1 use core::cell::RefCell;
2 use core::mem::{self, MaybeUninit};
3 use core::num::NonZeroUsize;
6 use std::fmt::{Debug, Display};
9 fn test_const_from_raw_parts() {
10 const SLICE: &[u8] = &[1, 2, 3, 4];
11 const FROM_RAW: &[u8] = unsafe { &*slice_from_raw_parts(SLICE.as_ptr(), SLICE.len()) };
12 assert_eq!(SLICE, FROM_RAW);
14 let slice = &[1, 2, 3, 4, 5];
15 let from_raw = unsafe { &*slice_from_raw_parts(slice.as_ptr(), 2) };
16 assert_eq!(&slice[..2], from_raw);
27 let mut p = Pair { fst: 10, snd: 20 };
28 let pptr: *mut Pair = &mut p;
29 let iptr: *mut isize = pptr as *mut isize;
30 assert_eq!(*iptr, 10);
32 assert_eq!(*iptr, 30);
33 assert_eq!(p.fst, 30);
35 *pptr = Pair { fst: 50, snd: 60 };
36 assert_eq!(*iptr, 50);
37 assert_eq!(p.fst, 50);
38 assert_eq!(p.snd, 60);
40 let v0 = vec![32000u16, 32001u16, 32002u16];
41 let mut v1 = vec![0u16, 0u16, 0u16];
43 copy(v0.as_ptr().offset(1), v1.as_mut_ptr().offset(1), 1);
44 assert!((v1[0] == 0u16 && v1[1] == 32001u16 && v1[2] == 0u16));
45 copy(v0.as_ptr().offset(2), v1.as_mut_ptr(), 1);
46 assert!((v1[0] == 32002u16 && v1[1] == 32001u16 && v1[2] == 0u16));
47 copy(v0.as_ptr(), v1.as_mut_ptr().offset(2), 1);
48 assert!((v1[0] == 32002u16 && v1[1] == 32001u16 && v1[2] == 32000u16));
54 let p: *const isize = null();
57 let q = p.wrapping_offset(1);
58 assert!(!q.is_null());
60 let mp: *mut isize = null_mut();
61 assert!(mp.is_null());
63 let mq = mp.wrapping_offset(1);
64 assert!(!mq.is_null());
66 // Pointers to unsized types -- slices
67 let s: &mut [u8] = &mut [1, 2, 3];
68 let cs: *const [u8] = s;
69 assert!(!cs.is_null());
71 let ms: *mut [u8] = s;
72 assert!(!ms.is_null());
74 let cz: *const [u8] = &[];
75 assert!(!cz.is_null());
77 let mz: *mut [u8] = &mut [];
78 assert!(!mz.is_null());
80 let ncs: *const [u8] = null::<[u8; 3]>();
81 assert!(ncs.is_null());
83 let nms: *mut [u8] = null_mut::<[u8; 3]>();
84 assert!(nms.is_null());
86 // Pointers to unsized types -- trait objects
87 let ci: *const dyn ToString = &3;
88 assert!(!ci.is_null());
90 let mi: *mut dyn ToString = &mut 3;
91 assert!(!mi.is_null());
93 let nci: *const dyn ToString = null::<isize>();
94 assert!(nci.is_null());
96 let nmi: *mut dyn ToString = null_mut::<isize>();
97 assert!(nmi.is_null());
102 let ec: *const Extern = null::<Extern>();
103 assert!(ec.is_null());
105 let em: *mut Extern = null_mut::<Extern>();
106 assert!(em.is_null());
112 let p: *const isize = null();
113 assert_eq!(p.as_ref(), None);
115 let q: *const isize = &2;
116 assert_eq!(q.as_ref().unwrap(), &2);
118 let p: *mut isize = null_mut();
119 assert_eq!(p.as_ref(), None);
121 let q: *mut isize = &mut 2;
122 assert_eq!(q.as_ref().unwrap(), &2);
124 // Lifetime inference
127 let p = &u as *const isize;
128 assert_eq!(p.as_ref().unwrap(), &2);
131 // Pointers to unsized types -- slices
132 let s: &mut [u8] = &mut [1, 2, 3];
133 let cs: *const [u8] = s;
134 assert_eq!(cs.as_ref(), Some(&*s));
136 let ms: *mut [u8] = s;
137 assert_eq!(ms.as_ref(), Some(&*s));
139 let cz: *const [u8] = &[];
140 assert_eq!(cz.as_ref(), Some(&[][..]));
142 let mz: *mut [u8] = &mut [];
143 assert_eq!(mz.as_ref(), Some(&[][..]));
145 let ncs: *const [u8] = null::<[u8; 3]>();
146 assert_eq!(ncs.as_ref(), None);
