Add a test for iterators that capture but don't lend

Author: eholk

tests/ui/iterators/generator_capture_no_lend.rs

@@ -0,0 +1,30 @@
+//@ run-pass
+
+#![feature(iter_macro, yield_expr)]
+
+// This test creates an iterator that captures a reference and ensure that doesn't force the
+// iterator to become lending.
+
+use std::iter::iter;
+
+fn main() {
+    let s = "foo".to_string();
+    let f = iter! { || {
+        for c in s.chars() {
+            yield c;
+        }
+    }};
+
+    let mut i = f();
+    let mut j = f();
+
+    assert_eq!(i.next(), Some('f'));
+    assert_eq!(i.next(), Some('o'));
+    assert_eq!(i.next(), Some('o'));
+    assert_eq!(i.next(), None);
+
+    assert_eq!(j.next(), Some('f'));
+    assert_eq!(j.next(), Some('o'));
+    assert_eq!(j.next(), Some('o'));
+    assert_eq!(j.next(), None);
+}