Cargo build hangs - minimized, a bit more rust-lang/rust#88862

Cargo.toml

[package]
name = "maybe"
version = "0.1.0"
edition = "2018"
resolver = "2"


[dependencies]
sqlx = { version = "0.5.7", default-features = false, features = [
    "runtime-tokio-native-tls",
    "postgres"
] }
actix-web = "4.0.0-beta.9"

main.rs

pub struct FooDb;

impl FooDb {
    async fn nested(&self) -> Result<Option<String>, ()>
where {
        (
            async move {
                match async move {
                    {
                        async move {
                            (
                                async move {
                                    match async move {
                                        {
                                            let db: sqlx::Pool<sqlx::postgres::Postgres> = todo!();
                                            let mut conn = db.acquire().await.unwrap();

                                            Ok::<_, ()>(String::default())
                                        }
                                    }
                                    .await
                                    {
                                        #[allow(clippy::unit_arg)]
                                        Ok(x) => Ok::<_, ()>(x),
                                        Err(_) => {
                                            todo!()
                                        }
                                    }
                                },
                                todo!(),
                            )
                                .0
                                .await
                        }
                        .await
                        .map_err(Into::into)
                        .map(Some)
                    }
                }
                .await
                {
                    #[allow(clippy::unit_arg)]
                    Ok(x) => Ok(x),
                    Err(e) => Err(e),
                }
            },
            todo!(),
        )
            .0
            .await
    }
}
use actix_web::{web, HttpResponse};
fn main() -> Result<(), Box<dyn std::error::Error + 'static>> {
    let __resource = actix_web::Resource::new("update").to(route);
    todo!()
}

async fn route(
    database: web::Data<FooDb>,
) -> Result<HttpResponse, Box<dyn std::error::Error + 'static>> {
    let _token = database.nested().await;
    todo!();
}