a19472a93e
Many tiny changes to stdlib doc comments to make them consistent (for example "Returns foo", rather than "Return foo", per RFC1574), adding missing periods, paragraph breaks, backticks for monospace style, and other minor nits. https://github.com/rust-lang/rfcs/blob/master/text/1574-more-api-documentation-conventions.md#appendix-a-full-conventions-text
1186 lines
39 KiB
Rust
1186 lines
39 KiB
Rust
use core::cell::RefCell;
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use core::marker::Freeze;
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use core::mem::{self, MaybeUninit};
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use core::num::NonZero;
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use core::ptr;
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use core::ptr::*;
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use std::fmt::{Debug, Display};
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#[test]
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fn test_const_from_raw_parts() {
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const SLICE: &[u8] = &[1, 2, 3, 4];
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const FROM_RAW: &[u8] = unsafe { &*slice_from_raw_parts(SLICE.as_ptr(), SLICE.len()) };
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assert_eq!(SLICE, FROM_RAW);
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let slice = &[1, 2, 3, 4, 5];
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let from_raw = unsafe { &*slice_from_raw_parts(slice.as_ptr(), 2) };
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assert_eq!(&slice[..2], from_raw);
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}
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#[test]
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fn test() {
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unsafe {
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#[repr(C)]
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struct Pair {
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fst: isize,
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snd: isize,
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}
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let mut p = Pair { fst: 10, snd: 20 };
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let pptr: *mut Pair = addr_of_mut!(p);
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let iptr: *mut isize = pptr as *mut isize;
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assert_eq!(*iptr, 10);
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*iptr = 30;
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assert_eq!(*iptr, 30);
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assert_eq!(p.fst, 30);
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*pptr = Pair { fst: 50, snd: 60 };
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assert_eq!(*iptr, 50);
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assert_eq!(p.fst, 50);
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assert_eq!(p.snd, 60);
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let v0 = vec![32000u16, 32001u16, 32002u16];
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let mut v1 = vec![0u16, 0u16, 0u16];
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copy(v0.as_ptr().offset(1), v1.as_mut_ptr().offset(1), 1);
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assert!((v1[0] == 0u16 && v1[1] == 32001u16 && v1[2] == 0u16));
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copy(v0.as_ptr().offset(2), v1.as_mut_ptr(), 1);
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assert!((v1[0] == 32002u16 && v1[1] == 32001u16 && v1[2] == 0u16));
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copy(v0.as_ptr(), v1.as_mut_ptr().offset(2), 1);
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assert!((v1[0] == 32002u16 && v1[1] == 32001u16 && v1[2] == 32000u16));
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}
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}
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#[test]
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fn test_is_null() {
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let p: *const isize = null();
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assert!(p.is_null());
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let q = p.wrapping_offset(1);
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assert!(!q.is_null());
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let mp: *mut isize = null_mut();
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assert!(mp.is_null());
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let mq = mp.wrapping_offset(1);
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assert!(!mq.is_null());
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// Pointers to unsized types -- slices
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let s: &mut [u8] = &mut [1, 2, 3];
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let cs: *const [u8] = s;
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assert!(!cs.is_null());
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let ms: *mut [u8] = s;
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assert!(!ms.is_null());
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let cz: *const [u8] = &[];
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assert!(!cz.is_null());
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let mz: *mut [u8] = &mut [];
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assert!(!mz.is_null());
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let ncs: *const [u8] = null::<[u8; 3]>();
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assert!(ncs.is_null());
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let nms: *mut [u8] = null_mut::<[u8; 3]>();
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assert!(nms.is_null());
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// Pointers to unsized types -- trait objects
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let ci: *const dyn ToString = &3;
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assert!(!ci.is_null());
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let mi: *mut dyn ToString = &mut 3;
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assert!(!mi.is_null());
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let nci: *const dyn ToString = null::<isize>();
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assert!(nci.is_null());
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let nmi: *mut dyn ToString = null_mut::<isize>();
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assert!(nmi.is_null());
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extern "C" {
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type Extern;
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}
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let ec: *const Extern = null::<Extern>();
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assert!(ec.is_null());
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let em: *mut Extern = null_mut::<Extern>();
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assert!(em.is_null());
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}
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#[test]
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fn test_as_ref() {
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unsafe {
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let p: *const isize = null();
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assert_eq!(p.as_ref(), None);
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let q: *const isize = &2;
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assert_eq!(q.as_ref().unwrap(), &2);
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let p: *mut isize = null_mut();
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assert_eq!(p.as_ref(), None);
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let q: *mut isize = &mut 2;
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assert_eq!(q.as_ref().unwrap(), &2);
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// Lifetime inference
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let u = 2isize;
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{
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let p = &u as *const isize;
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assert_eq!(p.as_ref().unwrap(), &2);
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}
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// Pointers to unsized types -- slices
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let s: &mut [u8] = &mut [1, 2, 3];
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let cs: *const [u8] = s;
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assert_eq!(cs.as_ref(), Some(&*s));
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let ms: *mut [u8] = s;
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assert_eq!(ms.as_ref(), Some(&*s));
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let cz: *const [u8] = &[];
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assert_eq!(cz.as_ref(), Some(&[][..]));
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let mz: *mut [u8] = &mut [];
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assert_eq!(mz.as_ref(), Some(&[][..]));
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let ncs: *const [u8] = null::<[u8; 3]>();
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assert_eq!(ncs.as_ref(), None);
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let nms: *mut [u8] = null_mut::<[u8; 3]>();
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assert_eq!(nms.as_ref(), None);
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// Pointers to unsized types -- trait objects
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let ci: *const dyn ToString = &3;
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assert!(ci.as_ref().is_some());
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let mi: *mut dyn ToString = &mut 3;
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assert!(mi.as_ref().is_some());
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let nci: *const dyn ToString = null::<isize>();
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assert!(nci.as_ref().is_none());
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let nmi: *mut dyn ToString = null_mut::<isize>();
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assert!(nmi.as_ref().is_none());
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}
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}
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#[test]
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fn test_as_mut() {
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unsafe {
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let p: *mut isize = null_mut();
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assert!(p.as_mut() == None);
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let q: *mut isize = &mut 2;
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assert!(q.as_mut().unwrap() == &mut 2);
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// Lifetime inference
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let mut u = 2isize;
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{
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let p = &mut u as *mut isize;
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assert!(p.as_mut().unwrap() == &mut 2);
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}
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// Pointers to unsized types -- slices
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let s: &mut [u8] = &mut [1, 2, 3];
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let ms: *mut [u8] = s;
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assert_eq!(ms.as_mut(), Some(&mut [1, 2, 3][..]));
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let mz: *mut [u8] = &mut [];
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assert_eq!(mz.as_mut(), Some(&mut [][..]));
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let nms: *mut [u8] = null_mut::<[u8; 3]>();
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assert_eq!(nms.as_mut(), None);
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// Pointers to unsized types -- trait objects
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let mi: *mut dyn ToString = &mut 3;
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assert!(mi.as_mut().is_some());
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let nmi: *mut dyn ToString = null_mut::<isize>();
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assert!(nmi.as_mut().is_none());
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}
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}
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#[test]
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fn test_ptr_addition() {
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unsafe {
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let xs = vec![5; 16];
