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//@ build-pass
//@ compile-flags: -Zmir-opt-level=3
use std::fmt::Debug;
use std::mem::ManuallyDrop;
use std::ptr;
pub trait BitRegister {}
macro_rules! register {
($($t:ty),+ $(,)?) => { $(
impl BitRegister for $t {
}
)* };
}
register!(u8, u16, u32);
pub trait BitStore: Sized + Debug {
/// The register type that the implementor describes.
type Mem: BitRegister + Into<Self>;
}
macro_rules! store {
($($t:ty),+ $(,)?) => { $(
impl BitStore for $t {
type Mem = Self;
}
)+ };
}
store!(u8, u16, u32,);
#[repr(C)]
pub struct BitVec<T>
where
T: BitStore,
{
/// Region pointer describing the live portion of the owned buffer.
pointer: ptr::NonNull<T>,
/// Allocated capacity, in elements `T`, of the owned buffer.
capacity: usize,
}
impl<T> BitVec<T>
where
T: BitStore,
{
pub fn new() -> Self {
let pointer = ptr::NonNull::<T>::new(ptr::null_mut()).unwrap();
BitVec { pointer, capacity: 10 }
}
pub fn clear(&mut self) {
unsafe {
self.set_len(0);
}
}
#[inline]
pub unsafe fn set_len(&mut self, new_len: usize) {}
fn with_vec<F, R>(&mut self, func: F) -> R
where
F: FnOnce(&mut ManuallyDrop<Vec<T::Mem>>) -> R,
{
let cap = self.capacity;
let elts = 10;
let mut vec = ManuallyDrop::new(unsafe { Vec::from_raw_parts(ptr::null_mut(), elts, cap) });
let out = func(&mut vec);
out
}
}
impl<T> Drop for BitVec<T>
where
T: BitStore,
{
#[inline]
fn drop(&mut self) {
// The buffer elements do not have destructors.
self.clear();
// Run the `Vec` destructor to deällocate the buffer.
self.with_vec(|vec| unsafe { ManuallyDrop::drop(vec) });
}
}
fn main() {
let bitvec = BitVec::<u32>::new();
}
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