Add a test case for const fn sizing, just to be safe.

Author: jld

src/test/run-pass/const-vec-of-fns.rs

@@ -0,0 +1,27 @@
+// Copyright 2013 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.
+
+/*!
+ * Try to double-check that const fns have the right size (with or
+ * without dummy env ptr, as appropriate) by iterating a size-2 array.
+ * If the const size differs from the runtime size, the second element
+ * should be read as a null or otherwise wrong pointer and crash.
+ */
+
+fn f() { }
+const bare_fns: &[extern fn()] = &[f, f];
+// NOTE Why does this not type without the struct?
+struct S(&fn());
+const closures: &[S] = &[S(f), S(f)];
+
+pub fn main() {
+    for bare_fns.each |&bare_fn| { bare_fn() }
+    for closures.each |&closure| { (*closure)() }
+}