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let mut ptr = xs.as_ptr();
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let end = ptr.offset(16);
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while ptr < end {
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assert_eq!(*ptr, 5);
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ptr = ptr.offset(1);
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}
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let mut xs_mut = xs;
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let mut m_ptr = xs_mut.as_mut_ptr();
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let m_end = m_ptr.offset(16);
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while m_ptr < m_end {
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*m_ptr += 5;
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m_ptr = m_ptr.offset(1);
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}
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assert!(xs_mut == vec![10; 16]);
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}
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}
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#[test]
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fn test_ptr_subtraction() {
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unsafe {
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let xs = vec![0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
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let mut idx = 9;
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let ptr = xs.as_ptr();
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while idx >= 0 {
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assert_eq!(*(ptr.offset(idx as isize)), idx as isize);
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idx = idx - 1;
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}
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let mut xs_mut = xs;
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let m_start = xs_mut.as_mut_ptr();
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let mut m_ptr = m_start.offset(9);
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loop {
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*m_ptr += *m_ptr;
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if m_ptr == m_start {
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break;
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}
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m_ptr = m_ptr.offset(-1);
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}
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assert_eq!(xs_mut, [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]);
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}
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}
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#[test]
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fn test_set_memory() {
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let mut xs = [0u8; 20];
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let ptr = xs.as_mut_ptr();
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unsafe {
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write_bytes(ptr, 5u8, xs.len());
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}
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assert!(xs == [5u8; 20]);
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}
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#[test]
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fn test_set_memory_const() {
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const XS: [u8; 20] = {
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let mut xs = [0u8; 20];
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let ptr = xs.as_mut_ptr();
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unsafe {
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ptr.write_bytes(5u8, xs.len());
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}
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xs
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};
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assert!(XS == [5u8; 20]);
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}
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#[test]
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fn test_unsized_nonnull() {
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let xs: &[i32] = &[1, 2, 3];
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let ptr = unsafe { NonNull::new_unchecked(xs as *const [i32] as *mut [i32]) };
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let ys = unsafe { ptr.as_ref() };
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let zs: &[i32] = &[1, 2, 3];
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assert!(ys == zs);
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}
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#[test]
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fn test_const_nonnull_new() {
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const {
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assert!(NonNull::new(core::ptr::null_mut::<()>()).is_none());
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let value = &mut 0u32;
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let mut ptr = NonNull::new(value).unwrap();
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unsafe { *ptr.as_mut() = 42 };
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let reference = unsafe { &*ptr.as_ref() };
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assert!(*reference == *value);
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assert!(*reference == 42);
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};
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}
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#[test]
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#[cfg(unix)] // printf may not be available on other platforms
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#[allow(deprecated)] // For SipHasher
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pub fn test_variadic_fnptr() {
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use core::ffi;
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use core::hash::{Hash, SipHasher};
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extern "C" {
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// This needs to use the correct function signature even though it isn't called as some
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// codegen backends make it UB to declare a function with multiple conflicting signatures
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// (like LLVM) while others straight up return an error (like Cranelift).
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fn printf(_: *const ffi::c_char, ...) -> ffi::c_int;
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}
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let p: unsafe extern "C" fn(*const ffi::c_char, ...) -> ffi::c_int = printf;
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let q = p.clone();
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assert_eq!(p, q);
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assert!(!(p < q));
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let mut s = SipHasher::new();
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assert_eq!(p.hash(&mut s), q.hash(&mut s));
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}
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#[test]
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fn write_unaligned_drop() {
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thread_local! {
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static DROPS: RefCell<Vec<u32>> = RefCell::new(Vec::new());
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}
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struct Dropper(u32);
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impl Drop for Dropper {
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fn drop(&mut self) {
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DROPS.with(|d| d.borrow_mut().push(self.0));
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}
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}
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{
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let c = Dropper(0);
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let mut t = Dropper(1);
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unsafe {
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write_unaligned(&mut t, c);
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}
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}
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DROPS.with(|d| assert_eq!(*d.borrow(), [0]));
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}
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#[test]
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fn align_offset_zst() {
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// For pointers of stride = 0, the pointer is already aligned or it cannot be aligned at
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// all, because no amount of elements will align the pointer.
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let mut p = 1;
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while p < 1024 {
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assert_eq!(ptr::without_provenance::<()>(p).align_offset(p), 0);
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if p != 1 {
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assert_eq!(ptr::without_provenance::<()>(p + 1).align_offset(p), !0);
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}
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p = (p + 1).next_power_of_two();
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}
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}
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#[test]
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fn align_offset_zst_const() {
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const {
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// For pointers of stride = 0, the pointer is already aligned or it cannot be aligned at
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// all, because no amount of elements will align the pointer.
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let mut p = 1;
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while p < 1024 {
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assert!(ptr::without_provenance::<()>(p).align_offset(p) == 0);
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if p != 1 {
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assert!(ptr::without_provenance::<()>(p + 1).align_offset(p) == !0);
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}
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p = (p + 1).next_power_of_two();
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}
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}
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}
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#[test]
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fn align_offset_stride_one() {
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// For pointers of stride = 1, the pointer can always be aligned. The offset is equal to
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// number of bytes.
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let mut align = 1;
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while align < 1024 {
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for ptr in 1..2 * align {
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let expected = ptr % align;
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let offset = if expected == 0 { 0 } else { align - expected };
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assert_eq!(
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ptr::without_provenance::<u8>(ptr).align_offset(align),
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offset,
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"ptr = {}, align = {}, size = 1",
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ptr,
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align
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);
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}
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align = (align + 1).next_power_of_two();
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}
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}
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#[test]
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fn align_offset_stride_one_const() {
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const {
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// For pointers of stride = 1, the pointer can always be aligned. The offset is equal to
|
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// number of bytes.
