Use 128 bit instead of Symbol for crate disambiguator

src/librustc/hir/map/collector.rs

@@ -11,6 +11,7 @@
 use super::*;
 
 use dep_graph::{DepGraph, DepKind, DepNodeIndex};
+use ich::Fingerprint;
 use hir::intravisit::{Visitor, NestedVisitorMap};
 use std::iter::repeat;
 use syntax::ast::{NodeId, CRATE_NODE_ID};
@@ -118,7 +119,7 @@ impl<'a, 'hir> NodeCollector<'a, 'hir> {
     }
 
     pub(super) fn finalize_and_compute_crate_hash(self,
-                                                  crate_disambiguator: &str)
+                                                  crate_disambiguator: &Fingerprint)
                                                   -> Vec<MapEntry<'hir>> {
         let mut node_hashes: Vec<_> = self
             .hir_body_nodes

src/librustc/hir/map/mod.rs

@@ -1014,7 +1014,7 @@ pub fn map_crate<'hir>(sess: &::session::Session,
                                                 hcx);
         intravisit::walk_crate(&mut collector, &forest.krate);
 
-        let crate_disambiguator = sess.local_crate_disambiguator().as_str();
+        let crate_disambiguator = sess.local_crate_disambiguator();
         collector.finalize_and_compute_crate_hash(&crate_disambiguator)
     };
 

src/librustc/middle/cstore.rs

@@ -267,7 +267,7 @@ pub trait CrateStore {
     fn export_macros_untracked(&self, cnum: CrateNum);
     fn dep_kind_untracked(&self, cnum: CrateNum) -> DepKind;
     fn crate_name_untracked(&self, cnum: CrateNum) -> Symbol;
-    fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> Symbol;
+    fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> ich::Fingerprint;
     fn crate_hash_untracked(&self, cnum: CrateNum) -> Svh;
     fn struct_field_names_untracked(&self, def: DefId) -> Vec<ast::Name>;
     fn item_children_untracked(&self, did: DefId, sess: &Session) -> Vec<def::Export>;
@@ -338,7 +338,7 @@ impl CrateStore for DummyCrateStore {
     fn dep_kind_untracked(&self, cnum: CrateNum) -> DepKind { bug!("is_explicitly_linked") }
     fn export_macros_untracked(&self, cnum: CrateNum) { bug!("export_macros") }
     fn crate_name_untracked(&self, cnum: CrateNum) -> Symbol { bug!("crate_name") }
-    fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> Symbol {
+    fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> ich::Fingerprint {
         bug!("crate_disambiguator")
     }
     fn crate_hash_untracked(&self, cnum: CrateNum) -> Svh { bug!("crate_hash") }

src/librustc/session/mod.rs

@@ -12,6 +12,7 @@ pub use self::code_stats::{CodeStats, DataTypeKind, FieldInfo};
 pub use self::code_stats::{SizeKind, TypeSizeInfo, VariantInfo};
 
 use hir::def_id::{CrateNum, DefIndex};
+use ich::Fingerprint;
 
 use lint;
 use middle::allocator::AllocatorKind;
@@ -29,7 +30,6 @@ use syntax::json::JsonEmitter;
 use syntax::feature_gate;
 use syntax::parse;
 use syntax::parse::ParseSess;
-use syntax::symbol::Symbol;
 use syntax::{ast, codemap};
 use syntax::feature_gate::AttributeType;
 use syntax_pos::{Span, MultiSpan};
@@ -88,7 +88,7 @@ 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: RefCell<Option<Symbol>>,
+    pub crate_disambiguator: RefCell<Option<Fingerprint>>,
     pub features: RefCell<feature_gate::Features>,
 
     /// The maximum recursion limit for potentially infinitely recursive
@@ -165,7 +165,7 @@ enum DiagnosticBuilderMethod {
 }
 
 impl Session {
-    pub fn local_crate_disambiguator(&self) -> Symbol {
+    pub fn local_crate_disambiguator(&self) -> Fingerprint {
         match *self.crate_disambiguator.borrow() {
             Some(sym) => sym,
             None => bug!("accessing disambiguator before initialization"),
@@ -471,14 +471,17 @@ impl Session {
 
