Store `crate_disambiguator` as an `InternedString`

We used to use `Name`, but the session outlives the tokenizer, which
means that attempts to read this field after trans has complete
otherwise panic. All reads want an `InternedString` anyhow.

src/librustc/session/mod.rs

@@ -80,7 +80,7 @@ pub struct Session {
     // forms a unique global identifier for the crate. It is used to allow
     // multiple crates with the same name to coexist. See the
     // trans::back::symbol_names module for more information.
-    pub crate_disambiguator: Cell<ast::Name>,
+    pub crate_disambiguator: RefCell<token::InternedString>,
     pub features: RefCell<feature_gate::Features>,
 
     /// The maximum recursion limit for potentially infinitely recursive
@@ -106,6 +106,9 @@ pub struct Session {
 }
 
 impl Session {
+    pub fn local_crate_disambiguator(&self) -> token::InternedString {
+        self.crate_disambiguator.borrow().clone()
+    }
     pub fn struct_span_warn<'a, S: Into<MultiSpan>>(&'a self,
                                                     sp: S,
                                                     msg: &str)
@@ -438,7 +441,7 @@ pub fn build_session_(sopts: config::Options,
         plugin_attributes: RefCell::new(Vec::new()),
         crate_types: RefCell::new(Vec::new()),
         dependency_formats: RefCell::new(FnvHashMap()),
-        crate_disambiguator: Cell::new(token::intern("")),
+        crate_disambiguator: RefCell::new(token::intern("").as_str()),
         features: RefCell::new(feature_gate::Features::new()),
         recursion_limit: Cell::new(64),
         next_node_id: Cell::new(1),

src/librustc/ty/context.rs

@@ -504,7 +504,7 @@ pub fn crate_name(self, cnum: ast::CrateNum) -> token::InternedString {
 
     pub fn crate_disambiguator(self, cnum: ast::CrateNum) -> token::InternedString {
         if cnum == LOCAL_CRATE {
-            self.sess.crate_disambiguator.get().as_str()
+            self.sess.local_crate_disambiguator()
         } else {
             self.sess.cstore.crate_disambiguator(cnum)
         }

src/librustc_driver/driver.rs

@@ -566,7 +566,8 @@ pub fn phase_2_configure_and_expand<'a, F>(sess: &Session,
     });
 
     *sess.crate_types.borrow_mut() = collect_crate_types(sess, &krate.attrs);
-    sess.crate_disambiguator.set(token::intern(&compute_crate_disambiguator(sess)));
+    *sess.crate_disambiguator.borrow_mut() =
+        token::intern(&compute_crate_disambiguator(sess)).as_str();
 
     time(time_passes, "recursion limit", || {
         middle::recursion_limit::update_recursion_limit(sess, &krate);

src/librustc_incremental/calculate_svh.rs

@@ -36,7 +36,7 @@ fn calculate_krate_hash(self) -> Svh {
         // to ensure it is not incorporating implementation artifacts into
         // the hash that are not otherwise visible.)
 
-        let crate_disambiguator = self.sess.crate_disambiguator.get();
+        let crate_disambiguator = self.sess.local_crate_disambiguator();
         let krate = self.map.krate();
 
         // FIXME: this should use SHA1, not SipHash. SipHash is not built to
@@ -47,10 +47,10 @@ fn calculate_krate_hash(self) -> Svh {
         // FIXME(#32753) -- at (*) we `to_le` for endianness, but is
         // this enough, and does it matter anyway?
         "crate_disambiguator".hash(&mut state);
-        crate_disambiguator.as_str().len().to_le().hash(&mut state); // (*)
-        crate_disambiguator.as_str().hash(&mut state);
+        crate_disambiguator.len().to_le().hash(&mut state); // (*)
+        crate_disambiguator.hash(&mut state);
 
-        debug!("crate_disambiguator: {:?}", crate_disambiguator.as_str());
+        debug!("crate_disambiguator: {:?}", crate_disambiguator);
         debug!("state: {:?}", state);
 
         {

src/librustc_metadata/creader.rs

@@ -243,7 +243,7 @@ fn verify_no_symbol_conflicts(&self,
 
         // Check for (potential) conflicts with the local crate
         if self.local_crate_name == crate_name &&
-           self.sess.crate_disambiguator.get().as_str() == disambiguator {
+           self.sess.local_crate_disambiguator() == disambiguator {
             span_fatal!(self.sess, span, E0519,
                         "the current crate is indistinguishable from one of its \
                          dependencies: it has the same crate-name `{}` and was \

src/librustc_metadata/encoder.rs

@@ -1893,7 +1893,7 @@ struct Stats {
     encode_crate_name(rbml_w, &ecx.link_meta.crate_name);
     encode_crate_triple(rbml_w, &ecx.tcx.sess.opts.target_triple);
     encode_hash(rbml_w, &ecx.link_meta.crate_hash);
-    encode_crate_disambiguator(rbml_w, &ecx.tcx.sess.crate_disambiguator.get().as_str());
+    encode_crate_disambiguator(rbml_w, &ecx.tcx.sess.local_crate_disambiguator());
     encode_dylib_dependency_formats(rbml_w, &ecx);
     encode_panic_strategy(rbml_w, &ecx);