add a test for const fn methods, as suggested by @pnkfelix

Author: nikomatsakis

src/test/run-pass/const-fn-method.rs

@@ -0,0 +1,25 @@
+// Copyright 2012 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.
+
+#![feature(const_fn)]
+
+struct Foo { val: u32 }
+
+impl Foo {
+    const fn new() -> Foo {
+        Foo { value: 22 }
+    }
+}
+
+const FOO: Foo = Foo::new();
+
+pub fn main() {
+    assert_eq!(FOO.value, 22);
+}