Test and gate empty structures and variants better

src/test/compile-fail/empty-struct-unit-expr.rs

@@ -0,0 +1,24 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+// Can't use unit struct as constructor function
+
+#![feature(braced_empty_structs)]
+
+struct Empty1;
+
+enum E {
+    Empty2
+}
+
+fn main() {
+    let e1 = Empty1(); //~ ERROR expected function, found `Empty1`
+    let e2 = E::Empty2(); //~ ERROR expected function, found `E`
+}