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//! Test that various operations involving pointer fragments work as expected.
//@ run-pass
//@ ignore-test: disabled due to <https://github.com/rust-lang/rust/issues/146291>
use std::mem::{self, MaybeUninit, transmute};
use std::ptr;
type Byte = MaybeUninit<u8>;
const unsafe fn memcpy(dst: *mut Byte, src: *const Byte, n: usize) {
let mut i = 0;
while i < n {
*dst.add(i) = *src.add(i);
i += 1;
}
}
const _MEMCPY: () = unsafe {
let ptr = &42;
let mut ptr2 = ptr::null::<i32>();
memcpy(&mut ptr2 as *mut _ as *mut _, &ptr as *const _ as *const _, mem::size_of::<&i32>());
assert!(*ptr2 == 42);
};
const _MEMCPY_OFFSET: () = unsafe {
// Same as above, but the pointer has a non-zero offset so not all the data bytes are the same.
let ptr = &(42, 18);
let ptr = &ptr.1;
let mut ptr2 = ptr::null::<i32>();
memcpy(&mut ptr2 as *mut _ as *mut _, &ptr as *const _ as *const _, mem::size_of::<&i32>());
assert!(*ptr2 == 18);
};
const MEMCPY_RET: MaybeUninit<*const i32> = unsafe {
let ptr = &42;
let mut ptr2 = MaybeUninit::new(ptr::null::<i32>());
memcpy(&mut ptr2 as *mut _ as *mut _, &ptr as *const _ as *const _, mem::size_of::<&i32>());
// Return in a MaybeUninit so it does not get treated as a scalar.
ptr2
};
#[allow(dead_code)]
fn reassemble_ptr_fragments_in_static() {
static DATA: i32 = 1i32;
#[cfg(target_pointer_width = "64")]
struct Thing {
x: MaybeUninit<u32>,
y: MaybeUninit<u32>,
}
#[cfg(target_pointer_width = "32")]
struct Thing {
x: MaybeUninit<u16>,
y: MaybeUninit<u16>,
}
static X: Thing = unsafe {
let Thing { x, y } = transmute(&raw const DATA);
Thing { x, y }
};
}
fn main() {
assert_eq!(unsafe { MEMCPY_RET.assume_init().read() }, 42);
}
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