148 let nms: *mut [u8] = null_mut::<[u8; 3]>();
149 assert_eq!(nms.as_ref(), None);
151 // Pointers to unsized types -- trait objects
152 let ci: *const dyn ToString = &3;
153 assert!(ci.as_ref().is_some());
155 let mi: *mut dyn ToString = &mut 3;
156 assert!(mi.as_ref().is_some());
158 let nci: *const dyn ToString = null::<isize>();
159 assert!(nci.as_ref().is_none());
161 let nmi: *mut dyn ToString = null_mut::<isize>();
162 assert!(nmi.as_ref().is_none());
169 let p: *mut isize = null_mut();
170 assert!(p.as_mut() == None);
172 let q: *mut isize = &mut 2;
173 assert!(q.as_mut().unwrap() == &mut 2);
175 // Lifetime inference
178 let p = &mut u as *mut isize;
179 assert!(p.as_mut().unwrap() == &mut 2);
182 // Pointers to unsized types -- slices
183 let s: &mut [u8] = &mut [1, 2, 3];
184 let ms: *mut [u8] = s;
185 assert_eq!(ms.as_mut(), Some(&mut [1, 2, 3][..]));
187 let mz: *mut [u8] = &mut [];
188 assert_eq!(mz.as_mut(), Some(&mut [][..]));
190 let nms: *mut [u8] = null_mut::<[u8; 3]>();
191 assert_eq!(nms.as_mut(), None);
193 // Pointers to unsized types -- trait objects
194 let mi: *mut dyn ToString = &mut 3;
195 assert!(mi.as_mut().is_some());
197 let nmi: *mut dyn ToString = null_mut::<isize>();
198 assert!(nmi.as_mut().is_none());
203 fn test_ptr_addition() {
205 let xs = vec![5; 16];
206 let mut ptr = xs.as_ptr();
207 let end = ptr.offset(16);
215 let mut m_ptr = xs_mut.as_mut_ptr();
216 let m_end = m_ptr.offset(16);
218 while m_ptr < m_end {
220 m_ptr = m_ptr.offset(1);
223 assert!(xs_mut == vec![10; 16]);
228 fn test_ptr_subtraction() {
230 let xs = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
232 let ptr = xs.as_ptr();
235 assert_eq!(*(ptr.offset(idx as isize)), idx as isize);
240 let m_start = xs_mut.as_mut_ptr();
241 let mut m_ptr = m_start.offset(9);
245 if m_ptr == m_start {
248 m_ptr = m_ptr.offset(-1);
251 assert_eq!(xs_mut, [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]);
256 fn test_set_memory() {
257 let mut xs = [0u8; 20];
258 let ptr = xs.as_mut_ptr();
260 write_bytes(ptr, 5u8, xs.len());
262 assert!(xs == [5u8; 20]);
266 fn test_set_memory_const() {
267 const XS: [u8; 20] = {
268 let mut xs = [0u8; 20];
269 let ptr = xs.as_mut_ptr();
271 ptr.write_bytes(5u8, xs.len());
276 assert!(XS == [5u8; 20]);
280 fn test_unsized_nonnull() {
281 let xs: &[i32] = &[1, 2, 3];
282 let ptr = unsafe { NonNull::new_unchecked(xs as *const [i32] as *mut [i32]) };
283 let ys = unsafe { ptr.as_ref() };
284 let zs: &[i32] = &[1, 2, 3];
289 fn test_const_nonnull_new() {
291 assert!(NonNull::new(core::ptr::null_mut::<()>()).is_none());
293 let value = &mut 0u32;
294 let mut ptr = NonNull::new(value).unwrap();
295 unsafe { *ptr.as_mut() = 42 };
297 let reference = unsafe { &*ptr.as_ref() };
298 assert!(*reference == *value);
299 assert!(*reference == 42);
304 #[cfg(unix)] // printf may not be available on other platforms
305 #[allow(deprecated)] // For SipHasher
306 pub fn test_variadic_fnptr() {
308 use core::hash::{Hash, SipHasher};
310 // This needs to use the correct function signature even though it isn't called as some
311 // codegen backends make it UB to declare a function with multiple conflicting signatures
312 // (like LLVM) while others straight up return an error (like Cranelift).
