a use
150 /// because it will attempt to drop the value previously at `*src`.
152 /// The pointer must be aligned; use `read_unaligned` if that is not the case.
160 /// let y = &x as *const i32;
163 /// assert_eq!(std::ptr::read(y), 12);
167 #[stable(feature = "rust1", since = "1.0.0")]
168 pub unsafe fn read<T>(src: *const T) -> T {
169 let mut tmp: T = mem::uninitialized();
170 copy_nonoverlapping(src, &mut tmp, 1);
174 /// Reads the value from `src` without moving it. This leaves the
175 /// memory in `src` unchanged.
177 /// Unlike `read`, the pointer may be unaligned.
181 /// Beyond accepting a raw pointer, this is unsafe because it semantically
182 /// moves the value out of `src` without preventing further usage of `src`.
183 /// If `T` is not `Copy`, then care must be taken to ensure that the value at
184 /// `src` is not used before the data is overwritten again (e.g. with `write`,
185 /// `zero_memory`, or `copy_memory`). Note that `*src = foo` counts as a use
186 /// because it will attempt to drop the value previously at `*src`.
194 /// let y = &x as *const i32;
197 /// assert_eq!(std::ptr::read_unaligned(y), 12);
201 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
202 pub unsafe fn read_unaligned<T>(src: *const T) -> T {
203 let mut tmp: T = mem::uninitialized();
204 copy_nonoverlapping(src as *const u8,
205 &mut tmp as *mut T as *mut u8,
206 mem::size_of::<T>());
210 /// Overwrites a memory location with the given value without reading or
211 /// dropping the old value.
215 /// This operation is marked unsafe because it accepts a raw pointer.
217 /// It does not drop the contents of `dst`. This is safe, but it could leak
218 /// allocations or resources, so care must be taken not to overwrite an object
219 /// that should be dropped.
221 /// Additionally, it does not drop `src`. Semantically, `src` is moved into the
222 /// location pointed to by `dst`.
224 /// This is appropriate for initializing uninitialized memory, or overwriting
225 /// memory that has previously been `read` from.
227 /// The pointer must be aligned; use `write_unaligned` if that is not the case.
235 /// let y = &mut x as *mut i32;
239 /// std::ptr::write(y, z);
240 /// assert_eq!(std::ptr::read(y), 12);
244 #[stable(feature = "rust1", since = "1.0.0")]
245 pub unsafe fn write<T>(dst: *mut T, src: T) {
246 intrinsics::move_val_init(&mut *dst, src)
249 /// Overwrites a memory location with the given value without reading or
250 /// dropping the old value.
252 /// Unlike `write`, the pointer may be unaligned.
256 /// This operation is marked unsafe because it accepts a raw pointer.
258 /// It does not drop the contents of `dst`. This is safe, but it could leak
259 /// allocations or resources, so care must be taken not to overwrite an object
260 /// that should be dropped.
262 /// Additionally, it does not drop `src`. Semantically, `src` is moved into the
263 /// location pointed to by `dst`.
265 /// This is appropriate for initializing uninitialized memory, or overwriting
266 /// memory that has previously been `read` from.
274 /// let y = &mut x as *mut i32;
278 /// std::ptr::write_unaligned(y, z);
279 /// assert_eq!(std::ptr::read_unaligned(y), 12);
283 #[stable(feature = "ptr_unaligned", since = "1.17.0")]
284 pub unsafe fn write_unaligned<T>(dst: *mut T, src: T) {
285 copy_nonoverlapping(&src as *const T as *const u8,
287 mem::size_of::<T>());
291 /// Performs a volatile read of the value from `src` without moving it. This
292 /// leaves the memory in `src` unchanged.
294 /// Volatile operations are intended to act on I/O memory, and are guaranteed
295 /// to not be elided or reordered by the compiler across other volatile
300 /// Rust does not currently have a rigorously and formally defined memory model,
301 /// so the precise semantics of what "volatile" means here is subject to change
302 /// over time. That being said, the semantics will almost always end up pretty
303 /// similar to [C11's definition of volatile][c11].
