Test that function types are actually zero-sized.

src/test/run-pass/fn-item-type-zero-sized.rs

@@ -0,0 +1,22 @@
+// Copyright 2016 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.
+
+// Test that fn item types are zero-sized.
+
+use std::mem::{size_of, size_of_val};
+
+fn main() {
+    assert_eq!(size_of_val(&main), 0);
+
+    let (a, b) = (size_of::<u8>, size_of::<u16>);
+    assert_eq!(size_of_val(&a), 0);
+    assert_eq!(size_of_val(&b), 0);
+    assert_eq!((a(), b()), (1, 2));
+}