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let mut align = 1;
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while align < 1024 {
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let mut ptr = 1;
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while ptr < 2 * align {
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let expected = ptr % align;
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let offset = if expected == 0 { 0 } else { align - expected };
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assert!(ptr::without_provenance::<u8>(ptr).align_offset(align) == offset);
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ptr += 1;
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}
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align = (align + 1).next_power_of_two();
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}
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}
|
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}
|
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|
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#[test]
|
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fn align_offset_various_strides() {
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unsafe fn test_stride<T>(ptr: *const T, align: usize) -> bool {
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let numptr = ptr as usize;
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let mut expected = usize::MAX;
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// Naive but definitely correct way to find the *first* aligned element of stride::<T>.
|
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for el in 0..align {
|
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if (numptr + el * ::std::mem::size_of::<T>()) % align == 0 {
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expected = el;
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break;
|
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}
|
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}
|
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let got = ptr.align_offset(align);
|
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if got != expected {
|
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eprintln!(
|
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"aligning {:p} (with stride of {}) to {}, expected {}, got {}",
|
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ptr,
|
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::std::mem::size_of::<T>(),
|
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align,
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expected,
|
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got
|
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);
|
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return true;
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||
}
|
||
return false;
|
||
}
|
||
|
||
// For pointers of stride != 1, we verify the algorithm against the naivest possible
|
||
// implementation
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||
let mut align = 1;
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let mut x = false;
|
||
// Miri is too slow
|
||
let limit = if cfg!(miri) { 32 } else { 1024 };
|
||
while align < limit {
|
||
for ptr in 1usize..4 * align {
|
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unsafe {
|
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#[repr(packed)]
|
||
struct A3(#[allow(dead_code)] u16, #[allow(dead_code)] u8);
|
||
x |= test_stride::<A3>(ptr::without_provenance::<A3>(ptr), align);
|
||
|
||
struct A4(#[allow(dead_code)] u32);
|
||
x |= test_stride::<A4>(ptr::without_provenance::<A4>(ptr), align);
|
||
|
||
#[repr(packed)]
|
||
struct A5(#[allow(dead_code)] u32, #[allow(dead_code)] u8);
|
||
x |= test_stride::<A5>(ptr::without_provenance::<A5>(ptr), align);
|
||
|
||
#[repr(packed)]
|
||
struct A6(#[allow(dead_code)] u32, #[allow(dead_code)] u16);
|
||
x |= test_stride::<A6>(ptr::without_provenance::<A6>(ptr), align);
|
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|
||
#[repr(packed)]
|
||
struct A7(#[allow(dead_code)] u32, #[allow(dead_code)] u16, #[allow(dead_code)] u8);
|
||
x |= test_stride::<A7>(ptr::without_provenance::<A7>(ptr), align);
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||
|
||
#[repr(packed)]
|
||
struct A8(#[allow(dead_code)] u32, #[allow(dead_code)] u32);
|
||
x |= test_stride::<A8>(ptr::without_provenance::<A8>(ptr), align);
|
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|
||
#[repr(packed)]
|
||
struct A9(#[allow(dead_code)] u32, #[allow(dead_code)] u32, #[allow(dead_code)] u8);
|
||
x |= test_stride::<A9>(ptr::without_provenance::<A9>(ptr), align);
|
||
|
||
#[repr(packed)]
|
||
struct A10(
|
||
#[allow(dead_code)] u32,
|
||
#[allow(dead_code)] u32,
|
||
#[allow(dead_code)] u16,
|
||
);
|
||
x |= test_stride::<A10>(ptr::without_provenance::<A10>(ptr), align);
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||
|
||
x |= test_stride::<u32>(ptr::without_provenance::<u32>(ptr), align);
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||
x |= test_stride::<u128>(ptr::without_provenance::<u128>(ptr), align);
|
||
}
|
||
}
|
||
align = (align + 1).next_power_of_two();
|
||
}
|
||
assert!(!x);
|
||
}
|
||
|
||
#[test]
|
||
fn align_offset_various_strides_const() {
|
||
const unsafe fn test_stride<T>(ptr: *const T, numptr: usize, align: usize) {
|
||
let mut expected = usize::MAX;
|
||
// Naive but definitely correct way to find the *first* aligned element of stride::<T>.
|
||
let mut el = 0;
|
||
while el < align {
|
||
if (numptr + el * ::std::mem::size_of::<T>()) % align == 0 {
|
||
expected = el;
|
||
break;
|
||
}
|
||
el += 1;
|
||
}
|
||
let got = ptr.align_offset(align);
|
||
assert!(got == expected);
|
||
}
|
||
|
||
const {
|
||
// For pointers of stride != 1, we verify the algorithm against the naivest possible
|
||
// implementation
|
||
let mut align = 1;
|
||
let limit = 32;
|
||
while align < limit {
|
||
let mut ptr = 1;
|
||
while ptr < 4 * align {
|
||
unsafe {
|
||
#[repr(packed)]
|
||
struct A3(#[allow(dead_code)] u16, #[allow(dead_code)] u8);
|
||
test_stride::<A3>(ptr::without_provenance::<A3>(ptr), ptr, align);
|
||
|
||
struct A4(#[allow(dead_code)] u32);
|
||
test_stride::<A4>(ptr::without_provenance::<A4>(ptr), ptr, align);
|
||
|
||
#[repr(packed)]
|
||
struct A5(#[allow(dead_code)] u32, #[allow(dead_code)] u8);
|
||
test_stride::<A5>(ptr::without_provenance::<A5>(ptr), ptr, align);
|
||
|
||
#[repr(packed)]
|
||
struct A6(#[allow(dead_code)] u32, #[allow(dead_code)] u16);
|
||
test_stride::<A6>(ptr::without_provenance::<A6>(ptr), ptr, align);
|
||
|
||
#[repr(packed)]
|
||
struct A7(
|
||
#[allow(dead_code)] u32,
|
||
#[allow(dead_code)] u16,
|
||
#[allow(dead_code)] u8,
|
||
);
|
||
test_stride::<A7>(ptr::without_provenance::<A7>(ptr), ptr, align);
|
||
|
||
#[repr(packed)]
|
||
struct A8(#[allow(dead_code)] u32, #[allow(dead_code)] u32);
|
||
test_stride::<A8>(ptr::without_provenance::<A8>(ptr), ptr, align);
|
||
|
||
#[repr(packed)]
|
||
struct A9(
|
||
#[allow(dead_code)] u32,
|
||
#[allow(dead_code)] u32,
|
||
#[allow(dead_code)] u8,
|
||
);
|
||
test_stride::<A9>(ptr::without_provenance::<A9>(ptr), ptr, align);
|
||
|
||
#[repr(packed)]
|
||
struct A10(
|
||
#[allow(dead_code)] u32,
|
||
#[allow(dead_code)] u32,
|
||
#[allow(dead_code)] u16,
|
||
);
|
||
test_stride::<A10>(ptr::without_provenance::<A10>(ptr), ptr, align);
|
||
|
||
test_stride::<u32>(ptr::without_provenance::<u32>(ptr), ptr, align);
|
||
test_stride::<u128>(ptr::without_provenance::<u128>(ptr), ptr, align);
|
||
}
|
||
ptr += 1;
|
||
}
|
||
align = (align + 1).next_power_of_two();
|
||
}
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn align_offset_with_provenance_const() {
|
||
const {
|
||
// On some platforms (e.g. msp430-none-elf), the alignment of `i32` is less than 4.
