Extra test for #2311

Author: catamorphism

src/test/run-pass/issue-2311-2.rs

@@ -0,0 +1,10 @@
+iface clam<A: copy> { }
+class foo<A: copy> {
+  let x: A;
+  new(b: A) { self.x = b; }
+   fn bar<B,C:clam<A>>(c: C) -> B {
+     fail;
+   }
+}
+
+fn main() { }