     /// Returns the symbol name for the registrar function,
     /// given the crate Svh and the function DefIndex.
-    pub fn generate_plugin_registrar_symbol(&self, disambiguator: Symbol, index: DefIndex)
+    pub fn generate_plugin_registrar_symbol(&self, disambiguator: Fingerprint,
+                                            index: DefIndex)
                                             -> String {
-        format!("__rustc_plugin_registrar__{}_{}", disambiguator, index.as_usize())
+        format!("__rustc_plugin_registrar__{}_{}", disambiguator.to_hex(),
+                                                   index.as_usize())
     }
 
-    pub fn generate_derive_registrar_symbol(&self, disambiguator: Symbol, index: DefIndex)
+    pub fn generate_derive_registrar_symbol(&self, disambiguator: Fingerprint, index: DefIndex)
                                             -> String {
-        format!("__rustc_derive_registrar__{}_{}", disambiguator, index.as_usize())
+        format!("__rustc_derive_registrar__{}_{}", disambiguator.to_hex(),
+                                                   index.as_usize())
     }
 
     pub fn sysroot<'a>(&'a self) -> &'a Path {

src/librustc/ty/context.rs

@@ -1251,7 +1251,7 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
                 crate_name,
                 // Don't print the whole crate disambiguator. That's just
                 // annoying in debug output.
-                &(crate_disambiguator.as_str())[..4],
+                &(crate_disambiguator.to_hex())[..4],
                 self.def_path(def_id).to_string_no_crate())
     }
 

src/librustc/ty/maps/mod.rs

@@ -10,6 +10,7 @@
 
 use dep_graph::{DepConstructor, DepNode};
 use errors::DiagnosticBuilder;
+use ich::Fingerprint;
 use hir::def_id::{CrateNum, DefId, DefIndex};
 use hir::def::{Def, Export};
 use hir::{self, TraitCandidate, ItemLocalId};
@@ -283,7 +284,7 @@ define_maps! { <'tcx>
     [] fn native_libraries: NativeLibraries(CrateNum) -> Rc<Vec<NativeLibrary>>,
     [] fn plugin_registrar_fn: PluginRegistrarFn(CrateNum) -> Option<DefId>,
     [] fn derive_registrar_fn: DeriveRegistrarFn(CrateNum) -> Option<DefId>,
-    [] fn crate_disambiguator: CrateDisambiguator(CrateNum) -> Symbol,
+    [] fn crate_disambiguator: CrateDisambiguator(CrateNum) -> Fingerprint,
     [] fn crate_hash: CrateHash(CrateNum) -> Svh,
     [] fn original_crate_name: OriginalCrateName(CrateNum) -> Symbol,
 

src/librustc/ty/mod.rs

@@ -19,7 +19,7 @@ use hir::{map as hir_map, FreevarMap, TraitMap};
 use hir::def::{Def, CtorKind, ExportMap};
 use hir::def_id::{CrateNum, DefId, DefIndex, CRATE_DEF_INDEX, LOCAL_CRATE};
 use hir::map::DefPathData;
-use ich::StableHashingContext;
+use ich::{Fingerprint, StableHashingContext};
 use middle::const_val::ConstVal;
 use middle::lang_items::{FnTraitLangItem, FnMutTraitLangItem, FnOnceTraitLangItem};
 use middle::privacy::AccessLevels;
@@ -2562,7 +2562,7 @@ fn param_env<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 }
 
 fn crate_disambiguator<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
-                                 crate_num: CrateNum) -> Symbol {
+                                 crate_num: CrateNum) -> Fingerprint {
     assert_eq!(crate_num, LOCAL_CRATE);
     tcx.sess.local_crate_disambiguator()
 }

src/librustc_driver/driver.rs

@@ -58,7 +58,6 @@ use syntax::{ast, diagnostics, visit};
 use syntax::attr;
 use syntax::ext::base::ExtCtxt;
 use syntax::parse::{self, PResult};
-use syntax::symbol::Symbol;
 use syntax::util::node_count::NodeCounter;
 use syntax;
 use syntax_ext;
@@ -633,12 +632,12 @@ pub fn phase_2_configure_and_expand<F>(sess: &Session,
 
     *sess.crate_types.borrow_mut() = collect_crate_types(sess, &krate.attrs);
 
