allow constant evaluation of function calls

src/test/compile-fail/const-eval-span.rs

@@ -14,7 +14,7 @@
 struct S(i32);
 
 const CONSTANT: S = S(0);
-//~^ ERROR: constant evaluation error: unsupported constant expr
+//~^ ERROR: constant evaluation error: non-constant path in constant expression [E0080]
 
 enum E {
     V = CONSTANT,

src/test/compile-fail/const-fn-destructuring-arg.rs

@@ -0,0 +1,18 @@
+// 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.
+
+// test that certain things are disallowed in const fn signatures
+
+#![feature(const_fn)]
+
+// no destructuring
+const fn i((a, b): (u32, u32)) -> u32 { a + b } //~ ERROR: E0022
+
+fn main() {}

src/test/compile-fail/const-fn-stability-calls-2.rs

@@ -17,5 +17,5 @@ extern crate const_fn_lib;
 use const_fn_lib::foo;
 
 fn main() {
-    let x: [usize; foo()] = []; //~ ERROR unsupported constant expr
+    let x: [usize; foo()] = []; //~ ERROR non-constant path in constant expr
 }