std::os::wasi::io::AsFd regression on Rust 1.64

[sunfishcode]

I tried this code:

#![allow(unused_imports)]

use std::os::wasi::io::AsFd;

I expected to see this happen: it compiles

Instead, this happened:

With Rust 1.63, it compiles. With Rust 1.64 and Rust nightly, it gets this error:

error[E0658]: use of unstable library feature 'wasi_ext'
 --> src/lib.rs:3:5
  |
3 | use std::os::wasi::io::AsFd;
  |     ^^^^^^^^^^^^^^^^^^^^^^^
  |
  = note: see issue #71213 <https://github.com/rust-lang/rust/issues/71213> for more information