Add E0571 test

Author: GuillaumeGomez

src/librustc_typeck/check/mod.rs

@@ -3707,7 +3707,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
           hir::ExprRet(ref expr_opt) => {
             if self.ret_ty.is_none() {
                 struct_span_err!(self.tcx.sess, expr.span, E0571,
-                                 "return statement cannot be out of a function scope").emit();
+                                 "return statement outside of function body").emit();
             } else if let Some(ref e) = *expr_opt {
                 self.check_expr_coercable_to_type(&e, self.ret_ty.unwrap());
             } else {

src/librustc_typeck/diagnostics.rs

@@ -4165,24 +4165,23 @@ If necessary, you can circumvent this check using custom target specifications.
 "##,
 
 E0571: r##"
-A return statement was outside a function scope.
+A return statement was found outside of a function body.
 
 Erroneous code example:
 
 ```compile_fail,E0571
-const FOO: u32 = return 0; // error: return statement cannot be out of a
-                           //        function scope
+const FOO: u32 = return 0; // error: return statement outside of function body
 
 fn main() {}
 ```
 
-To fix this issue, just remove the return statement or move it into a function
-scope. Example:
+To fix this issue, just remove the return keyword or move the expression into a
+function. Example:
 
 ```
 const FOO: u32 = 0;
 
-fn some_fn() -> i32 {
+fn some_fn() -> u32 {
     return FOO;
 }
 

src/test/compile-fail/E0571.rs

@@ -0,0 +1,13 @@
+// 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.
+
+const FOO: u32 = return 0; //~ ERROR E0571
+
+fn main() {}