305 /// [c11]: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
309 /// Beyond accepting a raw pointer, this is unsafe because it semantically
310 /// moves the value out of `src` without preventing further usage of `src`.
311 /// If `T` is not `Copy`, then care must be taken to ensure that the value at
312 /// `src` is not used before the data is overwritten again (e.g. with `write`,
313 /// `zero_memory`, or `copy_memory`). Note that `*src = foo` counts as a use
314 /// because it will attempt to drop the value previously at `*src`.
322 /// let y = &x as *const i32;
325 /// assert_eq!(std::ptr::read_volatile(y), 12);
329 #[stable(feature = "volatile", since = "1.9.0")]
330 pub unsafe fn read_volatile<T>(src: *const T) -> T {
331 intrinsics::volatile_load(src)
334 /// Performs a volatile write of a memory location with the given value without
335 /// reading or dropping the old value.
337 /// Volatile operations are intended to act on I/O memory, and are guaranteed
338 /// to not be elided or reordered by the compiler across other volatile
343 /// Rust does not currently have a rigorously and formally defined memory model,
344 /// so the precise semantics of what "volatile" means here is subject to change
345 /// over time. That being said, the semantics will almost always end up pretty
346 /// similar to [C11's definition of volatile][c11].
348 /// [c11]: http://www.open-std.org/jtc1/sc22/wg14/www/docs/n1570.pdf
352 /// This operation is marked unsafe because it accepts a raw pointer.
354 /// It does not drop the contents of `dst`. This is safe, but it could leak
355 /// allocations or resources, so care must be taken not to overwrite an object
356 /// that should be dropped.
358 /// This is appropriate for initializing uninitialized memory, or overwriting
359 /// memory that has previously been `read` from.
367 /// let y = &mut x as *mut i32;
371 /// std::ptr::write_volatile(y, z);
372 /// assert_eq!(std::ptr::read_volatile(y), 12);
376 #[stable(feature = "volatile", since = "1.9.0")]
377 pub unsafe fn write_volatile<T>(dst: *mut T, src: T) {
378 intrinsics::volatile_store(dst, src);
381 #[lang = "const_ptr"]
382 impl<T: ?Sized> *const T {
383 /// Returns `true` if the pointer is null.
390 /// let s: &str = "Follow the rabbit";
391 /// let ptr: *const u8 = s.as_ptr();
392 /// assert!(!ptr.is_null());
394 #[stable(feature = "rust1", since = "1.0.0")]
396 pub fn is_null(self) -> bool where T: Sized {
400 /// Returns `None` if the pointer is null, or else returns a reference to
401 /// the value wrapped in `Some`.
405 /// While this method and its mutable counterpart are useful for
406 /// null-safety, it is important to note that this is still an unsafe
407 /// operation because the returned value could be pointing to invalid
410 /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does
411 /// not necessarily reflect the actual lifetime of the data.
418 /// let val: *const u8 = &10u8 as *const u8;
421 /// if let Some(val_back) = val.as_ref() {
422 /// println!("We got back the value: {}!", val_back);
426 #[stable(feature = "ptr_as_ref", since = "1.9.0")]
428 pub unsafe fn as_ref<'a>(self) -> Option<&'a T> where T: Sized {
436 /// Calculates the offset from a pointer. `count` is in units of T; e.g. a
437 /// `count` of 3 represents a pointer offset of `3 * size_of::<T>()` bytes.
441 /// Both the starting and resulting pointer must be either in bounds or one
442 /// byte past the end of an allocated object. If either pointer is out of
443 /// bounds or arithmetic overflow occurs then
444 /// any further use of the returned value will result in undefined behavior.
451 /// let s: &str = "123";
452 /// let ptr: *const u8 = s.as_ptr();
455 /// println!("{}", *ptr.offset(1) as char);
456 /// println!("{}", *ptr.offset(2) as char);
459 #[stable(feature = "rust1", since = "1.0.0")]
461 pub unsafe fn offset(self, count: isize) -> *const T where T: Sized {
462 intrinsics::offset(self, count)
465 /// Calculates the offset from a pointer using wrapping arithmetic.
466 /// `count` is in units of T; e.g. a `count` of 3 represents a pointer
467 /// offset of `3 * size_of::<T>()` bytes.
