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

tokio-util/src/task/join_map.rs

@@ -345,8 +345,8 @@ where
         self.insert(key, task);
     }
 
-    /// Spawn the provided task on the current [`LocalSet`] and store it in this
-    /// `JoinMap` with the provided key.
+    /// Spawn the provided task on the current [`LocalSet`] or [`LocalRuntime`]
+    /// and store it in this `JoinMap` with the provided key.
     ///
     /// If a task previously existed in the `JoinMap` for this key, that task
     /// will be cancelled and replaced with the new one. The previous task will
@@ -355,9 +355,10 @@ where
     ///
     /// # 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`]: tokio::task::LocalSet
+    /// [`LocalRuntime`]: tokio::runtime::LocalRuntime
     /// [`join_next`]: Self::join_next
     #[track_caller]
     pub fn spawn_local<F>(&mut self, key: K, task: F)

tokio-util/src/task/join_queue.rs

@@ -88,9 +88,9 @@ impl<T> JoinQueue<T> {
         self.push_back(handle.spawn(task))
     }
 
-    /// Spawn the provided task on the current [`LocalSet`] and store it in this
-    /// [`JoinQueue`], 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 [`JoinQueue`], 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
@@ -98,9 +98,10 @@ impl<T> JoinQueue<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`]: tokio::task::LocalSet
+    /// [`LocalRuntime`]: tokio::runtime::LocalRuntime
     /// [`AbortHandle`]: tokio::task::AbortHandle
     #[track_caller]
     pub fn spawn_local<F>(&mut self, task: F) -> AbortHandle

tokio-util/src/task/task_tracker.rs

@@ -401,11 +401,17 @@ impl TaskTracker {
         handle.spawn(self.track_future(task))
     }
 
-    /// Spawn the provided future on the current [`LocalSet`], and track it in this `TaskTracker`.
+    /// Spawn the provided future on the current [`LocalSet`] or [`LocalRuntime`]
+    /// and track it in this `TaskTracker`.
     ///
     /// This is equivalent to `tokio::task::spawn_local(tracker.track_future(task))`.
     ///
+    /// # Panics
+    ///
+    /// This method panics if it is called outside of a `LocalSet` or `LocalRuntime`.
+    ///
     /// [`LocalSet`]: tokio::task::LocalSet
+    /// [`LocalRuntime`]: tokio::runtime::LocalRuntime
     #[inline]
     #[track_caller]
     #[cfg(feature = "rt")]