-    let disambiguator = Symbol::intern(&compute_crate_disambiguator(sess));
+    let disambiguator = compute_crate_disambiguator(sess);
     *sess.crate_disambiguator.borrow_mut() = Some(disambiguator);
     rustc_incremental::prepare_session_directory(
         sess,
         &crate_name,
-        &disambiguator.as_str(),
+        &disambiguator,
     );
 
     let dep_graph = if sess.opts.build_dep_graph() {
@@ -1312,16 +1311,13 @@ pub fn collect_crate_types(session: &Session, attrs: &[ast::Attribute]) -> Vec<c
         .collect()
 }
 
-pub fn compute_crate_disambiguator(session: &Session) -> String {
+pub fn compute_crate_disambiguator(session: &Session) -> Fingerprint {
     use std::hash::Hasher;
 
     // The crate_disambiguator is a 128 bit hash. The disambiguator is fed
     // into various other hashes quite a bit (symbol hashes, incr. comp. hashes,
     // debuginfo type IDs, etc), so we don't want it to be too wide. 128 bits
     // should still be safe enough to avoid collisions in practice.
-    // FIXME(mw): It seems that the crate_disambiguator is used everywhere as
-    //            a hex-string instead of raw bytes. We should really use the
-    //            smaller representation.
     let mut hasher = StableHasher::<Fingerprint>::new();
 
     let mut metadata = session.opts.cg.metadata.clone();
@@ -1340,11 +1336,13 @@ pub fn compute_crate_disambiguator(session: &Session) -> String {
         hasher.write(s.as_bytes());
     }
 
-    // If this is an executable, add a special suffix, so that we don't get
-    // symbol conflicts when linking against a library of the same name.
+    // Also incorporate crate type, so that we don't get symbol conflicts when
+    // linking against a library of the same name, if this is an executable.
     let is_exe = session.crate_types.borrow().contains(&config::CrateTypeExecutable);
+    hasher.write(if is_exe { b"exe" } else { b"lib" });
+
+    hasher.finish()
 
-    format!("{}{}", hasher.finish().to_hex(), if is_exe { "-exe" } else {""})
 }
 
 pub fn build_output_filenames(input: &Input,

src/librustc_incremental/persist/fs.rs

@@ -114,6 +114,7 @@
 //! unsupported file system and emit a warning in that case. This is not yet
 //! implemented.
 
+use rustc::ich::Fingerprint;
 use rustc::hir::svh::Svh;
 use rustc::session::Session;
 use rustc::util::fs as fs_util;
@@ -188,7 +189,7 @@ pub fn in_incr_comp_dir(incr_comp_session_dir: &Path, file_name: &str) -> PathBu
 /// The garbage collection will take care of it.
 pub fn prepare_session_directory(sess: &Session,
                                  crate_name: &str,
-                                 crate_disambiguator: &str) {
+                                 crate_disambiguator: &Fingerprint) {
     if sess.opts.incremental.is_none() {
         return
     }
@@ -614,21 +615,15 @@ fn string_to_timestamp(s: &str) -> Result<SystemTime, ()> {
 
 fn crate_path(sess: &Session,
               crate_name: &str,
-              crate_disambiguator: &str)
+              crate_disambiguator: &Fingerprint)
               -> PathBuf {
-    use std::hash::{Hasher, Hash};
-    use std::collections::hash_map::DefaultHasher;
 
     let incr_dir = sess.opts.incremental.as_ref().unwrap().clone();
 
-    // The full crate disambiguator is really long. A hash of it should be
-    // sufficient.
-    let mut hasher = DefaultHasher::new();
-    crate_disambiguator.hash(&mut hasher);
-
+    let crate_disambiguator = crate_disambiguator.to_smaller_hash();
     let crate_name = format!("{}-{}",
                              crate_name,
-                             base_n::encode(hasher.finish(), INT_ENCODE_BASE));
+                             base_n::encode(crate_disambiguator, INT_ENCODE_BASE));
     incr_dir.join(crate_name)
 }
 

src/librustc_metadata/creader.rs

@@ -15,6 +15,7 @@ use locator::{self, CratePaths};
 use native_libs::relevant_lib;
 use schema::CrateRoot;
 
