Relate the module hierarchy to directory paths in the parser

Introduces a temporary 'path2' attribute that will replace 'path' after
a snapshot

src/test/run-pass/mod_dir_recursive.rs

@@ -0,0 +1,24 @@
+// Copyright 2012 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.
+
+// xfail-pretty
+// xfail-fast
+
+// Testing that the parser for each file tracks its modules
+// and paths independently. The load_another_mod module should
+// not try to reuse the 'mod_dir_simple' path.
+
+mod mod_dir_simple {
+    pub mod load_another_mod;
+}
+
+fn main() {
+    assert mod_dir_simple::load_another_mod::test::foo() == 10;
+}