313 fn printf(_: *const ffi::c_char, ...) -> ffi::c_int;
315 let p: unsafe extern "C" fn(*const ffi::c_char, ...) -> ffi::c_int = printf;
319 let mut s = SipHasher::new();
320 assert_eq!(p.hash(&mut s), q.hash(&mut s));
324 fn write_unaligned_drop() {
326 static DROPS: RefCell<Vec<u32>> = RefCell::new(Vec::new());
331 impl Drop for Dropper {
333 DROPS.with(|d| d.borrow_mut().push(self.0));
339 let mut t = Dropper(1);
341 write_unaligned(&mut t, c);
344 DROPS.with(|d| assert_eq!(*d.borrow(), [0]));
348 fn align_offset_zst() {
349 // For pointers of stride = 0, the pointer is already aligned or it cannot be aligned at
350 // all, because no amount of elements will align the pointer.
353 assert_eq!(ptr::invalid::<()>(p).align_offset(p), 0);
355 assert_eq!(ptr::invalid::<()>(p + 1).align_offset(p), !0);
357 p = (p + 1).next_power_of_two();
362 fn align_offset_stride1() {
363 // For pointers of stride = 1, the pointer can always be aligned. The offset is equal to
367 for ptr in 1..2 * align {
368 let expected = ptr % align;
369 let offset = if expected == 0 { 0 } else { align - expected };
371 ptr::invalid::<u8>(ptr).align_offset(align),
373 "ptr = {}, align = {}, size = 1",
378 align = (align + 1).next_power_of_two();
383 fn align_offset_weird_strides() {
392 struct A7(u32, u16, u8);
396 struct A9(u32, u32, u8);
398 struct A10(u32, u32, u16);
400 unsafe fn test_weird_stride<T>(ptr: *const T, align: usize) -> bool {
401 let numptr = ptr as usize;
402 let mut expected = usize::MAX;
403 // Naive but definitely correct way to find the *first* aligned element of stride::<T>.
405 if (numptr + el * ::std::mem::size_of::<T>()) % align == 0 {
410 let got = ptr.align_offset(align);
413 "aligning {:p} (with stride of {}) to {}, expected {}, got {}",
415 ::std::mem::size_of::<T>(),
425 // For pointers of stride != 1, we verify the algorithm against the naivest possible
430 let limit = if cfg!(miri) { 32 } else { 1024 };
431 while align < limit {
432 for ptr in 1usize..4 * align {
434 x |= test_weird_stride::<A3>(ptr::invalid::<A3>(ptr), align);
435 x |= test_weird_stride::<A4>(ptr::invalid::<A4>(ptr), align);
436 x |= test_weird_stride::<A5>(ptr::invalid::<A5>(ptr), align);
437 x |= test_weird_stride::<A6>(ptr::invalid::<A6>(ptr), align);
438 x |= test_weird_stride::<A7>(ptr::invalid::<A7>(ptr), align);
439 x |= test_weird_stride::<A8>(ptr::invalid::<A8>(ptr), align);
440 x |= test_weird_stride::<A9>(ptr::invalid::<A9>(ptr), align);
441 x |= test_weird_stride::<A10>(ptr::invalid::<A10>(ptr), align);
444 align = (align + 1).next_power_of_two();
452 let ptr1: *mut i32 = &mut a[1];
453 let ptr2: *mut i32 = &mut a[3];
455 assert_eq!(ptr2.offset_from(ptr1), 2);
456 assert_eq!(ptr1.offset_from(ptr2), -2);
457 assert_eq!(ptr1.offset(2), ptr2);
458 assert_eq!(ptr2.offset(-2), ptr1);
465 struct Pair<A, B: ?Sized>(A, B);
469 let () = metadata(&());
470 let () = metadata(&Unit);
471 let () = metadata(&4_u32);
472 let () = metadata(&String::new());
473 let () = metadata(&Some(4_u32));
474 let () = metadata(&ptr_metadata);
475 let () = metadata(&|| {});
476 let () = metadata(&[4, 7]);
477 let () = metadata(&(4, String::new()));
478 let () = metadata(&Pair(4, String::new()));
479 let () = metadata(ptr::null::<()>() as *const Extern);
480 let () = metadata(ptr::null::<()>() as *const <&u32 as std::ops::Deref>::Target);
482 assert_eq!(metadata("foo"), 3_usize);
