Playing with async triggers compiler bug "TLS Waker not set"

[snakehand]

#![feature(futures_api,async_await,gen_future)]

extern crate core;
use std::future::Future;
use core::{pin::Pin, task::Poll};

async fn tst() -> i32 {
    42
}

fn main() {
    println!("Hi");
    let mut a = tst();
    let b = std::future::poll_with_tls_waker(unsafe { Pin::new_unchecked(&mut a) });
    println!("{:?}", b);
}

rustc 1.34.0-nightly (aadbc45 2019-02-23)

Causes:

Hi
thread 'main' panicked at 'TLS Waker not set. This is a rustc bug. Please file an issue on https://github.com/rust-lang/rust.', src/libcore/option.rs:1038:5

[cramertj]

This is intended. Those functions aren't designed to be stable, ever-- they're compiler implementation details.