|
||
#[repr(align(4))]
|
||
struct AlignedI32(i32);
|
||
|
||
let data = AlignedI32(42);
|
||
|
||
// `stride % align == 0` (usual case)
|
||
|
||
let ptr: *const i32 = &data.0;
|
||
assert!(ptr.align_offset(1) == 0);
|
||
assert!(ptr.align_offset(2) == 0);
|
||
assert!(ptr.align_offset(4) == 0);
|
||
assert!(ptr.align_offset(8) == usize::MAX);
|
||
assert!(ptr.wrapping_byte_add(1).align_offset(1) == 0);
|
||
assert!(ptr.wrapping_byte_add(1).align_offset(2) == usize::MAX);
|
||
assert!(ptr.wrapping_byte_add(2).align_offset(1) == 0);
|
||
assert!(ptr.wrapping_byte_add(2).align_offset(2) == 0);
|
||
assert!(ptr.wrapping_byte_add(2).align_offset(4) == usize::MAX);
|
||
assert!(ptr.wrapping_byte_add(3).align_offset(1) == 0);
|
||
assert!(ptr.wrapping_byte_add(3).align_offset(2) == usize::MAX);
|
||
|
||
assert!(ptr.wrapping_add(42).align_offset(4) == 0);
|
||
assert!(ptr.wrapping_add(42).align_offset(8) == usize::MAX);
|
||
|
||
let ptr1: *const i8 = ptr.cast();
|
||
assert!(ptr1.align_offset(1) == 0);
|
||
assert!(ptr1.align_offset(2) == 0);
|
||
assert!(ptr1.align_offset(4) == 0);
|
||
assert!(ptr1.align_offset(8) == usize::MAX);
|
||
assert!(ptr1.wrapping_byte_add(1).align_offset(1) == 0);
|
||
assert!(ptr1.wrapping_byte_add(1).align_offset(2) == 1);
|
||
assert!(ptr1.wrapping_byte_add(1).align_offset(4) == 3);
|
||
assert!(ptr1.wrapping_byte_add(1).align_offset(8) == usize::MAX);
|
||
assert!(ptr1.wrapping_byte_add(2).align_offset(1) == 0);
|
||
assert!(ptr1.wrapping_byte_add(2).align_offset(2) == 0);
|
||
assert!(ptr1.wrapping_byte_add(2).align_offset(4) == 2);
|
||
assert!(ptr1.wrapping_byte_add(2).align_offset(8) == usize::MAX);
|
||
assert!(ptr1.wrapping_byte_add(3).align_offset(1) == 0);
|
||
assert!(ptr1.wrapping_byte_add(3).align_offset(2) == 1);
|
||
assert!(ptr1.wrapping_byte_add(3).align_offset(4) == 1);
|
||
assert!(ptr1.wrapping_byte_add(3).align_offset(8) == usize::MAX);
|
||
|
||
let ptr2: *const i16 = ptr.cast();
|
||
assert!(ptr2.align_offset(1) == 0);
|
||
assert!(ptr2.align_offset(2) == 0);
|
||
assert!(ptr2.align_offset(4) == 0);
|
||
assert!(ptr2.align_offset(8) == usize::MAX);
|
||
assert!(ptr2.wrapping_byte_add(1).align_offset(1) == 0);
|
||
assert!(ptr2.wrapping_byte_add(1).align_offset(2) == usize::MAX);
|
||
assert!(ptr2.wrapping_byte_add(2).align_offset(1) == 0);
|
||
assert!(ptr2.wrapping_byte_add(2).align_offset(2) == 0);
|
||
assert!(ptr2.wrapping_byte_add(2).align_offset(4) == 1);
|
||
assert!(ptr2.wrapping_byte_add(2).align_offset(8) == usize::MAX);
|
||
assert!(ptr2.wrapping_byte_add(3).align_offset(1) == 0);
|
||
assert!(ptr2.wrapping_byte_add(3).align_offset(2) == usize::MAX);
|
||
|
||
let ptr3: *const i64 = ptr.cast();
|
||
assert!(ptr3.align_offset(1) == 0);
|
||
assert!(ptr3.align_offset(2) == 0);
|
||
assert!(ptr3.align_offset(4) == 0);
|
||
assert!(ptr3.align_offset(8) == usize::MAX);
|
||
assert!(ptr3.wrapping_byte_add(1).align_offset(1) == 0);
|
||
assert!(ptr3.wrapping_byte_add(1).align_offset(2) == usize::MAX);
|
||
|
||
// `stride % align != 0` (edge case)
|
||
|
||
let ptr4: *const [u8; 3] = ptr.cast();
|
||
assert!(ptr4.align_offset(1) == 0);
|
||
assert!(ptr4.align_offset(2) == 0);
|
||
assert!(ptr4.align_offset(4) == 0);
|
||
assert!(ptr4.align_offset(8) == usize::MAX);
|
||
assert!(ptr4.wrapping_byte_add(1).align_offset(1) == 0);
|
||
assert!(ptr4.wrapping_byte_add(1).align_offset(2) == 1);
|
||
assert!(ptr4.wrapping_byte_add(1).align_offset(4) == 1);
|
||
assert!(ptr4.wrapping_byte_add(1).align_offset(8) == usize::MAX);
|
||
assert!(ptr4.wrapping_byte_add(2).align_offset(1) == 0);
