Function current_task 

pub fn current_task() -> Option<CurrentTask>

The task running right now, if any.

Null outside a task, which is what makes it useful: a Rust closure handed to .task { } or to detached can tell whether Swift’s scheduler is what called it, and can ask that task whether it has been cancelled — which is the whole of structured cancellation from this side.

let v = views::task(
    &views::text("loading"),
    0,
    views::TaskPriority::Utility,
    file!(),
    line!() as i64,
    || {
        while !runtime::current_task().is_some_and(|t| t.is_cancelled()) {
            // …work…
            break;
        }
    },
);