1 files changed, 79 insertions, 0 deletions
diff --git a/src/test/ui/traits/issue-38033.rs b/src/test/ui/traits/issue-38033.rs
new file mode 100644
index 000000000..16b867ec8
--- /dev/null
+++ b/src/test/ui/traits/issue-38033.rs
@@ -0,0 +1,79 @@
+// run-pass
+use std::marker;
+use std::mem;
+
+fn main() {
+    let workers = (0..0).map(|_| result::<u32, ()>());
+    drop(join_all(workers).poll());
+}
+
+trait Future {
+    type Item;
+    type Error;
+
+    fn poll(&mut self) -> Result<Self::Item, Self::Error>;
+}
+
+trait IntoFuture {
+    type Future: Future<Item=Self::Item, Error=Self::Error>;
+    type Item;
+    type Error;
+
+    fn into_future(self) -> Self::Future;
+}
+
+impl<F: Future> IntoFuture for F {
+    type Future = F;
+    type Item = F::Item;
+    type Error = F::Error;
+
+    fn into_future(self) -> F {
+        self
+    }
+}
+
+struct FutureResult<T, E> {
+    _inner: marker::PhantomData<(T, E)>,
+}
+
+fn result<T, E>() -> FutureResult<T, E> {
+    loop {}
+}
+
+impl<T, E> Future for FutureResult<T, E> {
+    type Item = T;
+    type Error = E;
+
+    fn poll(&mut self) -> Result<T, E> {
+        loop {}
+    }
+}
+
+struct JoinAll<I>
+    where I: IntoIterator,
+          I::Item: IntoFuture,
+{
+    elems: Vec<<I::Item as IntoFuture>::Item>,
+}
+
+fn join_all<I>(_: I) -> JoinAll<I>
+    where I: IntoIterator,
+          I::Item: IntoFuture,
+{
+    JoinAll { elems: vec![] }
+}
+
+impl<I> Future for JoinAll<I>
+    where I: IntoIterator,
+          I::Item: IntoFuture,
+{
+    type Item = Vec<<I::Item as IntoFuture>::Item>;
+    type Error = <I::Item as IntoFuture>::Error;
+
+    fn poll(&mut self) -> Result<Self::Item, Self::Error> {
+        let elems = mem::replace(&mut self.elems, Vec::new());
+        Ok(elems.into_iter().map(|e| {
+            e
+        }).collect::<Vec<_>>())
+    }
+}