|
||
assert!(ptr4.wrapping_byte_add(2).align_offset(2) == 0);
|
||
assert!(ptr4.wrapping_byte_add(2).align_offset(4) == 2);
|
||
assert!(ptr4.wrapping_byte_add(2).align_offset(8) == usize::MAX);
|
||
assert!(ptr4.wrapping_byte_add(3).align_offset(1) == 0);
|
||
assert!(ptr4.wrapping_byte_add(3).align_offset(2) == 1);
|
||
assert!(ptr4.wrapping_byte_add(3).align_offset(4) == 3);
|
||
assert!(ptr4.wrapping_byte_add(3).align_offset(8) == usize::MAX);
|
||
|
||
let ptr5: *const [u8; 5] = ptr.cast();
|
||
assert!(ptr5.align_offset(1) == 0);
|
||
assert!(ptr5.align_offset(2) == 0);
|
||
assert!(ptr5.align_offset(4) == 0);
|
||
assert!(ptr5.align_offset(8) == usize::MAX);
|
||
assert!(ptr5.wrapping_byte_add(1).align_offset(1) == 0);
|
||
assert!(ptr5.wrapping_byte_add(1).align_offset(2) == 1);
|
||
assert!(ptr5.wrapping_byte_add(1).align_offset(4) == 3);
|
||
assert!(ptr5.wrapping_byte_add(1).align_offset(8) == usize::MAX);
|
||
assert!(ptr5.wrapping_byte_add(2).align_offset(1) == 0);
|
||
assert!(ptr5.wrapping_byte_add(2).align_offset(2) == 0);
|
||
assert!(ptr5.wrapping_byte_add(2).align_offset(4) == 2);
|
||
assert!(ptr5.wrapping_byte_add(2).align_offset(8) == usize::MAX);
|
||
assert!(ptr5.wrapping_byte_add(3).align_offset(1) == 0);
|
||
assert!(ptr5.wrapping_byte_add(3).align_offset(2) == 1);
|
||
assert!(ptr5.wrapping_byte_add(3).align_offset(4) == 1);
|
||
assert!(ptr5.wrapping_byte_add(3).align_offset(8) == usize::MAX);
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn align_offset_issue_103361() {
|
||
#[cfg(target_pointer_width = "64")]
|
||
const SIZE: usize = 1 << 47;
|
||
#[cfg(target_pointer_width = "32")]
|
||
const SIZE: usize = 1 << 30;
|
||
#[cfg(target_pointer_width = "16")]
|
||
const SIZE: usize = 1 << 13;
|
||
struct HugeSize(#[allow(dead_code)] [u8; SIZE - 1]);
|
||
let _ = ptr::without_provenance::<HugeSize>(SIZE).align_offset(SIZE);
|
||
}
|
||
|
||
#[test]
|
||
fn align_offset_issue_103361_const() {
|
||
#[cfg(target_pointer_width = "64")]
|
||
const SIZE: usize = 1 << 47;
|
||
#[cfg(target_pointer_width = "32")]
|
||
const SIZE: usize = 1 << 30;
|
||
#[cfg(target_pointer_width = "16")]
|
||
const SIZE: usize = 1 << 13;
|
||
struct HugeSize(#[allow(dead_code)] [u8; SIZE - 1]);
|
||
|
||
const {
|
||
assert!(ptr::without_provenance::<HugeSize>(SIZE - 1).align_offset(SIZE) == SIZE - 1);
|
||
assert!(ptr::without_provenance::<HugeSize>(SIZE).align_offset(SIZE) == 0);
|
||
assert!(ptr::without_provenance::<HugeSize>(SIZE + 1).align_offset(SIZE) == 1);
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn is_aligned() {
|
||
let data = 42;
|
||
let ptr: *const i32 = &data;
|
||
assert!(ptr.is_aligned());
|
||
assert!(ptr.is_aligned_to(1));
|
||
assert!(ptr.is_aligned_to(2));
|
||
assert!(ptr.is_aligned_to(4));
|
||
assert!(ptr.wrapping_byte_add(2).is_aligned_to(1));
|
||
assert!(ptr.wrapping_byte_add(2).is_aligned_to(2));
|
||
assert!(!ptr.wrapping_byte_add(2).is_aligned_to(4));
|
||
|
||
// At runtime either `ptr` or `ptr+1` is aligned to 8.
|
||
assert_ne!(ptr.is_aligned_to(8), ptr.wrapping_add(1).is_aligned_to(8));
|
||
}
|
||
|
||
#[test]
|
||
fn is_aligned_const() {
|
||
const {
|
||
let data = 42;
|
||
let ptr: *const i32 = &data;
|
||
assert!(ptr.is_aligned());
|
||
assert!(ptr.is_aligned_to(1));
|
||
assert!(ptr.is_aligned_to(2));
|
||
assert!(ptr.is_aligned_to(4));
|
||
assert!(ptr.wrapping_byte_add(2).is_aligned_to(1));
|
||
assert!(ptr.wrapping_byte_add(2).is_aligned_to(2));
|
||
assert!(!ptr.wrapping_byte_add(2).is_aligned_to(4));
|
||
|
||
// At comptime neither `ptr` nor `ptr+1` is aligned to 8.