+use rustc::ich::Fingerprint;
 use rustc::hir::def_id::{CrateNum, DefIndex, CRATE_DEF_INDEX};
 use rustc::hir::svh::Svh;
 use rustc::middle::allocator::AllocatorKind;
@@ -626,7 +627,7 @@ impl<'a> CrateLoader<'a> {
     pub fn find_plugin_registrar(&mut self,
                                  span: Span,
                                  name: &str)
-                                 -> Option<(PathBuf, Symbol, DefIndex)> {
+                                 -> Option<(PathBuf, Fingerprint, DefIndex)> {
         let ekrate = self.read_extension_crate(span, &ExternCrateInfo {
              name: Symbol::intern(name),
              ident: Symbol::intern(name),

src/librustc_metadata/cstore.rs

@@ -13,6 +13,7 @@
 
 use schema;
 
+use rustc::ich::Fingerprint;
 use rustc::hir::def_id::{CRATE_DEF_INDEX, CrateNum, DefIndex};
 use rustc::hir::map::definitions::DefPathTable;
 use rustc::hir::svh::Svh;
@@ -171,7 +172,7 @@ impl CrateMetadata {
     pub fn hash(&self) -> Svh {
         self.root.hash
     }
-    pub fn disambiguator(&self) -> Symbol {
+    pub fn disambiguator(&self) -> Fingerprint {
         self.root.disambiguator
     }
 

src/librustc_metadata/cstore_impl.rs

@@ -20,6 +20,7 @@ use rustc::middle::cstore::{CrateStore, DepKind,
                             LoadedMacro, EncodedMetadata,
                             EncodedMetadataHashes, NativeLibraryKind};
 use rustc::middle::stability::DeprecationEntry;
+use rustc::ich::Fingerprint;
 use rustc::hir::def;
 use rustc::session::Session;
 use rustc::ty::{self, TyCtxt};
@@ -384,7 +385,7 @@ impl CrateStore for cstore::CStore {
         self.get_crate_data(cnum).name
     }
 
-    fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> Symbol
+    fn crate_disambiguator_untracked(&self, cnum: CrateNum) -> Fingerprint
     {
         self.get_crate_data(cnum).disambiguator()
     }

src/librustc_metadata/schema.rs

@@ -14,7 +14,7 @@ use index;
 use rustc::hir;
 use rustc::hir::def::{self, CtorKind};
 use rustc::hir::def_id::{DefIndex, DefId, CrateNum};
-use rustc::ich::StableHashingContext;
+use rustc::ich::{Fingerprint, StableHashingContext};
 use rustc::middle::cstore::{DepKind, LinkagePreference, NativeLibrary};
 use rustc::middle::lang_items;
 use rustc::mir;
@@ -191,7 +191,7 @@ pub struct CrateRoot {
     pub name: Symbol,
     pub triple: String,
     pub hash: hir::svh::Svh,
-    pub disambiguator: Symbol,
+    pub disambiguator: Fingerprint,
     pub panic_strategy: PanicStrategy,
     pub has_global_allocator: bool,
     pub has_default_lib_allocator: bool,

src/librustc_resolve/lib.rs

@@ -1417,7 +1417,7 @@ impl<'a> Resolver<'a> {
 
         let mut definitions = Definitions::new();
         DefCollector::new(&mut definitions, Mark::root())
-            .collect_root(crate_name, &session.local_crate_disambiguator().as_str());
+            .collect_root(crate_name, &session.local_crate_disambiguator().to_hex());
 
         let mut invocations = FxHashMap();
         invocations.insert(Mark::root(),

src/librustc_trans/back/symbol_export.rs

@@ -34,7 +34,7 @@ pub fn threshold(tcx: TyCtxt) -> SymbolExportLevel {
 pub fn metadata_symbol_name(tcx: TyCtxt) -> String {
     format!("rust_metadata_{}_{}",
             tcx.crate_name(LOCAL_CRATE),
-            tcx.crate_disambiguator(LOCAL_CRATE))
+            tcx.crate_disambiguator(LOCAL_CRATE).to_hex())
 }
 
 fn crate_export_threshold(crate_type: config::CrateType) -> SymbolExportLevel {

src/librustc_trans/back/symbol_names.rs

@@ -220,7 +220,7 @@ fn get_symbol_hash<'a, 'tcx>(tcx: TyCtxt<'a, 'tcx, 'tcx>,
 
         if avoid_cross_crate_conflicts {
             hasher.hash(tcx.crate_name.as_str());
-            hasher.hash(tcx.sess.local_crate_disambiguator().as_str());
+            hasher.hash(tcx.sess.local_crate_disambiguator());
         }
     });