Cannot resolve PinBox on nightly

[tema3210]

My code is:

#![allow(dead_code)]
#![feature(generators, generator_trait,pin)]
use std::ops::{Generator, GeneratorState};
use std::boxed::PinBox;
use std::pin::Pin;

enum Node<T: Copy>{
	Leafs(Option< Box<Node<T>> >,Option< Box<Node<T>> >),
	Data(T),
}

impl<T: Copy> Node<T> {
...
}

fn IterateOverTreePreOrder<T: Copy>(trg: Node<T>)->PinBox<impl Generator<Yield=T,Return=()>>{
	...
}
...

But this doesn't compile because of:

tema3210@tema2-devhost:~/3kurs_alg_laby/05/rust$ cargo check
    Checking rust v0.1.0 (/home/tema3210/3kurs_alg_laby/05/rust)
error[E0432]: unresolved import `std::boxed::PinBox`
 --> src/main.rs:4:5
  |
4 | use std::boxed::PinBox;
  |     ^^^^^^^^^^^^^^^^^^ no `PinBox` in `boxed`

warning: unused import: `GeneratorState`
 --> src/main.rs:3:27
  |
3 | use std::ops::{Generator, GeneratorState};
  |                           ^^^^^^^^^^^^^^
  |
  = note: `#[warn(unused_imports)]` on by default

warning: unused import: `std::pin::Pin`
 --> src/main.rs:5:5
  |
5 | use std::pin::Pin;
  |     ^^^^^^^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0432`.
error: could not compile `rust`.

To learn more, run the command again with --verbose.

tema3210@tema2-devhost:~/3kurs_alg_laby/05/rust$ rustc --version
rustc 1.40.0-nightly (4f03f4a98 2019-11-12)

[jonas-schievink]

PinBox has been removed. See #49150.