task: clarify the behavior of several spawn_local methods (#7669)

tokio/src/task/join_set.rs

@@ -167,9 +167,9 @@ impl<T: 'static> JoinSet<T> {
         self.insert(handle.spawn(task))
     }
 
-    /// Spawn the provided task on the current [`LocalSet`] and store it in this
-    /// `JoinSet`, returning an [`AbortHandle`] that can be used to remotely
-    /// cancel the task.
+    /// Spawn the provided task on the current [`LocalSet`] or [`LocalRuntime`]
+    /// and store it in this `JoinSet`, returning an [`AbortHandle`] that can
+    /// be used to remotely cancel the task.
     ///
     /// The provided future will start running in the background immediately
     /// when this method is called, even if you don't await anything on this
@@ -177,9 +177,10 @@ impl<T: 'static> JoinSet<T> {
     ///
     /// # Panics
     ///
-    /// This method panics if it is called outside of a `LocalSet`.
+    /// This method panics if it is called outside of a `LocalSet`or `LocalRuntime`.
     ///
     /// [`LocalSet`]: crate::task::LocalSet
+    /// [`LocalRuntime`]: crate::runtime::LocalRuntime
     /// [`AbortHandle`]: crate::task::AbortHandle
     #[track_caller]
     pub fn spawn_local<F>(&mut self, task: F) -> AbortHandle

tokio/src/task/local.rs

@@ -345,7 +345,7 @@ cfg_rt! {
     ///
     /// # Panics
     ///
-    /// This function panics if called outside of a [`LocalSet`].
+    /// This function panics if called outside of a [`LocalSet`] or [`LocalRuntime`].
     ///
     /// Note that if [`tokio::spawn`] is used from within a `LocalSet`, the
     /// resulting new task will _not_ be inside the `LocalSet`, so you must use
@@ -428,7 +428,7 @@ cfg_rt! {
                 unsafe { handle.spawn_local(task, id, meta.spawned_at) }
             } else {
                 match CURRENT.with(|LocalData { ctx, .. }| ctx.get()) {
-                    None => panic!("`spawn_local` called from outside of a `task::LocalSet` or LocalRuntime"),
+                    None => panic!("`spawn_local` called from outside of a `task::LocalSet` or `runtime::LocalRuntime`"),
                     Some(cx) => cx.spawn(future.take().unwrap(), meta)
                 }
             })
@@ -438,7 +438,7 @@ cfg_rt! {
             Ok(None) => panic!("Local tasks can only be spawned on a LocalRuntime from the thread the runtime was created on"),
             Ok(Some(join_handle)) => join_handle,
             Err(_) => match CURRENT.with(|LocalData { ctx, .. }| ctx.get()) {
-                None => panic!("`spawn_local` called from outside of a `task::LocalSet` or LocalRuntime"),
+                None => panic!("`spawn_local` called from outside of a `task::LocalSet` or `runtime::LocalRuntime`"),
                 Some(cx) => cx.spawn(future.unwrap(), meta)
             }
         }