4 files changed, 26 insertions, 1 deletions
diff --git a/futures/src/executor/async_std.rs b/futures/src/executor/async_std.rs
index 27949e31..471be369 100644
--- a/futures/src/executor/async_std.rs
+++ b/futures/src/executor/async_std.rs
@@ -3,6 +3,7 @@ use crate::Executor;
 use futures::Future;
 
 /// An `async-std` runtime.
+#[cfg_attr(docsrs, doc(cfg(feature = "async-std")))]
 #[derive(Debug)]
 pub struct AsyncStd;
 
diff --git a/futures/src/executor/thread_pool.rs b/futures/src/executor/thread_pool.rs
index 1ec5bf69..a6c6168e 100644
--- a/futures/src/executor/thread_pool.rs
+++ b/futures/src/executor/thread_pool.rs
@@ -3,6 +3,7 @@ use crate::Executor;
 use futures::Future;
 
 /// A thread pool runtime for futures.
+#[cfg_attr(docsrs, doc(cfg(feature = "thread-pool")))]
 pub type ThreadPool = futures::executor::ThreadPool;
 
 impl Executor for futures::executor::ThreadPool {
diff --git a/futures/src/executor/tokio.rs b/futures/src/executor/tokio.rs
index 20802ceb..c6a21cec 100644
--- a/futures/src/executor/tokio.rs
+++ b/futures/src/executor/tokio.rs
@@ -3,6 +3,7 @@ use crate::Executor;
 use futures::Future;
 
 /// A `tokio` runtime.
+#[cfg_attr(docsrs, doc(cfg(feature = "tokio")))]
 pub type Tokio = tokio::runtime::Runtime;
 
 impl Executor for Tokio {
@@ -15,6 +16,7 @@ impl Executor for Tokio {
     }
 
     fn enter<R>(&self, f: impl FnOnce() -> R) -> R {
-        tokio::runtime::Runtime::enter(self, f)
+        let _guard = tokio::runtime::Runtime::enter(self);
+        f()
     }
 }
diff --git a/futures/src/executor/tokio_old.rs b/futures/src/executor/tokio_old.rs
new file mode 100644
index 00000000..d64729fa
--- /dev/null
+++ b/futures/src/executor/tokio_old.rs
@@ -0,0 +1,21 @@
+use crate::Executor;
+
+use futures::Future;
+
+/// An old `tokio` runtime.
+#[cfg_attr(docsrs, doc(cfg(feature = "tokio_old")))]
+pub type TokioOld = tokio_old::runtime::Runtime;
+
+impl Executor for TokioOld {
+    fn new() -> Result<Self, futures::io::Error> {
+        tokio_old::runtime::Runtime::new()
+    }
+
+    fn spawn(&self, future: impl Future<Output = ()> + Send + 'static) {
+        let _ = tokio_old::runtime::Runtime::spawn(self, future);
+    }
+
+    fn enter<R>(&self, f: impl FnOnce() -> R) -> R {
+        tokio_old::runtime::Runtime::enter(self, f)
+    }
+}