auto merge of #8831 : catamorphism/rust/extend_rust_path, r=catamorphism

r? @brson

@metajack requested the ability to violate the "only workspaces can be in the RUST_PATH" rule for the purpose of bootstrapping Servo without having to restructure all the directories. This patch gives rustpkg the ability to find sources if a directory in the RUST_PATH directly contains one of rustpkg's "special" files (lib.rs, main.rs, bench.rs, or test.rs), even if it's not a workspace. In this case, it puts the build artifacts in the first workspace in the RUST_PATH.

I'm not sure whether or not it's a good idea to keep this feature in rustpkg permanently. Thus, I added a flag, ```--use-rust-path-hack```, and only enabled it when the flag is set.

src/test/run-pass/rename-directory.rs

@@ -0,0 +1,57 @@
+// Copyright 2013 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.
+
+// This test can't be a unit test in std,
+// because it needs mkdtemp, which is in extra
+
+// xfail-fast
+extern mod extra;
+
+use extra::tempfile::mkdtemp;
+use std::os;
+use std::libc;
+use std::libc::*;
+
+fn rename_directory() {
+    #[fixed_stack_segment];
+    unsafe {
+        static U_RWX: i32 = (S_IRUSR | S_IWUSR | S_IXUSR) as i32;
+
+        let tmpdir = mkdtemp(&os::tmpdir(), "rename_directory").expect("rename_directory failed");
+        let old_path = tmpdir.push_many(["foo", "bar", "baz"]);
+        assert!(os::mkdir_recursive(&old_path, U_RWX));
+        let test_file = &old_path.push("temp.txt");
+
+        /* Write the temp input file */
+        let ostream = do test_file.to_str().with_c_str |fromp| {
+            do "w+b".with_c_str |modebuf| {
+                libc::fopen(fromp, modebuf)
+            }
+        };
+        assert!((ostream as uint != 0u));
+        let s = ~"hello";
+        do "hello".with_c_str |buf| {
+            let write_len = libc::fwrite(buf as *c_void,
+                                         1u as size_t,
+                                         (s.len() + 1u) as size_t,
+                                         ostream);
+            assert_eq!(write_len, (s.len() + 1) as size_t)
+        }
+        assert_eq!(libc::fclose(ostream), (0u as c_int));
+
+        let new_path = tmpdir.push_many(["quux", "blat"]);
+        assert!(os::mkdir_recursive(&new_path, U_RWX));
+        assert!(os::rename_file(&old_path, &new_path.push("newdir")));
+        assert!(os::path_is_dir(&new_path.push("newdir")));
+        assert!(os::path_exists(&new_path.push_many(["newdir", "temp.txt"])));
+    }
+}
+
+fn main() { rename_directory() }