Add test for two sequence repetitions in a row

src/test/compile-fail/macro-seq-followed-by-seq.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.
+
+// Check that we cannot have two sequence repetitions in a row.
+
+macro_rules! foo {
+  ( $($a:expr)* $($b:tt)* ) => { }; //~ ERROR sequence repetition followed by another sequence
+  ( $($a:tt)* $($b:tt)* ) => { }; //~ ERROR sequence repetition followed by another sequence
+}
+
+fn main() { }