///
/// * `ptr` needs to have been previously allocated via [`String`]/`Vec<T>`
/// (at least, it's highly likely to be incorrect if it wasn't).
+ /// * `ptr`'s `T` needs to have the same size and alignment as it was allocated with.
/// * `length` needs to be less than or equal to `capacity`.
/// * `capacity` needs to be the capacity that the pointer was allocated with.
///
/// // The no-copy, unsafe way, still using transmute, but not UB.
/// // This is equivalent to the original, but safer, and reuses the
/// // same Vec internals. Therefore the new inner type must have the
- /// // exact same size, and the same or lesser alignment, as the old
- /// // type. The same caveats exist for this method as transmute, for
+ /// // exact same size, and the same alignment, as the old type.
+ /// // The same caveats exist for this method as transmute, for
/// // the original inner type (`&i32`) to the converted inner type
/// // (`Option<&i32>`), so read the nomicon pages linked above.
/// let v_from_raw = unsafe {
- /// Vec::from_raw_parts(v_orig.as_mut_ptr(),
+ /// Vec::from_raw_parts(v_orig.as_mut_ptr() as *mut Option<&i32>,
/// v_orig.len(),
/// v_orig.capacity())
/// };