471 /// The resulting pointer does not need to be in bounds, but it is
472 /// potentially hazardous to dereference (which requires `unsafe`).
474 /// Always use `.offset(count)` instead when possible, because `offset`
475 /// allows the compiler to optimize better.
482 /// // Iterate using a raw pointer in increments of two elements
483 /// let data = [1u8, 2, 3, 4, 5];
484 /// let mut ptr: *const u8 = data.as_ptr();
486 /// let end_rounded_up = ptr.wrapping_offset(6);
488 /// // This loop prints "1, 3, 5, "
489 /// while ptr != end_rounded_up {
491 /// print!("{}, ", *ptr);
493 /// ptr = ptr.wrapping_offset(step);
496 #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")]
498 pub fn wrapping_offset(self, count: isize) -> *const T where T: Sized {
500 intrinsics::arith_offset(self, count)
504 /// Calculates the distance between two pointers. The returned value is in
505 /// units of T: the distance in bytes is divided by `mem::size_of::<T>()`.
507 /// If the address different between the two pointers ia not a multiple of
508 /// `mem::size_of::<T>()` then the result of the division is rounded towards
511 /// This function returns `None` if `T` is a zero-sized typed.
518 /// #![feature(offset_to)]
522 /// let ptr1: *const i32 = &a[1];
523 /// let ptr2: *const i32 = &a[3];
524 /// assert_eq!(ptr1.offset_to(ptr2), Some(2));
525 /// assert_eq!(ptr2.offset_to(ptr1), Some(-2));
526 /// assert_eq!(unsafe { ptr1.offset(2) }, ptr2);
527 /// assert_eq!(unsafe { ptr2.offset(-2) }, ptr1);
530 #[unstable(feature = "offset_to", issue = "0")]
532 pub fn offset_to(self, other: *const T) -> Option<isize> where T: Sized {
533 let size = mem::size_of::<T>();
537 let diff = (other as isize).wrapping_sub(self as isize);
538 Some(diff / size as isize)
544 impl<T: ?Sized> *mut T {
545 /// Returns `true` if the pointer is null.
552 /// let mut s = [1, 2, 3];
553 /// let ptr: *mut u32 = s.as_mut_ptr();
554 /// assert!(!ptr.is_null());
556 #[stable(feature = "rust1", since = "1.0.0")]
558 pub fn is_null(self) -> bool where T: Sized {
562 /// Returns `None` if the pointer is null, or else returns a reference to
563 /// the value wrapped in `Some`.
567 /// While this method and its mutable counterpart are useful for
568 /// null-safety, it is important to note that this is still an unsafe
569 /// operation because the returned value could be pointing to invalid
572 /// Additionally, the lifetime `'a` returned is arbitrarily chosen and does
573 /// not necessarily reflect the actual lifetime of the data.
580 /// let val: *mut u8 = &mut 10u8 as *mut u8;
583 /// if let Some(val_back) = val.as_ref() {
584 /// println!("We got back the value: {}!", val_back);
588 #[stable(feature = "ptr_as_ref", since = "1.9.0")]
590 pub unsafe fn as_ref<'a>(self) -> Option<&'a T> where T: Sized {
598 /// Calculates the offset from a pointer. `count` is in units of T; e.g. a
599 /// `count` of 3 represents a pointer offset of `3 * size_of::<T>()` bytes.
603 /// The offset must be in-bounds of the object, or one-byte-past-the-end.
604 /// Otherwise `offset` invokes Undefined Behavior, regardless of whether
605 /// the pointer is used.
612 /// let mut s = [1, 2, 3];
613 /// let ptr: *mut u32 = s.as_mut_ptr();
616 /// println!("{}", *ptr.offset(1));
617 /// println!("{}", *ptr.offset(2));
620 #[stable(feature = "rust1", since = "1.0.0")]
622 pub unsafe fn offset(self, count: isize) -> *mut T where T: Sized {
623 intrinsics::offset(self, count) as *mut T
626 /// Calculates the offset from a pointer using wrapping arithmetic.