483 assert_eq!(metadata(&[4, 7][..]), 2_usize);
485 let dst_tuple: &(bool, [u8]) = &(true, [0x66, 0x6F, 0x6F]);
486 let dst_struct: &Pair<bool, [u8]> = &Pair(true, [0x66, 0x6F, 0x6F]);
487 assert_eq!(metadata(dst_tuple), 3_usize);
488 assert_eq!(metadata(dst_struct), 3_usize);
490 let dst_tuple: &(bool, str) = std::mem::transmute(dst_tuple);
491 let dst_struct: &Pair<bool, str> = std::mem::transmute(dst_struct);
492 assert_eq!(&dst_tuple.1, "foo");
493 assert_eq!(&dst_struct.1, "foo");
494 assert_eq!(metadata(dst_tuple), 3_usize);
495 assert_eq!(metadata(dst_struct), 3_usize);
498 let vtable_1: DynMetadata<dyn Debug> = metadata(&4_u16 as &dyn Debug);
499 let vtable_2: DynMetadata<dyn Display> = metadata(&4_u16 as &dyn Display);
500 let vtable_3: DynMetadata<dyn Display> = metadata(&4_u32 as &dyn Display);
501 let vtable_4: DynMetadata<dyn Display> = metadata(&(true, 7_u32) as &(bool, dyn Display));
502 let vtable_5: DynMetadata<dyn Display> =
503 metadata(&Pair(true, 7_u32) as &Pair<bool, dyn Display>);
505 let address_1: *const () = std::mem::transmute(vtable_1);
506 let address_2: *const () = std::mem::transmute(vtable_2);
507 let address_3: *const () = std::mem::transmute(vtable_3);
508 let address_4: *const () = std::mem::transmute(vtable_4);
509 let address_5: *const () = std::mem::transmute(vtable_5);
510 // Different trait => different vtable pointer
511 assert_ne!(address_1, address_2);
512 // Different erased type => different vtable pointer
513 assert_ne!(address_2, address_3);
514 // Same erased type and same trait => same vtable pointer
515 assert_eq!(address_3, address_4);
516 assert_eq!(address_3, address_5);
521 fn ptr_metadata_bounds() {
522 fn metadata_eq_method_address<T: ?Sized>() -> usize {
523 // The `Metadata` associated type has an `Ord` bound, so this is valid:
524 <<T as Pointee>::Metadata as PartialEq>::eq as usize
526 // "Synthetic" trait impls generated by the compiler like those of `Pointee`
527 // are not checked for bounds of associated type.
528 // So with a buggy libcore we could have both:
529 // * `<dyn Display as Pointee>::Metadata == DynMetadata`
530 // * `DynMetadata: !PartialEq`
531 // … and cause an ICE here:
532 metadata_eq_method_address::<dyn Display>();
534 // For this reason, let’s check here that bounds are satisfied:
536 let _ = static_assert_expected_bounds_for_metadata::<()>;
537 let _ = static_assert_expected_bounds_for_metadata::<usize>;
538 let _ = static_assert_expected_bounds_for_metadata::<DynMetadata<dyn Display>>;
539 fn _static_assert_associated_type<T: ?Sized>() {
540 let _ = static_assert_expected_bounds_for_metadata::<<T as Pointee>::Metadata>;
543 fn static_assert_expected_bounds_for_metadata<Meta>()
545 // Keep this in sync with the associated type in `library/core/src/ptr/metadata.rs`
546 Meta: Copy + Send + Sync + Ord + std::hash::Hash + Unpin,
555 struct Something([u8; 47]);
557 let value = Something([0; 47]);
558 let trait_object: &dyn Debug = &value;
559 let meta = metadata(trait_object);
561 assert_eq!(meta.size_of(), 64);
562 assert_eq!(meta.size_of(), std::mem::size_of::<Something>());
563 assert_eq!(meta.align_of(), 32);
564 assert_eq!(meta.align_of(), std::mem::align_of::<Something>());
565 assert_eq!(meta.layout(), std::alloc::Layout::new::<Something>());
567 assert!(format!("{meta:?}").starts_with("DynMetadata(0x"));
571 fn from_raw_parts() {
