1 files changed, 44 insertions, 0 deletions
diff --git a/src/test/ui/associated-types/associated-types-nested-projections.rs b/src/test/ui/associated-types/associated-types-nested-projections.rs
new file mode 100644
index 000000000..76ba74962
--- /dev/null
+++ b/src/test/ui/associated-types/associated-types-nested-projections.rs
@@ -0,0 +1,44 @@
+// run-pass
+#![allow(unused_variables)]
+// Test that we can resolve nested projection types. Issue #20666.
+
+// pretty-expanded FIXME #23616
+
+use std::slice;
+
+trait Bound {}
+
+impl<'a> Bound for &'a i32 {}
+
+trait IntoIterator {
+    type Iter: Iterator;
+
+    fn into_iter(self) -> Self::Iter;
+}
+
+impl<'a, T> IntoIterator for &'a [T; 3] {
+    type Iter = slice::Iter<'a, T>;
+
+    fn into_iter(self) -> slice::Iter<'a, T> {
+        self.iter()
+    }
+}
+
+fn foo<X>(x: X) where
+    X: IntoIterator,
+    <<X as IntoIterator>::Iter as Iterator>::Item: Bound,
+{
+}
+
+fn bar<T, I, X>(x: X) where
+    T: Bound,
+    I: Iterator<Item=T>,
+    X: IntoIterator<Iter=I>,
+{
+
+}
+
+fn main() {
+    foo(&[0, 1, 2]);
+    bar(&[0, 1, 2]);
+}