|
||
assert!(!ptr.is_aligned_to(8));
|
||
assert!(!ptr.wrapping_add(1).is_aligned_to(8));
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn 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);
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn ptr_metadata() {
|
||
struct Unit;
|
||
struct Pair<A, B: ?Sized>(A, B);
|
||
extern "C" {
|
||
type Extern;
|
||
}
|
||
let () = metadata(&());
|
||
let () = metadata(&Unit);
|
||
let () = metadata(&4_u32);
|
||
let () = metadata(&String::new());
|
||
let () = metadata(&Some(4_u32));
|
||
let () = metadata(&ptr_metadata);
|
||
let () = metadata(&|| {});
|
||
let () = metadata(&[4, 7]);
|
||
let () = metadata(&(4, String::new()));
|
||
let () = metadata(&Pair(4, String::new()));
|
||
let () = metadata(ptr::null::<()>() as *const Extern);
|
||
let () = metadata(ptr::null::<()>() as *const <&u32 as std::ops::Deref>::Target);
|
||
|
||
assert_eq!(metadata("foo"), 3_usize);
|
||
assert_eq!(metadata(&[4, 7][..]), 2_usize);
|
||
|
||
let dst_tuple: &(bool, [u8]) = &(true, [0x66, 0x6F, 0x6F]);
|
||
let dst_struct: &Pair<bool, [u8]> = &Pair(true, [0x66, 0x6F, 0x6F]);
|
||
assert_eq!(metadata(dst_tuple), 3_usize);
|
||
assert_eq!(metadata(dst_struct), 3_usize);
|
||
unsafe {
|
||
let dst_tuple: &(bool, str) = std::mem::transmute(dst_tuple);
|
||
let dst_struct: &Pair<bool, str> = std::mem::transmute(dst_struct);
|
||
assert_eq!(&dst_tuple.1, "foo");
|
||
assert_eq!(&dst_struct.1, "foo");
|
||
assert_eq!(metadata(dst_tuple), 3_usize);
|
||
assert_eq!(metadata(dst_struct), 3_usize);
|
||
}
|
||
|
||
let vtable_1: DynMetadata<dyn Debug> = metadata(&4_u16 as &dyn Debug);
|
||
let vtable_2: DynMetadata<dyn Display> = metadata(&4_u16 as &dyn Display);
|
||
let vtable_3: DynMetadata<dyn Display> = metadata(&4_u32 as &dyn Display);
|
||
let vtable_4: DynMetadata<dyn Display> = metadata(&(true, 7_u32) as &(bool, dyn Display));
|
||
let vtable_5: DynMetadata<dyn Display> =
|
||
metadata(&Pair(true, 7_u32) as &Pair<bool, dyn Display>);
|
||
unsafe {
|
||
let address_1: *const () = std::mem::transmute(vtable_1);
|
||
let address_2: *const () = std::mem::transmute(vtable_2);
|
||
let address_3: *const () = std::mem::transmute(vtable_3);
|
||
let address_4: *const () = std::mem::transmute(vtable_4);
|
||
let address_5: *const () = std::mem::transmute(vtable_5);
|
||
// Different trait => different vtable pointer
|
||
assert_ne!(address_1, address_2);
|
||
// Different erased type => different vtable pointer
|
||
assert_ne!(address_2, address_3);
|
||
// Same erased type and same trait => same vtable pointer
|
||
assert_eq!(address_3, address_4);
|
||
assert_eq!(address_3, address_5);
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn ptr_metadata_bounds() {
|
||
fn metadata_eq_method_address<T: ?Sized>() -> usize {
|
||
// The `Metadata` associated type has an `Ord` bound, so this is valid:
|
||
<<T as Pointee>::Metadata as PartialEq>::eq as usize
|
||
}
|
||
// "Synthetic" trait impls generated by the compiler like those of `Pointee`
|
||
// are not checked for bounds of associated type.
|
||
// So with a buggy core we could have both:
|
||
// * `<dyn Display as Pointee>::Metadata == DynMetadata`
|
||
// * `DynMetadata: !PartialEq`
|
||
// … and cause an ICE here:
|
||
metadata_eq_method_address::<dyn Display>();
|
||
|
||
// For this reason, let’s check here that bounds are satisfied:
|
||
|
||
let _ = static_assert_expected_bounds_for_metadata::<()>;
|
||
let _ = static_assert_expected_bounds_for_metadata::<usize>;
|
||
let _ = static_assert_expected_bounds_for_metadata::<DynMetadata<dyn Display>>;
|
||
fn _static_assert_associated_type<T: ?Sized>() {
|
||
let _ = static_assert_expected_bounds_for_metadata::<<T as Pointee>::Metadata>;
|
||
}
|
||
|
||
fn static_assert_expected_bounds_for_metadata<Meta>()
|
||
where
|
||
// Keep this in sync with the associated type in `library/core/src/ptr/metadata.rs`
|
||
Meta: Debug + Copy + Send + Sync + Ord + std::hash::Hash + Unpin + Freeze,
|
||
{
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn pointee_metadata_debug() {
|
||
assert_eq!("()", format!("{:?}", metadata::<u32>(&17)));
|
||
assert_eq!("2", format!("{:?}", metadata::<[u32]>(&[19, 23])));
|
||
let for_dyn = format!("{:?}", metadata::<dyn Debug>(&29));
|
||
assert!(for_dyn.starts_with("DynMetadata(0x"), "{:?}", for_dyn);
|
||
}
|
||
|
||
#[test]
|
||
fn dyn_metadata() {
|
||
#[derive(Debug)]
|
||
#[repr(align(32))]
|
||
struct Something(#[allow(dead_code)] [u8; 47]);
|
||
|
||
let value = Something([0; 47]);
|
||
let trait_object: &dyn Debug = &value;
|
||
let meta = metadata(trait_object);
|
||
|
||
assert_eq!(meta.size_of(), 64);
|
||
assert_eq!(meta.size_of(), std::mem::size_of::<Something>());
|
||
assert_eq!(meta.align_of(), 32);
|
||
assert_eq!(meta.align_of(), std::mem::align_of::<Something>());
|
||
assert_eq!(meta.layout(), std::alloc::Layout::new::<Something>());
|
||
|
||
assert!(format!("{meta:?}").starts_with("DynMetadata(0x"));
|
||
}
|
||
|
||
#[test]
|
||
fn from_raw_parts() {
|
||
let mut value = 5_u32;
|
||
let address = &mut value as *mut _ as *mut ();
|
||
let trait_object: &dyn Display = &mut value;
|
||
let vtable = metadata(trait_object);
|
||
let trait_object = NonNull::from(trait_object);
|
||
|
||
assert_eq!(ptr::from_raw_parts(address, vtable), trait_object.as_ptr());
|
||
assert_eq!(ptr::from_raw_parts_mut(address, vtable), trait_object.as_ptr());
|
||
assert_eq!(NonNull::from_raw_parts(NonNull::new(address).unwrap(), vtable), trait_object);
|
||
|
||
let mut array = [5_u32, 5, 5, 5, 5];
|
||
let address = &mut array as *mut _ as *mut ();
|
||
let array_ptr = NonNull::from(&mut array);
|
||
let slice_ptr = NonNull::from(&mut array[..]);
|
||
|
||
assert_eq!(ptr::from_raw_parts(address, ()), array_ptr.as_ptr());
|
||
assert_eq!(ptr::from_raw_parts_mut(address, ()), array_ptr.as_ptr());
|
||
assert_eq!(NonNull::from_raw_parts(NonNull::new(address).unwrap(), ()), array_ptr);
|
||
|
||
assert_eq!(ptr::from_raw_parts(address, 5), slice_ptr.as_ptr());
|
||
assert_eq!(ptr::from_raw_parts_mut(address, 5), slice_ptr.as_ptr());
|
||
assert_eq!(NonNull::from_raw_parts(NonNull::new(address).unwrap(), 5), slice_ptr);
|
||
}
|
||
|
||
#[test]
|
||
fn thin_box() {
|
||
let foo = ThinBox::<dyn Display>::new(4);
|
||
assert_eq!(foo.to_string(), "4");
|
||
drop(foo);
|
||
let bar = ThinBox::<dyn Display>::new(7);
|
||
assert_eq!(bar.to_string(), "7");
|
||
|
||
// A slightly more interesting library that could be built on top of metadata APIs.