627 /// `count` is in units of T; e.g. a `count` of 3 represents a pointer
628 /// offset of `3 * size_of::<T>()` bytes.
632 /// The resulting pointer does not need to be in bounds, but it is
633 /// potentially hazardous to dereference (which requires `unsafe`).
635 /// Always use `.offset(count)` instead when possible, because `offset`
636 /// allows the compiler to optimize better.
643 /// // Iterate using a raw pointer in increments of two elements
644 /// let mut data = [1u8, 2, 3, 4, 5];
645 /// let mut ptr: *mut u8 = data.as_mut_ptr();
647 /// let end_rounded_up = ptr.wrapping_offset(6);
649 /// while ptr != end_rounded_up {
653 /// ptr = ptr.wrapping_offset(step);
655 /// assert_eq!(&data, &[0, 2, 0, 4, 0]);
657 #[stable(feature = "ptr_wrapping_offset", since = "1.16.0")]
659 pub fn wrapping_offset(self, count: isize) -> *mut T where T: Sized {
661 intrinsics::arith_offset(self, count) as *mut T
665 /// Returns `None` if the pointer is null, or else returns a mutable
666 /// reference to the value wrapped in `Some`.
670 /// As with `as_ref`, this is unsafe because it cannot verify the validity
671 /// of the returned pointer, nor can it ensure that the lifetime `'a`
672 /// returned is indeed a valid lifetime for the contained data.
679 /// let mut s = [1, 2, 3];
680 /// let ptr: *mut u32 = s.as_mut_ptr();
681 /// let first_value = unsafe { ptr.as_mut().unwrap() };
682 /// *first_value = 4;
683 /// println!("{:?}", s); // It'll print: "[4, 2, 3]".
685 #[stable(feature = "ptr_as_ref", since = "1.9.0")]
687 pub unsafe fn as_mut<'a>(self) -> Option<&'a mut T> where T: Sized {
695 /// Calculates the distance between two pointers. The returned value is in
696 /// units of T: the distance in bytes is divided by `mem::size_of::<T>()`.
698 /// If the address different between the two pointers ia not a multiple of
699 /// `mem::size_of::<T>()` then the result of the division is rounded towards
702 /// This function returns `None` if `T` is a zero-sized typed.
709 /// #![feature(offset_to)]
712 /// let mut a = [0; 5];
713 /// let ptr1: *mut i32 = &mut a[1];
714 /// let ptr2: *mut i32 = &mut a[3];
715 /// assert_eq!(ptr1.offset_to(ptr2), Some(2));
716 /// assert_eq!(ptr2.offset_to(ptr1), Some(-2));
717 /// assert_eq!(unsafe { ptr1.offset(2) }, ptr2);
718 /// assert_eq!(unsafe { ptr2.offset(-2) }, ptr1);
721 #[unstable(feature = "offset_to", issue = "0")]
723 pub fn offset_to(self, other: *const T) -> Option<isize> where T: Sized {
724 let size = mem::size_of::<T>();
728 let diff = (other as isize).wrapping_sub(self as isize);
729 Some(diff / size as isize)
734 // Equality for pointers
735 #[stable(feature = "rust1", since = "1.0.0")]
736 impl<T: ?Sized> PartialEq for *const T {
738 fn eq(&self, other: &*const T) -> bool { *self == *other }
741 #[stable(feature = "rust1", since = "1.0.0")]
742 impl<T: ?Sized> Eq for *const T {}
744 #[stable(feature = "rust1", since = "1.0.0")]
745 impl<T: ?Sized> PartialEq for *mut T {
747 fn eq(&self, other: &*mut T) -> bool { *self == *other }
750 #[stable(feature = "rust1", since = "1.0.0")]
751 impl<T: ?Sized> Eq for *mut T {}
753 /// Compare raw pointers for equality.
755 /// This is the same as using the `==` operator, but less generic:
756 /// the arguments have to be `*const T` raw pointers,
757 /// not anything that implements `PartialEq`.
759 /// This can be used to compare `&T` references (which coerce to `*const T` implicitly)
760 /// by their address rather than comparing the values they point to
761 /// (which is what the `PartialEq for &T` implementation does).
