Make CrateStore::crate_name() return an InternedString to avoid unnecessary allocations.

src/librustc/middle/cstore.rs

@@ -42,6 +42,7 @@ use syntax::ast_util::{IdVisitingOperation};
 use syntax::attr;
 use syntax::codemap::Span;
 use syntax::ptr::P;
+use syntax::parse::token::InternedString;
 use rustc_back::target::Target;
 use rustc_front::hir;
 use rustc_front::intravisit::Visitor;
@@ -203,7 +204,7 @@ pub trait CrateStore<'tcx> : Any {
     fn is_explicitly_linked(&self, cnum: ast::CrateNum) -> bool;
     fn is_allocator(&self, cnum: ast::CrateNum) -> bool;
     fn crate_attrs(&self, cnum: ast::CrateNum) -> Vec<ast::Attribute>;
-    fn crate_name(&self, cnum: ast::CrateNum) -> String;
+    fn crate_name(&self, cnum: ast::CrateNum) -> InternedString;
     fn crate_hash(&self, cnum: ast::CrateNum) -> Svh;
     fn crate_struct_field_attrs(&self, cnum: ast::CrateNum)
                                 -> FnvHashMap<DefId, Vec<ast::Attribute>>;
@@ -382,7 +383,7 @@ impl<'tcx> CrateStore<'tcx> for DummyCrateStore {
     fn is_allocator(&self, cnum: ast::CrateNum) -> bool { unimplemented!() }
     fn crate_attrs(&self, cnum: ast::CrateNum) -> Vec<ast::Attribute>
         { unimplemented!() }
-    fn crate_name(&self, cnum: ast::CrateNum) -> String { unimplemented!() }
+    fn crate_name(&self, cnum: ast::CrateNum) -> InternedString { unimplemented!() }
     fn crate_hash(&self, cnum: ast::CrateNum) -> Svh { unimplemented!() }
     fn crate_struct_field_attrs(&self, cnum: ast::CrateNum)
                                 -> FnvHashMap<DefId, Vec<ast::Attribute>>

src/librustc/middle/ty/mod.rs

@@ -2680,14 +2680,15 @@ impl<'tcx> TyCtxt<'tcx> {
     {
         dep_graph::visit_all_items_in_krate(self, dep_node_fn, visitor);
     }
+
     /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
     /// with the name of the crate containing the impl.
-    pub fn span_of_impl(&self, impl_did: DefId) -> Result<Span, String> {
+    pub fn span_of_impl(&self, impl_did: DefId) -> Result<Span, InternedString> {
         if impl_did.is_local() {
             let node_id = self.map.as_local_node_id(impl_did).unwrap();
             Ok(self.map.span(node_id))
         } else {
-            Err(self.sess.cstore.crate_name(impl_did.krate))
+            Err(self.crate_name(impl_did.krate))
         }
     }
 }

src/librustc_metadata/csearch.rs

@@ -334,9 +334,9 @@ impl<'tcx> CrateStore<'tcx> for cstore::CStore {
         decoder::get_crate_attributes(self.get_crate_data(cnum).data())
     }
 
-    fn crate_name(&self, cnum: ast::CrateNum) -> String
+    fn crate_name(&self, cnum: ast::CrateNum) -> token::InternedString
     {
-        self.get_crate_data(cnum).name.clone()
+        token::intern_and_get_ident(&self.get_crate_data(cnum).name[..])
     }
 
     fn crate_hash(&self, cnum: ast::CrateNum) -> Svh

src/librustc_trans/save/mod.rs

@@ -90,7 +90,7 @@ impl<'l, 'tcx: 'l> SaveContext<'l, 'tcx> {
 
         for n in self.tcx.sess.cstore.crates() {
             result.push(CrateData {
-                name: self.tcx.sess.cstore.crate_name(n),
+                name: (&self.tcx.sess.cstore.crate_name(n)[..]).to_owned(),
                 number: n,
             });
         }

src/librustdoc/clean/mod.rs

@@ -241,7 +241,7 @@ impl Clean<ExternalCrate> for CrateNum {
             }
         });
         ExternalCrate {
-            name: cx.sess().cstore.crate_name(self.0),
+            name: (&cx.sess().cstore.crate_name(self.0)[..]).to_owned(),
             attrs: cx.sess().cstore.crate_attrs(self.0).clean(cx),
             primitives: primitives,
         }