1 files changed, 36 insertions, 0 deletions
diff --git a/src/test/ui/associated-types/associated-types-binding-in-trait.rs b/src/test/ui/associated-types/associated-types-binding-in-trait.rs
new file mode 100644
index 000000000..2e42b3a2a
--- /dev/null
+++ b/src/test/ui/associated-types/associated-types-binding-in-trait.rs
@@ -0,0 +1,36 @@
+// run-pass
+// Test a case where the associated type binding (to `bool`, in this
+// case) is derived from the trait definition. Issue #21636.
+
+
+use std::vec;
+
+pub trait BitIter {
+    type Iter: Iterator<Item=bool>;
+    fn bit_iter(self) -> <Self as BitIter>::Iter;
+}
+
+impl BitIter for Vec<bool> {
+    type Iter = vec::IntoIter<bool>;
+    fn bit_iter(self) -> <Self as BitIter>::Iter {
+        self.into_iter()
+    }
+}
+
+fn count<T>(arg: T) -> usize
+    where T: BitIter
+{
+    let mut sum = 0;
+    for i in arg.bit_iter() {
+        if i {
+            sum += 1;
+        }
+    }
+    sum
+}
+
+fn main() {
+    let v = vec![true, false, true];
+    let c = count(v);
+    assert_eq!(c, 2);
+}