Auto merge of #25444 - nikomatsakis:macro-tt-fix, r=pnkfelix

Permit token trees, identifiers, and blocks to be following by sequences.

Fixes #25436.

r? @pnkfelix

src/test/compile-fail/macro-followed-by-seq-bad.rs

@@ -0,0 +1,19 @@
+// 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.
+
+// Regression test for issue #25436: check that things which can be
+// followed by any token also permit X* to come afterwards.
+
+macro_rules! foo {
+  ( $a:expr $($b:tt)* ) => { }; //~ ERROR not allowed for `expr` fragments
+  ( $a:ty $($b:tt)* ) => { };   //~ ERROR not allowed for `ty` fragments
+}
+
+fn main() { }

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() { }

src/test/run-pass/macro-followed-by-seq.rs

@@ -0,0 +1,22 @@
+// 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.
+
+// Regression test for issue #25436: check that things which can be
+// followed by any token also permit X* to come afterwards.
+
+macro_rules! foo {
+  ( $a:tt $($b:tt)* ) => { };
+  ( $a:ident $($b:tt)* ) => { };
+  ( $a:item $($b:tt)* ) => { };
+  ( $a:block $($b:tt)* ) => { };
+  ( $a:meta $($b:tt)* ) => { }
+}
+
+fn main() { }

src/test/run-pass/macro-tt-followed-by-seq.rs

@@ -0,0 +1,36 @@
+// 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.
+
+// Regression test for issue #25436: permit token-trees to be followed
+// by sequences, enabling more general parsing.
+
+use self::Join::*;
+
+#[derive(Debug)]
+enum Join<A,B> {
+  Keep(A,B),
+  Skip(A,B),
+}
+
+macro_rules! parse_list {
+  ( < $a:expr; > $($b:tt)* ) => { Keep(parse_item!($a),parse_list!($($b)*)) };
+  ( $a:tt $($b:tt)* ) => { Skip(parse_item!($a), parse_list!($($b)*)) };
+  ( ) => { () };
+}
+
+macro_rules! parse_item {
+  ( $x:expr ) => { $x }
+}
+
+fn main() {
+    let list = parse_list!(<1;> 2 <3;> 4);
+    assert_eq!("Keep(1, Skip(2, Keep(3, Skip(4, ()))))",
+               format!("{:?}", list));
+}