std: Add a new top-level thread_local module

This commit removes the `std::local_data` module in favor of a new
`std::thread_local` module providing thread local storage. The module provides
two variants of TLS: one which owns its contents and one which is based on
scoped references. Each implementation has pros and cons listed in the
documentation.

Both flavors have accessors through a function called `with` which yield a
reference to a closure provided. Both flavors also panic if a reference cannot
be yielded and provide a function to test whether an access would panic or not.
This is an implementation of [RFC 461][rfc] and full details can be found in
that RFC.

This is a breaking change due to the removal of the `std::local_data` module.
All users can migrate to the new thread local system like so:

    thread_local!(static FOO: Rc<RefCell<Option<T>>> = Rc::new(RefCell::new(None)))

The old `local_data` module inherently contained the `Rc<RefCell<Option<T>>>` as
an implementation detail which must now be explicitly stated by users.

[rfc]: https://github.com/rust-lang/rfcs/pull/461
[breaking-change]

1 files changed, 16 insertions, 15 deletions

diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index b35c49efdd8..77da727e94d 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -170,7 +170,6 @@ pub use core_collections::string;
 pub use core_collections::vec;
 
 pub use rustrt::c_str;
-pub use rustrt::local_data;
 
 pub use unicode::char;
 
@@ -209,17 +208,25 @@ pub mod prelude;
 #[path = "num/f32.rs"]   pub mod f32;
 #[path = "num/f64.rs"]   pub mod f64;
 
-pub mod rand;
-
 pub mod ascii;
 
-pub mod time;
-
 /* Common traits */
 
 pub mod error;
 pub mod num;
 
+/* Runtime and platform support */
+
+pub mod thread_local;
+pub mod c_vec;
+pub mod dynamic_lib;
+pub mod fmt;
+pub mod io;
+pub mod os;
+pub mod path;
+pub mod rand;
+pub mod time;
+
 /* Common data structures */
 
 pub mod collections;
@@ -230,15 +237,6 @@ pub mod hash;
 pub mod task;
 pub mod sync;
 
-/* Runtime and platform support */
-
-pub mod c_vec;
-pub mod dynamic_lib;
-pub mod os;
-pub mod io;
-pub mod path;
-pub mod fmt;
-
 #[cfg(unix)]
 #[path = "sys/unix/mod.rs"] mod sys;
 #[cfg(windows)]
@@ -263,10 +261,12 @@ mod std {
     pub use error; // used for try!()
     pub use fmt; // used for any formatting strings
     pub use io; // used for println!()
-    pub use local_data; // used for local_data_key!()
     pub use option; // used for bitflags!{}
     pub use rt; // used for panic!()
     pub use vec; // used for vec![]
+    pub use cell; // used for tls!
+    pub use thread_local; // used for thread_local!
+    pub use kinds; // used for tls!
 
     // The test runner calls ::std::os::args() but really wants realstd
     #[cfg(test)] pub use realstd::os as os;
@@ -276,4 +276,5 @@ mod std {
     pub use slice;
 
     pub use boxed; // used for vec![]
+
 }