Added regression function match value test, closes rust-lang#44333

Author: Aaron Power

src/test/run-pass/issue-44333.rs

@@ -0,0 +1,29 @@
+// Copyright 2018 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.
+
+type Func = fn(usize, usize) -> usize;
+
+fn foo(a: usize, b: usize) -> usize { a + b }
+fn bar(a: usize, b: usize) -> usize { a * b }
+fn test(x: usize) -> Func {
+    if x % 2 == 0 { foo }
+    else { bar }
+}
+
+const FOO: Func = foo;
+const BAR: Func = bar;
+
+fn main() {
+    match test(std::env::consts::ARCH.len()) {
+        FOO => println!("foo"),
+        BAR => println!("bar"),
+        _ => unreachable!(),
+    }
+}