Suggest desugaring to RPITIT when AFIT is required to be an auto trait

1 files changed, 20 insertions, 0 deletions

diff --git a/tests/ui/async-await/in-trait/send-on-async-fn-in-trait.rs b/tests/ui/async-await/in-trait/send-on-async-fn-in-trait.rs
new file mode 100644
index 00000000000..96b623d6988
--- /dev/null
+++ b/tests/ui/async-await/in-trait/send-on-async-fn-in-trait.rs
@@ -0,0 +1,20 @@
+// run-rustfix
+// edition: 2021
+
+#![feature(async_fn_in_trait, return_position_impl_trait_in_trait)]
+#![allow(unused)]
+
+trait Foo {
+    async fn test() -> () {}
+    async fn test2() -> i32 { 1 + 2 }
+}
+
+fn bar<T: Foo>() {
+    fn needs_send(_: impl Send) {}
+    needs_send(T::test());
+    //~^ ERROR `impl Future<Output = ()>` cannot be sent between threads safely
+    needs_send(T::test2());
+    //~^ ERROR `impl Future<Output = i32>` cannot be sent between threads safely
+}
+
+fn main() {}