Why we cannot await a future produced by a non-send struct even thought the struct is created in the same scope and we're on current_thread flavor?

[ogios]

struct ANotSendStruct {
    _marker: PhantomData<*const ()>,
}
impl ANotSendStruct {
    async fn run(&self) {}
}
#[tokio::main(flavor = "current_thread")]
async fn main() {
    tokio::spawn(async {
        ANotSendStruct {
            _marker: PhantomData,
        }
        .run()
        .await;

        println!("sff");
    });
}

the struct is created inside the async block and in the same scope, also we're on current_thread flavor, why do we still need the struct to be Send?

this brings some restriction

[Darksonn]

The current-thread runtime actually can be moved between threads. The Runtime object is Send, so you could call block_on on one thread, and then on another thread.

For !Send futures there is LocalSet and LocalRuntime.

Note that even if you use LocalSet/LocalRuntime, the tokio::spawn method still requires Send. However, when using either of those, you can use spawn_local instead to spawn a local task.

[ogios]

i figured out how to do it with LocalRuntime, but the code is rather weird and unsafe:

oneshot.rs
atomic_local_runtime.rs