|
||
//
|
||
// * It could be generalized to any `T: ?Sized` (not just trait object)
|
||
// if `{size,align}_of_for_meta<T: ?Sized>(T::Metadata)` are added.
|
||
// * Constructing a `ThinBox` without consuming and deallocating a `Box`
|
||
// requires either the unstable `Unsize` marker trait,
|
||
// or the unstable `unsized_locals` language feature,
|
||
// or taking `&dyn T` and restricting to `T: Copy`.
|
||
|
||
use std::alloc::*;
|
||
use std::marker::PhantomData;
|
||
|
||
struct ThinBox<T>
|
||
where
|
||
T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
|
||
{
|
||
ptr: NonNull<DynMetadata<T>>,
|
||
phantom: PhantomData<T>,
|
||
}
|
||
|
||
impl<T> ThinBox<T>
|
||
where
|
||
T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
|
||
{
|
||
pub fn new<Value: std::marker::Unsize<T>>(value: Value) -> Self {
|
||
let unsized_: &T = &value;
|
||
let meta = metadata(unsized_);
|
||
let meta_layout = Layout::for_value(&meta);
|
||
let value_layout = Layout::for_value(&value);
|
||
let (layout, offset) = meta_layout.extend(value_layout).unwrap();
|
||
// `DynMetadata` is pointer-sized:
|
||
assert!(layout.size() > 0);
|
||
// If `ThinBox<T>` is generalized to any `T: ?Sized`,
|
||
// handle ZSTs with a dangling pointer without going through `alloc()`,
|
||
// like `Box<T>` does.
|
||
unsafe {
|
||
let ptr = NonNull::new(alloc(layout))
|
||
.unwrap_or_else(|| handle_alloc_error(layout))
|
||
.cast::<DynMetadata<T>>();
|
||
ptr.as_ptr().write(meta);
|
||
ptr.as_ptr().byte_add(offset).cast::<Value>().write(value);
|
||
Self { ptr, phantom: PhantomData }
|
||
}
|
||
}
|
||
|
||
fn meta(&self) -> DynMetadata<T> {
|
||
unsafe { *self.ptr.as_ref() }
|
||
}
|
||
|
||
fn layout(&self) -> (Layout, usize) {
|
||
let meta = self.meta();
|
||
Layout::for_value(&meta).extend(meta.layout()).unwrap()
|
||
}
|
||
|
||
fn value_ptr(&self) -> *const T {
|
||
let (_, offset) = self.layout();
|
||
let data_ptr = unsafe { self.ptr.cast::<u8>().as_ptr().add(offset) };
|
||
ptr::from_raw_parts(data_ptr, self.meta())
|
||
}
|
||
|
||
fn value_mut_ptr(&mut self) -> *mut T {
|
||
let (_, offset) = self.layout();
|
||
// FIXME: can this line be shared with the same in `value_ptr()`
|
||
// without upsetting Stacked Borrows?
|
||
let data_ptr = unsafe { self.ptr.cast::<u8>().as_ptr().add(offset) };
|
||
from_raw_parts_mut(data_ptr, self.meta())
|
||
}
|
||
}
|
||
|
||
impl<T> std::ops::Deref for ThinBox<T>
|
||
where
|
||
T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
|
||
{
|
||
type Target = T;
|
||
|
||
fn deref(&self) -> &T {
|
||
unsafe { &*self.value_ptr() }
|
||
}
|
||
}
|
||
|
||
impl<T> std::ops::DerefMut for ThinBox<T>
|
||
where
|
||
T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
|
||
{
|
||
fn deref_mut(&mut self) -> &mut T {
|
||
unsafe { &mut *self.value_mut_ptr() }
|
||
}
|
||
}
|
||
|
||
impl<T> std::ops::Drop for ThinBox<T>
|
||
where
|
||
T: ?Sized + Pointee<Metadata = DynMetadata<T>>,
|
||
{
|
||
fn drop(&mut self) {
|
||
let (layout, _) = self.layout();
|
||
unsafe {
|
||
drop_in_place::<T>(&mut **self);
|
||
dealloc(self.ptr.cast().as_ptr(), layout);
|
||
}
|
||
}
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn nonnull_tagged_pointer_with_provenance() {
|
||
let raw_pointer = Box::into_raw(Box::new(10));
|
||
|
||
let mut p = TaggedPointer::new(raw_pointer).unwrap();
|
||
assert_eq!(p.tag(), 0);
|
||
|
||
p.set_tag(1);
|
||
assert_eq!(p.tag(), 1);
|
||
assert_eq!(unsafe { *p.pointer().as_ptr() }, 10);
|
||
|
||
p.set_tag(3);
|
||
assert_eq!(p.tag(), 3);
|
||
assert_eq!(unsafe { *p.pointer().as_ptr() }, 10);
|
||
|
||
unsafe { drop(Box::from_raw(p.pointer().as_ptr())) };
|
||
|
||
/// A non-null pointer type which carries several bits of metadata and maintains provenance.
|
||
#[repr(transparent)]
|
||
pub struct TaggedPointer<T>(NonNull<T>);
|
||
|
||
impl<T> Clone for TaggedPointer<T> {
|
||
fn clone(&self) -> Self {
|
||
Self(self.0)
|
||
}
|
||
}
|
||
|
||
impl<T> Copy for TaggedPointer<T> {}
|
||
|
||
impl<T> TaggedPointer<T> {
|
||
/// The ABI-required minimum alignment of the `P` type.
