Add test case for issue #1733

Author: marijnh

src/test/run-pass/operator-overloading.rs

@@ -23,4 +23,6 @@ fn main() {
     assert -p == {x: -11, y: -22};
     assert p[true] == 11;
     assert p[false] == 22;
+    // Issue #1733
+    fn~(_x: int){}(p[true]);
 }