Start cleaning up the string interner

src/librustc_driver/driver.rs

@@ -211,7 +211,7 @@ pub fn compile_input(sess: &Session,
             }
 
             // Discard interned strings as they are no longer required.
-            token::get_ident_interner().clear();
+            token::clear_ident_interner();
 
             Ok((outputs, trans))
         })??
@@ -480,7 +480,7 @@ pub fn phase_1_parse_input<'a>(sess: &'a Session,
                                input: &Input)
                                -> PResult<'a, ast::Crate> {
     // These may be left in an incoherent state after a previous compile.
-    // `clear_tables` and `get_ident_interner().clear()` can be used to free
+    // `clear_tables` and `clear_ident_interner` can be used to free
     // memory, but they do not restore the initial state.
     syntax::ext::mtwt::reset_tables();
     token::reset_ident_interner();

src/librustc_metadata/decoder.rs

@@ -442,7 +442,7 @@ pub fn get_adt_def<'a, 'tcx>(cdata: Cmd,
                                   struct_field_family_to_visibility(ff))
         }).chain(reader::tagged_docs(doc, tag_item_unnamed_field).map(|f| {
             let ff = item_family(f);
-            let name = token::get_ident_interner().intern(index.to_string());
+            let name = token::with_ident_interner(|interner| interner.intern(index.to_string()));
             index += 1;
             ty::FieldDefData::new(item_def_id(f, cdata), name,
                                   struct_field_family_to_visibility(ff))
@@ -1147,7 +1147,7 @@ pub fn get_struct_field_names(cdata: Cmd, id: DefIndex) -> Vec<ast::Name> {
     reader::tagged_docs(item, tag_item_field).map(|an_item| {
         item_name(an_item)
     }).chain(reader::tagged_docs(item, tag_item_unnamed_field).map(|_| {
-        let name = token::get_ident_interner().intern(index.to_string());
+        let name = token::with_ident_interner(|interner| interner.intern(index.to_string()));
         index += 1;
         name
     })).collect()

src/librustc_trans/trans_item.rs

@@ -31,7 +31,6 @@ use rustc::ty::subst;
 use std::hash::{Hash, Hasher};
 use syntax::ast::{self, NodeId};
 use syntax::{attr,errors};
-use syntax::parse::token;
 use type_of;
 use glue;
 use abi::{Abi, FnType};
@@ -562,8 +561,8 @@ fn push_type_params<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 
     for projection in projections {
         let projection = projection.skip_binder();
-        let name = token::get_ident_interner().get(projection.projection_ty.item_name);
-        output.push_str(&name[..]);
+        let name = &projection.projection_ty.item_name.as_str();
+        output.push_str(name);
         output.push_str("=");
         push_unique_type_name(tcx, projection.ty, output);
         output.push_str(", ");

src/libsyntax/parse/token.rs

@@ -477,17 +477,20 @@ pub type IdentInterner = Interner;
 // if an interner exists in TLS, return it. Otherwise, prepare a
 // fresh one.
 // FIXME(eddyb) #8726 This should probably use a thread-local reference.
-pub fn get_ident_interner() -> Rc<IdentInterner> {
-    thread_local!(static KEY: Rc<::parse::token::IdentInterner> = {
-        Rc::new(mk_fresh_ident_interner())
+pub fn with_ident_interner<T, F: FnOnce(&IdentInterner) -> T>(f: F) -> T {
+    thread_local!(static KEY: IdentInterner = {
+        mk_fresh_ident_interner()
     });
-    KEY.with(|k| k.clone())
+    KEY.with(f)
 }
 
 /// Reset the ident interner to its initial state.
 pub fn reset_ident_interner() {
-    let interner = get_ident_interner();
-    interner.reset(mk_fresh_ident_interner());
+    with_ident_interner(|interner| interner.reset(mk_fresh_ident_interner()));
+}
+
+pub fn clear_ident_interner() {
+    with_ident_interner(|interner| interner.clear());
 }
 
 /// Represents a string stored in the thread-local interner. Because the
@@ -521,8 +524,7 @@ impl InternedString {
 
     #[inline]
     pub fn new_from_name(name: ast::Name) -> InternedString {
-        let interner = get_ident_interner();
-        InternedString::new_from_rc_str(interner.get(name))
+        with_ident_interner(|interner| InternedString::new_from_rc_str(interner.get(name)))
     }
 }
 
@@ -610,13 +612,13 @@ pub fn intern_and_get_ident(s: &str) -> InternedString {
 /// Maps a string to its interned representation.
 #[inline]
 pub fn intern(s: &str) -> ast::Name {
-    get_ident_interner().intern(s)
+    with_ident_interner(|interner| interner.intern(s))
 }
 
 /// gensym's a new usize, using the current interner.
 #[inline]
 pub fn gensym(s: &str) -> ast::Name {
-    get_ident_interner().gensym(s)
+    with_ident_interner(|interner| interner.gensym(s))
 }
 
 /// Maps a string to an identifier with an empty syntax context.
@@ -635,8 +637,7 @@ pub fn gensym_ident(s: &str) -> ast::Ident {
 // note that this guarantees that str_ptr_eq(ident_to_string(src),interner_get(fresh_name(src)));
 // that is, that the new name and the old one are connected to ptr_eq strings.
 pub fn fresh_name(src: ast::Ident) -> ast::Name {
-    let interner = get_ident_interner();
-    interner.gensym_copy(src.name)
+    with_ident_interner(|interner| interner.gensym_copy(src.name))
     // following: debug version. Could work in final except that it's incompatible with
     // good error messages and uses of struct names in ambiguous could-be-binding
     // locations. Also definitely destroys the guarantee given above about ptr_eq.