572 let mut value = 5_u32;
573 let address = &mut value as *mut _ as *mut ();
574 let trait_object: &dyn Display = &mut value;
575 let vtable = metadata(trait_object);
576 let trait_object = NonNull::from(trait_object);
578 assert_eq!(ptr::from_raw_parts(address, vtable), trait_object.as_ptr());
579 assert_eq!(ptr::from_raw_parts_mut(address, vtable), trait_object.as_ptr());
580 assert_eq!(NonNull::from_raw_parts(NonNull::new(address).unwrap(), vtable), trait_object);
582 let mut array = [5_u32, 5, 5, 5, 5];
583 let address = &mut array as *mut _ as *mut ();
584 let array_ptr = NonNull::from(&mut array);
585 let slice_ptr = NonNull::from(&mut array[..]);
587 assert_eq!(ptr::from_raw_parts(address, ()), array_ptr.as_ptr());
588 assert_eq!(ptr::from_raw_parts_mut(address, ()), array_ptr.as_ptr());
589 assert_eq!(NonNull::from_raw_parts(NonNull::new(address).unwrap(), ()), array_ptr);
591 assert_eq!(ptr::from_raw_parts(address, 5), slice_ptr.as_ptr());
592 assert_eq!(ptr::from_raw_parts_mut(address, 5), slice_ptr.as_ptr());
593 assert_eq!(NonNull::from_raw_parts(NonNull::new(address).unwrap(), 5), slice_ptr);
598 let foo = ThinBox::<dyn Display>::new(4);
599 assert_eq!(foo.to_string(), "4");
601 let bar = ThinBox::<dyn Display>::new(7);
602 assert_eq!(bar.to_string(), "7");
604 // A slightly more interesting library that could be built on top of metadata APIs.
606 // * It could be generalized to any `T: ?Sized` (not just trait object)
607 // if `{size,align}_of_for_meta<T: ?Sized>(T::Metadata)` are added.
608 // * Constructing a `ThinBox` without consuming and deallocating a `Box`
609 // requires either the unstable `Unsize` marker trait,
610 // or the unstable `unsized_locals` language feature,
611 // or taking `&dyn T` and restricting to `T: Copy`.
614 use std::marker::PhantomData;
618 T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
620 ptr: NonNull<DynMetadata<T>>,
621 phantom: PhantomData<T>,
626 T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
628 pub fn new<Value: std::marker::Unsize<T>>(value: Value) -> Self {
629 let unsized_: &T = &value;
630 let meta = metadata(unsized_);
631 let meta_layout = Layout::for_value(&meta);
632 let value_layout = Layout::for_value(&value);
633 let (layout, offset) = meta_layout.extend(value_layout).unwrap();
634 // `DynMetadata` is pointer-sized:
635 assert!(layout.size() > 0);
636 // If `ThinBox<T>` is generalized to any `T: ?Sized`,
637 // handle ZSTs with a dangling pointer without going through `alloc()`,
638 // like `Box<T>` does.
640 let ptr = NonNull::new(alloc(layout))
641 .unwrap_or_else(|| handle_alloc_error(layout))
642 .cast::<DynMetadata<T>>();
643 ptr.as_ptr().write(meta);
644 ptr.cast::<u8>().as_ptr().add(offset).cast::<Value>().write(value);
645 Self { ptr, phantom: PhantomData }
649 fn meta(&self) -> DynMetadata<T> {
650 unsafe { *self.ptr.as_ref() }
653 fn layout(&self) -> (Layout, usize) {
654 let meta = self.meta();
655 Layout::for_value(&meta).extend(meta.layout()).unwrap()
658 fn value_ptr(&self) -> *const T {
659 let (_, offset) = self.layout();
660 let data_ptr = unsafe { self.ptr.cast::<u8>().as_ptr().add(offset) };
661 ptr::from_raw_parts(data_ptr.cast(), self.meta())
664 fn value_mut_ptr(&mut self) -> *mut T {
665 let (_, offset) = self.layout();
666 // FIXME: can this line be shared with the same in `value_ptr()`
667 // without upsetting Stacked Borrows?
