1 files changed, 30 insertions, 0 deletions
diff --git a/src/libsyntax/lib.rs b/src/libsyntax/lib.rs
index 50e94e5cba7..5f58b3bc3a0 100644
--- a/src/libsyntax/lib.rs
+++ b/src/libsyntax/lib.rs
@@ -39,9 +39,12 @@ extern crate std_unicode;
 pub extern crate rustc_errors as errors;
 extern crate syntax_pos;
 extern crate rustc_data_structures;
+#[macro_use] extern crate scoped_tls;
 
 extern crate serialize as rustc_serialize; // used by deriving
 
+use rustc_data_structures::sync::Lock;
+
 // A variant of 'try!' that panics on an Err. This is used as a crutch on the
 // way towards a non-panic!-prone parser. It should be used for fatal parsing
 // errors; eventually we plan to convert all code using panictry to just use
@@ -72,6 +75,33 @@ macro_rules! unwrap_or {
     }
 }
 
+struct Globals {
+    used_attrs: Lock<Vec<u64>>,
+    known_attrs: Lock<Vec<u64>>,
+    syntax_pos_globals: syntax_pos::Globals,
+}
+
+impl Globals {
+    fn new() -> Globals {
+        Globals {
+            used_attrs: Lock::new(Vec::new()),
+            known_attrs: Lock::new(Vec::new()),
+            syntax_pos_globals: syntax_pos::Globals::new(),
+        }
+    }
+}
+
+pub fn with_globals<F, R>(f: F) -> R
+    where F: FnOnce() -> R
+{
+    let globals = Globals::new();
+    GLOBALS.set(&globals, || {
+        syntax_pos::GLOBALS.set(&globals.syntax_pos_globals, f)
+    })
+}
+
+scoped_thread_local!(static GLOBALS: Globals);
+
 #[macro_use]
 pub mod diagnostics {
     #[macro_use]