core::rt: Add Local trait

src/libcore/rt/local.rs

+// 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.
+
+pub trait Local {
+    fn put_local(value: ~Self);
+    fn take_local() -> ~Self;
+    fn exists() -> bool;
+    fn borrow(f: &fn(&mut Self));
+    fn unsafe_borrow() -> *mut Self;
+}

src/libcore/rt/mod.rs

@@ -81,6 +81,10 @@
 #[path = "uv/mod.rs"]
 pub mod uv;
 
+/// The Local trait for types that are accessible via thread-local
+/// or task-local storage.
+pub mod local;
+
 // FIXME #5248: The import in `sched` doesn't resolve unless this is pub!
 /// Bindings to pthread/windows thread-local storage.
 pub mod thread_local_storage;