769 /// let other_five = 5;
770 /// let five_ref = &five;
771 /// let same_five_ref = &five;
772 /// let other_five_ref = &other_five;
774 /// assert!(five_ref == same_five_ref);
775 /// assert!(five_ref == other_five_ref);
777 /// assert!(ptr::eq(five_ref, same_five_ref));
778 /// assert!(!ptr::eq(five_ref, other_five_ref));
780 #[stable(feature = "ptr_eq", since = "1.17.0")]
782 pub fn eq<T: ?Sized>(a: *const T, b: *const T) -> bool {
786 #[stable(feature = "rust1", since = "1.0.0")]
787 impl<T: ?Sized> Clone for *const T {
789 fn clone(&self) -> *const T {
794 #[stable(feature = "rust1", since = "1.0.0")]
795 impl<T: ?Sized> Clone for *mut T {
797 fn clone(&self) -> *mut T {
802 // Impls for function pointers
803 macro_rules! fnptr_impls_safety_abi {
804 ($FnTy: ty, $($Arg: ident),*) => {
805 #[stable(feature = "rust1", since = "1.0.0")]
806 impl<Ret, $($Arg),*> Clone for $FnTy {
808 fn clone(&self) -> Self {
813 #[stable(feature = "fnptr_impls", since = "1.4.0")]
814 impl<Ret, $($Arg),*> PartialEq for $FnTy {
816 fn eq(&self, other: &Self) -> bool {
817 *self as usize == *other as usize
821 #[stable(feature = "fnptr_impls", since = "1.4.0")]
822 impl<Ret, $($Arg),*> Eq for $FnTy {}
824 #[stable(feature = "fnptr_impls", since = "1.4.0")]
825 impl<Ret, $($Arg),*> PartialOrd for $FnTy {
827 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
828 (*self as usize).partial_cmp(&(*other as usize))
832 #[stable(feature = "fnptr_impls", since = "1.4.0")]
833 impl<Ret, $($Arg),*> Ord for $FnTy {
835 fn cmp(&self, other: &Self) -> Ordering {
836 (*self as usize).cmp(&(*other as usize))
840 #[stable(feature = "fnptr_impls", since = "1.4.0")]
841 impl<Ret, $($Arg),*> hash::Hash for $FnTy {
842 fn hash<HH: hash::Hasher>(&self, state: &mut HH) {
843 state.write_usize(*self as usize)
847 #[stable(feature = "fnptr_impls", since = "1.4.0")]
848 impl<Ret, $($Arg),*> fmt::Pointer for $FnTy {
849 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
850 fmt::Pointer::fmt(&(*self as *const ()), f)
854 #[stable(feature = "fnptr_impls", since = "1.4.0")]
855 impl<Ret, $($Arg),*> fmt::Debug for $FnTy {
856 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
857 fmt::Pointer::fmt(&(*self as *const ()), f)
863 macro_rules! fnptr_impls_args {
864 ($($Arg: ident),+) => {
865 fnptr_impls_safety_abi! { extern "Rust" fn($($Arg),*) -> Ret, $($Arg),* }
866 fnptr_impls_safety_abi! { extern "C" fn($($Arg),*) -> Ret, $($Arg),* }
867 fnptr_impls_safety_abi! { extern "C" fn($($Arg),* , ...) -> Ret, $($Arg),* }
868 fnptr_impls_safety_abi! { unsafe extern "Rust" fn($($Arg),*) -> Ret, $($Arg),* }
869 fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),*) -> Ret, $($Arg),* }
870 fnptr_impls_safety_abi! { unsafe extern "C" fn($($Arg),* , ...) -> Ret, $($Arg),* }
873 // No variadic functions with 0 parameters
874 fnptr_impls_safety_abi! { extern "Rust" fn() -> Ret, }
875 fnptr_impls_safety_abi! { extern "C" fn() -> Ret, }
876 fnptr_impls_safety_abi! { unsafe extern "Rust" fn() -> Ret, }
877 fnptr_impls_safety_abi! { unsafe extern "C" fn() -> Ret, }
881 fnptr_impls_args! { }
882 fnptr_impls_args! { A }
883 fnptr_impls_args! { A, B }
884 fnptr_impls_args! { A, B, C }
885 fnptr_impls_args! { A, B, C, D }
886 fnptr_impls_args! { A, B, C, D, E }
887 fnptr_impls_args! { A, B, C, D, E, F }
888 fnptr_impls_args! { A, B, C, D, E, F, G }