|
||
pub const ALIGNMENT: usize = core::mem::align_of::<T>();
|
||
/// A mask for data-carrying bits of the address.
|
||
pub const DATA_MASK: usize = !Self::ADDRESS_MASK;
|
||
/// Number of available bits of storage in the address.
|
||
pub const NUM_BITS: u32 = Self::ALIGNMENT.trailing_zeros();
|
||
/// A mask for the non-data-carrying bits of the address.
|
||
pub const ADDRESS_MASK: usize = usize::MAX << Self::NUM_BITS;
|
||
|
||
/// Creates a new tagged pointer from a possibly null pointer.
|
||
pub fn new(pointer: *mut T) -> Option<TaggedPointer<T>> {
|
||
Some(TaggedPointer(NonNull::new(pointer)?))
|
||
}
|
||
|
||
/// Consume this tagged pointer and produce a raw mutable pointer to the
|
||
/// memory location.
|
||
pub fn pointer(self) -> NonNull<T> {
|
||
// SAFETY: The `addr` guaranteed to have bits set in the Self::ADDRESS_MASK, so the result will be non-null.
|
||
self.0
|
||
.map_addr(|addr| unsafe { NonZero::new_unchecked(addr.get() & Self::ADDRESS_MASK) })
|
||
}
|
||
|
||
/// Consume this tagged pointer and produce the data it carries.
|
||
pub fn tag(&self) -> usize {
|
||
self.0.addr().get() & Self::DATA_MASK
|
||
}
|
||
|
||
/// Update the data this tagged pointer carries to a new value.
|
||
pub fn set_tag(&mut self, data: usize) {
|
||
assert_eq!(
|
||
data & Self::ADDRESS_MASK,
|
||
0,
|
||
"cannot set more data beyond the lowest NUM_BITS"
|
||
);
|
||
let data = data & Self::DATA_MASK;
|
||
|
||
// SAFETY: This value will always be non-zero because the upper bits (from
|
||
// ADDRESS_MASK) will always be non-zero. This a property of the type and its
|
||
// construction.
|
||
self.0 = self.0.map_addr(|addr| unsafe {
|
||
NonZero::new_unchecked((addr.get() & Self::ADDRESS_MASK) | data)
|
||
})
|
||
}
|
||
}
|
||
}
|
||
|
||
#[test]
|
||
fn swap_copy_untyped() {
|
||
// We call `{swap,copy}{,_nonoverlapping}` at `bool` type on data that is not a valid bool.
|
||
// These should all do untyped copies, so this should work fine.
|
||
let mut x = 5u8;
|
||
let mut y = 6u8;
|
||
|
||
let ptr1 = addr_of_mut!(x).cast::<bool>();
|
||
let ptr2 = addr_of_mut!(y).cast::<bool>();
|
||
|
||
unsafe {
|
||
ptr::swap(ptr1, ptr2);
|
||
ptr::swap_nonoverlapping(ptr1, ptr2, 1);
|
||
}
|
||
assert_eq!(x, 5);
|
||
assert_eq!(y, 6);
|
||
|
||
unsafe {
|
||
ptr::copy(ptr1, ptr2, 1);
|
||
ptr::copy_nonoverlapping(ptr1, ptr2, 1);
|
||
}
|
||
assert_eq!(x, 5);
|
||
assert_eq!(y, 5);
|
||
}
|
||
|
||
#[test]
|
||
fn test_const_copy() {
|
||
const {
|
||
let ptr1 = &1;
|
||
let mut ptr2 = &666;
|
||
|
||
// Copy ptr1 to ptr2, bytewise.
|
||
unsafe {
|
||
ptr::copy(
|
||
&ptr1 as *const _ as *const MaybeUninit<u8>,
|
||
&mut ptr2 as *mut _ as *mut MaybeUninit<u8>,
|
||
mem::size_of::<&i32>(),
|
||
);
|
||
}
|
||
|
||
// Make sure they still work.
|
||
assert!(*ptr1 == 1);
|
||
assert!(*ptr2 == 1);
|
||
};
|
||
|
||
const {
|
||
let ptr1 = &1;
|
||
let mut ptr2 = &666;
|
||
|
||
// Copy ptr1 to ptr2, bytewise.
|
||
unsafe {
|
||
ptr::copy_nonoverlapping(
|
||
&ptr1 as *const _ as *const MaybeUninit<u8>,
|
||
&mut ptr2 as *mut _ as *mut MaybeUninit<u8>,
|
||
mem::size_of::<&i32>(),
|
||
);
|
||
}
|
||
|
||
// Make sure they still work.
|
||
assert!(*ptr1 == 1);
|
||
assert!(*ptr2 == 1);
|
||
};
|
||
}
|
||
|
||
#[test]
|
||
fn test_null_array_as_slice() {
|
||
let arr: *mut [u8; 4] = null_mut();
|
||
let ptr: *mut [u8] = arr.as_mut_slice();
|
||
assert!(ptr.is_null());
|
||
assert_eq!(ptr.len(), 4);
|
||
|
||
let arr: *const [u8; 4] = null();
|
||
let ptr: *const [u8] = arr.as_slice();
|
||
assert!(ptr.is_null());
|
||
assert_eq!(ptr.len(), 4);
|
||
}
|
||
|
||
#[test]
|
||
fn test_ptr_from_raw_parts_in_const() {
|
||
const EMPTY_SLICE_PTR: *const [i32] =
|
||
std::ptr::slice_from_raw_parts(std::ptr::without_provenance(123), 456);
|
||
assert_eq!(EMPTY_SLICE_PTR.addr(), 123);
|
||
assert_eq!(EMPTY_SLICE_PTR.len(), 456);
|
||
}
|
||
|
||
#[test]
|
||
fn test_ptr_metadata_in_const() {
|
||
use std::fmt::Debug;
|
||
|
||
const ARRAY_META: () = std::ptr::metadata::<[u16; 3]>(&[1, 2, 3]);
|
||
const SLICE_META: usize = std::ptr::metadata::<[u16]>(&[1, 2, 3]);
|
||
const DYN_META: DynMetadata<dyn Debug> = std::ptr::metadata::<dyn Debug>(&[0_u8; 42]);
|
||
assert_eq!(ARRAY_META, ());
|
||
assert_eq!(SLICE_META, 3);
|
||
assert_eq!(DYN_META.size_of(), 42);
|
||
}
|