668 let data_ptr = unsafe { self.ptr.cast::<u8>().as_ptr().add(offset) };
669 from_raw_parts_mut(data_ptr.cast(), self.meta())
673 impl<T> std::ops::Deref for ThinBox<T>
675 T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
679 fn deref(&self) -> &T {
680 unsafe { &*self.value_ptr() }
684 impl<T> std::ops::DerefMut for ThinBox<T>
686 T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
688 fn deref_mut(&mut self) -> &mut T {
689 unsafe { &mut *self.value_mut_ptr() }
693 impl<T> std::ops::Drop for ThinBox<T>
695 T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
698 let (layout, _) = self.layout();
700 drop_in_place::<T>(&mut **self);
701 dealloc(self.ptr.cast().as_ptr(), layout);
708 fn nonnull_tagged_pointer_with_provenance() {
709 let raw_pointer = Box::into_raw(Box::new(10));
711 let mut p = TaggedPointer::new(raw_pointer).unwrap();
712 assert_eq!(p.tag(), 0);
715 assert_eq!(p.tag(), 1);
716 assert_eq!(unsafe { *p.pointer().as_ptr() }, 10);
719 assert_eq!(p.tag(), 3);
720 assert_eq!(unsafe { *p.pointer().as_ptr() }, 10);
722 unsafe { Box::from_raw(p.pointer().as_ptr()) };
724 /// A non-null pointer type which carries several bits of metadata and maintains provenance.
726 pub struct TaggedPointer<T>(NonNull<T>);
728 impl<T> Clone for TaggedPointer<T> {
729 fn clone(&self) -> Self {
734 impl<T> Copy for TaggedPointer<T> {}
736 impl<T> TaggedPointer<T> {
737 /// The ABI-required minimum alignment of the `P` type.
738 pub const ALIGNMENT: usize = core::mem::align_of::<T>();
739 /// A mask for data-carrying bits of the address.
740 pub const DATA_MASK: usize = !Self::ADDRESS_MASK;
741 /// Number of available bits of storage in the address.
742 pub const NUM_BITS: u32 = Self::ALIGNMENT.trailing_zeros();
743 /// A mask for the non-data-carrying bits of the address.
744 pub const ADDRESS_MASK: usize = usize::MAX << Self::NUM_BITS;
746 /// Create a new tagged pointer from a possibly null pointer.
747 pub fn new(pointer: *mut T) -> Option<TaggedPointer<T>> {
748 Some(TaggedPointer(NonNull::new(pointer)?))
751 /// Consume this tagged pointer and produce a raw mutable pointer to the
753 pub fn pointer(self) -> NonNull<T> {
754 // SAFETY: The `addr` guaranteed to have bits set in the Self::ADDRESS_MASK, so the result will be non-null.
755 self.0.map_addr(|addr| unsafe {
756 NonZeroUsize::new_unchecked(addr.get() & Self::ADDRESS_MASK)
760 /// Consume this tagged pointer and produce the data it carries.
761 pub fn tag(&self) -> usize {
762 self.0.addr().get() & Self::DATA_MASK
765 /// Update the data this tagged pointer carries to a new value.
766 pub fn set_tag(&mut self, data: usize) {
768 data & Self::ADDRESS_MASK,
770 "cannot set more data beyond the lowest NUM_BITS"
772 let data = data & Self::DATA_MASK;
774 // SAFETY: This value will always be non-zero because the upper bits (from
775 // ADDRESS_MASK) will always be non-zero. This a property of the type and its
777 self.0 = self.0.map_addr(|addr| unsafe {
778 NonZeroUsize::new_unchecked((addr.get() & Self::ADDRESS_MASK) | data)
785 fn swap_copy_untyped() {
786 // We call `{swap,copy}{,_nonoverlapping}` at `bool` type on data that is not a valid bool.
787 // These should all do untyped copies, so this should work fine.
791 let ptr1 = &mut x as *mut u8 as *mut bool;
792 let ptr2 = &mut y as *mut u8 as *mut bool;
795 ptr::swap(ptr1, ptr2);
796 ptr::swap_nonoverlapping(ptr1, ptr2, 1);
802 ptr::copy(ptr1, ptr2, 1);
803 ptr::copy_nonoverlapping(ptr1, ptr2, 1);
810 fn test_const_copy() {
815 // Copy ptr1 to ptr2, bytewise.
818 &ptr1 as *const _ as *const MaybeUninit<u8>,
819 &mut ptr2 as *mut _ as *mut MaybeUninit<u8>,
820 mem::size_of::<&i32>(),
824 // Make sure they still work.
833 // Copy ptr1 to ptr2, bytewise.
835 ptr::copy_nonoverlapping(
836 &ptr1 as *const _ as *const MaybeUninit<u8>,
837 &mut ptr2 as *mut _ as *mut MaybeUninit<u8>,
838 mem::size_of::<&i32>(),
842 // Make sure they still work.