pub fn __from_str(value: &str) -> Rc<str> {
unsafe {
// Allocate enough space for `RcBox<str>`.
- let aligned_len = (value.len() + size_of::<usize>() - 1) / size_of::<usize>();
- let vec = RawVec::<usize>::with_capacity(2 + aligned_len);
+ let aligned_len = 2 + (value.len() + size_of::<usize>() - 1) / size_of::<usize>();
+ let vec = RawVec::<usize>::with_capacity(aligned_len);
let ptr = vec.ptr();
forget(vec);
// Initialize fields of `RcBox<str>`.
*ptr.offset(1) = 1; // weak: Cell::new(1)
ptr::copy_nonoverlapping(value.as_ptr(), ptr.offset(2) as *mut u8, value.len());
// Combine the allocation address and the string length into a fat pointer to `RcBox`.
- let rcbox_ptr = mem::transmute([ptr as usize, value.len()]);
+ let rcbox_ptr: *mut RcBox<str> = mem::transmute([ptr as usize, value.len()]);
+ assert!(aligned_len * size_of::<usize>() == size_of_val(&*rcbox_ptr));
Rc { ptr: Shared::new(rcbox_ptr) }
}
}