tokio: Fix empty join! and try_join!

This closes tokio-rs#5502.
adrianheine · Feb 25, 2023 · 0b8be26 · 0b8be26
1 parent c894069
commit 0b8be26
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Showing 4 changed files with 16 additions and 2 deletions.
diff --git a/tokio/src/macros/join.rs b/tokio/src/macros/join.rs
@@ -158,7 +158,9 @@ macro_rules! join {
 
     // ===== Entry point =====
 
-    ( $($e:expr),* $(,)?) => {
+    ( $($e:expr),+ $(,)?) => {
         $crate::join!(@{ () (0) } $($e,)*)
     };
+
+    () => { async {}.await }
 }
diff --git a/tokio/src/macros/try_join.rs b/tokio/src/macros/try_join.rs
@@ -210,7 +210,9 @@ macro_rules! try_join {
 
     // ===== Entry point =====
 
-    ( $($e:expr),* $(,)?) => {
+    ( $($e:expr),+ $(,)?) => {
         $crate::try_join!(@{ () (0) } $($e,)*)
     };
+
+    () => { async { Ok(()) }.await }
 }
diff --git a/tokio/tests/macros_join.rs b/tokio/tests/macros_join.rs
@@ -153,3 +153,8 @@ async fn a_different_future_is_polled_first_every_time_poll_fn_is_polled() {
         *poll_order.lock().unwrap()
     );
 }
+
+#[tokio::test]
+async fn empty_join() {
+    assert_eq!(tokio::join!(), ());
+}
diff --git a/tokio/tests/macros_try_join.rs b/tokio/tests/macros_try_join.rs
@@ -183,3 +183,8 @@ async fn a_different_future_is_polled_first_every_time_poll_fn_is_polled() {
         *poll_order.lock().unwrap()
     );
 }
+
+#[tokio::test]
+async fn empty_try_join() {
+    assert_eq!(tokio::try_join!() as Result<_, ()>, Ok(()));
+}