add an unstable task::spawn_blocking function

Signed-off-by: Yoshua Wuyts <yoshuawuyts@gmail.com>

src/task/mod.rs

@@ -48,3 +48,17 @@ mod task_local;
 mod worker;
 
 pub(crate) mod blocking;
+
+/// Spawns a blocking task.
+///
+/// The task will be spawned onto a thread pool specifically dedicated to blocking tasks.
+#[cfg(any(feature = "unstable", feature = "docs"))]
+#[cfg_attr(feature = "docs", doc(cfg(unstable)))]
+#[inline]
+pub fn spawn_blocking<F, R>(future: F) -> blocking::JoinHandle<R>
+where
+    F: crate::future::Future<Output = R> + Send + 'static,
+    R: Send + 'static,
+{
+    blocking::spawn(future)
+}