mirror of
https://github.com/rust-lang/rust.git
synced 2024-11-27 09:14:20 +00:00
106 lines
3.4 KiB
Rust
106 lines
3.4 KiB
Rust
// run-pass
|
|
#![feature(
|
|
slice_from_ptr_range,
|
|
const_slice_from_ptr_range,
|
|
pointer_byte_offsets,
|
|
const_pointer_byte_offsets
|
|
)]
|
|
use std::{
|
|
mem::MaybeUninit,
|
|
ptr,
|
|
slice::{from_ptr_range, from_raw_parts},
|
|
};
|
|
|
|
// Dangling is ok, as long as it's either for ZST reads or for no reads
|
|
pub static S0: &[u32] = unsafe { from_raw_parts(dangling(), 0) };
|
|
pub static S1: &[()] = unsafe { from_raw_parts(dangling(), 3) };
|
|
|
|
// References are always valid of reads of a single element (basically `slice::from_ref`)
|
|
pub static S2: &[u32] = unsafe { from_raw_parts(&D0, 1) };
|
|
pub static S3: &[MaybeUninit<&u32>] = unsafe { from_raw_parts(&D1, 1) };
|
|
|
|
// Reinterpreting data is fine, as long as layouts match
|
|
pub static S4: &[u8] = unsafe { from_raw_parts((&D0) as *const _ as _, 3) };
|
|
// This is only valid because D1 has uninitialized bytes, if it was an initialized pointer,
|
|
// that would reinterpret pointers as integers which is UB in CTFE.
|
|
pub static S5: &[MaybeUninit<u8>] = unsafe { from_raw_parts((&D1) as *const _ as _, 2) };
|
|
// Even though u32 and [bool; 4] have different layouts, D0 has a value that
|
|
// is valid as [bool; 4], so this is not UB (it's basically a transmute)
|
|
pub static S6: &[bool] = unsafe { from_raw_parts((&D0) as *const _ as _, 4) };
|
|
|
|
// Structs are considered single allocated objects,
|
|
// as long as you don't reinterpret padding as initialized
|
|
// data everything is ok.
|
|
pub static S7: &[u16] = unsafe {
|
|
let ptr = (&D2 as *const Struct as *const u16).byte_add(4);
|
|
|
|
from_raw_parts(ptr, 3)
|
|
};
|
|
pub static S8: &[MaybeUninit<u16>] = unsafe {
|
|
let ptr = &D2 as *const Struct as *const MaybeUninit<u16>;
|
|
|
|
from_raw_parts(ptr, 6)
|
|
};
|
|
|
|
pub static R0: &[u32] = unsafe { from_ptr_range(dangling()..dangling()) };
|
|
// from_ptr_range panics on zst
|
|
//pub static R1: &[()] = unsafe { from_ptr_range(dangling(), dangling().byte_add(3)) };
|
|
pub static R2: &[u32] = unsafe {
|
|
let ptr = &D0 as *const u32;
|
|
from_ptr_range(ptr..ptr.add(1))
|
|
};
|
|
pub static R3: &[MaybeUninit<&u32>] = unsafe {
|
|
let ptr = &D1 as *const MaybeUninit<&u32>;
|
|
from_ptr_range(ptr..ptr.add(1))
|
|
};
|
|
pub static R4: &[u8] = unsafe {
|
|
let ptr = &D0 as *const u32 as *const u8;
|
|
from_ptr_range(ptr..ptr.add(3))
|
|
};
|
|
pub static R5: &[MaybeUninit<u8>] = unsafe {
|
|
let ptr = &D1 as *const MaybeUninit<&u32> as *const MaybeUninit<u8>;
|
|
from_ptr_range(ptr..ptr.add(2))
|
|
};
|
|
pub static R6: &[bool] = unsafe {
|
|
let ptr = &D0 as *const u32 as *const bool;
|
|
from_ptr_range(ptr..ptr.add(4))
|
|
};
|
|
pub static R7: &[u16] = unsafe {
|
|
let d2 = &D2;
|
|
let l = &d2.b as *const u32 as *const u16;
|
|
let r = &d2.d as *const u8 as *const u16;
|
|
|
|
from_ptr_range(l..r)
|
|
};
|
|
pub static R8: &[MaybeUninit<u16>] = unsafe {
|
|
let d2 = &D2;
|
|
let l = d2 as *const Struct as *const MaybeUninit<u16>;
|
|
let r = &d2.d as *const u8 as *const MaybeUninit<u16>;
|
|
|
|
from_ptr_range(l..r)
|
|
};
|
|
|
|
// Using valid slice is always valid
|
|
pub static R9: &[u32] = unsafe { from_ptr_range(R0.as_ptr_range()) };
|
|
pub static R10: &[u32] = unsafe { from_ptr_range(R2.as_ptr_range()) };
|
|
|
|
const D0: u32 = (1 << 16) | 1;
|
|
const D1: MaybeUninit<&u32> = MaybeUninit::uninit();
|
|
const D2: Struct = Struct { a: 1, b: 2, c: 3, d: 4 };
|
|
|
|
const fn dangling<T>() -> *const T {
|
|
ptr::NonNull::dangling().as_ptr() as _
|
|
}
|
|
|
|
#[repr(C)]
|
|
struct Struct {
|
|
a: u8,
|
|
// _pad: [MaybeUninit<u8>; 3]
|
|
b: u32,
|
|
c: u16,
|
|
d: u8,
|
|
// _pad: [MaybeUninit<u8>; 1]
|
|
}
|
|
|
|
fn main() {}
|