889 fnptr_impls_args! { A, B, C, D, E, F, G, H }
890 fnptr_impls_args! { A, B, C, D, E, F, G, H, I }
891 fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J }
892 fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K }
893 fnptr_impls_args! { A, B, C, D, E, F, G, H, I, J, K, L }
895 // Comparison for pointers
896 #[stable(feature = "rust1", since = "1.0.0")]
897 impl<T: ?Sized> Ord for *const T {
899 fn cmp(&self, other: &*const T) -> Ordering {
902 } else if self == other {
910 #[stable(feature = "rust1", since = "1.0.0")]
911 impl<T: ?Sized> PartialOrd for *const T {
913 fn partial_cmp(&self, other: &*const T) -> Option<Ordering> {
914 Some(self.cmp(other))
918 fn lt(&self, other: &*const T) -> bool { *self < *other }
921 fn le(&self, other: &*const T) -> bool { *self <= *other }
924 fn gt(&self, other: &*const T) -> bool { *self > *other }
927 fn ge(&self, other: &*const T) -> bool { *self >= *other }
930 #[stable(feature = "rust1", since = "1.0.0")]
931 impl<T: ?Sized> Ord for *mut T {
933 fn cmp(&self, other: &*mut T) -> Ordering {
936 } else if self == other {
944 #[stable(feature = "rust1", since = "1.0.0")]
945 impl<T: ?Sized> PartialOrd for *mut T {
947 fn partial_cmp(&self, other: &*mut T) -> Option<Ordering> {
948 Some(self.cmp(other))
952 fn lt(&self, other: &*mut T) -> bool { *self < *other }
955 fn le(&self, other: &*mut T) -> bool { *self <= *other }
958 fn gt(&self, other: &*mut T) -> bool { *self > *other }
961 fn ge(&self, other: &*mut T) -> bool { *self >= *other }
964 /// A wrapper around a raw non-null `*mut T` that indicates that the possessor
965 /// of this wrapper owns the referent. This in turn implies that the
966 /// `Unique<T>` is `Send`/`Sync` if `T` is `Send`/`Sync`, unlike a raw
967 /// `*mut T` (which conveys no particular ownership semantics). It
968 /// also implies that the referent of the pointer should not be
969 /// modified without a unique path to the `Unique` reference. Useful
970 /// for building abstractions like `Vec<T>` or `Box<T>`, which
971 /// internally use raw pointers to manage the memory that they own.
972 #[allow(missing_debug_implementations)]
973 #[unstable(feature = "unique", reason = "needs an RFC to flesh out design",
975 pub struct Unique<T: ?Sized> {
976 pointer: NonZero<*const T>,
977 // NOTE: this marker has no consequences for variance, but is necessary
978 // for dropck to understand that we logically own a `T`.
981 // https://github.com/rust-lang/rfcs/blob/master/text/0769-sound-generic-drop.md#phantom-data
982 _marker: PhantomData<T>,
985 /// `Unique` pointers are `Send` if `T` is `Send` because the data they
986 /// reference is unaliased. Note that this aliasing invariant is
987 /// unenforced by the type system; the abstraction using the
988 /// `Unique` must enforce it.
989 #[unstable(feature = "unique", issue = "27730")]
990 unsafe impl<T: Send + ?Sized> Send for Unique<T> { }
992 /// `Unique` pointers are `Sync` if `T` is `Sync` because the data they
993 /// reference is unaliased. Note that this aliasing invariant is
994 /// unenforced by the type system; the abstraction using the
995 /// `Unique` must enforce it.
996 #[unstable(feature = "unique", issue = "27730")]
997 unsafe impl<T: Sync + ?Sized> Sync for Unique<T> { }
999 #[unstable(feature = "unique", issue = "27730")]
1000 impl<T: ?Sized> Unique<T> {
1001 /// Creates a new `Unique`.
