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    use crate::runtime;
    use crate::task::JoinHandle;

    use std::future::Future;

    cfg_rt! {
        /// Spawns a new asynchronous task, returning a
        /// [`JoinHandle`](super::JoinHandle) for it.
        ///
        /// Spawning a task enables the task to execute concurrently to other tasks. The
        /// spawned task may execute on the current thread, or it may be sent to a
        /// different thread to be executed. The specifics depend on the current
        /// [`Runtime`](crate::runtime::Runtime) configuration.
        ///
        /// There is no guarantee that a spawned task will execute to completion.
        /// When a runtime is shutdown, all outstanding tasks are dropped,
        /// regardless of the lifecycle of that task.
        ///
        /// This function must be called from the context of a Tokio runtime. Tasks running on
        /// the Tokio runtime are always inside its context, but you can also enter the context
        /// using the [`Runtime::enter`](crate::runtime::Runtime::enter()) method.
        ///
        /// # Examples
        ///
        /// In this example, a server is started and `spawn` is used to start a new task
        /// that processes each received connection.
        ///
        /// ```no_run
        /// use tokio::net::{TcpListener, TcpStream};
        ///
        /// use std::io;
        ///
        /// async fn process(socket: TcpStream) {
        ///     // ...
        /// # drop(socket);
        /// }
        ///
        /// #[tokio::main]
        /// async fn main() -> io::Result<()> {
        ///     let listener = TcpListener::bind("127.0.0.1:8080").await?;
        ///
        ///     loop {
        ///         let (socket, _) = listener.accept().await?;
        ///
        ///         tokio::spawn(async move {
        ///             // Process each socket concurrently.
        ///             process(socket).await
        ///         });
        ///     }
        /// }
        /// ```
        ///
        /// # Panics
        ///
        /// Panics if called from **outside** of the Tokio runtime.
        ///
        /// # Using `!Send` values from a task
        ///
        /// The task supplied to `spawn` must implement `Send`. However, it is
        /// possible to **use** `!Send` values from the task as long as they only
        /// exist between calls to `.await`.
        ///
        /// For example, this will work:
        ///
        /// ```
        /// use tokio::task;
        ///
        /// use std::rc::Rc;
        ///
        /// fn use_rc(rc: Rc<()>) {
        ///     // Do stuff w/ rc
        /// # drop(rc);
        /// }
        ///
        /// #[tokio::main]
        /// async fn main() {
        ///     tokio::spawn(async {
        ///         // Force the `Rc` to stay in a scope with no `.await`
        ///         {
        ///             let rc = Rc::new(());
        ///             use_rc(rc.clone());
        ///         }
        ///
        ///         task::yield_now().await;
        ///     }).await.unwrap();
        /// }
        /// ```
        ///
        /// This will **not** work:
        ///
        /// ```compile_fail
        /// use tokio::task;
        ///
        /// use std::rc::Rc;
        ///
        /// fn use_rc(rc: Rc<()>) {
        ///     // Do stuff w/ rc
        /// # drop(rc);
        /// }
        ///
        /// #[tokio::main]
        /// async fn main() {
        ///     tokio::spawn(async {
        ///         let rc = Rc::new(());
        ///
        ///         task::yield_now().await;
        ///
        ///         use_rc(rc.clone());
        ///     }).await.unwrap();
        /// }
        /// ```
        ///
        /// Holding on to a `!Send` value across calls to `.await` will result in
        /// an unfriendly compile error message similar to:
        ///
        /// ```text
        /// `[... some type ...]` cannot be sent between threads safely
        /// ```
        ///
        /// or:
        ///
        /// ```text
        /// error[E0391]: cycle detected when processing `main`
        /// ```
        #[cfg_attr(tokio_track_caller, track_caller)]
        pub fn spawn<T>(task: T) -> JoinHandle<T::Output>
        where
            T: Future + Send + 'static,
            T::Output: Send + 'static,
        {
            let spawn_handle = runtime::context::spawn_handle()
            .expect("must be called from the context of Tokio runtime configured with either `basic_scheduler` or `threaded_scheduler`");
            let task = crate::util::trace::task(task, "task");
            spawn_handle.spawn(task)
        }
    }