1 files changed, 38 insertions, 0 deletions
diff --git a/src/test/ui/associated-types/associated-types-stream.rs b/src/test/ui/associated-types/associated-types-stream.rs
new file mode 100644
index 000000000..c9b302b96
--- /dev/null
+++ b/src/test/ui/associated-types/associated-types-stream.rs
@@ -0,0 +1,38 @@
+// run-pass
+// Test references to the trait `Stream` in the bounds for associated
+// types defined on `Stream`. Issue #20551.
+
+trait Stream {
+    type Car;
+    type Cdr: Stream;
+
+    fn car(&self) -> Self::Car;
+    fn cdr(self) -> Self::Cdr;
+}
+
+impl Stream for () {
+    type Car = ();
+    type Cdr = ();
+    fn car(&self) -> () { () }
+    fn cdr(self) -> () { self }
+}
+
+impl<T,U> Stream for (T, U)
+    where T : Clone, U : Stream
+{
+    type Car = T;
+    type Cdr = U;
+    fn car(&self) -> T { self.0.clone() }
+    fn cdr(self) -> U { self.1 }
+}
+
+fn main() {
+    let p = (22, (44, (66, ())));
+    assert_eq!(p.car(), 22);
+
+    let p = p.cdr();
+    assert_eq!(p.car(), 44);
+
+    let p = p.cdr();
+    assert_eq!(p.car(), 66);
+}