Function deadlock

crates/common/src/lock/cell_lock.rs:206–208

(lock_kind: &str, ty: &str)

#[cold]
#[inline(never)]
fn deadlock(lock_kind: &str, ty: &str) -> ! {
    panic!("deadlock: tried to {lock_kind}lock a Cell{ty} twice")
}

#[derive(Clone, Copy)]
pub struct SingleThreadId(());