`Unexpected initial operand type` with async closures and `FnOnce`

[compiler-errors]

Something is still wrong w/ async call shims. I think I'm not doing the FnOnce transform correctly or something.

Putting this up so I don't forget about it, but I'll fix it.

#![feature(async_closure)]

#[inline(never)]
async fn call_once(x: impl async FnOnce()) {
    x().await
}

#[tokio::main]
async fn main() {
    let v = &1;
    call_once(async || {
        println!("{v}");
    }).await;
}

Unexpected initial operand type: expected *mut Coroutine(DefId(0:8 ~ playground[5acf]::main::{closure#0}::{closure#0}::{closure#0}), [i32, std::future::ResumeTy, (), (), CoroutineWitness(DefId(0:8 ~ playground[5acf]::main::{closure#0}::{closure#0}::{closure#0}), []), (&'{erased} i32,)]), found *mut Coroutine(DefId(0:8 ~ playground[5acf]::main::{closure#0}::{closure#0}::{closure#0}), [i32, std::future::ResumeTy, (), (), CoroutineWitness(DefId(0:8 ~ playground[5acf]::main::{closure#0}::{closure#0}::{closure#0}), []), (&'{erased} &'{erased} i32,)]).

[compiler-errors]

ohhhhh lol it's drop glue. Huh.

[compiler-errors]

Oh hell yes this is actually totally wrong wtf: https://play.rust-lang.org/?version=nightly&mode=debug&edition=2021&gist=27705c62015311f886426e3aa87157e9