Add some tests for closures that return !

Author: ftxqxd

src/test/compile-fail/closure-that-fails.rs

@@ -13,5 +13,8 @@ fn foo(f: || -> !) {}
 fn main() {
     // Type inference didn't use to be able to handle this:
     foo(|| fail!());
+    foo(|| -> ! fail!());
     foo(|| 22); //~ ERROR mismatched types
+    foo(|| -> ! 22); //~ ERROR mismatched types
+    let x = || -> ! 1; //~ ERROR mismatched types
 }

src/test/compile-fail/dead-code-closure-bang.rs

@@ -0,0 +1,17 @@
+// Copyright 2014 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.
+
+#![deny(unreachable_code)]
+
+fn main() {
+    let x: || -> ! = || fail!();
+    x();
+    println!("Foo bar"); //~ ERROR: unreachable statement
+}

src/test/run-pass/closure-return-bang.rs

@@ -0,0 +1,20 @@
+// Copyright 2014 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.
+
+#![allow(dead_code)]
+
+fn f(x: || -> !) -> ! {
+    x();
+}
+
+fn main() {
+    let x: || -> ! = || fail!();
+    let _y: || -> ! = || x();
+}