syntax: add a local_data_key macro that creates a key for access to the TLS.

This allows the internal implementation details of the TLS keys to be
changed without requiring the update of all the users. (Or, applying
changes that have to be applied for the keys to work correctly, e.g.
forcing LLVM to not merge these constants.)

1 files changed, 11 insertions, 0 deletions

diff --git a/src/libsyntax/ext/expand.rs b/src/libsyntax/ext/expand.rs
index 1547446957e..49eb9f12212 100644
--- a/src/libsyntax/ext/expand.rs
+++ b/src/libsyntax/ext/expand.rs
@@ -957,6 +957,17 @@ pub fn std_macros() -> @str {
             println(fmt!($($arg),+))
         )
     )
+
+    // NOTE: use this after a snapshot lands to abstract the details
+    // of the TLS interface.
+    macro_rules! local_data_key (
+        ($name:ident: $ty:ty) => (
+            static $name: ::std::local_data::Key<$ty> = &::std::local_data::Key;
+        );
+        (pub $name:ident: $ty:ty) => (
+            pub static $name: ::std::local_data::Key<$ty> = &::std::local_data::Key;
+        )
+    )
 }";
 }