1005 /// `ptr` must be non-null.
1006 pub const unsafe fn new(ptr: *mut T) -> Unique<T> {
1007 Unique { pointer: NonZero::new(ptr), _marker: PhantomData }
1010 /// Dereferences the content.
1011 pub unsafe fn get(&self) -> &T {
1015 /// Mutably dereferences the content.
1016 pub unsafe fn get_mut(&mut self) -> &mut T {
1021 #[unstable(feature = "unique", issue = "27730")]
1022 impl<T: ?Sized, U: ?Sized> CoerceUnsized<Unique<U>> for Unique<T> where T: Unsize<U> { }
1024 #[unstable(feature = "unique", issue= "27730")]
1025 impl<T:?Sized> Deref for Unique<T> {
1026 type Target = *mut T;
1029 fn deref(&self) -> &*mut T {
1030 unsafe { mem::transmute(&*self.pointer) }
1034 #[unstable(feature = "unique", issue = "27730")]
1035 impl<T> fmt::Pointer for Unique<T> {
1036 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1037 fmt::Pointer::fmt(&*self.pointer, f)
1041 /// A wrapper around a raw non-null `*mut T` that indicates that the possessor
1042 /// of this wrapper has shared ownership of the referent. Useful for
1043 /// building abstractions like `Rc<T>` or `Arc<T>`, which internally
1044 /// use raw pointers to manage the memory that they own.
1045 #[allow(missing_debug_implementations)]
1046 #[unstable(feature = "shared", reason = "needs an RFC to flesh out design",
1048 pub struct Shared<T: ?Sized> {
1049 pointer: NonZero<*const T>,
1050 // NOTE: this marker has no consequences for variance, but is necessary
1051 // for dropck to understand that we logically own a `T`.
1053 // For details, see:
1054 // https://github.com/rust-lang/rfcs/blob/master/text/0769-sound-generic-drop.md#phantom-data
1055 _marker: PhantomData<T>,
1058 /// `Shared` pointers are not `Send` because the data they reference may be aliased.
1059 // NB: This impl is unnecessary, but should provide better error messages.
1060 #[unstable(feature = "shared", issue = "27730")]
1061 impl<T: ?Sized> !Send for Shared<T> { }
1063 /// `Shared` pointers are not `Sync` because the data they reference may be aliased.
1064 // NB: This impl is unnecessary, but should provide better error messages.
1065 #[unstable(feature = "shared", issue = "27730")]
1066 impl<T: ?Sized> !Sync for Shared<T> { }
1068 #[unstable(feature = "shared", issue = "27730")]
1069 impl<T: ?Sized> Shared<T> {
1070 /// Creates a new `Shared`.
1074 /// `ptr` must be non-null.
1075 pub unsafe fn new(ptr: *const T) -> Self {
1076 Shared { pointer: NonZero::new(ptr), _marker: PhantomData }
1080 #[unstable(feature = "shared", issue = "27730")]
1081 impl<T: ?Sized> Shared<T> {
1082 /// Acquires the underlying pointer as a `*mut` pointer.
1083 pub unsafe fn as_mut_ptr(&self) -> *mut T {
1088 #[unstable(feature = "shared", issue = "27730")]
1089 impl<T: ?Sized> Clone for Shared<T> {
1090 fn clone(&self) -> Self {
1095 #[unstable(feature = "shared", issue = "27730")]
1096 impl<T: ?Sized> Copy for Shared<T> { }
1098 #[unstable(feature = "shared", issue = "27730")]
1099 impl<T: ?Sized, U: ?Sized> CoerceUnsized<Shared<U>> for Shared<T> where T: Unsize<U> { }
1101 #[unstable(feature = "shared", issue = "27730")]
1102 impl<T: ?Sized> Deref for Shared<T> {
1103 type Target = *const T;
1106 fn deref(&self) -> &*const T {
1107 unsafe { mem::transmute(&*self.pointer) }
1111 #[unstable(feature = "shared", issue = "27730")]
1112 impl<T> fmt::Pointer for Shared<T> {
1113 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
1114 fmt::Pointer::fmt(&*self.pointer, f)